RAMAN AND INFRARED-SPECTRA OF [HB(3,5-ME(2)PZ)(3)]MCL3 AND [HB(3,5-ME(2)PZ)(3)]M(OSIPH3)CL-2, (PZ = PYRAZOLYL, M = ZR, HF)

FT-Raman (4000-200 cm(-1)) and IR (4000-400 cm(-1)) spectra of hydrotr is(3,5-dimethylpyrazolyl)borato trichloro zirconium(IV) [TpZrCl3], hy drotris(3,5-dimethylpyrazolyl)borato dichloro triphenylsiloxy zirconiu m (IV) [TpZr(OSiPh3)Cl-2], Tp* = HB(3,5-Me(2)pz)(3) and the similar h afnium complexes have been recorded. Vibrational assignments have been made for most of the observed bands. To assist this, FT-Raman and IR spectra of the free ligands and of 3,5-dimethylpyrazole have been reco rded under similar conditions. The B-H signal is shifted to higher wav enumbers in both complexes compared to the original ligand (measured a s KHB(3,5-Me(2)pz)(3), KTp) and is weaker in the Raman than the IR. I n the spectra of KTp and the Zr and Hf complexes several bands assign ed to the pz moieties are doubled due to coupling through the boron at om. Similarly, doublings are observed for various phenyl bands of the OSiPh, groups present in the dichloro compounds. Here the doubling may be mediated in part through the d orbitals of the moderately light si licon atoms. Bands due to B-N, Si-C, Si-O and M-Cl motions are also as signed. (C) 1997 Elsevier Science B.V.