Self-assembly of dialkyltin moieties and mercaptobenzoic acid into macrocyclic complexes with hydrophobic "pseudo-cage" or double-cavity structures: supramolecular infrastructures involving intermolecular C-H...S weak hydrogen bonds and pi-pi interactions

Four novel organotin complexes of two types--R2Sn(o-SC6H4CO2)]6 (R = Me, 1 x H2O; nBu, 2) and {R2Sn(m-CO2C6H4S)R2Sn(m-SC6H4CO2)SnR2]O}2 (R = Me, 3; nBu, 4)--have been prepared by treatment of o- or m-mercaptobenzoic acid and the corresponding R2SnCl2 (R = Me, nBu) with sodium ethoxide in ethanol (95%). All the complexes were characterized by elemental analysis, FT-IR and NMR (1H, (3C, 119Sn) spectroscopy, TGA, and X-ray crystallography diffraction analysis. The molecular structure analyses reveal that both 1 and 2 are hexanuclear macrocycles with hydrophobic "pseudo-cage" structures, while 3 and 4 are hexanuclear macrocycles with double-cavity structures. Furthermore, the supramolecular structure analyses show that looser and more intriguing supramolecular infrastructures were also found in complexes 1-4, which exist either as one-dimensional chains of rings or as two-dimensional networks assembled from the organometallic subunits through intermolecular C-H...S weak hydrogen bonds (WHBs) and pi-pi interactions.