Comparative Study of the Structural, Electronic, and Magnetic Properties of the Layered Ternary Vanadium Oxides CaV4O9, Cs2V4O9, and [H2N(CH2)4NH2]V4O9

We report the preparation, single-crystal X-ray structure determination, and magnetic susceptibility measurements of a new ternary vanadium oxide, [H 2 N(CH 2 ) 4 NH 2 ]V 4 O 9 . This compound has isolated V 4 O 9 2 - layers made up of edge-sharing VO 5 square pyramids. The V 4 O 9 2 - layers of [H 2 N(CH 2 ) 4 NH 2 ]V 4 O 9 ([H 2 N(CH 2 ) 4 NH 2 ] = piperidinium) differ from those of two other ternary vanadium oxides, CaV 4 O 9 and A 2 V 4 O 9 (A = Rb, Cs), in the way the VO 5 square pyramids are shared, and the magnetic susceptibilities of the three oxides are widely different in their maximum susceptibility values and the temperatures where these values occur. To explain these observations, the electronic structures of the three oxides were analyzed based on molecular orbital calculations.