Preparation of half-sandwich ethylene complexes of Osmium(II)

Ethylene complexes [OsCl(η6-p-cymene)(η2-CH2double bond; length as m-dashCH2)L]BPh4 (1, 2) [L = P(OMe)3, P(OEt)3, PPh(OEt)2, tBuNC) were prepared by allowing the dichloro compounds OsCl2(η6-p-cymene)L to react with CH2double bond; length as m-dashCH2 in mild conditions (1 atm). Treatment of 1 with amine or hydrazine yielded [OsCl(p-tolyl-NH2)(η6-p-cymene){PPh(OEt)2}]BPh4 (3) or [OsCl(η6-p-cymene)(CH3NHNH2){PPh(OEt)2}]BPh4 (4) derivatives. The vinylidene cation [OsCl{double bond; length as m-dashCdouble bond; length as m-dashC(H)Ph}(η6-p-cymene){PPh(OEt)2}]+ (5+) was also prepared from 1 and PhCtriple bond; length of mdashCH. The complexes were characterized spectroscopically and by X-ray crystal structure determination of [OsCl(η6-p-cymene)(η2-CH2double bond; length as m-dashCH2){P(OMe)3}]BPh4 (1a). The nature of the Os–ethylene bond was investigated from a computational point of view.