Skip to the main content

Croatica Chemica Acta, Vol. 74 No. 3, 2001.

Original scientific paper

Equilibria in Complexes of N-Heterocycles. Part 50.1 The Formation and Properties in Solution of the 1:1 Adducts of Bis(2,2'-bipyridine)platinum(II) and Related Ions with Hydroxide

Armanda Maria Formigao Gameiro ; Department of Chemistry, University of Wales, P.O. Box 912, Cardiff CF1 3TB, U.K.
Robert D. Gillard ; Department of Chemistry, University of Wales, P.O. Box 912, Cardiff CF1 3TB, U.K.
Norman H. Rees ; Department of Chemistry, University of Wales, P.O. Box 912, Cardiff CF1 3TB, U.K.
Jurgen Schulte ; Department of Chemistry, University of Wales, P.O. Box 912, Cardiff CF1 3TB, U.K.
Abdurrahman Sengül ; Department of Chemistry, University of Wales, P.O. Box 912, Cardiff CF1 3TB, U.K.

Full text: english pdf 191 Kb

page 641-665

downloads: 808

cite

Abstract

Equilibrium constants are given for addition (mol ratio 1:1) of hy-droxide to several palladium(II) and platimim(II) cations. [Pt(bpy)2]2+ (bpy: 2,2’-bipyridine) and hydroxide ion form the well-known 1:1 adduct rapidly in water; the rate is given at 25 °C by k = 1.6 × 102 mol-1 dm3 s-1. The equilibrium constants for adding hydroxide to [Pt(bpy)2]2+ and to [Pt(3,3’-[2H]2-bpy)2]2+ are the same, but differ considerably from those for [Pt([2H]8-bpy)2]2+ and for [Pt(6,6'-[2H]2-bpy)2]2+ with hydroxide. In this reaction, the infrared spectrum (1700-900 cm-1) of the cation initially [Pt(bpy)2]2+ in the aqueous solution shows distinct changes between pH = 7.0 and pH = 11.0, notably in the aromatic region, where the intensity of the band due to C=N at ca. 1600 cm-1 is much reduced. At pH = 7.0, the methyl groups in [Pt(5,5’-dmbpy)2]2+ (dmbpy: dimethyl-2,2'-bipyridine) or the 4,4'-isomer are equivalent in magnetic resonance but become inequivalent in the 1:1 adducts with hydroxide. In the presence of (−)-methylbenzylamine, both [Pt(terpy)Cl]Cl (terpy: 2,2',2"-ter-pyridine) and [Pt(bpy)2]2+ manifest a strong Pfeiffer effect, but not the exciton coupling characteristic of cis-octahedral ions. These observations are interpreted in terms of addition of hydroxide to the bipyridine ligands.

Keywords

platinum(II); palladium(II); complexes with padine (py); 2,2'-bipyridine (bipy); 1,10-phenanthroline (phen); 2,2',2"-terpyridine (terpy); equilibrium constant with hydroxide; electronic spectra (UV-Vis, CD); NMR spectra <sup>13</sup>C, <sup>195</sup>Pt); deuterium substitution; kinetic isotope effect; Pfeiffer effect; Cotton effect

Hrčak ID:

131884

URI

https://hrcak.srce.hr/131884

Publication date:

1.8.2001.

Visits: 1.526 *