Geometrical parameters obtained at the B3LYP, M06-2X, MP2 and CCSD levels of theory.
Table S1. Mg-Cl distances (Å) at the B3LYP/6-311+G(3df,2p) level of theory for MgCl2 and the different Cl2Mg···LB complexes.
Compound / Mg-Cl distance (Å) / Deviation with respect to MgCl2 (Å)MgCl2 / 2.117, 2.117
Cl2Mg···NH3 / 2.218, 2.218 / 0.101, 0.101
Cl2Mg···OH2 / 2.212, 2.212 / 0.095, 0.095
Cl2Mg···FH / 2.182, 2.263 / 0.065, 0.146
Cl2Mg···PH3 / 2.206, 2.210 / 0.089, 0.093
Cl2Mg···SH2 / 2.206, 2.206 / 0.089, 0.089
Cl2Mg···ClH / 2.189, 2.221 / 0.072, 0.104
Cl2Mg···BrH / 2.194, 2.207 / 0.077, 0.090
Distance* / Angle
B3LYP / 6-31+G(d) / 6-311+G(3df,2p) / 6-31+G(d) / 6-311+G(3df,2p)
Cl2Mg···FH / 2.070 / 2.065 / 155.6 / 155.5
Cl2Mg···ClH / 2.638 / 2.603 / 158.7 / 157.3
Cl2Mg···BrH / 2.767 / 2.777 / 158.0 / 157.7
Cl2Mg···OH2 / 2.053 / 2.041 / 154.9 / 153.9
Cl2Mg···SH2 / 2.637 / 2.638 / 154.1 / 153.7
Cl2Mg···NH3 / 2.161 / 2.157 / 148.8 / 148.5
Cl2Mg···PH3 / 2.700 / 2.694 / 152.2 / 152.3
Table S2. Mg···Y bond distances (Å) and Cl-Mg-Cl angles (º) in Cl2Mg···LB complexes (Y linking atom from LB) at the B3LYP/6-31+G(d) and B3LYP/6-311+G(3df.2p) levels of theory.
*Average distance deviation on going from 6-31+G(d) to 6-311+G(3df.2p) basis set: 0.007 Å.
Table S3. Mg···Y bond distances (Å) and Cl-Mg-Cl angles (º) in Cl2Mg···LB complexes (Y linking atom from LB) at the M06-2X/6-31+G(d) and M06-2X/6-311+G(3df.2p) levels of theory.
Distance* / AngleM06-2X / 6-31+G(d) / 6-311+G(3df,2p) / 6-31+G(d) / 6-311+G(3df,2p)
Cl2Mg···FH / 2.042 / 2.033 / 156.2 / 155.3
Cl2Mg···ClH / 2.564 / 2.543 / 158.4 / 158.2
Cl2Mg···BrH / 2.706 / 2.711 / 157.4 / 158.4
Cl2Mg···OH2 / 2.018 / 2.003 / 156.2 / 155.6
Cl2Mg···SH2 / 2.583 / 2.583 / 154.4 / 154.8
Cl2Mg···NH3 / 2.133 / 2.126 / 149.1 / 149.2
Cl2Mg···PH3 / 2.661 / 2.652 / 153.0 / 153.5
*Average distance deviation on going from 6-31+G(d) to 6-311+G(3df.2p) basis set: 0.008 Å.
Table S4. Mg···Y bond distances (Å) and Cl-Mg-Cl angles (º) in Cl2Mg···LB complexes (Y linking atom from LB) at the MP2/6-31+G(d) and MP2/6-311+G(3df.2p) levels of theory.
Distance* / AngleMP2 / 6-31+G(d) / 6-311+G(3df,2p) / 6-31+G(d) / 6-311+G(3df,2p)
Cl2Mg···FH / 2.090 / 2.079 / 156.2 / 156.3
Cl2Mg···ClH / 2.584 / 2.586 / 157.8 / 158.7
Cl2Mg···BrH / 2.764 / 2.744 / 158.1 / 158.8
Cl2Mg···OH2 / 2.055 / 2.042 / 155.6 / 155.1
Cl2Mg···SH2 / 2.597 / 2.616 / 153.9 / 155.3
Cl2Mg···NH3 / 2.162 / 2.158 / 149.7 / 149.7
Cl2Mg···PH3 / 2.678 / 2.682 / 151.8 / 153.8
*Average distance deviation on going from 6-31+G(d) to 6-311+G(3df.2p) basis set: 0.003 Å.
Table S5. Mg···Y bond distances (Å) and Cl-Mg-Cl angles (º) in Cl2Mg···LB complexes (Y linking atom from LB) at the CCSD/6-31+G(d) level of theory.
CCSD / Distance / AngleCl2Mg···FH / 2.090 / 156.7
Cl2Mg···ClH / 2.592 / 157.8
Cl2Mg···BrH / 2.769 / 157.8
Cl2Mg···OH2 / 2.053 / 155.1
Cl2Mg···SH2 / 2.603 / 153.6
Cl2Mg···NH3 / 2.161 / 149.4
Cl2Mg···PH3 / 2.677 / 151.5
*Average distance deviation with respect to B3LYP/6-31+G(d): 0.018 Å, M06-2X/6-31+G(d): 0.034 Å, MP2/6-31+G(d): 0.003 Å.
Interaction and binding energies obtained at the B3LYP, M06-2X, MP2 and CCSD(T)//CCSD levels of theory.
Table S6. Interaction and binding energies (kJ/mol) at the B3LYP/6-31+G(d) and B3LYP/6-311+G(3df,2p) levels of theory.
Int E / Binding EB3LYP / 6-31+G(d) / 6-311+G(3df,2p) / 6-31+G(d) / 6-311+G(3df,2p)
Cl2Mg···FH / -75.9 / -75.7 / -59.4 / -58.4
Cl2Mg···ClH / -38.3 / -39.3 / -31.1 / -30.5
Cl2Mg···BrH / -38.5 / -35.8 / -30.9 / -28.1
Cl2Mg···OH2 / -106.3 / -104.5 / -95.0 / -92.2
Cl2Mg···SH2 / -62.1 / -60.1 / -51.5 / -49.2
Cl2Mg···NH3 / -129.4 / -125.3 / -113.8 / -109.3
Cl2Mg···PH3 / -67.3 / -63.9 / -51.0 / -47.7
Table S7. Interaction and binding energies (kJ/mol) at the M06-2X/6-31+G(d) and M06-2X/6-311+G(3df,2p) levels of theory.
Int E / Binding EM062X / 6-31+G(d) / 6-311+G(3df,2p) / 6-31+G(d) / 6-311+G(3df,2p)
Cl2Mg···FH / -83.9 / -83.8 / -72.8 / -70.9
Cl2Mg···ClH / -54.9 / -55.6 / -48.4 / -48.4
Cl2Mg···BrH / -55.5 / -52.6 / -48.7 / -45.9
Cl2Mg···OH2 / -124.6 / -122.1 / -115.4 / -111.6
Cl2Mg···SH2 / -79.0 / -76.9 / -70.0 / -67.6
Cl2Mg···NH3 / -148.3 / -143.3 / -134.9 / -129.4
Cl2Mg···PH3 / -81.2 / -78.8 / -66.6 / -64.3
Table S8. Interaction and binding energies (kJ/mol) at the MP2/6-31+G(d) and MP2/6-311+G(3df,2p) levels of theory.
Int E / Binding EMP2 / 6-31+G(d) / 6-311+G(3df,2p) / 6-31+G(d) / 6-311+G(3df,2p)
Cl2Mg···FH / -65.7 / -72.8 / -58.2 / -53.3
Cl2Mg···ClH / -37.9 / -45.4 / -37.8 / -30.1
Cl2Mg···BrH / -39.7 / -43.9 / -36.9 / -32.1
Cl2Mg···OH2 / -106.6 / -109.1 / -97.9 / -95.8
Cl2Mg···SH2 / -62.8 / -66.7 / -57.1 / -51.5
Cl2Mg···NH3 / -131.2 / -130.8 / -116.2 / -113.8
Cl2Mg···PH3 / -70.4 / -71.3 / -56.4 / -54.5
Table S9. Interaction and binding energies (kJ/mol) at the CCSD(T)/6-31+G(d)//CCSD/6-31+G(d) level of theory and absolute deviations of the B3LYP, M06-2X and MP2 values with the same basis set from the CCSD(T) ones.
CCSD(T)/6-31G(d)//CCSD/6-31+G(d) / Int E / B3LYP
deviation / M06-2X
deviation / MP2
deviation
Cl2Mg···FH / -63.1 / 12.8 / 20.9 / 2.7
Cl2Mg···ClH / -36.5 / 1.8 / 18.3 / 1.3
Cl2Mg···BrH / -38.5 / 0.0 / 17.1 / 1.2
Cl2Mg···OH2 / -113.8 / 1.1 / 19.4 / 1.4
Cl2Mg···SH2 / -61.2 / 0.9 / 17.8 / 1.6
Cl2Mg···NH3 / -134.6 / 1.9 / 20.8 / 3.7
Cl2Mg···PH3 / -67.3 / 0.4 / 13.5 / 2.7
Average (kJ/mol) / 2.7* / 18.2 / 2.1*
*The average deviation of B3LYP is somehow altered by the FH value (see note below). The average deviation with respect to CCSD(T) is only 1.0 kJ/mol if this value is not considered, whereas the MP2 one remains almost unchanged. See the note below.
Note on Table S9. It is interesting to note that B3LYP/6-31+G(d) interaction energies are in excellent agreement with the corresponding CCSD(T)/6-31+G(d)//CCSD/6-31+G(d) values, with the only exception of the HF complex. However, looking at the MP2 interaction energy on changing the basis set (from -65.7 to -72.8 kJ/mol), it seemsreasonable to think that the CCSD(T)/6-31+G(d) value (-63.1 kJ/mol) could beunderestimated. In general, these complexes are not severely affected by the change of the basis set, as seen in Tables S5-S7, but the HF complex might be an exception. To check this point, we carried out a more expensive CCSD(T)/6-311+G(3df,2p)//CCSD/6-311+G(3df,2p) calculation for the HF complex, obtaining a significantly larger value of -69.2 kJ/mol.
AIM charges
Table S10.AIM charges at the B3LYP/6-311+G(3df,2p) level of theory.
Lewis base / Mg charge / Y chargeNH3 / +1.68 / -1.10
H2O / +1.70 / -1.27
HF / +1.70 / -0.80
PH3 / +1.66 / 1.41
H2S / +1.67 / -0.02
HCl / +1.68 / -0.33
HBr / +1.67 / -0.13
Magnesium bonds visualized through NCIPLOT.
Figure S1. Linear correlation between the length of the magnesium bonds and the electron density at the corresponding Mg-Cl bond critical point (BCP). The linear regression obeys the equation, RMgCl = 8.9036 BCP + 2.6801, r2 = 0.976.
Cartesian coordinates.Cartesian coordinates for all Cl2Mg···LB (LB=NH3, H2O, HF, HCl, HBr, H2S, PH3) at the B3LYP/6-311+G(3df,2p) level of theory are listed:
Cl2Mg···NH3
Mg -0.000008 -0.040004 0.005466
Cl -2.134214 -0.642508 -0.001895
Cl 2.134082 -0.642951 -0.001882
N 0.000341 2.117069 -0.001495
H -0.822701 2.485557 -0.470065
H -0.000091 2.508861 0.936237
H 0.824066 2.485164 -0.469173
Cl2Mg···OH2
Mg 0.000000 0.000000 0.083178
Cl 0.000148 2.154507 0.582067
Cl -0.000148 -2.154507 0.582067
O 0.000000 0.000000 -1.957682
H -0.000008 0.787652 -2.510411
H 0.000008 -0.787652 -2.510411
Cl2Mg···FH
Mg 0.001353 0.181847 0.000000
Cl 0.184819 2.356246 0.000000
Cl -1.106684 -1.791015 0.000000
H 0.973152 -1.829796 0.000000
F 1.614782 -1.107524 0.000000
Cl2Mg···PH3
Mg -0.155049 -0.484451 -0.000101
Cl 1.823278 -1.469097 -0.000037
Cl -2.360597 -0.533067 -0.000152
H 1.378202 2.555918 1.061595
H 1.380574 2.555422 -1.059587
H -0.368239 3.159970 -0.001056
P 0.568778 2.110699 0.000199
Cl2Mg···SH2
Mg -0.000004 -0.478700 -0.025523
Cl -2.148544 -0.978923 0.013093
Cl 2.148530 -0.978947 0.013096
H -0.983600 2.372841 0.782620
H 0.983630 2.372827 0.782621
S 0.000014 2.158302 -0.107283
Cl2Mg···ClH
Mg -0.030148 0.475702 0.000000
Cl -1.985943 1.459550 0.000000
Cl 2.185242 0.321886 0.000000
H 1.040223 -2.022383 0.000000
Cl -0.253858 -2.118114 0.000000
Cl2Mg···BrH
Mg 0.000000 1.043795 0.000000
Cl -2.100045 1.680166 0.000000
Cl 2.197555 1.251560 0.000000
H 1.345752 -1.738390 0.000000
Br -0.085812 -1.732186 0.000000