A Unique μ‐dichloro‐Bridged Butterfly‐shaped Dimer: Synthesis and Crystal Structure of [Cu(bpmh)Cl₂]₂ (bpmh=2,2′‐bipyridyl‐3‐carbomethoxy‐3′‐formylhydrazine), Roles of π–π Interaction and Steric Hindrance Effect in Crystal Packing

Abstract

The title complex, [Cu(bpmh)Cl₂]₂, was formed from Cu(II) with 2,2′‐bipyridyl‐3‐ carbomethoxy‐3′‐formyhydrazine (bpmh), by‐product of the reaction of 2,2′‐bipyridyl‐3,3′‐dicarbomethoxy (bpdc) with hydrazine hydrate, during the preparation of the copper(II) complex of bpdh (bpdh=2,2′‐bipyridyl‐3,3′‐diformylhydrazine) in acetone. The structure of [Cu(bpmh)Cl₂]₂ has been determined by X‐ray diffraction analysis as a μ‐dichloro‐bridged, butterfly‐shaped dimer. The dimer unit, [Cu(bpmh)Cl₂]₂, crystallizes in the monoclinic space group C2/c. The geometry of the copper centers is tetragonal‐pyramidal with two chlorine atoms and two pyridine nitrogen atoms in the base and one bridged chlorine atom at the apex. The values of the bridging angle, out‐of‐plane Cu(1B)‐Cl(2A) distance, and Cu(1)‐Cu(1A) separation are 87.7°, 2.881 Å and 3.584 Å, respectively. The crystal packing pattern of [Cu(bpmh)Cl₂]₂ is influenced by π−π interaction and steric hindrance.

Keywords:

• Crystal structure
• dichloro‐bridged dimeric copper
• π−π interaction
• steric hindrance effect

Acknowledgments

We thank the Natural Science Foundation of China (20271046), the Natural Science Foundation of Henan Education Department (20011500001), and the Natural Science Foundation of Henan Province (0211020300) for the support.