OH OH

Rhenium(V) complexes of potentially tetradentate ligands have been well studied during the last three decades.1 These ligands were mainly of the amine-phenol and amine-acetylace-tone type with the ONNO donor atom set, and monomeric complexes of the general formula [ReOCl(ONNO)] were isolated if air and moisture were excluded from the reaction mixtures. However, if the reactions were carried out in air and wet solvents, so that some water was present, dimeric oxo-bridged complexes of the type [Re2O3(ONNO)2] were formed, with a linear O=Re-O-Re=O axis.1 As a matter of fact, multidentate ligand-bridged dimers of oxorhenium(V) are very rare in the literature, and dimers of the ReO3+ core are mainly of the oxo-bridged type. In fact, the coordination chemistry of dinuclear and polynuclear oxo complexes have received increased attention recently, since these species exhibit structures, reactions and properties which are unusual for mononuclear complexes.2 Also, these compounds are important in catalysis, electron-transfer reactions, biological mimicry and metal-metal interactions.3 Described here is the detail of the synthesis of the molecule 1,3-di(pyridin-2-yl)but-1-ene-1,3-diol (H2dbd), and the synthesis and crystal structure of a novel dbd-bridged dimeric complex (µ-dbd)[ReOCl2(PPh3)]2, prepared from H2dbd and trans