Vibrational spectroscopy studies and density functional theory calculations on square-planar vinylidene, carbonyl and ethylene rhodium(I) complexes

Density functional theory (DFT) calculations have been carried out for tran s-[RhF(=C=CH2)(PMe3)(2)] (5), trans-[RhF(CO)(PMe3)(2)] (6) and trans-[RhF(C 2H4)(PMe3)(2)] (7) which serve as model compounds for the analysis of the v ibrational structure of related rhodium (I) compounds. The calculated struc tures were in good agreement with the geometries determined from the experi mental data of related compounds. The calculated vibrational modes have bee n used to classify the bands found in the Raman spectra of the rhodium (I) complexes: trans-[RhF(=C=CH2)(PiPr(3))(2)] (1), trans-[RhF(=C-13=(CH2)-C-13 )(PiPr(3))(2)] (2), trans-[RhF(CO)(PiPr(3))(2)] (3) and trans-[RhF(C2H4)(Pi Pr(3))(2)] (4). The comparison of the vibrational behavior of the vinyliden e complexes 1 and 2 allow for a characterization of the Rh=C stretching mod e. The IR and FT-Raman spectra of complexes 1-4 exhibit one vibrational mod e between 425 and 465 cm(-1) with strong to medium intensity. This band can be assigned to the nu (RhF) mode. (C) 2000 Elsevier Science B.V. All right s reserved.