Mechanism of thermal decomposition of trans-diethylbis(tertiary phosphine)palladium(II). Steric effects of tertiary phosphine ligands on the stability of diethylpalladium complexes
作者:Fumiyuki Ozawa、Takashi Ito、Akio Yamamoto
DOI:10.1021/ja00541a013
日期:1980.10
phosphine. Activation enthalpies for thermolysis of the ethylpalladium complexes having various steric bulkiness were virtually constant in the range of 26.0 +- 1.0 kcal/mol whereas activation entropies showed considerable variation with increasing bulkiness of the phosphine. Thermolysis of trans-(Pd(CH/sub 2/CD/sub 3/)/sub 2/(PMePh/sub 2/)/sub 2/) cleanly liberated CH/sub 2/==CD/sub 2/ and CH/sub 2/DCD/sub
trans-(PdR'/sub 2/(PR/sub 3/)/sub 2/) 具有一系列烷基和各种空间体积的叔膦配体 (R' = Et, PR/sub 3/ = PMe/sub 2/Ph、PEt/sub 3/、PEt/sub 2/Ph、PMePh/sub 2/、PEtPh/sub 2/;R' = Pr、Bu、PR/sub 3/ = PMe/sub 2/Ph)通过..β..-消除过程在溶液中热解,以 1:1 的比例释放烷烃和烯烃。trans-(PdEt/sub 2/(PR/sub 3/)/sub 2/) 热解的动力学研究表明,它们分解遵守关于钯配合物浓度的一级速率定律。热解主要从四配位络合物进行,而没有叔膦配体的解离。涉及膦解离的次要平行热解途径被膦的加入完全阻断。具有各种空间体积的乙基钯配合物的热解的活化焓实际上恒定在26.0±1.0kcal/mol的范围内,而活化熵随着膦体积的增加而显示出