INVESTIGATION OF THE FORMATION REACTION AND STRUCTURAL CHARACTERIZATION OF THE PLATINUM GRIGNARD-REAGENT [PT(MGCL)(2)(THF)(X)] BY EXTENDED X-RAY-ABSORPTION FINE-STRUCTURE (EXAFS) AND OTHER METHODS

The ''platinum Grignard reagent'' [Pt(MgCl)(2)(THF)(x)] (2), obtained by the reaction of PtCl2 and Et2Mg in a 1:2 molar ratio, as well as fi nely divided platinum (Pt)-a possible intermediate formed during: the preparation of 2-have been investigated by EXAFS spectroscopy at the Pt L-III edge, Parallel investigations were carried out on Pt obtaine d from PtCl2 and 9,10-anthracenediyl)tris(tetrahydrofuran)magnesium (M gA), and on 2 obtained from Pt, MgA, and MgCl2. The EXAFS results sug gest that Pt consists of extremely small particles (approximate to 5- 11 Angstrom) with strongly reduced Pt-Pt distances compared to bulk Pt (approximate to 0.09 Angstrom). The EXAFS spectra of 2 indicate the p resence of Mg shells in addition to Pt shells in the Pt environment: M g atoms are at a bonding distance from Pt atoms (2.78-2.80 Angstrom). These results suggest that 2 consists of very small Pt-Mg clusters and confirm their formation from organomagnesium reagents and PtCl2 or Pt .