title: Dinuclear ruthenium nitrido complexes supported by an oxygen tripodal ligand.
abstract: Dinuclear ruthenium nitrido complexes supported by the Kläui's tripodal ligand [CpCo{P(O)(OEt)(2)}(3)](-) (L(OEt)(-)) have been synthesized starting from the ruthenium(VI) nitrido precursor [L(OEt)Ru(VI)(N)Cl(2)] (1). Heating a solution of 1 in CCl(4) at reflux, followed by recrystallization from hexane under nitrogen, afforded the mixed-valence ruthenium(V)-ruthenium(IV) μ-nitrido complex [L(OEt)Cl(2)Ru(V)(μ-N)Ru(IV)Cl(2)L(OEt)] (2). The cyclic voltammogram of 2 exhibited reversible couples at 0.19 and 1.13 V versus Cp(2)Fe(+/0), which are assigned as the Ru(V)-Ru(IV)/Ru(IV)-Ru(IV) and Ru(V)-Ru(V)/Ru(V)-Ru(IV) couples, respectively. Recrystallization of 2 from Et(2)O/heptane in air yielded the diamagnetic Ru(IV)-Ru(IV) complex [H(13)O(6)][{L(OEt)Ru(IV)Cl(2)}(2)(μ-N)] ([H(13)O(6)][2]), which underwent cation exchange with n-Bu(4)NOH to give [n-Bu(4)N][2]. X-ray diffraction revealed that the complex anions in [H(13)O(6)][2] and [n-Bu(4)N][2] contain linear, symmetric Ru-N-Ru bridges. Treatment of 1 with [(η(6)-p-cymene)Ru(II)Cl(2)](2) in benzene afforded the tetranuclear ruthenium(IV) complex [L(OEt)Cl(2)Ru(IV)(μ-N)Ru(IV)(H(2)O)Cl(2)](2) (3) containing symmetric Ru(IV)-N-Ru(IV) bridges. The reaction of 1 with [Ru(II)(H)(Cl)(CO)(PCy(3))(2)] (Cy = cyclohexyl) gave the ruthenium(VI)-ruthenium(II) nitrido complex [L(OEt)Cl(2)Ru(VI)(μ-N)Ru(II)(H)Cl(CO)(PCy(3))(2)] (4). The observed short Ru(II)-N bond distance [1.915(5) Å] and high C-O stretching frequency (1985 cm(-1)) in 4 are suggestive of π interaction between Ru(II) and the nitride.
authors.affiliation: School of Chemistry and Chemical Engineering, Central South University, Changsha, Hunan 410083, People's Republic of China.
authors.forename: Xiao-Yi
authors.initials: XY
authors.lastname: Yi
authors.forename: Ho-Yuen
authors.initials: HY
authors.lastname: Ng
authors.forename: Wai-Man
authors.initials: WM
authors.lastname: Cheung
authors.forename: Herman H Y
authors.initials: HH
authors.lastname: Sung
authors.forename: Ian D
authors.initials: ID
authors.lastname: Williams
authors.forename: Wa-Hung
authors.initials: WH
authors.lastname: Leung