Preparation and reactivity of germyl complexes of ruthenium and osmium stabilised by cyclopentadienyl, indenyl and tris(pyrazolyl)borate fragments

•Synthesis of half-sandwich trichlorogermyl complexes of ruthenium.•Treatment with LiAlH4 or NaBH4 affords trihydridogermyl and triethoxygermyl.•Tp complexes of Ru and Os containing GeCl3, GeH3, Ge(OEt)3 were also prepared.

Half-sandwich trichlorogermyl complexes Ru(GeCl3)(η5-C5H5)(PPh3)L (1) and Ru(GeCl3)(η5-C9H7)(PPh3)L (2) [L = P(OMe)3 (a), P(OEt)3 (b) and PPh(OEt)2 (c)] were prepared by allowing chloro compounds RuCl(η5-C5H5)(PPh3)L and RuCl(η5-C9H7)(PPh3)L to react with an excess of GeCl2·dioxane in ethanol. Treatment of trichlorogermyl complexes 1 and 2 with LiAlH4 in THF yielded trihydridogermyl derivatives Ru(GeH3)(η5-C5H5)(PPh3)L (3) and Ru(GeH3)(η5-C9H7)(PPh3)L (4). Instead, reaction of trichlorogermyl complexes 1 and 2 with NaBH4 in ethanol afforded triethoxygermyl complexes Ru[Ge(OEt)3](η5-C5H5)(PPh3)L (5) and Ru[Ge(OEt)3](η5-C9H7)(PPh3)L (6). Trichlorogermyl complexes with the tris(pyrazolyl)borate ligand M(GeCl3)(Tp)(PPh3)L [M = Ru (7), Os (10)] were prepared by reacting chloro compounds MCl(Tp)(PPh3)L with an excess of GeCl2·dioxane. Depending on metal centre, nature of phosphite and experimental conditions, the reaction of trichlorogermyl complexes 7 and 10 with LiAlH4 or NaBH4 afforded trihydridogermyl M(GeH3)(Tp)(PPh3)L (8, 12) and triethoxygermyl derivatives M[Ge(OEt)3](Tp)(PPh3)L (9, 11). The complexes were characterised by IR and multinuclear NMR spectroscopy and by X-ray crystal structure determination of 3a.

Graphical abstractThe preparation of trichlorogermyl complexes of ruthenium and osmium, stabilised by cyclopentadienyl, indenyl and tris(pyrazolyl)borate ligands, is described. Their reactions with LiAlH4 and NaBH4, affording trihydridogermyl and triethoxygermyl derivatives, is also reported.Figure optionsDownload full-size imageDownload as PowerPoint slide