ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Kinetics of chloride substitution in [Pt(bpma)Cl]⁺ and [Pt(gly-met-S,N,N)Cl] complexes by thiourea, nitrites, and iodides

Adrian Topolski and Živadin Bugarčić

Faculty of Chemistry, Nicolaus Copernicus University, Gagarina 7, 87-100, Toruń, Poland

E-mail: topolski@umk.pl

Abstract: Substitution of chloride in [PtCl(bpma)]⁺ and [PtCl(gly-met-S,N,N)], where bpma is bis(2-pyridylmethyl)amine and gly-met-S,N,N is glycyl-l-methionine, was studied as a function of the entering nucleophile concentration and temperature. Reactions between the platinum(II) complexes and thiourea (TU), iodides (I⁻), and nitrites(III) (NO ₂ ⁻) were carried out in aqueous solutions using conventional UV-VIS spectrophotometry. Suitable ionic conditions were reached by an addition of 0.1 M NaClO₄ and 0.01 M NaCl (to suppress hydrolysis). The second-order rate constants, k ₂, for the studied reactions with NO ₂ ⁻ varied between 0.036–0.038 M⁻¹ s⁻¹, and for the reactions with TU between 0.095–1.06 M⁻¹ s⁻¹, respectively. The reaction between TU and the [PtCl(bpma)]⁺ ion is ten times faster than that of the [PtCl(gly-met-S,N,N)] complex. An analysis of the activation parameters, ΔH ^≠ and ΔS ^≠, for the selected reactions clearly shows their associative nature.

Keywords: platinum(II) complexes – substitution – kinetics – thiourea – nitrites(III) – iodides

Full paper is available at www.springerlink.com.

DOI: 10.2478/s11696-013-0418-5

Chemical Papers 68 (1) 130–135 (2014)