Crystal packing motifs for mixed oxalate/phenanthroline metal complexes

Abstract

The preparations and crystal structures of (Ph4P)[Cr(phen)(ox)2](H2O) 1, [Co(phen)2(ox)](BF4) 2 and [Co(phen)2(ox)]I(H2O)2(EtOH)0.53 are described (phen⊕=⊕1,10-phenanthroline, ox⊕=⊕oxalate), and their crystal packing analysed in terms of the crystal supramolecular motifs and multiple aryl embraces. The crystal packing of 1 is determined by embrace motifs involving both the Ph4P+ cation and the anion [Cr(phen)(ox)2]−, principally an eight component concerted embrace (Ph4P+)·{[Cr(phen)(ox)2]−}2·(Ph4P+) comprised of three offset face-to-face (OFF) and six edge-to-face (EF) primary motifs. Complex 2 is dominated by well developed OFF-chain motifs for the phen ligands, reinforced by multiple C–H⋯O hydrogen bonds, to form a strongly hydrophobic lattice crystallising from water. Structure 3 crystallises with an efficient three-dimensional net using all three ligands of [Co(phen)2(ox)]+ in primary embrace motifs, with separate domains for the hydrogen bonded solvent molecules. The analyses identify crystal packing principles, especially the favourability of OFF phen embraces, the segregation of hydrophobic M(phen)n domains, and the prevalence of C–H⋯O hydrogen bonds involving oxalate or water. Predictions about crystal packing are made.