title: Probing the Reactivity of the Ce═O Multiple Bond in a Cerium(IV) Oxo Complex.
abstract: The reactivity of the cerium(IV) oxo complex [(LOEt)2CeIV(═O)(H2O)]·MeC(O)NH2(1; LOEt-= [CoCp{P(O)(OEt)2}3]-, where Cp = η5-C5H5) toward electrophiles and Brønsted acids has been investigated. The treatment of 1 with acetic anhydride afforded the diacetate complex [CeIV(LOEt)2(O2CMe)2] (2). The reaction of 1 with B(C6F5)3yielded [CeIV(LOEt)2(Me2CONH2)2][B(C6F5)3(OH)]2(3), in which the [B(C6F5)3(OH)]-anions are H-bonded to the O-bound acetamide ligands. The treatment of 1 with HCl and HNO3afforded [CeIV(LOEt)2Cl2] and [CeIV(LOEt)2(NO3)2], respectively. Protonation of 1 with triflic acid (HOTf) gave the diaqua complex [CeIV(LOEt)2(H2O)2](OTf)2(4), in which the triflate anions are H-bonded to the two aqua ligands. The treatment of 1 with phenol afforded the phenoxide complex [CeIV(LOEt)2(OPh)2] (5). The oxo-bridged bimetallic complex [(LOEt)2(Me2CONH2)CeIV(O)NaLOEt] (6) with the Ce-Ooxoand Na-Ooxodistances of 1.953(4) and 2.341(4) Å, respectively, was obtained from the reaction of 1 with [NaLOEt]. Density functional theory calculations showed that the model complex [(LOMe)2CeIV(Me2CONH2)(O)NaLOMe] (6A; LOMe-= [CoCp{P(O)(OMe)2}3]-) contains a polarized Ce═O multiple bond. The energy for dissociation of the {NaLOMe} fragment from 6A in acetonitrile was calculated to be +33.7 kcal/mol, which is higher than that for dissociation of the H-bonded acetamide from [(LOMe)2CeIV(═O)(H2O)]·MeC(O)NH2(1A) (calculated to be +17.4 kcal/mol). In hexanes containing trace water, complex 1 decomposed readily to a mixture of a tetranuclear cerium(IV) oxo cluster, [CeIV4(LOEt)4(μ4-O)(μ2-O)4(μ2-OH)2] (7), and a cerium(III) complex, [CeIII(LOEt)2(H2O)2][LOEt] [8(LOEt)], whereas the cerium/sodium oxo complex 6 is stable under the same conditions. The crystal structures of 3, 4·H2O, 6, and 8(LOEt) have been determined.
authors.affiliation: Department of Chemistry, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong, P. R. China.
authors.forename: Yat-Ming
authors.initials: YM
authors.lastname: So
authors.affiliation: Department of Chemistry, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong, P. R. China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Chemistry, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong, P. R. China.
authors.forename: Ka-Chun
authors.initials: KC
authors.lastname: Au-Yeung
authors.affiliation: Department of Chemistry, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong, P. R. China.
authors.forename: Guo-Cang
authors.initials: GC
authors.lastname: Wang
authors.affiliation: Department of Chemistry, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong, P. R. China.
authors.forename: Kang-Long
authors.initials: KL
authors.lastname: Wong
authors.affiliation: Department of Chemistry, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong, P. R. China.
authors.forename: Herman H Y
authors.initials: HH
authors.lastname: Sung
authors.affiliation: EaStCHEM School of Chemistry, University of Edinburgh , Joseph Black Building, The King's Buildings, Edinburgh EH9 3FJ, U.K.
authors.forename: Polly L
authors.initials: PL
authors.lastname: Arnold
authors.affiliation: Department of Chemistry, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong, P. R. China.
authors.forename: Ian D
authors.initials: ID
authors.lastname: Williams
authors.affiliation: Department of Chemistry, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong, P. R. China.
authors.forename: Zhenyang
authors.initials: Z
authors.lastname: Lin
authors.affiliation: Department of Chemistry, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong, P. R. China.
authors.forename: Wa-Hung
authors.initials: WH
authors.lastname: Leung