Meridional anchorage of coordinate occupancy by a planar tridentate ligand and its effect on ligand substitution reactions of octahedral ruthenium(II) complexes

摘要

A kinetic study of the substitution behavior of octahedral [Ru(terpy)(bipy)(OH_2)]~(2+) and [Ru(terpy)(tmen)(OH_2)]~(2+) {terpy=2,2:6′,2 ″-terpyridine, bipy 2,2'-bipyridine and tmen=N,N,N′,N′-tetramethylethylenediamine} with thiourea, 1,3′-dimethyl-2-thiourea, and acetonitrile nucleophiles (Nu) as a function of concentration in pH of 4.0 aqueous media using UV-Vis spectroscopy has been made. The reactions are first order in both the concentration of the Nu and the ruthenium complex in accordance to the two-term rate law k_(obs)=k_2[Nu]+k_(-2). The ligand effect of the cis-coordinated bidentates (NN) on the substitutional lability of the aqua leaving group in the [Ru(terpy)(NN)(OH_2)]~(2+) complexes increases in the order:NN=dppro