[1H,15N] NMR studies of the aquation of cis-diamine platinum(II) complexes
作者:Leticia Cubo、Donald S. Thomas、Junyong Zhang、Adoración G. Quiroga、Carmen Navarro-Ranninger、Susan J. Berners-Price
DOI:10.1016/j.ica.2008.03.117
日期:2009.2
Two N-15-labelled cis-Pt(II) diamine complexes with dimethylamine (N-15-dma) and isopropylamine (N-15-ipa) ligands have been prepared and characterised. [H-1,N-15] HSQC NMR spectroscopy is used to obtain the rate and equilibrium constants for the aquation of cis-[PtCl2(N-15-dma)(2)] at 298 K in 0.1 M NaClO4 and to determine the pK(a) values of cis-[PtCl(H2O)(N-15-dma)(2)](+) (6.37) and cis-[Pt(H2O)(2)(N-15-dma)(2)](2+) (pK(a1) = 5.17, pK(a2) = 6.47). The rate constants for the first and second aquation steps (k(1) = (2.12 +/- 0.01) x 10(5) s(1), k(2) = (8.7 +/- 0.7) x 10(6) s(1)) and anation steps (k(1) = (6.7 +/- 0.8) x 10(3) M-1 s(1), k(2) = 0.043 +/- 0.004 M-1 s(1)) are very similar to those reported for cisplatin under similar conditions, and a minor difference is that slow formation of the hydroxo-bridged dimer is observed. Aquation studies of cis-[PtCl2(N-15-ipa)(2)] were precluded by the close proximity of the NH proton signal to the (H2O)-H-1 resonance. Crown Copyright (C) 2008 Published by Elsevier B. V. All rights reserved.