Ferrocene-Functionalized Dithiocarbamate Zinc(II) Complexes as Efficient Bifunctional Catalysts for the One-Pot Synthesis of Chromene and Imidazopyrimidine Derivatives via Knoevenagel Condensation Reaction.

Four new mononuclear/coordination polymeric (CP) zinc(II) complexes (-) of ferrocenyl/pyridyl-functionalized dithiocarbamate ligands, -ferrocenylmethyl--butyl dithiocarbamate (), -ferrocenylmethyl--ethylmorpholine dithiocarbamate (), -ferrocenylmethyl--2-(diethylamino)ethylamine dithiocarbamate (), and -4-methoxybenzyl--3-methylpyridyl dithiocarbamate (), have been synthesized and characterized by elemental analyses, IR, UV-vis, and H and C{H} NMR spectroscopic techniques. The solid-state structures of complexes , , and have been determined by single-crystal X-ray crystallography as well as powder X-ray diffraction. Single-crystal X-ray crystallography revealed a monomeric structure for complex but 1D polymeric structures for complexes and . In all complexes, dithiocarbamate ligands are bonded to the Zn(II) metal ion in a S^S chelating mode, and in the CPs, N atoms on the 2-(diethylamino)ethylamine and 3-pyridyl functionalities in the ligands on the neighboring molecules are also bonded to metal centers, leading to the formation of either a discrete tetrahedral molecule in or 1D CP structures in and . The Zn(II) metal centers in the polymeric structures exhibited either square-pyramidal or octahedral geometries. The supramolecular structures in these complexes are sustained via C-H···π (ZnCS, chelate; and ), C-H···π, and H···H interactions. The catalytic performances of complexes have also been assessed in the Knoevenagel condensation and one-pot multicomponent reactions. Catalysis results showed that the CP acts as a heterogeneous bifunctional catalyst with excellent transformation efficiency at low catalyst loading.