Water Exchange Mechanism of Tetraaquapalladium(II). A Variable Pressure and Variable Temperature Oxygen-217 NMR Study

Research output: Contribution to journalArticle

Abstract

Water exchange of square-planar Pd(H2O)42+ has been studied as a function of temperature (240 to 345 K) and pressure (0.1 to 260 MPa, at 324 K) by measuring the 17/O-FT-NMR line-widths of the resonance from coordinated water at 27.11 and 48.78 MHz. The following exchange parameters were obtained: k298ex = (560 ± 40) s−1, ΔH* = (49.5 ± 1.9) kJ mol−1, ΔS* = – (26 ± 6) J K−1 mol−1 and ΔV* = – (2.2 ± 0.2) cm3 mol−1. The values refer to an aqueous perchlorate medium with an ionic strength between 2.0 and 2.6 m and a perchloric acid concentration between 0.8 and 1.7 m, and are interpreted in terms of an associative (a) activation for the exchange. The exchange rate for Pd(H2O)42+ is 1.4 × 106 times faster than for Pt(H2O)42+ at 298 K. A comparison with reactions between other nucleophiles and Pd(H2O)42+ is also made.

Details

Authors
Organisations
External organisations
  • Ecole Polytechnique Federale de Lausanne
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Physical Chemistry
  • Water Engineering

Keywords

  • Palladium(II), Tetraaqua complex, Water exchange, Stopped-flow kinetics, High-pressure stopped flow, Reaction mechanism, Activation volume, Activation entropy, Associative process
Original languageEnglish
Pages (from-to)1453-1460
Number of pages8
JournalHelvetica Chimica Acta
Volume67
Issue number6
StatePublished - 1984 Sep
Publication categoryResearch
Peer-reviewedYes

Bibliographic note

Part 23 of the series ‘High-Pressure NMR Kinetics’