IR SPECTRA OF DIMOLYBDENUM TETRA-μ2-PHENYLACETATE COMPLEX AND ITS DERIVATIVES

Abstract

The study describes the synthesis, thermal and spectral characteristics of tetra-μ2-phenylacetate complex of dimolybdenum – Мо2(O2CCH2C6H5)4 and its derivatives in the type [Мо2(O2CCH2C6H5)4]L2' [where L' = α-, β-picoline (α-, β-Pic), 4-vinylpyridine (4-VinPy), quinoline (Q). The comparison of IR spectra of the synthesized [Мо2(O2CCH2C6H5)4]L2' complexes with the spectra of liquid L' ligands reveals their great similarity. Nearly every band in the IR spectra of the free L' ligands is reproduced in the spectra of the complex with a slight long-wavelength shift or splitting, which is a consequence of the coordination of L' through the nitrogen heteroatom. However, when comparing the shift values of the stretching vibration frequencies ν(ring), non-planar and planar bending vibrations of the C-H and C-C bonds of heterocyclic rings, as well as the values of bending vibrations of the frequencies δ(CCC), δ(CNC) in the spectra of the [Мо2(O2CCH2C6H5)4]L'2 complexes and the previously obtained [Мо2(O2CH)4]L''2 complex [1] [where, L' and L'' = α-, β-Pic, 4-VinPy, Q], it turns out that the coordination bonds of Mo-L' in axial positions in these adducts are weak. It also revealed that when heating adducts with the composition [Мо2(O2CCH2C6H5)4]L'2, the L' ligands are completely removed at 70-100 oC. After heating of each sample at the appropriate temperature for 2 hours (Table 3), their IR spectra completely coincided with the spectra of the original dimolybdenum tetra-μ2-phenylacetate complex.