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

Ethylene complexes [OsCl(h6-p-cymene)(h2-CH2]CH2)L]BPh4 (1, 2) [L ¼ P(OMe)3, P(OEt)3, PPh(OEt)2, tBuNC) were prepared by allowing the dichloro compounds OsCl2(h6-p-cymene)L to react with CH2]CH2 in mild conditions (1 atm). Treatment of 1 with amine or hydrazine yielded [OsCl(p-tolyl-NH2)(h6-pcymene){ PPh(OEt)2}]BPh4 (3) or [OsCl(h6-p-cymene)(CH3NHNH2){PPh(OEt)2}]BPh4 (4) derivatives. The vinylidene cation [OsCl{]C]C(H)Ph}(h6-p-cymene){PPh(OEt)2}]þ (5D) was also prepared from 1 and PhC^CH. The complexes were characterized spectroscopically and by X-ray crystal structure determination of [OsCl(h6-p-cymene)(h2-CH2]CH2){P(OMe)3}]BPh4 (1a). The nature of the Oseethylene bond was investigated from a computational point of view.