Synthesis of alkynyl, cyclic carbene and vinylidene osmium(II) complexes: first indenyl half-sandwich osmium(II) complexes

Abstract

The reaction of [OsCl(η⁵-C₉H₇)(PPh₃)₂]1 with 3,3-dimethylbut-1-yne and NaPF₆ in refluxing methanol gave the vinylidene complex [Os{CC(H)Bu^t}(η⁵-C₉H₇)(PPh₃)₂][PF₆]2a and with HCCSiMe₃ and NH₄PF₆ in refluxing methanol gave the unsubstituted vinylidene complex [Os(CCH₂)(η⁵-C₉H₇)(PPh₃)₂][PF₆]2b. 2-Oxacyclo-pentylidene and -hexylidene complexes [Os{[graphic omitted]H₂}(η⁵-C₉H₇)(PPh₃)₂][PF₆](n= 1 3a or 2 3b) have been prepared by reaction of 1 with HCC(CH₂)_nCH₂OH. Reaction of 1 and hex-5-yn-1-ol afforded the hydroxyvinylidene complex [Os{CC(H)(CH₂)₃CH₂OH}(η⁵-C₉H₇)(PPh₃)₂][PF₆]4 and with 1-ethynyl-1-cycloalkanols in the presence of NaPF₆ in refluxing methanol it gave regioselectively the alkenylvinylidene complexes [Os{CC(H)[graphic omitted]H₂}(η⁵-C₉H₇)(PPh₃)₂][PF₆](n= 1 5a, 2 5b or 3 5c). Deprotonation of the vinylidene complexes 2a, 2b and 5a–5c with potassium tert-butoxide yielded the neutral alkynyl complexes [Os(CCR)(η⁵-C₉H₇)(PPh₃)₂](R = Bu^t6a or H 6b) and [Os{CC[graphic omitted]H₂}(η⁵-C₉H₇)(PPh₃)₂]7a–7c respectively. Methylation of complex 6a with MeOSO₂CF₃ yielded the vinylidene complex [Os{CC(Me)Bu^t}(η⁵-C₉H₇)(PPh₃)₂][CF₃SO₃]8.