title: Are formal oxidation states above one viable in cyclopentadienylcopper cyanides?
abstract: Recent experiments have led to the discovery of the thermally unstable organocopper compounds (η(3)-C(3)H(5))CuMe(2), [(η(3)-C(3)H(5))CuMe(3)](-), and CuMe (4)(-) in which the copper atom is in the +3 formal oxidation state. In a quest for more stable organocopper compounds with copper in formal oxidation states above one, the binuclear cyclopentadienylcopper cyanides Cp(2)Cu(2)(CN)(n) (Cp = η(5)-C(5)H(5); n = 1, 2, 3) have been studied using density functional theory (DFT). The lowest energy structures are found to have terminal Cp rings and bridging cyanide ligands up to a maximum of two bridges. Higher-energy Cp(2)Cu(2)(CN)(n) (n = 1, 2, 3) structures are found with bridging Cp rings. The Cp(2)Cu(2)(CN)(3) derivatives, with the copper atoms in an average +2.5 oxidation state, are clearly thermodynamically disfavored with respect to cyanogen loss. However, Cp(2)Cu(2)(CN)(2) and Cp(2)Cu(2)(CN), with the copper atoms in the average oxidation states +1.5 and +2, respectively, are predicted to have marginal viability. The prospects for the copper(II) derivative Cp(2)Cu(2)(CN)(2) contrast with that of the "simple" Cu(CN)(2), which is shown both experimentally and theoretically to be unstable with respect to cyanogen loss to give CuCN.
authors: Key Laboratory of Cluster Science, Ministry of Education of China, Department of Chemistry, Beijing Institute of Technology, Beijing, Peoples Republic of China.
authors: Congzhi
authors: C
authors: Wang
authors: Xiuhui
authors: X
authors: Zhang
authors: Qian-shu
authors: QS
authors: Li
authors: Yaoming
authors: Y
authors: Xie
authors: R Bruce
authors: RB
authors: King
authors: Henry F
authors: HF
authors: Schaefer
mesh_terms: D056831:Coordination Complexes / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D003486:Cyanides / Q000737:chemistry*; D003517:Cyclopentanes / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D010084:Oxidation-Reduction; D011789:Quantum Theory; D013816:Thermodynamics
chemical_list: D056831:Coordination Complexes; D003486:Cyanides; D003517:Cyclopentanes; D003300:Copper