PREPARATION, VIBRATIONAL-SPECTRA AND NORMAL-COORDINATE ANALYSIS OF DECAHALOGENODITECHNETATES(IV), [TC2X10]2-, X=CL, BR

The reaction of [TcX6]2-, X = Cl, Br, with trifluoroacetic acid yield at room temperature the edge-sharing bioctahedral anions [Tc2X10]2-, which IR and Raman spectra are assigned according to point group D2h. Using the crystal data of isostructural osmium complexes a normal coordinate analysis based on a general valence force field has been performed for [Tc2X10]2-, revealing a good agreement of the calculated frequencies with the bands observed in the IR and Raman spectra. The stronger bonding of the terminal as compared to the bridging ligands is shown by the valence force constants, f(d)(TcX(t)) > F(d)(TCX(b)).