Reactions of Bis(β-diketonato)platinum(II) and -palladium(II) with Diphosphines Ph2PCHRPPh2 (R=H, Me): Unexpected Formation of the Homoleptic Bis(diphenylphosphino)methanido and Related Complexes

The reactions of [M(β-dik)2] (M=Pt(II), Pd(II); β-dik=acetylacetonate (acac), dipivaloylmethanate (dpm), hexafluoroacetylacetonate (hfac) ions) with dppm (dppm=Ph2PCH2PPh2) and mdppm (mdppm=Ph2PCH(Me)PPh2) have been investigated. [M(hfac)2] complexes react with dppm to afford the stable cationic complexes, [M(dppm)2](hfac)2. By contrast, [M(acac)2] complexes react to give the homoleptic bis(diphenylphosphino)methanido complexes, [M(Ph2PCHPPh2)2], through deprotonation of dppm by the displaced acac anions. The analogous complexes, [M(Ph2PC(Me)PPh2)2], are obtained using mdppm, instead of dppm. A complete reaction scheme leading to these products is proposed, based on the IR and 1H, 13C, and 31P NMR spectral data. Some consideration is given to the dependence of these reactions on the metals and the β-diketonate ligands, employed.