Influence of ligand substituent on structural assembly and coordination geometry

Abstract

In this study, N-(aryl)-2-pyrazinecarboxamide ligands with two different aryl groups (o-anisidyl, LOMe, and o-phenitidyl, LOEt, groups) have been employed for the synthesis of six Hg(II) complexes, [HgCl2(LOMe)2]n, 1, [HgBr2(LOMe)]n, 2, [HgI2(LOMe)]n, 3, [Hg3Cl6(LOEt)3·HgCl2(LOEt)], 4, [HgBr2(LOEt)], 5, and [HgI2(LOEt)], 6, in order to get insights into the substituent effects on the molecular architecture of complexes. Structural analysis of mercury(II) halides containing LOMe ligand demonstrated that the assembly process produced an infinite 1D linear chain, 1D double chain and 1D ladder chain in 1, 2 and 3 respectively. Structural analysis showed that compounds 4–6 have non-polymeric structures. 4 resulted in a trimeric/monomeric motif while isostructural 5 and 6 compounds formed a discrete three coordinated mercury compound. Our results show that when compared to the LOMe substituent, the steric properties of the LOEt group significantly alter the molecular architecture and coordination sphere of complexes.