VINYLIDE-TRANSITION-METAL COMPLEXES .16. SYNTHESIS AND REACTIONS OF ALKINYL-OSMIUM(II), VINYLIDENE-OSMIUM(II) AND VINYL-OSMIUM(II) COMPLEXES WITH [C6H6OS(PR3)] AS STRUCTURAL ELEMENT

The compounds [C6H6Os(PR3)I2] react with AgPF6 and 1-alkynes R'C = CH to give, depending on the substituent R', either neutral alkinyl or cationic vinylidene complexes, [C6H6Os(C = CR')(PR3)I] (R' = Ph, Tol) and [C6H6Os(= C = CHR')(PR3)I]+ (R' = H, Me, (n)Bu, (t)Bu), respectively. The reaction of [C6H6Os(PMe(t)Bu2)I2] with AgPF6 and HC = CCO2Me gives the five-membered ring compound [C6H6 activated OsCH = C(I)C(OMe)O(PMe(t)Bu2)]PF6 which on treatment with NaI and subsequent elimination of CH3I forms the neutral complex [C6H6 activated OsCH = C(I)C(O)O(PMe(t)Bu2)]. The cations [C6H6Os(= C = CHR')(PR3)I]+ (R' = Me, (n)Bu, (t)Bu) react either with base (MeNH2, Me2NH, 1,8-C10H6(NMe2)2, KO(t)Bu) or with Al2O3 to give the corresponding alkinyl compounds [C6H6Os(C = CR')(PR3)I]. The reaction of [C6H6Os(= C = CH2)(PMe(t)Bu2)I]PF6 with pyridine leads to the formation of a mixture of {C6H6Os[C(py) = CH2](PMe(t)Bu2)I}PF6 and [C6H6Os(py)(PMe(t)Bu2)I]PF6. Whereas from [C6H6Os(= C = CHR')(PMe(t)Bu2)I]PF6 (R' = H, Me, (n)Bu) and methanol or ethanol (ROH) the carbene complexes {C6H6Os[= C(OR)CH2R'](PMe(t)Bu2)I}PF6 are obtained, the reaction of [C6H6Os(= C = CHR')(PMe(t)Bu2)I]PF6 (R' = H, Me) with water gives the carbonylosmium compound [C6H6Os(CO)(PMe(t)Bu2)I]PF6. The acidic nature of the OCH3 and CCH3 protons of the carbene ligand in {C6H6Os[= C(OCH3)CH3](PMe(t)Bu2)I}+ is confirmed by the smooth formation of {C6H6Os[= C(OCD3)CD3](PMe(t)Bu2)I}+ on treatment with CD3OD.