Triplet excited state distortions in a pyrazolate bridged platinum dimer measured by X-ray transient absorption spectroscopy

J Phys Chem A. 2010 Dec 9;114(48):12780-7. doi: 10.1021/jp1088299. Epub 2010 Nov 10.

Abstract

The excited-state structure of a dinuclear platinum(II) complex with tert-butyl substituted pyrazolate bridging units, [Pt(ppy)(μ-(t)Bu(2)pz)](2) (ppy = 2-phenylpyridine; (t)Bu(2)pz = 3,5-di-tert-butylpyrazolate) is studied by X-ray transient absorption (XTA) spectroscopy to reveal the transient electronic and nuclear geometry. DFT calculations predict that the lowest energy triplet excited state, assigned to a metal-metal-to-ligand charge transfer (MMLCT) transition, has a contraction in the Pt-Pt distance. The Pt-Pt bond length and other structural parameters extracted from fitting the experimental XTA difference spectra from full multiple scattering (FMS) and multidimensional interpolation calculations indicates a metal-metal distance decrease by approximately 0.2 Å in the triplet excited state. The advantages and challenges of this approach in resolving dynamic transient structures of nonbonding or weak-bonding dinuclear metal complexes in solution are discussed.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Dimerization
  • Models, Molecular
  • Molecular Structure
  • Organoplatinum Compounds / chemical synthesis
  • Organoplatinum Compounds / chemistry*
  • Platinum / chemistry*
  • Pyrazoles / chemistry*
  • Quantum Theory*
  • X-Ray Absorption Spectroscopy

Substances

  • Organoplatinum Compounds
  • Pyrazoles
  • Platinum