Synthesis, NMR spectral and structural studies on mixed ligand complexes of Pd(II) dithiocarbamates: First structural report on palladium(II) dithiocarbamate with SCN^-ligand

Three new mixed ligand complexes of palladium(II) dithiocarbamates; [Pd(4-dpmpzdtc)(PPh₃)(SCN)] (1), [Pd(4-dpmpzdtc)(PPh₃)Cl] (2) and [Pd(bzbudtc)(PPh₃)Cl] (3), (where, 4-dpmpzdtc = 4-(diphenylmethyl)piperazinecarbodithioato anion, bzbudtc = N-benzyl-N-butyldithiocarbamato anion and PPh₃ = triphenylphosphine) have been synthesized from their respective parent dithiocarbamates by ligand exchange reactions and characterized by IR and NMR (¹H, ¹³C and ³¹P) spectroscopy. IR and NMR spectral data support the isobidentate coordination of the dithiocarbamate ligands in all complexes (1-3) in solid and in solution, respectively. Single crystal diffraction analysis of complexes 1-3 evidences that all three complexes are exhibiting distorted square planar geometry. The Pd-S distances in 1-3 vary in accordance with the differences in trans influences of PPh₃, SCN^- and Cl^- and it is in the order of PPh₃ > SCN^- > and Cl^-. Interchange of the anionic auxiliary ligand (SCN^- to Cl^-) induces asymmetry to the dithiocarbamate-metal bonds. Thioureide C-N bond distances are short in 1-3, supporting a contribution of thioureide form to the structures. The observed distortions in the square planar geometry for 1-3, are in the order of 1 > 2 > 3.