title: Synthesis, structure, and transformation of novel osmium azine and ylide complexes.
abstract: Three novel triosmium complexes with unusual coordination characteristics are reported. Treatment of the hydridotriosmium cluster (mu-H)2Os3(CO)10 with CNNPPh3 in CH2Cl2 gave complexes (mu-H)Os3(CO)(10)(mu2-eta2-C(H)NNPPh3) (1) and (mu-H)Os3(CO)10(mu2-eta1-CHPPh3) (2). Complex 1 represents the first example of the existence of a coordinated phosphinazine ligand. An in-situ 1H NMR study showed that the reaction of (mu-H)2Os3(CO)10 with CNNPPh3 produced complex 1 as the initial product in 100% conversion. The latter is not stable in solution and slowly eliminates nitrogen to form an unusual ylide complex 2 in quantitative yield. The thermolysis of 2 in refluxing toluene afforded (mu-H)3Os3(CO)9(mu3-eta1-CCO2CH2Ph) (3) as a colorless compound. Complexes 1-3 were characterized by spectroscopic methods and single-crystal X-ray diffraction analysis. The interesting feature of structure 3 is the presence of a mu3-alkylidyne ligand where the symmetrically triply bridged CCO2CH2Ph fragment lies perpendicular to and above the triosmium triangle.
authors.affiliation: Institute of Chemistry, Academia Sinica, Taipei 115, Taiwan.
authors.forename: Te-Wei
authors.initials: TW
authors.lastname: Chiu
authors.forename: Yen-Hsiang
authors.initials: YH
authors.lastname: Liu
authors.forename: Kai-Ming
authors.initials: KM
authors.lastname: Chi
authors.forename: Yuh-Sheng
authors.initials: YS
authors.lastname: Wen
authors.forename: Kuang-Lieh
authors.initials: KL
authors.lastname: Lu