Atomic XAFS as a Probe of Charge Redistribution within Organometallic Complexes

The Atomic XAFS contributions in the Pt L2,3 X-ray absorption fine structure spectra (XAFS) of [PtCl(NCN)-Z] pincer complexes are shown to be a sensitive probe of changes in the electron density on the Pt atom induced by changes in a para-substituent on the neighboring benzene ring. Such electron density information is similar yet complementary to NMR data. These complexes provide a unique system for examining inductive effects on the AXAFS data, since the geometry around the Pt atom remains unchanged. The results presented here validate the AXAFS technique and the AXAFS theoretical interpretation in particular. The isolation of the AXAFS data from the oscillatory part of the XAFS spectrum is extensively described. The different effects on the AXAFS shape and intensity are shown and discussed in detail.