d-Orbital Effects on Stereochemical Non-Rigidity: Twisted Ti<sup>IV</sup> Intramolecular Dynamics
作者:Anna V. Davis、Timothy K. Firman、Benjamin P. Hay、Kenneth N. Raymond
DOI:10.1021/ja0617946
日期:2006.7.1
The isomerization dynamics of tris-catecholate complexes have been investigated by variable-temperature NMR methods, demonstrating that the intramolecular racemization of Delta and Lambda enantiomers of d0 Ti(IV) is facile and faster than that of d10 Ga(III) and Ge(IV) analogues. Activation parameters for the racemization of K2[Ti2(3)] (H(2)2 = 2,3-dihydroxy-N,N'-diisopropylterephthalamide) were determined
已通过变温 NMR 方法研究了三邻苯二酚配合物的异构化动力学,表明 d0 Ti(IV) 的 Delta 和 Lambda 对映体的分子内消旋化比 d10 Ga(III) 和 Ge(IV) 的分子内消旋化更容易且更快) 类似物。K2[Ti2(3)](H(2)2 = 2,3-二羟基-N,N'-二异丙基对苯二甲酰胺)外消旋化的活化参数由 1H NMR 谱线形分析确定 [甲醇-d4: deltaH++ = 47(1)千焦/摩尔;deltaS++ = -34(4) J/mol K;deltaG++(298) = 57(3) kJ/mol;DMF-d7:deltaH++ = 55(1) kJ/mol;deltaS++ = -16(4) J/mol K;deltaG++(298) = 59(3) kJ/mol;D2O (pD* = 8.6, 20% MeOD): deltaH++ = 48(3) kJ/mol;deltaS++