An oxo-bridged binuclear vanadium(III) 2,2 prime -bipyridine complex and its vanadium(IV) and vanadium(V) oxidation products

Vanadium(III) in water reacts with 2,2{prime}-bipyridine to form an oxo-bridged binuclear complex that in its crystalline form has a magnetic moment per vanadium of 3.176 {plus minus} 0.002 {mu}{sub B}, an unusually high value, considering all available evidence supports the III oxidation state. Aerial oxidation of this complex yields an oxovanadium(IV) complex that crystallizes from an aqueous acetone perchlorate solution as (VOCl(bpy){sub 2}) ClO{sub 4} of this complex. Further oxidation in aqueous tetrahydrofuran produces crystals of (VO{sub 2}(bpy){sub 2})Cl {times} 4H{sub 2}O. The crystal structures of the three complexes have been measured and are reported. The coordination geometries show similar distortions from a regular octahedral structure dictated by repulsions between the two anionic ligands, the small bite angle of the chelates, and the effects of trans ligands on the coordinate bond lengths. The binuclear complex has a C{sub 2} axis relating the two units, which are twisted 61.6{degree} relative to each other. The V-O-V group is close to linear with a bond angle of 173.5 (4){degree}. 35 refs., 6 figs., 6 tabs.