A novel slat formed by mixed-valence vanadium(IV,V)[(VO)_2(C_2O_4)_2] anions and ferromagnetic [Cu_2(bpy)_4(C_2O_4)] cations:structure,spectroscopic characterization and magnetic properties

摘要

The new heterometallic,mixed-valence compound [Cu_2(bpy)_4(C_2O_4)][VO)_2O(bpy)_2(C_2O_4)]centre dot 10H_2O has been synthesized,its crystal structure determined and its spectroscoic characterization accomplished by means of solid-state vibrational (far and mid FTIR)spectroscopy.The title compound crystallises in the triclinic system, space group P1 (No.2) [a=13.488(5)A,b=14.160(6)A,c=15.829(9)A,#alpha#=87.22(2)deg,#beta#=66.33(2)deg,#gamma#=64.49(2)deg,V=2471(2)A~3,Z=1].The compound consists of the cationic binuclear copper(II) complex [Cu_2(bpy)_4(C_2O_4)]~(2+),two anionic binuclear mixed valence vanadium(IV)-vanadium(V) complexes [(VO)_2O-(bpy)_2(C_2O_4)_2]~-,and ten uncoordianted water moelcules.The copper atomexhibits a Jahn-Teller-distorted octahedral cooctahedral coordination and form a characteristic O=V-O-V=O moiety with a significantly bent V-O-V link.The temperature dependence of the magnetic susceptibilities has been investigated in the temperature range 2-300K and explained in terms of the ferromagnetic interaction between Cu~(II0 ions giving J=22.7 yJ(1.14 cm~(-1)) and g=2.014.