Vibrational study of hydrotris(pyrazolyl)borato complexes of rhenium(I) tricarbonyl

Abstract

The Fourier transform infrared and Raman spectra of the complexes hydrotris(pyrazolyl)borato rhenium tricarbonyl [TpRe(CO)3] and hydrotris(3,5-dimethylpyrazolyl)borato rhenium tricarbonyl [Tp*Re(CO)3] and their ligand salts NaTp and KTp* have been recorded. From the vibrational assignment the better donor ability of the hydrotris(pyrazolyl)borato in comparison with the cyclopentadlenyl ligand coordinated to the Re(CO)3 fragment was deduced. The vibrational assignment was completed with a normal coordinate analysis based on a simplified model. The frequencies of ν(Re-N) and ν(B-N) were located at about 370 and 770 cm-1, respectively. The corresponding force constants were proposed equal to 1.25 and 3.9 mdyn Å-1