Molecular and Electronic Structure of Re2Br4(PMe3)(4)

作者：Johnstone Erik V^*; Poineau Frederic; Todorova Tanya K; Forster Paul M; Sorensen Lasse K; Galvan Ignacio Fdez; Lindh Roland; Czerwinski Kenneth R; Sattelberger Alfred P

来源：Inorganic Chemistry, 2016, 55(14): 7111-7116.

DOI：10.1021/acs.inorgchem.6b01052

The dinuclear rhenium(II) complex Re2Br4(PMe3)(4) was prepared from the reduction of [Re2Br8](2-) with (n-Bu4N)BH4 in the presence of PMe3 in propanol. The complex was characterized by single-crystal X-ray diffraction (SCXRD) and UV-visible spectroscopy. It crystallizes in the monoclinic C2/c space group and is isostructural with its molybdenum and technetium analogues. The Re-Re distance (2.2521(3) angstrom) is slightly longer than the one in Re2Cl4(PMe3)(4) (2.247(1) angstrom). The molecular and electronic structure of Re2X4(PMe3)(4) (X = Cl, Br) were studied by multiconfigurational quantum chemical methods. The computed ground-state geometry is in excellent agreement with the experimental structure determined by SCXRD. The calculated total bond order (2.75) is consistent with the presence of an electron-rich triple bond and is similar to the one found for Re2Cl4(PMe3)(4). The electronic absorption spectrum of Re2Br4(PMe3)(4) was recorded in benzene and shows a series of low-intensity bands in the range 10 000-26 000 cm(-1). The absorption bands were assigned based on calculations of the excitation energies with the multireference wave functions followed by second-order perturbation theory using the CASSCF/CASPT2 method. Calculations predict that the lowest energy band corresponds to the delta* -> sigma* transition, while the next higher energy bands were attributed to the delta* -> pi*, delta -> sigma*, and delta -> pi* transitions.

• 出版日期2016-7-18