Silatranyl, hydride complexes of osmium(II) and osmium(IV): crystal structure of Os(Si{OCH2CH2}3N)H3(PPh3)3

Reaction between Os(CO)2(PPh3)3 and the silatrane, HSi{OCH2CH2}3N, gives the osmium(II) silatranyl, hydride complex Os(Si{OCH2CH2}3N)H(CO)2(PPh3)2 (1), as a mixture of three isomers, the structures of which were determined by NMR spectroscopy. Reaction between OsH4(PPh3)3 and the silatrane, HSi{OCH2CH2}3N, gives the osmium(IV) silatranyl, trihydride complex Os(Si{OCH2CH2}3N)H3(PPh3)3 (2). The crystal structure of 2 has been determined and all three hydride ligands located. The three hydrides all make close approaches to the silicon atom but the distances between silicon and each of the hydrides suggests that any Si⋯H interactions must be weak. The interatomic distance between Si and N in the silatranyl ligand is large and the nitrogen atom has near planar geometry. Compound 2 can be methylated or protonated at nitrogen giving the complexes [Os(Si{OCH2CH2}3NMe)H3(PPh3)3]I (3), and [Os(Si{OCH2CH2}3NH)H3(PPh3)3]CF3SO3 (4), respectively.