Synthesis, Structure and Reactivity of Electron Deficient Triosmium Cluster Bearing 2,6-Dimethylbenzothiazolide Ligand

Abstract

Reaction of [Os3(CO)10(NCMe)2] with 2,6-dimethylbenzothiazole at room temperature affords [Os3(CO)10(μ-H){μ-η 2-C7H2NS(Me)2}] (1) in 45% yield. Decarbonylation of 1 in refluxing toluene furnishes the electron-deficient cluster [Os3(CO)9(μ-H){μ 3-η 2-C7H2NS(Me)2}] (2) in almost quantitative yield. Treatment of 2 with PPh3 at 40 °C gives the addition product [Os3(CO)9(PPh3)(μ-H){μ-η 2-C7H2NS(Me)2}] (3) in 85% in which the PPh3 ligand is coordinated to the rear osmium atom. A similar treatment of 2 with P(OMe)3 gives [Os3(CO)9{P(OMe)3}(μ-H){μ-η 2-C7H2NS(Me)2}] (4) in 60% yield with P(OMe)3 ligand also coordinated to the rear metal. Compounds 3 and 4 differ by the disposition of the hydride ligands. In compound 4 both the hydride and the heterocyclic ligands simultaneously bridge the same metal–metal edge whereas they bridge different metal–metal edges in 3. Compounds 1–4 have been characterized by a combination of elemental analysis, infrared, NMR and mass spectral data together with single crystal X-ray diffraction studies for 3. Compound 3 crystallizes in the monoclinic space group P21/n with a = 9.2659(10), b = 23.643(2), c = 16.382(3) A, β = 91.324(12)°, Z = 4 and V = 3,587.8(8) A3. Synthesis and reactivity of electron-deficient 2,6-dimethylbenzothiazole osmium cluster [Os3(CO)9(μ-H){μ 3-η 2-C7H2NS(Me)2}] (2) are described. Reaction of 2 with PR3 (R = Ph, OMe) furnishes [Os3(CO)9(PR3)(μ-H){μ-η 2-C7H2NS(Me)2}] (3, R = Ph; 4, R = OMe) in which the PR3 ligand is coordinated to the rear osmium atom.