N-Picolyl-N′-benzoylthiourea, H2picbtu – A new ligand with a remarkable coordination mode. Synthesis and structures of H2picbtu and its tetrameric oxorhenium(V) complex

(NBu4)[ReOCl4] reacts with N-picolyl-N′-benzoylthiourea (H2picbtu) in acetone under formation of the deep-green oxorhenium(V) complex (NBu4)2[{Re2O2Cl5(Hpicbtu)}2O], which was studied by X-ray diffraction. Two dimeric units with each one bridging, singly deprotonated thiourea ligand are connected by an oxo ligand. Inside the subunits, Hpicbtu− coordinates as S,O chelate with a six-membered chelate ring to one rhenium atom, while a five-membered chelate ring is established with the second Re atom and the nitrogen atoms of the picolylamine building block. The compound represents one of the very rare examples of anionic μ-oxorhenium(V) complexes.