111410-22-1Relevant academic research and scientific papers
Synthesis and reactions of mesitylplatinum complexes. Molecular structure of bromo(mesityl)(1,5-cyclooctadiene)platinum(II)
Fallis, Kathleen A.,Anderson, Gordon K.,Rath, Nigam P.
, p. 2435 - 2439 (1993)
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 Rw = 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.
Selective cleavage of the Pt-C(alkyl) bond in alkylarylplatinum(II) complexes and mechanism of cis to trans isomerization of the resulting solvento complexes
Alibrandi, Giuseppe,Minniti, Domenico,Scolaro, Luigi Monsù,Romeo, Raffaello
, p. 318 - 324 (2008/10/08)
Protonolysis of the complexes cis-[Pt(PEt3)2(R)(Me)] (R = Me, Ph, mesityl) by H+A- (A- = ClO4-, BF4-, p-toluenesulfonate) in methanol selectively cleaves the alkyl group, yielding cis-[Pt(PEt3)2(R)(MeOH)]+ and methane. The rates show first-order dependence on complex and on proton concentrations, obeying the simple rate law kobsd = kH[H+]. Steric hindrance on the Pt-C bond causes a decrease in rate. A mechanism is proposed that involves rate-determining attack of the proton on the Pt-C bond with release of methane in a three-center transition state. The resulting methanol intermediate spontaneously converts to its trans isomer, and for all systems the isomeric equilibrium lies well to the side of the trans form. At 303.16 K for R = Me, ki = 6.76 × 10-3 s-1, ΔH≠ = 106 ± 4 kJ mol-1, ΔS≠ = +63 ± 12 J K-1 mol-1; for R = Ph, ki = 11.9 × 10-3 s-1, ΔH≠ = 112 ± 3 kJ mol-1, ΔS≠ = +84 ± 8 J K-1 mol-1; for R = mesityl, ki = 28.8 × 10-3 s-1, ΔH≠ = 106 ± 3 kJ mol-1, ΔS≠ = + 75 ± 8 J K-1 mol-1. Isomerization of cis-[Pt(PEt3)2(Me)(MeOH)]+ in diethyl ether-methanol mixtures undergoes mass law retardation by [MeOH]. The rates of isomerization of cis-[Pt(PEt3)2(Me)(S)]+ (S = a series of hydroxylic solvents) are little influenced by the nature of the solvent. As in the case of the related halide species, the isomerization mechanism involves interconversion of two T-shaped 3-coordinate intermediates that show discriminating ability toward scavenging agents.
