Darstellung, Schwingungsspektren und Normalkoordinatenanalyse der Acetatochloroditechnetate(III), cis-Tc2(O2CCH3)2Cl4L2 (L = axiale Donorbase) sowie Kristallstruktur von cis-Tc2(O2CCH3)2Cl4((CH3)2NCOCH3)2 / Preparation, Vibrational Spectra and Normal Coordinate Analysis of Acetatochloroditechnetates(III), cis-Tc2(O2CCH3)2Cl4L2 (L = Axial Donorbase) and the Crystal Structure of cis-Tc2(O2CCH3)2Cl4((CH3)2NCOCH3)2

Abstract

Tc2(O2CCH3)2Cl4(H2O)2 has been prepared by reaction of [Tc2Cl8]2- with acetic anhydride and fluoroboric acid. By treatment with the donor bases L = N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAA), dimethylsulfoxide (DMSO), triphenylphosphinoxide (TPO) and pyridine (Py), the green adducts Tc2(O2CCH3)2Cl4L2 are formed. The structure of Tc2(O2CCH3)2Cl4(DMAA)2 was determined by X-ray diffraction; space group C2/c with a = 29.604(4), b = 10.895(2), c = 14.404(2) Å, β = 97.87(2)°, Ζ = 8, Rw = 2.7%. The Tc-Tc distance is 2.1835(7) Å, the bridging acetate groups are in cis-positions. The IR and Raman spectra have been recorded at 80 K and assigned according to point group C2v, supported by a normal coordinate analysis of Tc2(O2CCH3)2Cl4(DMAA)2 based on a general valence force field. The stretching interaction constant fd(TcTc) is determined to 3.38 mdyn/Å. With increasing donor strength of the axial ligands, the intense Raman vibration v(TcTc), showing up to three overtones, is lowered from 311 to 282 cm-1. The δ-δ* transitions of all adducts are observed at 648-652 nm.