SYNTHESIS OF ALKYNYL, CYCLIC CARBENE AND VINYLIDENE OSMIUM(II) COMPLEXES - FIRST INDENYL HALF-SANDWICH OSMIUM(II) COMPLEXES

The reaction of [OsCl(eta(5)-C9H7)(PPh(3))(2)] 1 with 3,3-dimethylbut- 1-yne and NaPF6 in refluxing methanol gave the vinylidene complex [Os{ =C=C(H)Bu(t)}(eta(5)-C9H7)(PPh(3))(2)][PF6] 2a and with HC=CSiMe(3) an d NH4PF6 in refluxing methanol gave the unsubstituted vinylidene compl ex [Os(=C=CH2)(eta(5)-C9H7)(PPh(3))(2)][PF6] 2b. 2-Oxacyclo-pentyliden e and -hexylidene complexes [Os{=COCH2(CH2)(n)CH2}(eta(5)-C9H7)(PPh(3) )(2)] [PF6] (n = 1 3a or 2 3b) have been prepared by reaction of 1 wit h HC=C(CH2)(n)CH2OH. Reaction of 1 and hex-5-yn-1-ol afforded the hydr oxyvinylidene complex C=C(H)(CH2)(3)CH2OH}(eta(5)-C9H7)(PPh(3))(2)][PF 6] 4 and with 1-ethynyl-1-cycloalkanols in the presence of NaPF6 in re fluxing methanol it gave regioselectively-the alkenyl-vinylidene compl exes H)CCHCH2(CH2)(n)CH2}(eta(5)-C2H7)(PPh(3))(2)][PF6] (n = 1 5a, 2 5 b or 3 5c). Deprotonation of the vinylidene complexes 2a, 2b and 5a-5c with potassium tert-butoxide yielded the neutral alkynyl complexes [O s(C=CR)(eta(5)-C9H7)(PPh(3))(2)] (R = Bu(t) 6a or H 6b) and Os{C=CCCHC H2(CH2)(n)CH2}-(eta(5)-C9H7)(PPh(3))(2)] 7a-7c respectively: Methylati on of complex 6a with MeOSO(2)CF(3) yielded the vinylidene complex Os{ =C=C(Me)Bu(t)}(eta(5)-C9H7)(PPh(3))(2)][CF3SO3] 8.