Intramolecular exchange of coordinated and dangling phosphines in pentacarbonyl group 6 complexes of 1,1,2-tris(diphenylphosphino)ethane
作者:Richard L. Keiter、Ping Ye、Ellen A. Keiter、John William Benson、Weiying Lin、Douglas E. Brandt、Joel S. Southern、Arnold L. Rheingold、Ilia Guzei、Kraig A. Wheeler、Lew W. Cary
DOI:10.1016/j.ica.2010.08.039
日期:2010.12
activation for 1Cr ⇌ 2Cr and 1W ⇌ 2W are 119.0 and 92.6 kJ mol −1 , respectively, and entropies of activation are 1.4 and −28.2 J K −1 mol −1 , respectively. Isomerization is 10 4 times faster for these complexes than for (OC) 5 M[κ 1 -PPh 2 CH 2 CH 2 P( p -tolyl) 2 ]. A novel mechanism is proposed to account for the rate differences. The X-ray crystal structure of 2W shows that the phosphorus atom of the
连接异构体(OC)5 M [κ1 -PPh 2 CH 2 CH(PPh 2)2] 1和(OC)5 M [κ1 -PPh 2 CH(PPh 2)CH 2 PPh 2] 2(M = Cr,Mo和W在室温下平衡存在。CDCl 3中在25°C下1Cr Cr 2Cr,1Mo⇌2Mo和1W⇌2W的平衡常数分别为2.61、5.0和4.74。焓有利于正向反应(分别为ΔH = -13.5,−12和-12.2 kJ mol -1),而熵有利于逆反应(分别为ΔS = −37.6,−28和-28.2 JK -1 mol -1)。 )。异构化比螯合1Mo≫ 2Mo≫ 1W lation 2W> 1Cr⇌2Cr快得多。1Cr⇌2Cr和1W⇌2W的活化焓分别为119.0和92.6 kJ mol -1,活化熵分别为1.4和-28.2 J K -1 mol -1。这些配合物的异构化速度比(OC)5 M [κ1 -PPh 2