Cd(II) and Pd(II) Mixed Ligand Complexes of Dithiocarbamate and Tertiary Phosphine Ligands-Spectroscopic, Anti-Microbial, and Computational Studies

Mixed ligand complexes of Pd(II) and Cd(II) with N-picolyl-amine dithiocarbamate (PAC-dtc) as primary ligand and tertiary phosphine ligand as secondary ligands have been synthesized and characterized via elemental analysis, molar conductance, NMR (H-1 and P-31), and IR techniques. The PAC-dtc ligand displayed in a monodentate fashion via sulfur atom whereas diphosphine ligands coordinated as a bidentate mode to afford a square planner around the Pd(II) ion or tetrahedral around the Cd(II) ion. Except for complexes [Cd(PAC-dtc)(2)(dppe)] and [Cd(PAC-dtc)(2)(PPh3)(2)], the prepared complexes showed significant antimicrobial activity when evaluated against Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans and Aspergillus niger. Moreover, DFT calculations were performed to investigate three complexes {[Pd(PAC-dtc)(2)(dppe)](1), [Cd(PAC-dtc)(2)(dppe)](2), [Cd(PAC-dtc)(2)(PPh3)(2)](7)}, and their quantum parameters were evaluated using the Gaussian 09 program at the B3LYP/Lanl2dz theoretical level. The optimized structures of the three complexes were square planar and tetrahedral geometry. The calculated bond lengths and bond angles showed a slightly distorted tetrahedral geometry for [Cd(PAC-dtc)(2)(dppe)](2) compared to [Cd(PAC-dtc)(2)(PPh3)(2)](7) due to the ring constrain in the dppe ligand. Moreover, the [Pd(PAC-dtc)(2)(dppe)](1) complex showed higher stability compared to Cd(2) and Cd(7) complexes which can be attributed to the higher back-donation of Pd(1) complex.

Automated summary

Mixed ligand complexes of Pd(II) and Cd(II) with N-picolyl-amine dithiocarbamate (PAC-dtc) as primary ligand and tertiary phosphine ligand as secondary ligands have been synthesized and characterized. The complexes showed significant antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans and Aspergillus niger. DFT calculations were performed to investigate the quantum parameters of three complexes and their geometries were optimized.