Experimental, DFT and TD-DFT studies of rhenium complexes with thiocyanate ligands

The rhenium(V) compound (NBu4)2[ReO(NCS)5] (1) was afforded from a Re(IV) precursor by a two-step synthetic path. The crystal structure of 1, determined by single-crystal X-ray diffraction studies, consists of mononuclear dianionic units containing the monooxido [ReO]3+ core. The Re(V) central ion is also bonded to five thiocyanate ligands completing a distorted octahedral coordination environment. Comparative theoretical studies on equilibrium geometries and electronic properties were undertaken in the framework of the Density Functional Theory (DFT). In order to test the reliability of the employed methodology (PBE1PBE/STMIDI) in studying complexes with rhenium in oxidation states other than +5 bearing different donor atoms, geometry calculations on the Re(IV) thiocyanato-containing linkage isomers [Re(NCS)6]2− and [Re(NCS)5(SCN)]2− were also conducted.