Charly Mayeux,1Peeter Burk*,1 Jean-Francois Gal,2Ivarikaljurand*,1Ilmar Koppel,1 Ivo

Supplementary Information

Gas-phase Lithium Cation Basicity: revisiting the high basicity range by experiment and theory

Charly Mayeux,1Peeter Burk*,1 Jean-Francois Gal,2IvariKaljurand*,1Ilmar Koppel,1 Ivo Leito,1Lauri Sikk1

[1] Institute of Chemistry, University of Tartu, Estonia

[2] Institute of Chemistry, University Nice Sophia Antipolis, France

1- Equilibrium measurements2

2- G2(MP2) calculations3

3- Kinetic model for Li+ exchange

a- Equilibrium measurements in the presence of Li+-bound dimers5

b- Equilibrium measurements in the presence of a third ligand10

4- Kinetic method15

5- TCIDmeasurements16

6- Sensitivity factors of Bayard-Alpert ionization gauges19

7- MALDI matrix preparation20

8- Theoretical calculations21

1. Equilibrium measurements

The relative Lithium CationBasicity (LiCB) is calculated by means of

(S1)

wherePBAis thetotal pressure reading of theBayard-Alpert gauge, with subscripts: BL for the baseline pressure (or background), L1for L1 added (pressure BL+L1), and L2for L2added (pressure BL+L1+L2). Therefore, pressures in equation S1 represent the total pressure readings before and after L1 and L2 additions.

Note that in the main text, PBALrefers to the differences in readings, i.e.the individual pressure (corrected) readings for L1 and L2.

Uncertainties of equation 6 in the main document can be estimated by means of propagation of uncertainty and the partial derivative method (using standard deviations).

(S2)

The contribution to uncertainties due to the gas constant R (8.314 462175 ± 0.00000091 J mol-1 K-1) [[1]] can be neglected (< 10-5 J/mol).

1. G2(MP2) calculations

Table S1.Previous experimental LiCB values from equilibrium constant measurements at 373 K (Laurence C.; Gal, J.-F.Lewis Basicity and Affinity Scales: Data and Measurement. Wiley, Chichester, UK, 2010, Chap. 6)and calculated at G2(MP2) levelLiCA and LiCB at 373 K.

Ligands / LiCB (exp) / LiCB / LiCA / rS / Deviation a
kJ mol-1 / kJ mol-1 / kJ mol-1 / J mol-1 K-1 / kJ mol-1
Chlorobenzene / 99.4 / 93.2 / 133.7 / 108.4 / -6.2
Bromobenzene / 101.8 / 94.6 / 134.8 / 107.8 / -7.2
Water / 103.6 / 102.7 / 136.0 / 89.3 / -0.9
Formaldehyde / 106.5 / 108.7 / 142.9 / 91.8 / 2.2
Thiophenol / 112.3 / 110.6 / 152.3 / 111.7 / -1.7
Phenol / 117.8 / 113.3 / 154.6 / 110.5 / -4.5
Methanol / 119.5 / 114.2 / 149.6 / 95.0 / -5.3
Dimethyl ether / 123.6 / 118.7 / 154.0 / 94.6 / -4.9
Ammonia / 126.4 / 121.0 / 155.3 / 91.8 / -5.4
Naphthalene / 127.9 / 121.3 / 161.7 / 108.2 / -6.6
Methylamine / 131.2 / 125.4 / 163.3 / 101.7 / -5.8
Ethanol / 127.4 / 125.6 / 161.4 / 96.2 / -1.8
Trimethylamine / 134.1 / 126.9 / 165.1 / 102.5 / -7.2
Dimethylamine / 134.5 / 127.6 / 165.7 / 102.0 / -6.9
Acetaldehyde / 133.3 / 131.1 / 165.6 / 92.5 / -2.2
2-Propanol / 135.4 / 132.5 / 168.5 / 96.5 / -2.9
Propionaldehyde / 137.4 / 134.7 / 169.4 / 93.2 / -2.7
Tetrahydrofuran / 137.2 / 135.4 / 173.7 / 102.7 / -1.8
2-Butanol / 139.5 / 138.4 / 176.8 / 103.0 / -1.1
Diethyl ether / 139.7 / 138.7 / 174.2 / 95.0 / -1.0
Pyrazole / 140.8 / 139.7 / 176.7 / 99.2 / -1.1
Ethyl formate / 142.1 / 140.1 / 171.1 / 83.0 / -2.0
Trifluoroacetamide / 141.9 / 140.5 / 181.2 / 109.1 / -1.4
2-Methyltetrahydrofuran / 143.7 / 140.5 / 181.2 / 109.1 / -3.2
Acetonitrile / 142.1 / 141.1 / 177.1 / 96.5 / -1.0
Pyridine / 146.7 / 144.4 / 181.7 / 100.1 / -2.3
Acetone / 147.9 / 146.2 / 182.7 / 97.9 / -1.7
Methyl propionate / 151.9 / 150.6 / 185.6 / 93.9 / -1.3
Diisopropyl ether / 148.7 / 151.5 / 186.4 / 93.6 / 2.8
Methyl acetate / 147.4 / 152.6 / 182.0 / 78.7 / 5.2
Methyl benzoate / 154.8 / 155.4 / 189.7 / 92.1 / 0.6
Ethyl acetate / 150.8 / 156.6 / 185.6 / 77.8 / 5.8
Methyl cyclopropyl ketone / 156.7 / 156.7 / 192.1 / 94.7 / 0.0
2,4-Dimethylpentan-3-one / 157.1 / 158.1 / 193.6 / 95.2 / 1.0
Formamide / 157.4 / 158.9 / 199.6 / 109.3 / 1.5
1,3,5-Trimethylpyrazole / 160.6 / 164.1 / 200.7 / 98.0 / 3.5
Dimethyl sulfone / 155.4 / 165.2 / 199.2 / 90.9 / 9.8
Acetamide / 166.6 / 173.5 / 214.5 / 109.6 / 6.9
N-Methylformamide / 165.9 / 173.9 / 212.3 / 102.9 / 8.0
1-Methylimidazole / 167.8 / 178.4 / 217.1 / 103.7 / 10.6
Pyridazine / 173.3 / 182.2 / 221.8 / 106.0 / 8.9
1,2-Dimethylimidazole / 174.5 / 184.2 / 222.4 / 102.2 / 9.7
N,N-Dimethylformamide / 173.7 / 185.2 / 222.1 / 98.9 / 11.5
4-Dimethylaminopyridine / 175.9 / 186.0 / 223.9 / 101.7 / 10.1
Diphenylsulfone / 169.5 / 187.6 / 224.7 / 99.3 / 18.1
Dimethyl sulfoxide / 175.1 / 189.7 / 225.0 / 94.4 / 14.6
N,N-Dimethylacetamide / 179.1 / 195.2 / 231.5 / 97.3 / 16.1
Dimethyl methyl phosphonate / 183.7 / 199.2 / 240.1 / 109.6 / 15.5
Trimethyl phosphate / 183.1 / 199.3 / 234.8 / 95.1 / 16.2
Tetramethylguanidine / 177.5 / 200.8 / 238.7 / 101.7 / 23.3
1,2-Dimethoxyethane / 187.9 / 205.8 / 249.9 / 118.2 / 17.9
Acetylacetone / 180.5 / 210.0 / 252.3 / 113.4 / 29.5

aDifference between calculated LiCB(373 K) and experimental LiCB(373 K).

1. Kinetic modelfor Li+ exchange
2. Equilibrium measurements in the presence of Li+-bound dimers

The rates of reaction and equation of equilibrium reactions from scheme 2 in the main text are

(S3)

(S4)

(S5)

(S6)

(S7)

(S8)

It should be noted that k7, k8, k9 and k10 can be expressedas a function of k1 or k2 if we consider that the transition state of reaction 2 (in the main text) is similar to the one leading to the lithium cation bound heterodimers L1L2Li+.

The Laplace transforms of X (ℒ{X(t)}) and X at starting time (t = 0) are written LX and respectively. As a result, the Laplace transform of equations S3-S8 are respectively

(S9)

(S10)

(S11)

(S12)

(S13)

(S14)

The next step consists in solving a linear system of 6 equations (Equations S9-S14) with 6 unknowns (LX).

Step 1:Solve equations S11-S14 in function of , , and respectively

(S15)

(S16)

(S17)

(S18)

Step 2: Substitute and from equations S16 and S18 respectively in equation S10 and then solve equation thus obtained in function of .

(S19)

Step 3:Substitute, and from equations S15, S17 and S19 respectively in equation S9 and then solve equation thus obtained in function of .

(S20)

or

(S20’)

with

Step 4: Substitute from equation S20 in equation S19.

(S21)

It is necessary to expand, factorize and then simplify expression to get the equation S21, by means of

with , , , , ,

Step 5: Substitute from equation S20’ in equation S15. Equation thus obtained is factoredaccording to

with ,,,

and

with ,,

thus

(S22)

Step 6: Substitute from equation S21 in equation S16.

Step 7: Substitute from equation S20’ in equation S17, andfactorize according to

with ,,,

and

with ,, ,

,

thus

(S23)

Step 8: Substitute from equation S21 in equation S18.

(S24)

The Laplace transforms of X are given below with some simplifications.

(S25)

(S26)

(S27)

(S28)

(S29)

(S30)

The Laplace transforms are the ratio of two polynomials for which the degree of the numerator (degree 4 and 5) is lower than for the denominator (degree 6). Thus, the Heaviside expansion theorem[[2]] can be used to obtain the inverse Laplace transform, through the general formula

(S31)

in which siare the roots of polynomials Q(s).

Therefore, the activity of ions in the gas phase can be expressed as a sum of exponentials. Furthermore, all constants in equations S25-S30 (e.g.an, bn, etc. and A, B, etc.) are sumsand products of rate constants. Thus, these values are always positive. As a consequence si is negative or null. From equations S25-S30, it is obvious that one of the roots is s = 0. Thus, equations S31 becomes

(S32)

and because roots are negative, we obtain

(S33)

At equilibrium, equation S33 becomes

(S34)

Expressions of fX are

(S35)

(S36)

(S37)

(S38)

(S39)

(S40)

It is evident that the activity ratio between the Li+-adducts is

(S41)

thus

(S42)

As a result, the standard equation works as long as the reaction time allows for equilibrium to be established. Therefore, equilibrium measurements can be performed regardless of the formation of Li+-bound dimers.It should be also noted that the isolation step is not required to obtain a constant value of the ratio between the both Li+-adducts.

In the same manner, the pairs of Li+-bound dimers can also reach a constant value according to equations S37-40, leading to

(S43)

(S44)

(S45)

This is illustrated by Figure S1.

(a)(b)

Figure S1. Plots of the ratio of Li+-dimers vs. reaction time t (s).

1. Equilibrium measurements in the presence of a third ligand

The reactions equations are given equations S46-S48.

L1Li+ + L2 L1 + L2Li+(S46)

L1Li+ + L3 L1 + L3Li+(S47)

L2Li+ + L3 L2 + L3Li+(S48)

The rates of reaction are

(S49)

(S50)

(S51)

The Laplace transforms of equations S49-S51are

(S52)

(S53)

(S54)

The next steps consist in solving a linear system of 3 equations with 3 unknowns (LX).

Step 1: Solve equation S52in function of

(S55)

Step 2: Substitute from equation S55in equation S53and rewrite the equation as a function of .

(S56)

Step 3: Substitute from equation S56in equation S55’.

(S55’)

then

(S57)

Step 4: Substitute and from equations S56and S57respectively in equation S54and then write equation as a function of .

(S58)

Step 5: Substitute from equation S58in equation S57’.

(S57’)

then

(S59)

It is necessary to expand, simplify and then factorize expression to obtain equation S16:

.and

with , , , ,, and .

Step 6:Substitute from equation S58in equation S57.

(S60)

It is necessary to expand, simplify and then factorize expression to obtain equationS60:

.

and

with , , ,,, ,, and .

The Heaviside expansion theorem is utilized to obtain the inverseLaplace transform. As si are negative or null, at equilibrium, equation S58, S59and S60becomes

(S61)

(S62)

(S63)

The ratio between the Li+-adducts are

(S64)

(S65)

(S66)

The forward and reverse reactions described by equations S46-S48follow first order rate laws. Then we can derive the relationship between rate constants and equilibrium constants.

, and

thus

(S67)

If we substitute from equations S67, the activity ratio between the Li+ adducts becomes

(S68)

(S69)

(S70)

An illustration of this kinetic model is given in Figures S2 and S3, by simulating the apparent relative basicity as afunction of time. An experimental measurement illustrating the effect of an impurity is shown Figure S4.

(a)(b)

(c)

Figure S2.Illustration of the kinetic model by means of plots of RTln[(IL2LiPL1)/(IL1LiPL2)] vs. reaction time t (s) at three different pressures of L3.(a) LiCB of L3 is a weaker base (lower LiCB) than L1 and L2; (b) LiCB of L3 is close to LiCBs of L1 and L2; (c) LiCB of L3 is larger than LiCBs of L1 and L2. Reactivity of L3 toward L1Li+ and L2Li+ is the same.

(a)(b)

Figure S3. Illustration of the kinetic model by means of plots of RTln[(IL2LiPL1)/(IL1LiPL2)] vs. reaction time t (s). LiCB of L3 is larger than LiCBs of L1 and L2.Reactivities of L3 toward L1Li+ and L2Li+are different.

Figure S4. Variation of LiCB= RTln((IBPA)/( IAPB))(in J mol-1) vs. reaction time D4 (ms) after isolation of each of the equilibrium partners in the presence of an unknown impurity (L3). L1 and L2 are 1-methyl tetrahydrofuran and methyl acetate, respectively.

1. Kinetic method

Part of the measurements reported Table 1 and S1 were calibrated using equilibrium data at 373 K from the Taft laboratory,and the calibration equation was utilized to obtain LiCB(373K) values. The values in the high basicity range were out of the calibration range; hence they correspond to extrapolated values that are more prone to systematic errors than interpolated values.The following calibrationequations were utilized to estimate LiCB from the kinetic method data obtained under different experimental conditions (CID at various pressures and collision energies in a FT-ICR mass spectrometer):S71 forlow pressure and extrapolation at zero collision energy;[[3]]S71’forhigher pressure and averaged at different collision energies.[[4]]

(S71)

(S71’)

Equation S71and S71’ can be written

(S72)

thus

(S72)

The uncertainty at standard deviation level ofthe ∆LiCB valueis:

(S74)

Thus

(S75)

(S75’)

The uncertainty increases with the values of the ∆LiCBmeasurementsobtained by the kinetic method. In fact, the uncertainties associated to these values are probably higher than 9.2 kJ mol-1. The errors on the slope and on the intercept may generate a shift in the range of 9.1-18.1kJ mol-1 on LiCB values between trimethylphosphate and triphenylphosphine oxide. This shift is large enough to explain the deviations observed which are about 15-16kJ mol-1 for the highest LiCB values. Additionally, the temperature of the initial equilibrium measurements[42] may have been slightly underestimated.

1. TCIDmeasurements

LiCA and LiCB values at 373 K are estimated from TCID results at 0 K, using calculated temperature corrections and entropiesfrom respective articles given in the last column of Table S2:

(S76)

or(S76’)

(S77)

Combined uncertainties (as standard deviations)are given by

(S78)

(S79)

Uncertainties of S are not always available. In that case, we considered an average of these values:S = 11.4 J mol-1 K-1.

Table S2.Data (kJ mol-1, at the indicated temperature in K) from TCIDmeasurements (uncertainties given when available; references listed below the table), and from measurements reported in Chapter 6 of Lewis Basicity and Affinity Scales: Data and Measurement; Wiley, Chichester, UK, 2010 for the FTICR measurements.

Lewis base / LiCA / LiCA / LiCB / rS / LiCA / LiCB / LiCB / Deviation / Ref. for
0.0 / 298.15 / 298.15 / 298.15 / 373.15 / 373.15 / 373.15 / TCID data
TCID / TCID / TCID / (calc) / TCID / TCID / FTICR
Trimethyl phosphate / 280.8
± 14.5 / 282.1
± 14.5 / 256.2
± 15. / 86.9 / 282.4
± 18.5 / 240.0
± 19.0 / 183.1 / 66.9 / 1
Proline / 278.8
± 9.7 / 282.
± 10. / 248.
± 11. / 114.
± 16.8 / 282.8
± 12.4 / 240.3
± 13.9 / 2
Pipecolic acid / 272.0
± 16.0 / 274.
± 16. / 244.
± 17. / 100.6
± 16.8 / 274.5
± 20.4 / 237.0
± 21.4 / 2
Azetidine-2-carboxylic acid / 250.0
± 14. / 253.
± 14. / 223.
± 15. / 100.6
± 16.8 / 253.8
± 17.9 / 216.2
± 18.9 / 2
1-Methylimidazole / 242.3
± 20.2 / 244.6
± 20.3 / 213.7
± 20.9 / 103.6
± 16.8 / 245.2
± 25.8 / 206.5
± 26.5 / 167.8 / 38.7 / 3
2-Aminopyridine / 237.8
± 21.1 / 241.1
± 21.2 / 211.8
± 21.6 / 98.3
± 14.4 / 241.9
± 26.9 / 205.3
± 27.5 / 4
Pyridazine / 234.4
± 10.6 / 237.2
± 10.6 / 207.7
± 10.6 / 98.9
± 1. / 237.9
± 13.5 / 201.0
± 13.5 / 173.3 / 27.7 / 5
1,2-Dimethoxyethane / 241.2
± 18.3 / 245.1
± 18.3 / 209.1
± 19.4 / 120.7 / 246.1
± 23.4 / 201.0
± 23.7 / 187.9 / 13.1 / 6
Adenine / 226.1
± 6.1 / 230.
± 6.1 / 195.9
± 6.1 / 114.4 / 231.
± 7.8 / 188.3
± 8.9 / 7
4-Aminopyridine / 216.9
± 20.2 / 217.4
± 20.3 / 192.9
± 20.8 / 82.2
± 15.4 / 217.5
± 25.8 / 186.9
± 26.4 / 4
Uracile / 211.5
± 6.1 / 213.8
± 6.1 / 186.2
± 6.1 / 92.6 / 214.4
± 7.8 / 179.8
± 8.9 / 7
Imidazole / 210.8
± 9.5 / 213.2
± 9.7 / 185.2
± 10.2 / 93.9
± 10.7 / 213.8
± 12.1 / 178.8
± 12.8 / 159.6 / 19.2 / 3
Thymine / 210.1
± 7.0 / 212.4
± 7. / 184.8
± 7. / 92.6 / 213.
± 8.9 / 178.4
± 9.9 / 7
1-Methylpyrazole / 207.2
± 18.4 / 209.4
± 18.5 / 178.8
± 19.1 / 102.6
± 16.7 / 210.
± 23.5 / 171.7
± 24.3 / 143.7 / 28.0 / 3
3-Aminopyridine / 201.7
± 10.0 / 203.4
± 10.2 / 175.6
± 10.9 / 93.2
± 13.4 / 203.8
± 12.8 / 169.0
± 13.7 / 4
Indole / 204.5
± 8.7 / 207.7
± 8.7 / 173.6
± 8.7 / 114.4
± 1.7 / 208.5
± 11.1 / 165.8
± 11.1 / 8
4-Methylpyridine / 196.2
± 13.4 / 198.2
± 13.5 / 170.3
± 13.9 / 93.6
± 11.7 / 198.7
± 17.1 / 163.8
± 17.7 / 9
3-Methylpyridine / 196.6
± 14.7 / 198.7
± 14.8 / 169.1
± 15.2 / 99.3
± 11.4 / 199.2
± 18.8 / 162.2
± 19.2 / 152.9 / 9.3 / 9
2-Methylpyridine / 194.0
± 6.5 / 196.2
± 6.7 / 168.4
± 7.6 / 93.2
± 11.7 / 196.8
± 8.3 / 162.0
± 9.4 / 9
1-H-1,2,4-Triazole / 191.3
± 7.8 / 193.7 / 165.6 / 94.2 / 194.3 / 159.1
± 4.2 / 136.9 / 22.2 / 10
Aniline / 191.5
± 22.4 / 194.5
± 22.5 / 163.7
± 23.4 / 103.3
± 21.5 / 195.3
± 28.6 / 156.7
± 29.7 / 11
Butan-2-one / 190.1
± 7.0 / 192.2
± 7. / 161.4
± 9.5 / 103.3 / 192.7
± 8.9 / 154.2
± 9.9 / 150.8 / 3.4 / 6
Pyrazole / 187.1
± 16.1 / 189.2
± 16.2 / 159.5
± 16.9 / 99.6
± 16.8 / 189.7
± 20.6 / 152.6
± 21.5 / 140.8 / 11.8 / 3
Naphthalene / 187.2
± 15.4 / 189.8
± 15.6 / 156.9
± 17.1 / 110.3
± 23.1 / 190.5
± 19.7 / 149.3
± 21.5 / 127.9 / 21.4 / 12
Pyridine / 181.0
± 14.5 / 183.
± 14.5 / 155.1
± 14.5 / 93.6
± 1.3 / 183.5
± 18.5 / 148.6
± 18.5 / 146.7 / 1.9 / 5
1-Methylpyrrole / 186.2
± 16.8 / 189.8
± 16.8 / 154.8
± 17.6 / 117.4
± 15.8 / 190.7
± 21.4 / 146.9
± 22.2 / 3
Anisole / 184.4
± 18.3 / 187.2
± 18.5 / 153.8
± 19.8 / 112.
± 24.1 / 187.9
± 23.4 / 146.1
± 25. / 126.6 / 19.5 / 13
tert-Butanol / 178.2
± 10.2 / 180.1
± 10.2 / 150.8
± 10.3 / 98.3
± 5.4 / 180.6
± 13. / 143.9
± 13.2 / 139.5 / 4.4 / 14
Phenol / 178.5
± 16.1 / 181.6
± 16.3 / 150.8
± 17.5 / 103.3
± 21.5 / 182.4
± 20.6 / 143.8
± 22.1 / 117.8 / 25.2 / 15
Toluene / 183.1
± 16.0 / 186.4
± 16.3 / 150.1
± 17.5 / 121.8
± 21.5 / 187.2
± 20.4 / 141.8
± 22. / 124.5 / 17.3 / 16
2-Butanol / 174.3
± 8.9 / 176.2
± 8.9 / 146.3
± 9.1 / 100.3
± 5.4 / 176.7
± 11.4 / 139.3
± 11.5 / 139.5 / -0.2 / 14
Pyrrole / 177.4
± 16.6 / 181.1
± 16.7 / 147.1
± 17.4 / 114.
± 15.4 / 182.
± 21.2 / 139.5
± 22. / 3
2-Propanol / 172.8
± 7.5 / 174.9
± 7.5 / 144.9
± 7.7 / 100.6
± 5. / 175.4
± 9.6 / 137.9
± 9.8 / 135.4 / 2.5 / 14
n-Propanol / 170.3
± 8.6 / 172.8
± 8.6 / 141.1
± 8.8 / 106.3
± 6. / 173.4
± 11. / 133.8
± 11.2 / 131.6 / 2.2 / 14
Dimethyl ether / 165.0
± 10.6 / 166.8
± 10.7 / 138.9
± 11.8 / 93.6 / 167.3
± 13.5 / 132.3
± 14.2 / 123.6 / 8.7 / 6
2-Methyl-1-propanol / 168.8
± 7.6 / 171.1
± 7.6 / 139.6
± 7.8 / 105.7
± 5.4 / 171.7
± 9.7 / 132.3
± 9.9 / 136.2 / -3.9 / 14
n-Butanol / 168.6
± 8.2 / 171.3
± 8.2 / 138.7
± 8.4 / 109.3
± 5. / 172.
± 10.5 / 131.2
± 10.6 / 137.4 / -6.2 / 14
Ethanol / 163.5
± 6.5 / 165.5
± 6.5 / 136.4
± 6.7 / 97.6
± 5.4 / 166.
± 8.3 / 129.6
± 8.5 / 127.4 / 2.2 / 6
Benzene / 161.1
± 13.5 / 164.4
± 13.6 / 132.2
± 14.3 / 108.
± 14.8 / 165.2
± 17.2 / 124.9
± 18.1 / 112.8 / 12.1 / 17
Pyrimidine / 154.3
± 10.5 / 156.3
± 10.5 / 128.3
± 10.5 / 93.9
± 1.3 / 156.8
± 13.4 / 121.8
± 13.4 / 124.9 / -3.1 / 5
Methanol / 155.0
± 8.5 / 156.8
± 8.5 / 127.7
± 8.6 / 97.6
± 5. / 157.3
± 10.9 / 120.8
± 11. / 119.5 / 1.3 / 6
2-H-Tetrazole / 151.3
± 6.6 / 153.4 / 125.8 / 92.6 / 153.9 / 119.4
± 4.2 / 139.4 / -20.0 / 10
Pyrazine / 149.1
± 13.2 / 151.1
± 13.2 / 123.1
± 13.2 / 93.9
± 1.3 / 151.6
± 16.9 / 116.6
± 16.9 / 119.9 / -3.3 / 5
Fluorobenzene / 146.9
± 20.1 / 149.6
± 20.3 / 116.7
± 21.4 / 110.3
± 22.1 / 150.3
± 25.7 / 109.1
± 27. / 18
2-H-1,2,3-Triazole / 136.2
± 7.3 / 138.8 / 110.5 / 94.9 / 139.5 / 104.0
± 4.2 / 134.4 / -30.4 / 10
Water / 133.1
± 13.5 / 137.2
± 13.7 / 109.2
± 14.3 / 93.9
± 1.7 / 138.2
± 17.2 / 103.2
± 17.3 / 103.6 / -0.4 / 6
1,3,5-Triazine / 127.4
± 12.6 / 129.4
± 12.6 / 101.4
± 12.6 / 93.9
± 1.3 / 129.9
± 16.1 / 94.9
± 16.1 / 5

References:

[1] Ruan, C.; Huang, H.; Rodgers.M.T.A Simple Model for Metal Cation-Phosphate Interactions in Nucleic Acids in the Gas Phase: Alkali Metal Cations and Trimethyl Phosphate.J. Am. Soc. Mass Spectrom.2008, 19, 305–314.

[2] Moision; R.M.; Armentrout.P.B.The Special Five-Membered Ring of Proline: An Experimental and Theoretical Investigation of Alkali Metal Cation Interactions with Proline and Its Four- and Six-Membered Ring Analogues. J. Phys. Chem. A2006, 110, 3933-3946.

[3] Huang, H.; Rodgers. M.T. Sigma versus Pi Interactions in Alkali Metal Ion Binding to Azoles: Threshold Collision-Induced Dissociation and ab Initio Theory Studies. J. Phys. Chem. A2002, 106, 4277-4289.

[4] Rodgers. M.T. Substituent Effects in the Binding of Alkali Metal Ions to Pyridines Studied by Threshold Collision-Induced Dissociation and ab Initio Theory: The Aminopyridines. J. Phys. Chem. A2001, 105, 8145–8153.

[5] Amunugamaa, R.; Rodgers. M.T. Absolute Alkali Metal Ion Binding Affinities of Several AzinesDetermined by Threshold Collision-Induced Dissociation and AbInitio Theory.Int. J. Mass Spectrom.2000, 195-196, 439-457.

[6] Rodgers, M.T.;Armentrout. P.B.A Critical Evaluation of the Experimental and Theoretical Determination of Lithium CationAffinities.Int. J. Mass Spectrom.2007, 267, 167-182.

[7] Rodgers, M.T.; Armentrout. P.B. Noncovalent Interactions of Nucleic Acid Bases (Uracil, Thymine, and Adenine) with Alkali Metal Ions.Threshold Collision-Induced Dissociation and Theoretical Studies.J. Am. Chem. Soc.2000, 122, 8548–8558.

[8] Ruan, C.;Yang, Z.;Hallowita, N.;Rodgers. M.T. Cation−π Interactions with a Model for the Side Chain of Tryptophan: Structures and Absolute Binding Energies of Alkali Metal Cation−Indole Complexes. J. Phys. Chem. A2005, 109, 11539–11550.

[9] Rodgers. M.T. Substituent Effects in the Binding of Alkali Metal Ions to Pyridines, Studied by Threshold Collision-Induced Dissociation and ab Initio Theory: The Methylpyridines. J. Phys. Chem. A2001, 105, 2374–2383.

[10] Rodgers, M.T;Armentrout. P.B Absolute Alkali Metal Ion Binding Affinities of Several Azoles Determined by Threshold Collision-Induced Dissociation.Int. J. Mass Spectrom.1999, 185-187, 359-380.

[11] Amunugama, R.;Rodgers. M.T. Influence of Substituents on Cation-π Interactions. 3: Absolute Binding Energies of Alkali Metal Cation−Aniline Complexes Determined by Threshold Collision-Induced Dissociation and Theoretical Studies. Int. J. Mass Spectrom.2003, 227, 339-360.

[12] Amunugama, R.;Rodgers. M.T. Cation-π Interactions with a Model for an Extended π Network: Absolute Binding Energies of Alkali Metal Cation–Naphthalene Complexes Determined by Threshold Collision-Induced Dissociation and Theoretical Studies. Int. J. Mass Spectrom.2003, 227, 1-20.

[13] Amunugama, R.;Rodgers. M.T. Influence of Substituents on Cation–π Interactions: 5. Absolute Binding Energies of Alkali Metal Cation–Anisole Complexes Determined by Threshold Collision-Induced Dissociation and Theoretical Studies. Int. J. Mass Spectrom.2003, 222, 1-3.

[14] Rodgers, M.T.;Armentrout. P.B. Absolute Binding Energies of Lithium Ions to Short Chain Alcohols, CnH2n+2O, n = 1−4, Determined by Threshold Collision-Induced Dissociation. J. Phys. Chem. A1997, 101, 2614–2625.

[15] Amunugama, R.;Rodgers. M.T.The Influence of Substituents on Cation−π Interactions. 4. Absolute Binding Energies of Alkali Metal Cation−Phenol Complexes Determined by Threshold Collision-Induced Dissociation and Theoretical Studies. J. Phys. Chem. A2002, 106, 9718–9728.

[16] Amunugama, R.;Rodgers. M.T. Influence of Substituents on Cation−π Interactions. 1. Absolute Binding Energies of Alkali Metal Cation−Toluene Complexes Determined by Threshold Collision-Induced Dissociation and Theoretical Studies. J. Phys. Chem. A 2002, 106, 5529–5539.

[17] Amicangelo, J.C.;Armentrout. P.B Absolute Binding Energies of Alkali-Metal Cation Complexes with Benzene Determined by Threshold Collision-Induced Dissociation Experiments and ab Initio Theory. J. Phys. Chem. A 2000, 104, 11420–11432.

[18] Amunugama, R.;Rodgers. M.T. Influence of Substituents on Cation−π Interactions. 2. Absolute Binding Energies of Alkali Metal Cation−Fluorobenzene Complexes Determined by Threshold Collision-Induced Dissociation and Theoretical Studies. J. Phys. Chem. A 2002, 106, 9092–9103.

1. Relative sensitivity factors of Bayard-Alpert ionization gauges

Table S3. Relative sensitivity factors of the Bayard-Alpert gauge (Sr) from Tämm et al.[1] and from the Bartmess and Geogiadis equation[2] using calculated polarizabilities;[3]the corresponding experimental LiCB values at 373 K are also given; the last column reports LiCB without any correction of the gauge readings.

Lewis base / Sr / LiCB / Sr / LiCB / LiCB
[1] / [1] / [2] / [2] / no correction
1,2-Dimethoxyethane / 3.18 / 202.7 / 4.49 / 202.9 / 202.8
Dimethyl methyl phosphonate / 3.37 / 199.9 / 5.50 / 200.5 / 199.8
Trimethyl phosphate / 3.57 / 198.8 / 5.91 / 199.5 / 198.5
Tetramethylguanidine / 4.42 / 198.4 / 5.69 / 198.4 / 197.5
N,N-Dimethylacetamide / 3.08 / 195.7 / 4.24 / 195.8 / 195.9
Dimethyl sulfoxide / 2.67 / 189.8 / 3.35 / 189.7 / 190.5
N,N-Dimethylformamide / 2.53 / 187.4 / 3.44 / 187.5 / 188.2
1,2-Dimethylimidazole / 3.14 / 187.3 / 4.74 / 187.7 / 187.4
Pyridazine / 3.03 / 183.9 / 4.07 / 184.0 / 184.2
Trimethoxymethane / 3.37 / 182.7 / 4.84 / 182.9 / 182.5
1-Methylimidazole / 2.59 / 180.3 / 4.00 / 180.8 / 181.0
N-Methylformamide / 1.98 / 175.1 / 2.59 / 175.1 / 176.7
Tripropylamine / 5.95 / 170.1 / 7.36 / 169.9 / 168.2
1,3,5-Trimethylpyrazole / 4.01 / 166.6 / 5.45 / 166.7 / 165.9
2,4-Dimethylpentan-3-one / 4.47 / 163.4 / 5.68 / 163.3 / 162.4
Ethyl 2,2-dimethylpropanoate / 4.66 / 163.2 / 6.07 / 163.2 / 162.1
Methyl cyclopropyl ketone / 3.14 / 161.9 / 3.91 / 161.7 / 162.0
Butyl ethanoate / 4.11 / 159.3 / 5.18 / 159.1 / 158.5
Isopropyl ethanoate / 3.56 / 158.6 / 4.64 / 158.6 / 158.4
Di-n-butyl ether / 5.19 / 158.9 / 6.60 / 158.8 / 157.5
Ethyl acetate / 3.01 / 154.1 / 4.11 / 154.2 / 154.4
Methyl propionate / 3.01 / 152.2 / 4.16 / 152.4 / 152.5
Diisopropyl ether / 4.09 / 151.2 / 5.52 / 151.3 / 150.5
Methyl acetate / 2.46 / 148.3 / 3.32 / 148.4 / 149.2
Acetone / 2.27 / 147.4 / 3.06 / 147.5 / 148.5
Pyridine / 3.26 / 146.7 / 4.30 / 146.7 / 146.7
2-Methyltetrahydrofuran / 3.30 / 145.1 / 4.32 / 145.0 / 145.0
Ethyl formate / 2.46 / 141.1 / 3.15 / 141.0 / 142.0
Acetonitrile / 1.70 / 139.3 / 2.36 / 139.5 / 141.3
Diethyl ether / 2.99 / 138.3 / 4.12 / 138.5 / 138.6
Tetrahydrofuran / 2.75 / 137.2 / 3.60 / 137.2 / 137.7

[1] Tämm, K.;Mayeux, C.;Sikk, L.;Gal, J.-F.;Burk. P. Theoretical Modeling of Sensitivity Factors of Bayard-Alpert Ionization Gauges.Int. J. Mass Spectrom.2013, 341-342, 52-58.

[2] Bartmess, J.E.;Georgiadis. R.M. Empirical Method for the Determination of Ion Gauge Sensitivities to Different Gases.Vacuum1983, 33, 149-153.

[3] Miller.K.J. AdditivityMethods in Molecular Polarizability.J. Am. Chem. Soc.1990, 112, 8533-8542.

1. MALDI matrix preparation

Positive ions containing Li+ were generated in the MALDI source from a target obtained by evaporation under vacuum of a HPLC grade methanol/ultrapure water (25/75, v:v) solution of a LiOH/-cyano-4-hydroxy-trans-cinnamic acid (CHCA) mixture (2:1 mol:mol) deposited ( 10 microliters)on a stainless steel MALDI target plate.CHCA salts (mono- and di-lithium salts, yellow and orange solid respectively) are soluble in water. They are weakly soluble in usual organic solvents utilized in matrix preparation (methanol, ethanol, acetonitrile, etc.).

Water can be utilized alone but the drying steprequires attention:

(1) The target plate should be kept under ultra-high vacuum for 1-2 days.

(2) The matrix can be dried at 140°C atatmospheric pressure for 5 min maximum, and then putunder vacuum for 5-10 minutes.

Addition of methanol (5-25 %) to theaqueous solution eases the drying of the matrix, but maycause difficultiesin dissolvingthe lithium salts.Slow or fast drying does not affectthe crystallization or the total intensity of mass spectra. The target thickness obtained with 10 microliters of a 0.5 mol L-1 of the CHCA salt spread on an area of 5 x 5 mm is sufficient for 30 shots. The matrix (solution) is stable enoughto be kept forseveral months (6-12 months) ifprotected from light. The solid deposit may be utilized over several weeks.

1. Theoretical calculations

Table S4. Experimental and calculated lithium cation affinities at 0 K in kJ mol−1from ref 44 in main text.

Ligand / Exp. / cp-DZ / DZ / cp-aug-DZ / aug-DZ / cp-aug-TZ / aug-TZ / cp-aug-QZ / aug-QZ / CBS//DZ / CBS //aug-DZ
Ar / 32.8 / 17.1 / 25.0 / 20.0 / 23.0 / 24.0 / 26.1 / 25.0 / 27.0 / 27.1 / 28.0
NO / 59.8 / 49.4 / 63.6 / 48.4 / 51.0 / 52.9 / 55.5 / 53.9 / 55.2 / 54.4 / 54.3
CO / 55.0 / 62.5 / 72.7 / 62.0 / 65.1 / 66.2 / 69.7 / 66.7 / 68.2 / 66.4 / 68.0
H2O / 133.1 / 145.4 / 169.4 / 129.2 / 132.2 / 133.6 / 135.1 / 136.0 / 136.8 / 137.9 / 137.5
CH3OH / 155.0 / 152.8 / 175.8 / 145.4 / 148.3 / 149.5 / 151.5 / 151.9 / 152.8 / 153.7 / 153.2
C6H6 / 161.1 / 141.0 / 159.5 / 142.9 / 152.5 / 149.7 / 156.7 / 150.7 / 153.0 / 150.8 / 150.5
CH3OCH3 / 165.0 / 153.1 / 175.0 / 150.5 / 153.8 / 153.8 / 156.6 / 156.2 / 157.6 / 158.2 / 158.6
NH3 / 159.1 / 164.2 / 182.0 / 150.7 / 154.3 / 154.9 / 156.2 / 156.7 / 157.5 / 158.5 / 157.3
C2H5OH / 163.5 / 162.3 / 186.1 / 156.7 / 160.3 / 161.0 / 163.5 / 163.5 / 164.8 / 165.5 / 165.2
CH3NH2 / 165.5 / 166.6 / 185.9 / 160.4 / 163.9 / 163.9 / 165.9 / 165.6 / 166.5 / 167.0 / 165.8
CH3CHO / 166.3 / 158.0 / 177.7 / 158.3 / 161.7 / 163.2 / 166.0 / 165.6 / 167.0 / 167.4 / 167.4
C2H5CO2H / 165.0 / 167.5 / 187.3 / 164.3 / 168.6 / 168.7 / 172.1 / 171.5 / 173.1 / 173.6 / 173.2
1-C3H7OH / 170.3 / 168.4 / 192.9 / 163.9 / 168.1 / 169.0 / 171.9 / 170.9 / 172.4 / 172.5 / 171.9
2-C3H7OH / 172.8 / 168.1 / 191.9 / 164.1 / 167.9 / 168.3 / 171.0 / 172.8 / 173.7 / 175.7 / 173.6
Pyrrole / 177.4 / 159.2 / 176.8 / 156.1 / 163.4 / 161.2 / 166.1 / 163.2 / 165.3 / 164.4 / 164.8
C6H5OH / 178.5 / 145.4 / 165.0 / 144.9 / 154.5 / 150.8 / 157.8 / 152.6 / 155.2 / 152.6 / 154.5
Pyridine / 181.0 / 179.2 / 196.1 / 178.3 / 182.2 / 182.1 / 185.2 / 183.8 / 185.2 / 184.8 / 184.9
CH3COCH3 / 182.6 / 194.4 / 174.9 / 175.7 / 179.4 / 180.8 / 184.3 / 183.2 / 185.0 / 185.1 / 184.7
CH3COC2H5 / 190.1 / 176.0 / 194.5 / 178.1 / 181.8 / 183.6 / 187.1 / 185.8 / 187.3 / 187.1 / 187.4
1-C3H7NH2 / 197.8 / 184.6 / 205.0 / 181.0 / 185.8 / 185.2 / 188.4 / 187.1 / 188.5 / 188.5 / 187.0
Imidazole / 210.8 / 206.0 / 224.2 / 201.5 / 205.1 / 205.9 / 208.4 / 207.6 / 209.1 / 209.2 / 209.3
Uracil / 211.5 / 201.2 / 222.6 / 193.8 / 197.5 / 199.7 / 203.4 / 201.7 / 203.2 / 202.5 / 202.6
Glycine / 220.0 / 244.7 / 276.1 / 231.9 / 237.8 / 236.5 / 240.6 / 239.6 / 241.5 / 242.2 / 241.2
Adenine / 226.1 / 219.1 / 247.0 / 200.8 / 206.7 / 202.2 / 206.6 / 202.6 / 204.6 / 203.0 / 205.1
(CH3)2NCHO / 208.5 / 215.3 / 238.4 / 214.9 / 218.5 / 220.0 / 223.0 / 222.4 / 223.9 / 224.2 / 224.4
2-NH2pyridine / 237.8 / 224.3 / 250.4 / 216.2 / 221.5 / 218.7 / 222.8 / 219.8 / 221.6 / 220.5 / 219.7
(CH3OCH2)2 / 241.2 / 249.7 / 285.7 / 244.9 / 250.5 / 248.1 / 252.8 / 251.4 / 253.5 / 254.0 / 254.2
Proline / 278.8 / 242.3 / 278.0 / 256.0 / 260.2 / 259.0 / 262.6 / 261.3 / 263.0 / 263.4 / 262.6
HOC2H4NH2 / 289.5 / 271.9 / 305.3 / 256.2 / 261.7 / 259.8 / 263.4 / 263.3 / 264.9 / 266.1 / 262.4
12-crown-4 / 371.5 / 341.4 / 400.6 / 343.5 / 353.3 / 342.1 / 351.1
AAD / 11.9 / 17.4 / 13.2 / 10.0 / 10.5 / 8.8 / 9.0 / 8.7 / 9.1 / 9.0
s(AAD) / 9.4 / 12.7 / 8.9 / 7.0 / 8.7 / 7.5 / 8.0 / 7.5 / 7.7 / 7.8
a / 0.982 / 0.892 / 1.022 / 1.016 / 1.027 / 1.022 / 1.018 / 1.017 / 1.010 / 1.019
s(a) / 0.045 / 0.042 / 0.038 / 0.036 / 0.039 / 0.037 / 0.039 / 0.039 / 0.040 / 0.041
b / 8.827 / 5.962 / 6.907 / 3.446 / 1.780 / -0.822 / 1.200 / -0.271 / 0.929 / -0.318
s(b) / 8.128 / 8.566 / 6.742 / 6.442 / 6.996 / 6.847 / 7.179 / 7.143 / 7.388 / 7.422
r2 / 0.947 / 0.943 / 0.963 / 0.968 / 0.963 / 0.965 / 0.961 / 0.962 / 0.959 / 0.959
s(y) / 13.5 / 14.0 / 11.2 / 10.5 / 11.3 / 10.9 / 11.6 / 11.4 / 11.9 / 11.8

Table S4. Experimental and calculated lithium cation affinities at 0 K in kJ mol−1 from ref 44 in main text.

Ligand / Exp. / MP2(full) / MP2(full)/
/B3LYPb / B3LYP / B3P86 / MPW1
PW91b / CBS-
4M / CBS-
Q / CBS-
QB3 / G2 / G3 / G2(MP2)
Ar / 32,8 / 22,1 / 22,2 / 26,3 / 22,5 / 24,5 / 18,8 / 24,0 / 23,8 / 26,7 / 30,8
NO / 59,8 / 54,1 / 25,2 / 52,5 / 48,3 / 51,4 / 33,4 / 45,6 / 49,7 / 49,8 / 47,1
CO / 55,0 / 65,1 / 64,7 / 64,2 / 60,5 / 61,5 / 56,7 / 60,7 / 60,7 / 61,5 / 63,2
H2O / 133,1 / 130,5 / 130,1 / 138,0 / 133,2 / 135,3 / 129,9 / 131,9 / 132,5 / 132,5 / 137,0 / 131,3
CH3OH / 155,0 / 147,0 / 146,6 / 154,2 / 147,4 / 148,8 / 143,9 / 147,9 / 147,6 / 147,8 / 152,8 / 147,2
C6H6 / 161,1 / 143,4 / 145,0 / 153,2 / 151,2 / 157,4 / 150,3 / 155,8 / 146,7 / 151,1 / 154,6
CH3OCH3 / 165,0 / 152,2 / 151,6 / 158,7 / 151,1 / 153,4 / 148,6 / 153,1 / 152,0 / 152,8 / 157,9 / 152,3
NH3 / 159,1 / 150,8 / 150,4 / 157,6 / 154,0 / 156,4 / 154,1 / 151,8 / 152,1 / 151,6 / 156,3 / 150,3
C2H5OH / 163,5 / 158,0 / 157,4 / 166,9 / 160,6 / 162,1 / 154,9 / 159,3 / 159,2 / 170,1 / 165,1 / 159,3
CH3NH2 / 165,5 / 160,4 / 159,7 / 166,8 / 162,3 / 164,2 / 159,7 / 160,9 / 160,5 / 161,0 / 165,6 / 160,0
CH3CHO / 166,3 / 159,2 / 159,0 / 175,3 / 168,9 / 171,0 / 159,8 / 165,0 / 164,3 / 163,7 / 168,2 / 163,9
C2H5CO2H / 165,0 / 163,8 / 164,3 / 181,6 / 175,9 / 178,1 / 166,2 / 170,0 / 170,6 / 170,1 / 176,1
1-C3H7OH / 170,3 / 163,4 / 164,6 / 175,3 / 166,6 / 169,5 / 159,9 / 164,8 / 166,0 / 168,4 / 174,8
2-C3H7OH / 172,8 / 165,3 / 164,7 / 175,6 / 169,2 / 171,6 / 161,9 / 167,6 / 166,4 / 166,8 / 172,3 / 166,5
Pyrrole / 177,4 / 158,1 / 158,2 / 166,3 / 163,6 / 169,0 / 158,7 / 161,9 / 158,9 / 160,1 / 167,6
C6H5OH / 178,5 / 145,3 / 146,7 / 156,1 / 154,9 / 161,0 / 152,0 / 156,4 / 148,7 / 153,2 / 157,1 / 151,9
Pyridine / 181,0 / 179,1 / 178,8 / 189,5 / 183,6 / 185,7 / 178,4 / 178,6 / 179,5 / 179,8 / 184,9 / 179,8
CH3COCH3 / 182,6 / 176,7 / 176,4 / 194,6 / 187,7 / 190,2 / 178,1 / 181,9 / 181,8 / 181,2 / 186,4 / 180,9
CH3COC2H5 / 190,1 / 178,8 / 178,5 / 198,9 / 192,2 / 193,2 / 184,0 / 184,6 / 184,0 / 187,6 / 189,0
1-C3H7NH2 / 197,8 / 180,8 / 180,0 / 188,7 / 183,9 / 185,4 / 179,7 / 181,2 / 180,8 / 181,9 / 188,5
Imidazole / 210,8 / 202,7 / 202,3 / 211,9 / 206,5 / 208,7 / 203,1 / 204,6 / 204,0 / 203,9 / 209,5
Uracil / 211,5 / 194,9 / 194,7 / 212,4 / 204,9 / 209,7 / 196,3 / 200,6 / 199,5 / 198,8 / 204,7
Glycine / 220,0 / 232,7 / 229,8 / 245,9 / 239,5 / 242,7 / 229,6 / 237,4 / 234,2 / 236,3 / 244,1
Adenine / 226,1 / 199,8 / 200,4 / 204,9 / 196,7 / 200,3 / 202,4 / 208,6 / 201,1 / 201,6 / 208,0
(CH3)2NCHO / 208,5 / 216,5 / 216,2 / 229,4 / 221,2 / 222,9 / 216,4 / 220,3 / 220,6 / 219,9 / 225,7 / 219,9
2-NH2pyridine / 237,8 / 214,9 / 214,7 / 220,0 / 212,4 / 216,1 / 218,0 / 212,2 / 214,6 / 214,0 / 220,8
(CH3OCH2)2 / 241,2 / 245,8 / 244,9 / 254,3 / 244,6 / 245,8 / 240,6 / 246,1 / 245,0 / 246,8 / 255,4 / 246,2
Proline / 278,8 / 251,6 / 252,2 / 266,4 / 258,3 / 261,0 / 248,7 / 266,5 / 253,4 / 255,0 / 260,6
HOC2H4NH2 / 289,5 / 255,8 / 254,5 / 264,4 / 257,8 / 259,6 / 253,0 / 254,3 / 257,2 / 253,4 / 261,8
12-crown-4 / 371,5 / 345,7 / 359,2 / 371,5 / 347,3 / 352,1 / 344,1 / 353,1 / 344,9 / 366,1 / 356,6
AAD / 12,8 / 13,2 / 9,8 / 11,0 / 9,5 / 12,9 / 10,3 / 11,7 / 10,7 / 8,8 / 8,1
s(AAD) / 9,2 / 9,6 / 7,6 / 8,9 / 8,2 / 9,6 / 8,0 / 9,1 / 8,9 / 7,7 / 7,1
a / 1,041 / 0,999 / 0,986 / 1,008 / 1,009 / 1,006 / 1,010 / 1,026 / 1,033 / 1,003
s(a) / 0,041 / 0,042 / 0,043 / 0,043 / 0,041 / 0,038 / 0,037 / 0,041 / 0,042 / 0,040
b / 2,966 / 11,335 / 2,780 / 4,664 / 1,803 / 10,061 / 5,313 / 3,946 / 1,529 / 1,820
s(b) / 7,219 / 7,340 / 8,018 / 7,697 / 7,508 / 6,642 / 6,721 / 7,225 / 7,525 / 7,403
r2 / 0,960 / 0,955 / 0,951 / 0,954 / 0,957 / 0,963 / 0,964 / 0,959 / 0,957 / 0,958
s(y) / 11,7 / 12,4 / 12,9 / 12,6 / 12,1 / 11,2 / 11,1 / 11,8 / 12,1 / 11,9

Table S5. Treatment of low vibrational modes: vibrations vs. hindered rotors (HR).G is the difference between the vibrations vs. HR treatments.

E / ZPVE / H / G / TCE / S / TCE
(HR) / S
(HR) / H(HR) / G(HR) / G / G
a.u / a.u / a.u / a.u / kJ/mol / J/mol/K / kJ/mol / J/mol/K / a.u / a.u / a.u / kJ/mol
1,1,3,3-Tetramethyl
guanidine / -360.22279 / 0.20322 / -360.00458 / -360.06506 / 136.19 / 101.70 / 136.47 / 107.70 / -360.00412 / -360.06814 / 0.00308 / -7.17
1,1,3,3-Tetramethyl
Guanidine
+ Li+ / -367.55756 / 0.20583 / -367.33464 / -367.39988 / 139.14 / 109.71 / 139.36 / 110.95 / -367.33428 / -367.40023 / 0.00035
1,2-Dimethyl
Imidazole / -302.88837 / 0.13640 / -302.74104 / -302.79342 / 91.71 / 88.08 / 91.53 / 87.89 / -302.74133 / -302.79358 / 0.00016 / -0.56
1,2-Dimethyl
Imidazole
+ Li+ / -310.21600 / 0.13883 / -310.06411 / -310.12193 / 94.58 / 97.25 / 94.27 / 96.35 / -310.06460 / -310.12187 / -0.00006
1,3,5-Trimethyl
Pyrazole / -341.90912 / 0.16573 / -341.73003 / -341.78805 / 111.64 / 97.56 / 111.37 / 97.52 / -341.73046 / -341.78843 / 0.00038 / -0.27
1,3,5-Trimethyl
Pyrazole
+ Li+ / -349.22792 / 0.16784 / -349.04456 / -349.10778 / 114.32 / 106.31 / 114.09 / 106.23 / -349.04492 / -349.10806 / 0.00028
1-Methyl
Imidazole / -263.84636 / 0.10693 / -263.73084 / -263.77733 / 71.75 / 78.19 / 71.65 / 78.18 / -263.73100 / -263.77747 / 0.00014 / 0.01
1-Methyl
Imidazole
+ Li+ / -271.17222 / 0.10962 / -271.05202 / -271.10307 / 74.68 / 85.84 / 74.58 / 85.84 / -271.05218 / -271.10321 / 0.00014
2-Butanol / -232.15010 / 0.14656 / -231.99299 / -232.04245 / 97.85 / 83.17 / 98.03 / 84.53 / -231.99270 / -232.04294 / 0.00049 / -1.14
2-Butanol
+ Li+ / -239.45834 / 0.14887 / -239.29704 / -239.35110 / 100.48 / 90.90 / 100.53 / 91.17 / -239.29696 / -239.35116 / 0.00006
2-Methyl
Tetrahydrofuran / -270.01624 / 0.15585 / -269.85052 / -269.90110 / 103.25 / 85.05 / 103.29 / 85.30 / -269.85045 / -269.90116 / 0.00006 / -0.01
2-Methyl
Tetrahydrofuran
+ Li+ / -277.32774 / 0.15797 / -277.15777 / -277.21193 / 105.92 / 91.08 / 105.96 / 91.32 / -277.15770 / -277.21198 / 0.00005
Acetamide / -207.97601 / 0.07898 / -207.88879 / -207.93372 / 53.99 / 75.55 / 53.79 / 75.04 / -207.88911 / -207.93371 / 0.00000 / 2.50
Acetamide
+ Li+ / -215.30451 / 0.08238 / -215.21237 / -215.26102 / 57.07 / 81.81 / 56.96 / 83.13 / -215.21255 / -215.26197 / 0.00095
Acetone / -191.96224 / 0.08991 / -191.86387 / -191.90942 / 60.98 / 76.60 / 60.83 / 76.59 / -191.86411 / -191.90964 / 0.00022 / 7.24
Acetone
+ Li+ / -199.27692 / 0.09185 / -199.17447 / -199.22536 / 63.55 / 85.58 / 63.47 / 90.41 / -199.17459 / -199.22833 / 0.00297
Acetonitrile / -131.92753 / 0.04890 / -131.87271 / -131.90989 / 33.66 / 62.53 / 0.00
Acetonitrile
+ Li+ / -139.23503 / 0.05072 / -139.17626 / -139.21897 / 36.13 / 71.81
Acetophenone / -382.47638 / 0.14827 / -382.31593 / -382.37119 / 99.94 / 92.93 / 100.09 / 95.07 / -382.31570 / -382.37221 / 0.00102 / -0.09
Acetophenone
+ Li+ / -389.79601 / 0.15019 / -389.63138 / -389.69250 / 102.57 / 102.79 / 102.66 / 104.74 / -389.63123 / -389.69349 / 0.00099
Acetylacetone / -343.72830 / 0.13153 / -343.58416 / -343.64127 / 89.71 / 96.04 / 89.94 / 99.19 / -343.58379 / -343.64275 / 0.00147 / -2.89
Acetylacetone
+ Li+ / -351.07554 / 0.13374 / -350.92754 / -350.98778 / 92.13 / 101.30 / 92.09 / 101.85 / -350.92761 / -350.98815 / 0.00037
Benzonitrile / -322.43877 / 0.10662 / -322.32239 / -322.37170 / 72.29 / 82.92 / 0.00
Benzonitrile
+ Li+ / -329.75220 / 0.10853 / -329.63170 / -329.68660 / 74.88 / 92.33
Bromo
Benzene / -2800.01034 / 0.09722 / -2799.90395 / -2799.95336 / 66.02 / 83.08 / 0.00
Bromo
Benzene
+ Li+ / -2807.30255 / 0.09950 / -2807.19194 / -2807.24525 / 68.67 / 89.65
Diethylamine / -212.31405 / 0.16039 / -212.14295 / -212.19325 / 106.62 / 84.59 / 106.87 / 85.88 / -212.14256 / -212.19361 / 0.00036 / 1.66
Diethylamine
+ Li+ / -219.62274 / 0.16303 / -219.44697 / -219.50250 / 109.56 / 93.38 / 109.66 / 95.36 / -219.44680 / -219.50349 / 0.00099
Diethylether / -232.14489 / 0.14689 / -231.98746 / -232.03762 / 98.04 / 84.35 / 98.30 / 85.83 / -231.98704 / -232.03806 / 0.00044 / 2.03
Diethylether
+ Li+ / -239.45213 / 0.14884 / -239.29052 / -239.34638 / 100.67 / 93.94 / 100.91 / 96.66 / -239.29013 / -239.34759 / 0.00121
Di-iso-
propylether / -310.21885 / 0.20659 / -309.99798 / -310.05699 / 137.86 / 99.24 / 138.19 / 101.04 / -309.99745 / -310.05752 / 0.00052 / 5.65
Di-iso-
propylether
+ Li+ / -317.52863 / 0.20855 / -317.30359 / -317.36835 / 140.47 / 108.91 / 140.71 / 114.09 / -317.30321 / -317.37103 / 0.00268
Di-iso-propyl
Ketone / -348.10038 / 0.21240 / -347.87234 / -347.93532 / 142.36 / 105.92 / 142.62 / 107.72 / -347.87192 / -347.93595 / 0.00062 / 8.27
Di-iso-propyl
Ketone
+ Li+ / -355.41869 / 0.21440 / -355.18638 / -355.25507 / 145.04 / 115.51 / 145.37 / 122.82 / -355.18584 / -355.25885 / 0.00377
Dimethyl
Acetamide / -286.03017 / 0.14022 / -285.87819 / -285.93197 / 94.63 / 90.43 / 94.66 / 91.48 / -285.87814 / -285.93252 / 0.00055 / -0.39
Dimethyl
Acetamide
+ Li+ / -293.36268 / 0.14290 / -293.20593 / -293.26502 / 97.62 / 99.36 / 97.56 / 99.92 / -293.20602 / -293.26542 / 0.00040
Dimethyl
Amine / -134.23885 / 0.09946 / -134.13226 / -134.17266 / 66.14 / 67.93 / 66.26 / 68.59 / -134.13207 / -134.17284 / 0.00019 / -0.49
Dimethyl
Amine
+ Li+ / -141.54411 / 0.10259 / -141.43255 / -141.47769 / 69.26 / 75.91
Dimethyl
ether / -154.06475 / 0.08614 / -153.97164 / -154.01177 / 57.68 / 67.49 / 57.82 / 68.32 / -153.97142 / -154.01203 / 0.00026 / 0.10
Dimethyl
Ether
+ Li+ / -161.36621 / 0.08849 / -161.26859 / -161.31445 / 60.51 / 77.11 / 60.65 / 78.00 / -161.26838 / -161.31474 / 0.00029
Dimethylethyl
amine / -212.30391 / 0.16003 / -212.13330 / -212.18294 / 106.32 / 83.49 / 106.54 / 84.69 / -212.13295 / -212.18329 / 0.00035 / -0.65
Dimethylethyl
amine + Li+ / -219.60900 / 0.16247 / -219.43387 / -219.48841 / 109.15 / 91.73 / 109.20 / 92.04 / -219.43380 / -219.48851 / 0.00010
Dimethyl
formamide / -246.99100 / 0.11043 / -246.87096 / -246.91923 / 74.59 / 81.17 / 74.67 / 84.18 / -246.87083 / -246.92087 / 0.00164 / -3.33
Dimethyl
Formamide
+ Li+ / -254.32032 / 0.11335 / -254.19533 / -254.24882 / 77.69 / 89.96 / 77.46 / 90.01 / -254.19569 / -254.24919 / 0.00037
Dimethyl
Methyl
Phosphonate / -684.21712 / 0.13884 / -684.06386 / -684.12469 / 95.44 / 102.30 / 95.29 / 102.59 / -684.06408 / -684.12507 / 0.00038 / 0.32
Dimethyl
Methyl
Phosphonate
+ Li+ / -691.55710 / 0.14076 / -691.39959 / -691.46629 / 98.10 / 112.17 / 98.03 / 112.88 / -691.39969 / -691.46679 / 0.00050
Dimethyl
Sulfone / -626.39173 / 0.09221 / -626.29000 / -626.33773 / 63.09 / 80.26 / 63.23 / 81.04 / -626.28979 / -626.33796 / 0.00023 / 6.90
Dimethyl
Sulfone
+ Li+ / -633.71306 / 0.09371 / -633.60777 / -633.65992 / 65.33 / 87.71 / 65.47 / 92.92 / -633.60754 / -633.66278 / 0.00285
Dimethyl
sulfoxide / -551.53728 / 0.08585 / -551.44270 / -551.48830 / 58.61 / 76.68 / 58.73 / 77.36 / -551.44250 / -551.48849 / 0.00019 / 0.46
Dimethyl
Sulfoxide
+ Li+ / -558.87458 / 0.08809 / -558.77553 / -558.82697 / 61.41 / 86.51 / 61.43 / 87.19 / -558.77551 / -558.82734 / 0.00036
Diphenyl
sulfone / -1007.40842 / 0.20651 / -1007.18348 / -1007.25528 / 140.41 / 120.73 / 140.51 / 121.29 / -1007.18332 / -1007.25542 / 0.00014 / 0.13
Diphenyl
Sulfone
+ Li+ / -1014.74280 / 0.20823 / -1014.51404 / -1014.59093 / 142.81 / 129.30 / 142.83 / 129.74 / -1014.51400 / -1014.59112 / 0.00019
Diphenyl
sulfoxide / -932.55540 / 0.20014 / -932.33768 / -932.40816 / 135.88 / 118.52 / 135.93 / 119.00 / -932.33760 / -932.40833 / 0.00018 / 0.69
Diphenyl
Sulfoxide
+ Li+ / -939.89563 / 0.20219 / -939.67349 / -939.74993 / 138.66 / 128.55 / 138.66 / 129.35 / -939.67348 / -939.75037 / 0.00044
Dimethoxy
ethane / -306.98020 / 0.15300 / -306.81517 / -306.86976 / 102.82 / 91.81 / 103.18 / 93.91 / -306.81458 / -306.87041 / 0.00064 / 4.64
Dimethoxy
Ethane
+ Li+ / -314.32205 / 0.15675 / -314.15191 / -314.20895 / 106.02 / 95.92 / 106.16 / 100.38 / -314.15169 / -314.21136 / 0.00241
Ethanal / -152.91597 / 0.05993 / -152.84967 / -152.88860 / 40.86 / 65.46 / 40.86 / 65.80 / -152.84967 / -152.88879 / 0.00019 / -0.04
Ethanal
+ Li+ / -160.22434 / 0.06199 / -160.15380 / -160.19880 / 43.52 / 75.68 / 43.55 / 76.08 / -160.15376 / -160.19898 / 0.00018
Ethanol / -154.07575 / 0.08602 / -153.98276 / -154.02284 / 57.61 / 67.40 / 57.70 / 70.44 / -153.98262 / -154.02449 / 0.00165 / 0.61
Ethanol
+ Li+ / -161.38051 / 0.08827 / -161.28327 / -161.32891 / 60.28 / 76.76 / 60.38 / 80.22 / -161.28311 / -161.33080 / 0.00188
Ethyl
ethanoate / -305.87589 / 0.12752 / -305.73728 / -305.78969 / 86.24 / 88.14 / 86.38 / 89.32 / -305.73705 / -305.79014 / 0.00045 / 2.30
Ethyl
ethanoate
+ Li+ / -313.19101 / 0.12926 / -313.04943 / -313.10515 / 88.11 / 93.70 / 88.16 / 96.11 / -313.04934 / -313.10647 / 0.00133
Ethyl
formate / -266.82938 / 0.09789 / -266.72254 / -266.76946 / 66.30 / 78.90 / 66.41 / 79.72 / -266.72236 / -266.76974 / 0.00028 / 2.47
Ethyl
Formate
+ Li+ / -274.13904 / 0.09960 / -274.02805 / -274.08237 / 68.90 / 91.34 / 68.90 / 93.42 / -274.02806 / -274.08359 / 0.00122
Formamide / -168.93070 / 0.04899 / -168.87534 / -168.91429 / 34.00 / 65.49 / -0.26
Formamide
+ Li+ / -176.25395 / 0.05266 / -176.19353 / -176.23632 / 37.17 / 71.96 / 36.89 / 71.07 / -176.19398 / -176.23622 / -0.00010
Methanal / -113.86633 / 0.02920 / -113.83232 / -113.86445 / 20.60 / 54.02 / 0.00
Methanal
+ Li+ / -121.16653 / 0.03159 / -121.12804 / -121.16717 / 23.41 / 65.80
Methanol / -115.03542 / 0.05533 / -114.97458 / -115.00968 / 37.43 / 59.03 / 37.42 / 59.42 / -114.97460 / -115.00992 / 0.00024 / -0.16
Methanol
+ Li+ / -122.33709 / 0.05789 / -122.27180 / -122.31264 / 40.23 / 68.68 / 40.18 / 68.89 / -122.27187 / -122.31282 / 0.00018
Methyl
amine / -95.20983 / 0.06891 / -95.13525 / -95.17076 / 46.06 / 59.72 / 46.12 / 60.15 / -95.13515 / -95.17091 / 0.00015 / -0.40
Methyl
Amine
+ Li+ / -102.51664 / 0.07243 / -102.43700 / -102.47731 / 49.24 / 67.80
Methyl
benzoate / -457.35139 / 0.15477 / -457.18320 / -457.24180 / 104.80 / 98.54 / 104.90 / 101.42 / -457.18304 / -457.24333 / 0.00153 / -0.09
Methyl
benzoate
+ Li+ / -464.66883 / 0.15660 / -464.49653 / -464.56126 / 107.38 / 108.86 / 107.46 / 111.62 / -464.49640 / -464.56275 / 0.00149
Methyl
Cyclopropyl
ketone / -268.83486 / 0.12822 / -268.69645 / -268.74650 / 86.12 / 84.17 / 86.24 / 85.04 / -268.69625 / -268.74679 / 0.00030 / 1.98
Methyl
Cyclopropyl
ketone
+ Li+ / -276.15308 / 0.13013 / -276.01051 / -276.06631 / 88.73 / 93.84 / 88.77 / 95.78 / -276.01043 / -276.06736 / 0.00105
Methyldiethyl
amine / -251.33736 / 0.19041 / -251.13444 / -251.18911 / 126.59 / 91.93 / 126.86 / 93.56 / -251.13400 / -251.18962 / 0.00051 / -0.86
Methyldiethyl
amine + Li+ / -258.64491 / 0.19263 / -258.43752 / -258.49854 / 129.40 / 102.62 / 129.51 / 103.27 / -258.43734 / -258.49873 / 0.00018
Methyl
ethanoate / -266.83683 / 0.09707 / -266.73038 / -266.77823 / 66.06 / 80.47 / 66.12 / 81.33 / -266.73028 / -266.77862 / 0.00039 / -0.24
Methyl
Ethanoate
+ Li+ / -274.15072 / 0.09890 / -274.04125 / -274.09225 / 67.95 / 85.77 / 67.81 / 85.93 / -274.04147 / -274.09255 / 0.00030
Methyl
formamide / -207.96129 / 0.08009 / -207.87439 / -207.91552 / 53.79 / 69.17 / 53.79 / 69.17 / -207.87439 / -207.91550 / -0.00002 / 0.02
Methyl
formamide
+ Li+ / -215.28806 / 0.08325 / -215.19507 / -215.24408 / 57.61 / 82.42 / 57.16 / 81.23 / -215.19579 / -215.24407 / -0.00001
Methyl
propionate / -305.87260 / 0.12778 / -305.73368 / -305.78620 / 86.43 / 88.32 / 86.60 / 91.86 / -305.73341 / -305.78802 / 0.00182 / -2.91
Methyl
propionate
+ Li+ / -313.18736 / 0.12969 / -313.04431 / -313.10275 / 89.03 / 98.27 / 89.05 / 99.57 / -313.04427 / -313.10345 / 0.00071
Naphthalene / -383.35505 / 0.15816 / -383.18580 / -383.23782 / 105.46 / 87.48 / 0.00
Naphthalene
+ Li+ / -390.65815 / 0.16068 / -390.48444 / -390.54029 / 108.27 / 93.92
n-Butylamine / -212.31709 / 0.16082 / -212.14548 / -212.19596 / 106.94 / 84.90 / 107.20 / 87.71 / -212.14507 / -212.19720 / 0.00124 / -3.25
n-Butylamine
+ Li+ / -219.63020 / 0.16464 / -219.45367 / -219.50615 / 110.03 / 88.25
NH3 / -56.18436 / 0.03701 / -56.14255 / -56.17095 / 25.49 / 47.75 / 0.00
NH3
+ Li+ / -63.49065 / 0.04124 / -63.44373 / -63.47840 / 28.70 / 58.31
Phenol / -305.55806 / 0.11230 / -305.43667 / -305.48370 / 75.43 / 79.08 / 75.49 / 79.44 / -305.43658 / -305.48380 / 0.00010 / 0.20
Phenol
+ Li+ / -312.85784 / 0.11492 / -312.73204 / -312.78260 / 78.20 / 85.02 / 78.24 / 85.48 / -312.73197 / -312.78278 / 0.00018
Piperidine / -250.18741 / 0.17094 / -250.00726 / -250.05403 / 112.31 / 78.66 / 0.00
Piperidine
+ Li+ / -257.49771 / 0.17389 / -257.31259 / -257.36417 / 115.42 / 86.74
Propanal / -191.95227 / 0.09094 / -191.85340 / -191.89697 / 61.30 / 73.25 / 61.44 / 76.29 / -191.85318 / -191.89853 / 0.00156 / -0.12
Propanal
+ Li+ / -199.26161 / 0.09294 / -199.15854 / -199.20806 / 63.94 / 83.29 / 64.07 / 86.25 / -199.15831 / -199.20958 / 0.00152
2-Propanol / -193.11542 / 0.11599 / -192.99073 / -193.03530 / 77.50 / 74.95 / 77.62 / 75.99 / -192.99053 / -193.03570 / 0.00040 / 1.89
2-Propanol
+ Li+ / -200.42235 / 0.11805 / -200.29350 / -200.34359 / 80.11 / 84.23 / 80.27 / 86.58 / -200.29325 / -200.34471 / 0.00112
Propene / -117.07147 / 0.08546 / -116.97928 / -117.01868 / 57.11 / 66.26 / 57.17 / 66.72 / -116.97918 / -117.01884 / 0.00015 / -0.06
Propene
+ Li+ / -124.34761 / 0.08696 / -124.25168 / -124.29713 / 59.46 / 76.44 / 59.53 / 76.88 / -124.25157 / -124.29727 / 0.00013
Pyrazole / -224.79349 / 0.07711 / -224.71003 / -224.75048 / 51.63 / 68.01 / 0.00
Pyrazole
+ Li+ / -232.10367 / 0.07940 / -232.01583 / -232.06140 / 54.38 / 76.64
Pyridazine / -262.65003 / 0.08240 / -262.56060 / -262.60316 / 55.38 / 71.58 / 0.00
Pyridazine
+ Li+ / -269.97724 / 0.08528 / -269.88304 / -269.92977 / 58.37 / 78.59
Pyridine / -246.69582 / 0.09544 / -246.59319 / -246.63600 / 63.66 / 71.98 / 0.00
Pyridine
+ Li+ / -254.00696 / 0.09786 / -253.89980 / -253.94760 / 66.50 / 80.39
Tetrahydro
Furane / -230.97645 / 0.12592 / -230.84255 / -230.88734 / 83.28 / 75.32 / 0.00
Tetrahydro
Furane
+ Li+ / -238.28567 / 0.12843 / -238.14725 / -238.19666 / 86.11 / 83.09
Thiophenol / -628.21031 / 0.10683 / -628.09350 / -628.14361 / 72.56 / 84.27 / 72.57 / 84.65 / -628.09347 / -628.14379 / 0.00018 / 0.04
Thiophenol
+ Li+ / -635.50582 / 0.10938 / -635.38464 / -635.43810 / 75.30 / 89.91 / 75.27 / 90.19 / -635.38468 / -635.43829 / 0.00019
Toluene / -269.74016 / 0.13687 / -269.59446 / -269.64109 / 90.69 / 78.41 / 90.69 / 78.41 / -269.59446 / -269.64107 / -0.00002 / 0.37
Toluene
+ Li+ / -277.04405 / 0.13988 / -276.89256 / -276.94504 / 94.32 / 88.25 / 94.19 / 88.15 / -276.89276 / -276.94516 / 0.00012 / 1.19
Triethyl
Amine / -290.37123 / 0.22096 / -290.13590 / -290.19558 / 146.93 / 100.36 / 147.27 / 102.29 / -290.13535 / -290.19616 / 0.00058
Triethyl
Amine + Li+ / -297.68181 / 0.22290 / -297.44245 / -297.50650 / 149.46 / 107.71 / 149.63 / 108.62 / -297.44218 / -297.50674 / 0.00024 / 6.15
Trimethyl
Amine / -173.26930 / 0.12950 / -173.13110 / -173.17433 / 85.98 / 72.70 / 86.11 / 73.41 / -173.13090 / -173.17453 / 0.00020 / -0.53
Trimethyl
Amine + Li+ / -180.57226 / 0.13222 / -180.42932 / -180.47851 / 88.95 / 82.72
Trimethyl
Phosphate / -759.09647 / 0.14534 / -758.93528 / -759.00070 / 100.41 / 110.02 / 100.31 / 110.86 / -758.93544 / -759.00133 / 0.00064 / 0.05
Trimethyl
Phosphate + Li+ / -766.43250 / 0.14723 / -766.26709 / -766.33821 / 103.06 / 119.59 / 102.92 / 120.38 / -766.26730 / -766.33886 / 0.00065
Water / -76.01075 / 0.02298 / -75.98304 / -76.01087 / 16.65 / 46.81 / 0.00
Water
+ Li+ / -83.30932 / 0.02625 / -83.27723 / -83.31164 / 19.40 / 57.87

1

[1]Mohr, P.J.; Taylor,B.N.; Newell,D.B. CODATA recommended values of the fundamental physical constants: 2010. J. Phys. Chem. Ref. Data2012, 41, 67.

[2]Deakin.M.A.B. Successive Discoveriesof the Heaviside Expansion Theorem. Int. J. Math. Educ. Sci. Technol.1986, 17, 51-60.

[3]Buncel,E.; Decouzon,M.; Formento,A.; Gal,J.-F.; Herreros,M.; Li,L.; Maria,P.-C.; Koppel,I.; Kurg,. R. Lithium-Cation and Proton Affinities of Sulfoxides and Sulfones: A Fourier Transform Ion Cyclotron Resonance Study. J. Am. Soc. Mass Spectrom.1996, 8, 262-269.

[4]Buncel,E.; Chen,A.;Decouzon,M.; Ann Fancy,S.; Gal,J.-F.;Herreros,M.; Maria. P.-C. Fourier Transform Ion Cyclotron Resonance Determination of Lithium CationBasicities by the Kinetic Method: Upward Extension of the Scale to Phosphoryl Compounds. J. Mass Spectrom.1998, 33, 757-765.