title: Structural snapshots of a flexible Cu2P2 core that accommodates the oxidation states Cu(I)Cu(I), Cu1.5Cu1.5, and Cu(II)Cu(II).
abstract: The phosphido-bridged dicopper(I) complex {(PPP)Cu}2 has been synthesized and structurally characterized ([PPP]- = bis(2-di-iso-propylphosphinophenyl)phosphide). Cyclic voltammetry of {(PPP)Cu}2 in THF shows fully reversible oxidations at -1.02 V (Cu1.5Cu1.5/CuICuI) and -0.423 V (CuIICuII/Cu1.5Cu1.5). Chemical oxidation of {(PPP)Cu}2 by one electron yields the class III mixed-valence species [{(PPP)Cu}2]+ (EPR, UV-vis). Structural data establish an unexpectedly large change (0.538 A) in the Cu...Cu distance upon oxidation state. Oxidation of {(PPP)Cu}2 by two electrons yields the dication [{(PPP)Cu}2]2+, an antiferromagnetically coupled dicopper(II) complex. Maintenance of a pseudotetrahedral geometry that is midway between a square plane and an ideal tetrahedron at the copper centers, along with a high degree of flexibility at the phosphide hinges, allows for efficient access to CuICuI, Cu1.5Cu1.5, and CuIICuII redox states without the need for ligand exchange, substitution, or redistribution processes.
authors.affiliation: Division of Chemistry and Chemical Engineering, Arnold and Mabel Beckman Laboratories of Chemical Synthesis, California Institute of Technology, Pasadena, California 91125, USA.
authors.forename: Neal P
authors.initials: NP
authors.lastname: Mankad
authors.forename: Eric
authors.initials: E
authors.lastname: Rivard
authors.forename: Seth B
authors.initials: SB
authors.lastname: Harkins
authors.forename: Jonas C
authors.initials: JC
authors.lastname: Peters