title: C- and Z-shaped coordination compounds. synthesis, structure, and spectroelectrochemistry of cis- and trans-[Re(CO)3(L)]2-2,2'-bisbenzimidizolate with L = 4-phenylpyridine, 2,4'-bipyridine, or pyridine.
abstract: A series of C- and Z-shaped complexes of the form cis- and trans-[Re(CO)3(L)]2BiBzIm, where L = 4-phenylpyridine, 2,4'-bipyridine, or pyridine and BiBzIm = 2,2'-bisbenzimidizolate, have been synthesized by the reaction of [Re(CO)4]2BiBzIm with a slight excess of L in refluxing tetrahydrofuran. Five of the six compounds have been isolated and crystallographically and electrochemically characterized. Formation of the sixth, the cis form of the [Re(CO)3(4-phenylpyridine)]2BiBzIm, is evidently inhibited by the torsional steric demands of proximal 4-phenylpyridines. The compounds are acyclic analogues of recently studied tetrarhenium molecular rectangles and are of interest, in part, because of their potential to form ligand-centered mixed-valence (LCMV) compounds upon reduction by one electron. Spectroelectrochemical measurements corroborated the formation of a LCMV version of cis-[Re(CO)3(L)]2BiBzIm but failed to uncover a ligand-based intervalence transition. Electrochemical measurements revealed isomer-dependent L/L electrostatic effects, resulting in greater mixed-valence ion comproportionation for C-shaped assemblies versus Z-shaped assemblies.
authors.affiliation: Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, USA.
authors.forename: Peter H
authors.initials: PH
authors.lastname: Dinolfo
authors.forename: Kurt D
authors.initials: KD
authors.lastname: Benkstein
authors.forename: Charlotte L
authors.initials: CL
authors.lastname: Stern
authors.forename: Joseph T
authors.initials: JT
authors.lastname: Hupp