title: Synthesis, structure, and dissociation equilibrium of [Co(eta5-C5H5)(Se2C6H4)]2, a novel metalladiselenolene complex.
abstract: A (phenylenediselenolato)cobalt complex dimer, [Co(eta(5)-C(5)H(5))(Se(2)C(6)H(4))](2) (1), was synthesized by a reaction of carbonyl(eta(5)-cyclopentadienyl)diiodocobalt(III) ([Co(eta(5)-C(5)H(5))I(2)(CO)]) with poly(o-diselenobenzene). The structure of 1, determined by single-crystal X-ray crystallography, was found to be located in the space group of P2(1)/c (No. 14), with a = 9.3346(5) A, b = 11.6477(9) A, c = 10.2179(5) A, beta = 111.491(1) degrees, and Z = 2. Covalent Co-Se bonds bridge the metal centers. In solution, dimers and monomers coexist at equilibrium. The dissociation equilibrium constant of 1 in solution was evaluated by (1)H NMR spectra at several temperatures between 20 and 80 degrees C. Dissociation enthalpies/entropies were found to be 50/110, 60/120, and 88 kJ mol(-1)/200 J K(-1) mol(-1) in dimethyl sulfoxide-d(6), benzene-d(6), and chloroform-d(1), respectively.
authors.affiliation: Department of Chemistry, School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Habe
authors.forename: Teppei
authors.initials: T
authors.lastname: Yamada
authors.forename: Takuya
authors.initials: T
authors.lastname: Nankawa
authors.forename: Jun
authors.initials: J
authors.lastname: Mizutani
authors.forename: Masaki
authors.initials: M
authors.lastname: Murata
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nishihara