Synthesis and reactions of mesitylplatinum complexes. Molecular structure of bromo(mesityl)(1,5-cyclooctadiene)platinum(II)

Article abstract of DOI:10.1021/om00031a013

The reaction of [PtCl₂(cod)] with mesitylmagnesium bromide yields [PtBr(Mes)(cod)]. The compound crystallizes in the monoclinic space group P2₁/c with a = 27.151 (5) ?, b = 7.987 (2) ?, c = 15.308 (2) ?, β = 96.24 (2)°, V = 3300.2 (11) ?³, and Z = 8. Least-squares refinement converged at R = 0.0776 and R_w = 0.0641 on the basis of 4049 reflections with F > 4.0σ(F). The cyclooctadiene may be displaced by PPh₃ or PEt₃ to give the cis-bis(phosphine) complexes, which isomerize slowly to their trans forms. Carbonylation of trans-[PtBr(Mes)(PEt₃)₂] leads to the corresponding aroyl complex, but the PPh₃ complex shows no tendency to undergo carbonyl insertion. Methylation of [PtBr(Mes)(cod)] yields the mixed organoplatinum complex [PtMe-(Mes)(cod)]. Treatment with HCl results in cleavage of the platinum-mesityl bond exclusively. Reaction of [PtClBz(cod)] with MeMgBr produces [PtMeBz(cod)]. Displacement of the diene from these mixed organoplatinum species by PPh₃ or PEt₃ generates the corresponding cis-bis(phosphine) compound.