Bimetallic and trimetallic Cd(II) and Hg(II) mixed-ligand complexes with 1,1-dicyanoethylene-2,2-dithiolate and polyamines: Synthesis, crystal structure, Hirshfeld surface analysis, and antimicrobial study

Abstract

Two new neutral bimetallic and trimetallic mixed-ligand complexes of Cd(II) and Hg(II) were obtained by using potential flexible molecular building blocks, 1,1-dicyanoethylene-2,2-dithiolate dipotassium salt (K2i-mnt) and polyamines. X-ray diffraction analysis revealed that dithiolate (i-mnt−2) acts as a bridging unit in the slightly distorted square pyramidal non-polymeric bimetallic cadmium derivative [Cd2(tn)2(i-mnt)2] (1). The tri-metallic Hg(II) based cocrystallized aggregates of [Hg2(tren)(i-mnt)2] and [Hg(tren)(i-mnt)](2), has three different coordination environments around Hg(II) metal centers and one thiolate end of i-mnt−2 links two Hg atoms in bridging mode. The N–H⋯S, N–H⋯N, C–H⋯S and C–H⋯N type hydrogen bonds contribute in crystal packing architecture, revealing interesting geometrical patterns and graph-set-motifs. The Hirshfeld surface mapped over dnorm exhibited N⋯H/H⋯N type intermolecular interactions as the principal contributors in crystal packing. The in-vitro antimicrobial study evaluated by disk diffusion and broth dilution method with the compounds 1,2 and ligand K2i-mnt against Gram-positive (Staphylococcus aureus 9542 and Streptococcus pneumonia 2672) and Gram-negative (Klebsiella pneumonia 7407 and Shigella flexneri 1457) human pathogenic bacterial strains show their promising antimicrobial activities.