ENERGETICS AND MECHANISMS OF CARBON-CARBON AND CARBON-IODIDE REDUCTIVE ELIMINATION FROM A PT(IV) CENTER
ENERGETICS AND MECHANISMS OF CARBON-CARBON AND CARBON-IODIDE REDUCTIVE ELIMINATION FROM A PT(IV) CENTER
复制标题
DOI：
10.1021/ja00131a010
复制
发表时间：
1995-07-05
影响因子：
15
通讯作者：
BREITUNG, EM
中科院分区：
文献类型：
--
作者：
GOLDBERG, KI;YAN, JY;BREITUNG, EM
DppePtMe(3)I(1，dppe=Ph(2)PCH(2)CH(2)PPh(2))在固相和溶液(丙酮-d(6))中的热分解导致甲基碘和乙烷的竞争性生成。这些还原消除反应的预期产物dppePtMe(2)(2)和dppePtMeI(3)也被观察到。在添加碘的存在下(在丙酮-d(6)中)，形成还原消除反应的碳-碳键基本上被抑制，并且在1和碳-碘还原消除产物2/Mei之间建立了平衡。在此条件下测定了还原消除碘甲烷的热力学和动力学参数(Delta H=66+/-3kJ/mol，Delta S=153+/-7J/(mol.K)，Delta(Re)(双匕首)=104+/-1kJ/mol，Delta S-Re(双匕首)=-12+/-1J/(mol.K))。估算了碳-碳还原消除反应的热值(Delta H=-105kJ/mol)以及铂-IV-C和铂-IV-I键强度(分别为132和196kJ/mol)。由DSC数据制成。溶液热解的机理研究支持共同的五配位阳离子中间体的参与(由碘的解离形成)，由此产生碳-碳和碳-碘消除产物。通过在反应中分别添加或去除碘，可以实现甲基碘化溴乙烷的专有生产。
Thermolysis of dppePtMe(3)I (1, dppe = Ph(2)PCH(2)CH(2)PPh(2)) in both solid state and solution (acetone-d(6)) results in competitive methyl iodide and ethane production. The expected Pt(II) products of these reductive elimination reactions, dppePtMe(2) (2) and dppePtMeI (3), are also observed. In the presence of added iodide (in acetone-d(6)), the carbon-carbon bond forming reductive elimination reaction is substantially inhibited, and an equilibrium is established between 1 and the carbon-iodide reductive elimination products, 2/MeI. Thermodynamic and kinetic parameters for the reductive elimination of methyl iodide from 1 were measured under these conditions (Delta H = 66 +/- 3 kJ/mol, Delta S = 153 +/- 7J/(mol . K); Delta(re)(double dagger) = 104 +/- 1 kJ/mol, Delta S-re(double dagger) = -12 +/- 1 J/(mol . K)). Estimates of the enthalpy of the carbon-carbon reductive elimination reaction (Delta H = -105 kJ/mol) and of Pt-IV-C and Pt-IV-I bond strengths (132 and 196 kJ/mol, respectively) were. made from DSC data. Mechanistic studies of the solution thermolysis support the involvement of a common five-coordinate cationic intermediate (formed by dissociation of iodide), from which both carbon-carbon and carbon-iodide elimination products result. Exclusive production of methyl iodide br ethane can be achieved by the addition or removal of iodide, respectively, from the reaction.