Unsaturated Pd(0), Pd(I), and Pd(II) Complexes of a New Methoxy-Substituted Benzyl Phosphine. Aryl−X (X = Cl, I) Oxidative Addition, C−O Cleavage, and Suzuki−Miyaura Coupling of Aryl Chlorides
作者:Haim Weissman、Linda J. W. Shimon、David Milstein
DOI:10.1021/om0497588
日期:2004.8.1
was structurally characterized. Partial reduction of [Pd(2-methylallyl)Cl]2 in the presence of the ligand 1 leads to the Pd(I) dimer 3, which can be converted to the Pd(0) complex 2 by addition of ligand 1 and a base. This complex, which bears only one phosphine for each Pd atom, is a suitable precursor to a presumed catalytically active 12e- Pd(0) catalyst. Complexes 2 and 3 catalyze the Suzuki−Miyaura
14e - Pd(0)L 2络合物2是通过在新的,富电子的,大体积的甲氧基苄基膦(dmobp)配体1的存在下还原[Pd(2-甲基烯丙基)Cl] 2制备的。该络合物的结构表征表明甲氧基未与金属中心配位。配合物2在室温下经过碘和氯苯的氧化加成反应生成单膦配合物LPd(Ph)X(4,X = I; 5,X = Cl),其中甲氧基与Pd(II)中心配位处于固态,如4的X射线结构所示。在溶液中没有证据为甲氧基协调,表示的Pd(II)14e的可用性-复合物。在ME-O键4比在相应的键长2,表示甲氧基的这种协调削弱了C-O键。配合物4或5与游离配体1的反应导致亲核攻击和C-O裂解,从而导致二聚苯氧基桥连的配合物7的结构得以表征。在配体1存在下[Pd(2-甲基烯丙基)Cl] 2的部分还原会生成Pd(I)二聚体3,该二聚体3可转化为Pd(0)络合物2通过添加配体1和碱。该络合物的每个Pd原子仅带有一个膦,是假定的具有催化活性的12e