Supplimentary Information:
The Hirshfeld surfaces of the complexes are illustrated in Figure S3 and Figure S4, showing surfaces that have been mapped over a dnorm (range of -0.5 to 1.5 Å), shape index and curvedness. The surfaces are shown as transparent to allow visualization of the molecular moiety, in a similar orientation for all structures, around which they were calculated.
The fingerprint plots highlights the complementary regions where one molecule act as donor (de > di) and the other as an acceptor (de < di). The fingerprint plots can be decomposed to highlight particular atom pair close contacts. This decomposition enables separation of contributions from different interaction types, which overlap in the full fingerprint. The S•••H/H•••S intermolecular interactions appear as distinct spikes in the 2D fingerprint plot [Figures S3 and S4] in all the thiocyanate complexes with 12.2% and 16.3% of the Hirshfeld surfaces for each molecule of complexes 1 and 2 respectively. The S•••H interactions are represented by a significant spike with di as 1.743, 1.813 Å and de as 1.056, 1.142 Å respectively in the bottom left (donor) area of the fingerprint plots indicating H-atoms of Schiff bases are interacting with S-atom of the thiocyanate group for same series of molecules. The H•••S interactions are represented by another common spike with di as 1.051, 1.142 Å and de as 1.743, 1.818 Å respectively in the bottom right (acceptor) region of all the fingerprint plots for same series of molecules [Figures S3 and S4], where thiocyanate nitrogen also acts as acceptor to the H atoms of the Schiff base of another molecule.
In complex 2, O•••H/H•••O interactions comprises 4% and Cu•••N/N•••Cu interactions comprises 1.6% of the Hirshfeld surfaces for each molecule. The O•••H interactions and H•••O interactions are represented by two different spikes with (di = 1.272, de = 0.931Å) in the bottom left (donor) area of the fingerprint plot and (di = 0.931, de = 1.267 Å) in the bottom right (acceptor) region of Fingerprint plot (Figure S4) respectively, indicating aminal H-atoms of Schiff base are interacting with Phenolic O-atom of the Schiff base of another molecule and these oxygen-based interactions represent the closest supramolecular contacts in the structures which is an hydrogen bonding interaction in nature and can be viewed as a pair of large red spots on the dnorm surface (Figure S4(e)). The Cu•••N and N•••Cu interactions are represented by another two different spikes with (di = 1.372, de = 1.322 Å) in the bottom left (donor) area of the fingerprint plot and (di = 1.322, de = 1.377 Å) in the bottom right (acceptor) region of Fingerprint plot (Figure S4(f)) respectively, indicating N-atoms of thiocyanate are interacting with copper atom of the of another molecule which is quite obvious for this type of dimeric complex and can be viewed as a pair of red spots on the dnorm surface (Figure S4(f)).
Legends to the Figures:
Figure S1: A plot of absorbance at 389 nm against mole ratio of reactants having different molar concentration of metal (Cu2+) ion and ligand (HL1). [NaSCN] = 0.5 mM, Temp = 25ºC.
Figure S2: A plot of absorbance at 381 nm against mole ratio of reactants having different molar concentration of metal (Cu2+) ion and ligand (HL2). [NaSCN] = 0.5 mM, Temp = 25ºC.
Figure S3: Hirshfeld surfaces mapped with (a) dnorm, (b) curvedness, (c) shape index and 2D Fingerprint plot of (d) S⋯H/H⋯S contacts showing the percentage of contact contributed to the total Hirshfeld Surface area of a molecule for complex 1 where, full fingerprint is shown in the background.
Figure S4: Hirshfeld surfaces mapped with (a) dnorm, (b) curvedness, (c) shape index and 2D Fingerprint plot of (d) S⋯H/H⋯S, (e) O⋯H/H⋯O with interaction spot on dnorm, (f) Cu⋯N/N⋯Cu with interaction spot on dnorm contacts showing the percentage of contact contributed to the total Hirshfeld Surface area of a molecule for complex 2 where, full fingerprint is shown in the background.
Figure S1
Figure S2
Figure S3