XAFS spectroscopic study of Tc2(O2CCH3)4X2 (X = Cl,Br)

Technetium dimers Tc₂(O₂CCH₃)₄X₂ (X =?Cl, Br) were synthesized and studied by X-ray Absorption Fine Structure spectroscopy (XAFS). EXAFS analysis gave for Tc₂(O₂CCH₃)₄Cl₂: d Tc-Tc =?2.18(1) Å, d Tc–Cl =?2.43(1) Å and for Tc₂(O₂CCH₃)₄Br₂: d Tc–Tc =?2.19(1) Å, d Tc-Br =?2.63(1) Å. The Tc Tc separations are in agreement with Raman studies while the Tc–X distances are somewhat larger. Comparison with other Tc(III) quadruply bonded dimers indicates that the carboxylate compounds exhibit larger Tc–Tc separations. The effect of the terminal ligand (nature and position) on the Tc–Tc separation is discussed.