Complexes of Copper with a Flexible Bis-benzimidazole Ligand

Abstract

The flexible bidentate ligand 1,3-bis(benzimidazol-2-yl)propane, L³, and its N-methylated derivative L⁴, form complexes with CU^I and CU^II. The X-ray crystal structure of [Cu(L⁴)(MeCN)] (PF₆) (1) shows a trigonal coordination of the Cu^I with the eight-membered chelate ring adopting a half-chair conformation. With Cu^II in EtOH, L³ forms dimeric [(L³)Cu(μ-EtO)2Cu(L³)](ClO₄)₂ · 2EtOH (2) whose X-ray crystal structure shows Cu^II in a distorted square-planar environment with one bidentate ligand and two bridging ethoxides. The chelate ring now has a boat-chair conformation which forms a hydrophobic pocket around the metal.