On the differing acidities of tri- vs. tetradentate copper(II) chelates and its effects on their catalytic properties

The Solution Chemistry of Cu2+–tren Complexes Revisited: Exploring the Role of Species That Are Not Trigonal Bipyramidal

“…In accordance with the conditions in which it is formed, this intermediate must be a protonated species of the form H x CuL (2+x)+ , although the value of x cannot be deduced from the information available. The absorption maximum is close to that observed for Cu(dien) 2+ (625 nm), [23,24] which suggests a tridentate coordination of tren in intermediate I. However, as the same intermediate is also formed in the decomposition of the HCuL 3+ species, which already contains tridentate tren, it can be supposed that I corresponds to a metastable H 2 CuL 4+ species with tren acting as bidentate, which is not detectable with the potentiometric studies.…”

The Palladium(Ii)-Picolylamine Promoted Hydrolysis of Amino Acid Esters; Kinetic Evidence for Inter- and Intramolecular Mechanisms

“…The linear dependence of rate on the OH À ion concentration is consistent with the direct attack of OH-ion on the coordinated ester carbonyl group as given in Eqn (5). The rate constants (k OH ) at different temperatures are given in Table 2.…”

“…indicative of a mechanism involving nucleophilic attack by external OH À on the complexed ester group as shown in Eqn (5). The activation parameters for intramolecuar hydrolysis of [Pd(pic)(GlyOMe)] 2 þ are DH = ¼ 46:6 kJ mol À 1 and DS = ¼ À150 J K À 1 mol À 1 .…”

Hydrolysis of α-amino-acid esters in mixed-ligand complexes with 2,2′-bipyridylpalladium(II)

“…= ko + koHIOH-], the ko term arising from attack of water on the mixed-ligand complex. Values of kHPO == k0155.5, previously reported for the base hydrolysis reaction, equation (2). For the a-amino-acid esters methyl koa(eater)…”