PALLADIUM AND PLATINUM COMPLEXES OF ALPHA-KETOESTERS - CRYSTAL-STRUCTURE OF TRANS-[PT(P(C6H11)3)2(H)(OC=CHC(ME)(COOET)OCO)]

The reactions of M(PCy3)2 (3) (a, M = Pd; b, M = Pt; Cy = cyclohexyl) and trans-PtH2(PCy3)2 (4) with the ?-ketoesters diethyloxomalonate (1) and ethylpyruvate (2) have been investigated. At room temperature 1 coordinates strongly to 3, whereas 2 yields labile adducts. At higher temperatures 2 reacts with 3b to yield the enolate trans-[Pt(PCy3)2(H){OO}] (8), the structure of which has been determined by X-ray diffraction. The ester 1 behaves like CO2 in undergoing rapid insertion into the Pt?H bond of 4. Unexpectedly reaction of 2 with 1 does not yield an insertion product, but again gives complex 8.