Probing the presence of multiple metal-metal bonds in technetium chlorides by X-ray absorption spectroscopy: implications for synthetic chemistry

Inorg Chem. 2012 Sep 3;51(17):9563-70. doi: 10.1021/ic3014859. Epub 2012 Aug 20.

Abstract

The cesium salts of [Tc(2)X(8)](3-) (X = Cl, Br), the reduction product of (n-Bu(4)N)[TcOCl(4)] with (n-Bu(4)N)BH(4) in THF, and the product obtained from reaction of Tc(2)(O(2)CCH(3))(4)Cl(2) with HCl(g) at 300 °C have been characterized by extended X-ray absorption fine structure (EXAFS) spectroscopy. For the [Tc(2)X(8)](3-) anions, the Tc-Tc separations found by EXAFS spectroscopy (2.12(2) Å for both X = Cl and Br) are in excellent agreement with those found by single-crystal X-ray diffraction (SCXRD) measurements (2.117[4] Å for X = Cl and 2.1265(1) Å for X = Br). The Tc-Tc separation found by EXAFS in these anions is slightly shorter than those found in the [Tc(2)X(8)](2-) anions (2.16(2) Å for X = Cl and Br). Spectroscopic and SCXRD characterization of the reduction product of (n-Bu(4)N)[TcOCl(4)] with (n-Bu(4)N)BH(4) are consistent with the presence of dinuclear species that are related to the [Tc(2)Cl(8)](n-) (n = 2, 3) anions. From these results, a new preparation of (n-Bu(4)N)(2)[Tc(2)Cl(8)] was developed. Finally, EXAFS characterization of the product obtained from reaction of Tc(2)(O(2)CCH(3))(4)Cl(2) with HCl(g) at 300 °C indicates the presence of amorphous α-TcCl(3). The Tc-Tc separation (i.e., 2.46(2) Å) measured in this compound is consistent with the presence of Tc═Tc double bonds in the [Tc(3)](9+) core.

Publication types

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

MeSH terms

  • Cesium / chemistry
  • Chemistry Techniques, Synthetic
  • Chlorides / chemical synthesis*
  • Chlorides / chemistry*
  • Furans / chemistry
  • Hydrochloric Acid / chemistry
  • Models, Molecular
  • Molecular Conformation
  • Technetium / chemistry*
  • Temperature
  • X-Ray Absorption Spectroscopy

Substances

  • Chlorides
  • Furans
  • Cesium
  • tetrahydrofuran
  • Technetium
  • Hydrochloric Acid