The kinetics of base hydrolysis of [Pt(bpma)Cl]Cl [bpma = bis(2-pyridylmethyl)amine] have been studied (5 × 10-4 ≤ [OH-] ≤ 0.2 mol dm-3) at 25°C and I = 0.2 mol dm-3 by UV-Vis spectrophotometry. The derived rate law is consistent with a mechanism involving a rapid preequilibrium between the substrate [Pt(bpma)Cl]+ and the amido species [Pt(bpmaH-1)Cl] (pKa1 = 12.3) followed by slow solvolysis to give the corresponding aqua species [Pt(bpma)(OH2)]2+ [ks = (2.8 ± 0.2) × 10-4 s-1] and [Pt(bpmaH-1)(OH2)]+ [ks′ = (3.28 × 0.02) × 10-3 s-1] which undergo deprotonation and are converted to unreactive hydroxo species. The aqua complex [Pt(bpma)(OH2)](ClO4) 2·2H2O, independently isolated in the solid, behaves as a dibasic acid in water solution(25°C, I = 0.2 mol dm-3), the two ionization constants being related to the dissociation of the water molecule in the aquoamine (pK1 = 5.4 ± 0.1) and of the amino group in the hydroxo-amino species (pK2 = 11.5 ± 0.1), respectively. The X-ray crystal structures of [Pt(bpma)Cl]Cl·H2O and [Pt(bpma)(OH2)](ClO4) 2·2H2O are reported. © 2002 Elsevier Science Ltd. All rights reserved.
Base hydrolysis kinetics and equilibria of [bis(2-pyridylmethyl)amine]chloroplatinum(II) and crystal and molecular structures of [Pt(bpma)Cl]Cl·H2o and [Pt(bpma)(OH2)](ClO4) 2·2H2O
BERTOLASI, Valerio;FERRETTI, Valeria
2002
Abstract
The kinetics of base hydrolysis of [Pt(bpma)Cl]Cl [bpma = bis(2-pyridylmethyl)amine] have been studied (5 × 10-4 ≤ [OH-] ≤ 0.2 mol dm-3) at 25°C and I = 0.2 mol dm-3 by UV-Vis spectrophotometry. The derived rate law is consistent with a mechanism involving a rapid preequilibrium between the substrate [Pt(bpma)Cl]+ and the amido species [Pt(bpmaH-1)Cl] (pKa1 = 12.3) followed by slow solvolysis to give the corresponding aqua species [Pt(bpma)(OH2)]2+ [ks = (2.8 ± 0.2) × 10-4 s-1] and [Pt(bpmaH-1)(OH2)]+ [ks′ = (3.28 × 0.02) × 10-3 s-1] which undergo deprotonation and are converted to unreactive hydroxo species. The aqua complex [Pt(bpma)(OH2)](ClO4) 2·2H2O, independently isolated in the solid, behaves as a dibasic acid in water solution(25°C, I = 0.2 mol dm-3), the two ionization constants being related to the dissociation of the water molecule in the aquoamine (pK1 = 5.4 ± 0.1) and of the amino group in the hydroxo-amino species (pK2 = 11.5 ± 0.1), respectively. The X-ray crystal structures of [Pt(bpma)Cl]Cl·H2O and [Pt(bpma)(OH2)](ClO4) 2·2H2O are reported. © 2002 Elsevier Science Ltd. All rights reserved.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
