Synthesis and characterization of 2,5-bis(benzylthio)-1,3,4-thiadiazole complexes with fac-image

Reactions of 2,5-bis(benzylthio)-1,3,4-thiadiazole (1) with a common organometallic rhenium starting material [NEt4]2[fac-[Re(I)Br3(CO)3] yielded two distinct types of complexes. Both complexes coordinate only through the nitrogen of the thiadiazole ring. Reaction of 1 with the rhenium starting material alone yielded a bimetallic complex fac-(di-μ-bromo)(μ-2,5-bis(benzylthio)-1,3,4-thiadiazole-κN:κ′N)bis(tricarbonyl rhenium (I)) (2). The nitrogens of the thiadiazole ring of 1 each coordinate to a different rhenium center combined with two bridging bromide ligands in 2. A “2+1” complex was prepared in a two step process by reacting the rhenium starting material with picolinic acid followed by 1 to yield fac-Re(I)(2,5-bis(benzylthio)-1,3,4-thiadiazole)(CO)3(picolinate) (3). Compounds 2 and 3 were characterized by NMR, IR, UV, elemental analysis, and single crystal X-ray diffraction.