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
Gallium(III) Catecholate Complexes as Probes for the Kinetics and Mechanism of Inversion and Isomerization of Siderophore Complexes<sup>1</sup>
作者:Berthold Kersting、Jason R. Telford、Michel Meyer、Kenneth N. Raymond
DOI:10.1021/ja953545f
日期:1996.1.1
experiments demonstrate that the inversion of the enantiomers of 4 in D2O is facile. The rate of inversion is independent of pH above pH 8. The mechanism is intramolecular. From line-shape analysis the free energy of activation ΔG⧧298 = 67.4(9) kJ mol-1 in D2O at pD 12.1, with ΔH⧧ = 58.5(6) kJ mol-1 and ΔS⧧ = −0.030(9) kJ mol-1 K-1. Below pD 8 the rate of inversion for 4 is pD dependent and initially