Effect of ligand steric bulk on coordination geometry of pyridine adducts of cadmium(II) carbamodithioates

Pyridine adducts of four different carbodithiolate cadmium compounds [Cd (2-mpipdtc)2(py)] (5); [Cd (4-mpipdtc)2(py)2] (6); [Cd(thqdtc)2(py)] (7) and [Cd(padtc)2(py)2] (8) have been successfully prepared and analysed by using Infrared and nuclear magnetic resonance spectroscopies and single crystal X-ray structural analysis. The N 13CS2 carbon signal for 5 and 6 noticed at 202.7 and 202.9 ppm due to an upfield shift of about 5 ppm matched with that found in 7 (208.2 ppm) and 8 (208.5 ppm). The observed shielding in 5 and 6 expresses the more electron density movement from 2-mpipdtc and 4-mpipdtc to cadmium and closer approach of the 2-mpipdtc & 4-mpipdtc and cadmium. Single crystal X-ray structural analysis showed that the structural pat-terns of [Cd (2-mpipdtc)2(py)], [Cd (4-mpipdtc)2(py)2], [Cd(thqdtc)2(py)] and [Cd(padtc)2(py)2] compounds are mononuclear distorted trigonal bipyramidal, mononuclear distorted octahedral, dimeric distorted octahedral and mononuclear highly distorted octahedral i.e. trigonal prismatic geometry, respectively. The variation in structure is due to the steric influence of organic substituents of corresponding ligands as well as the size of metal. This point is also supported by bond valence sum analysis.