Hydrothermal synthesis and crystal structures of two novel vanadium oxides containing interlamellar transition metal complexes

Abstract

Two new vanadium oxide compounds, which contain interlamellar transition metal complexes bound to vanadium oxide sheets, were synthesized hydrothermally. The crystal structure of each reveals unusual coordination geometries and interlayer bonding. [Ni(2,2′-bipyridine)] 2[V 12O 32] ( 1) was prepared from the reaction of V 2O 5, NiO, H 2O and 2,2′-bipyridyl in the molar ratio 4:8:3312:0.5. The isomorphous compounds [M(2,2′-bipy)] 2[V 12O 32] (where M is Co ( 1a) and Cu ( 1b)) were prepared in a similar fashion. The Ni coordination compound 1 crystallizes as amber needles, and the structure was solved in the space group C2/ m (#12) with unit cell parameters a=24.344(3) A ̊ , b=6.897(3) A ̊ , c=12.028(2) A ̊ , β=93.60(2)° ( R( Rw)=0.039(0.038)). This compound is composed of vanadium(V) oxide layers with nickel atoms coordinated within a single layer via four Ni–O–V linkages. Bidentate bipyridine (bpy) ligands complete the coordination sphere of the nickel atoms and interdigitate via π–π stacking with bpy ligands from the adjacent layer. Cu(en) 2[V 6O 14] ( 2) crystallizes as black plates in the space group P2 1/ n (#14) with unit cell parameters a=8.934(2) A ̊ , b=6.558(1) A ̊ , c=15.694(2) A ̊ , β=99.93(2)° ( R( Rw)=0.039(0.035)), from the reaction of CuCl 2·2H 2O, V 2O 5, H 2O and ethylenediamine in the ratio 1:1:447:4. This structure consists of mixed-valent vanadium(IV,V) oxide sheets forming weak O–Cu bonds to intercalated copper bis(ethylenediamine) complexes.