Imido/oxo exchange between osmium and tantalum as a route to Os(NAr)2R2 and OsO(NAr)R2 complexes (NAr = N-2,6-i-Pr2C6H3; R = CH2CMe3, CH2CMe2Ph, CH2SiMe3) and attempts to induce α-hydrogen abstraction to give alkylidene complexes

Article abstract of DOI:10.1021/om00006a016

OsO₂R₂ (R = CH₂-t-Bu, CH₂CMe₂Ph) or [OsO₂(CH₂SiMe₃)₂]_n, reacts with 1 or 2 equiv of Ta(NAr)(O-t-Bu)₃ (NAr = N-2,6-i-Pr₂C₆H₃) to form complexes of the type OsO(NAr)R₂ or Os(NAr)₂R₂. OsO(NAr)(CH₂-t-Bu)₂ reacts with 2 equiv of HCl or Me₃SiI in CH₂Cl₂ or DME to form Os(NAr)(CH₂-t-Bu)₂Cl₂ or Os(NAr)(CH₂-t-Bu)₂I₂, respectively, or with SiMe₃X in CH₂-Cl₂ to form green, crystalline Os(NAr)(CH₂-t-Bu)₂(OSiMe₃)(X) (X = Cl, OTf). An X-ray structure of Os(NAr)(CH₂-t-Bu)₂(OSiMe₃)(OTf) showed it to be an approximate square pyramid with a neopentyl group in the apical position. The reaction of OsO(NAr)(CH₂-t-Bu)₂ with 2 equiv of trimethylaluminum in pentane yields red trans-Os(NAr)(CH₂-t-Bu)₂-(CH₃)₂. None of the Os(VI) dineopentyl complexes shows any evidence for controlled α-hydrogen abstraction reactions.