文摘
Reaction of [ReOCl3(PPh3)2] with 3,5-di-tert-butyl-1,2-benzoquinone (3,5-DTBQ) in hot toluene produces a new complex [(3,5-di-tert-Bu2C6H2O2)Re(OPPh3)Cl3] (1), which was isolated and characterized by elemental analysis, IR, UV鈥搗is spectroscopy, and cyclic voltammetry. In order to clarify the charge state of rhenium and the coordinated dioxolene ligand, X-ray experiments at 150 and 290 K were carried out. The C鈥揙, C鈥揅, and Re鈥揙 bond distances at both 150 and 290 K fall between those for semiquinolate (3,5-DTBSQ) and catecholate (3,5-DTBCat) forms; an empirical 鈥渕etrical oxidation state鈥?of the dioxolene ligand was estimated to be 鈭?.5. High-level ab initio calculations (SOC-CASSCF/NEVPT2) revealed a mixed valence nature of the triplet ground state of complex 1 corresponding to a superposition of the ReIV鈥?i>SQ and ReV鈥?i>cat forms. In agreement with the high-level ab initio and DFT calculations, the temperature dependence of the magnetic susceptibility (5鈥?00 K) is well described in the assumption of the triplet ground state, with the anomalously large zero-field splitting (ZFS) arising from the spin鈥搊rbit coupling. According to the ab initio calculations, all absorption bands in the visible region of the electronic absorptions spectrum are assigned to the LMCT bands, with significant contribution of the intraligand transition in the most intense band at 555 nm.