TETRANUCLEAR VANADIUM(III) CARBOXYLATE CHEMISTRY, AND A NEW EXAMPLE OF A METAL BUTTERFLY COMPLEX EXHIBITING SPIN FRUSTRATION - STRUCTURE AND PROPERTIES OF [V4O2(O(2)CET)(7)(BPY)(2)](CLO4)

Treatment of [VCI3(thf)(3)] (thf = tetrahydrofuran) with bpy (bpy = 2, 2'-bipyridine) and NaO(2)CEt in a 1:1:3 molar ratio in Me(2)CO followe d by addition of CIO4- allows isolation of [V4O2(O(2)CEt)(7)(bpy)(2)]( CIO4) [4(CIO4)], which contains a butterfly-like V-4 unit; variable-te mperature magnetic susceptibility studies show 1 to possess both ferro - and antiferro-magnetic exchange interactions leading to spin-frustra tion effects and an S = 3 ground state.