SYNTHESIS AND REACTIONS OF MESITYLPLATINUM COMPLEXES - MOLECULAR-STRUCTURE OF BROMO(MESITYL)(1,5-CYCLOOCTADIENE)PLATINUM(II)

The reaction of [PtCl2(cod)] with mesitylmagnesium bromide yields [PtB r(Mes)(cod)]. The compound crystallizes in the monoclinic space group P2(1)/c with a = 27.151 (5) angstrom, b = 7.987 (2) angstrom, c = 15.3 08 (2) angstrom, beta = 96.24 (2)degrees, V = 3300.2 (11) angstrom3, a nd Z = 8. Least-squares refinement converged at R = 0.0776 and R(w) = 0.0641 on the basis of 4049 reflections with F > 4.0sigma(F). The cycl ooctadiene may be displaced by PPh3 or PEt3 to give the cis-bis(phosph ine) complexes, which isomerize slowly to their trans forms. Carbonyla tion of trans-[PtBr(Mes)(PEt3)2] leads to the corresponding aroyl comp lex, but the PPh3 complex shows no tendency to undergo carbonyl insert ion. Methylation of [PtBr(Mes)(cod)] yields the mixed organoplatinum c omplex [PtMe-(Mes)(cod)]. Treatment with HCl results in cleavage of th e platinum-mesityl bond exclusively. Reaction of [PtClBz(cod)] with Me MgBr produces [PtMeBz(cod)]. Displacement of the diene from these mixe d organoplatinum species by PPh3 or PEt3 generates the corresponding c is-bis(phosphine) compound.