Abstract/Summary

New functionalized homoleptic dithiocarbamates of the form [M(L)2] (M = Ni(II), L = L1, N-(3-methoxybenzyl)-N-(methylbenzyl)dithiocarbamate (1), L3, N-(3,4,5-trimethoxybenzyl)-N-(3-methylpyridyl)dithiocarbamate (3), L4, N-(4-methoxybenzyl)-N-benzyldithiocarbamate (4); Pd(II), L2, N-(N′-methyl-2-pyrrole)-N-benzyldithiocarbamate (2)) have been synthesized and characterized by microanalysis and their structures have been investigated using X-ray crystallography. All the four structures are centrosymmetric with the metal located in a square plane with minor distortions, Pd(II) greater than Ni(II). The crystal structures of 1 and 2 revealed the existence of unique intermolecular C–H⋯M (Ni, Pd) anagostic interactions between the methylene hydrogen atom on the ligand substituents and the metal centres and these enable the formation of 1-D polymeric chains. Particularly, geometric parameters (Pd⋯H–C = 2.61 Å; ∠Pd⋯H–C = 173°) for the C–H⋯Pd interactions in 2 are at the border of anagostic and hydrogen bonding. By contrast, 4 shows interactions between the methylene hydrogen atom and the CS2Ni ring rather than the metal alone, while the interaction in 3 is intermediate between the two aforementioned types. These interactions are not shown in solution as revealed by their 1H NMR studies. DFT calculations have been performed to analyse these rare interactions. 1, 3 and 4 are weakly conducting, σrt = 10−10–10−12 S cm−1, and show semiconductor behaviour in the 313–373 K range.