Synthesis and crystal structures of (NH 3CH 2CH 2NH 3) 1.5[(VO) 2(HPO 4) 2(PO 4)] and (C 4H 12N 2) 2[V 4O 6H(HPO 4) 2(PO 4) 2], two layered vanadium phosphates templated with organic diamines

Abstract

Two new layered vanadium phosphates templated by ethylenediamine, (NH 3CH 2CH 2NH 3) 1.5[(VO) 2(HPO 4) 2(PO 4)] ( 1), and piperazine, (C 4H 12N 2) 2[V 4O 6H(HPO 4) 2(PO 4) 2] ( 2), have been synthesized hydrothermally and their structures determined by single-crystal X-ray diffraction. Compound 1 crystallizes in the monoclinic space group C2/c (no. 15) with a=18.6051(5), b=7.1193(1), c=23.4597(7) Å, β=96.558(2)°, V=3087.03 Å 3, Z=8, and R1=0.0583. The structure consists of infinite chains of trans-corner-shared VO 6 octahedra, which are bridged by phosphate groups. The infinite chains are connected by VO 5 square pyramids via V–O–P bonds to form layers with 10-sided windows. Adjacent layers are aligned such that infinite tunnels along the [001] direction are generated. Ethylenediammonium cations are located at sites both in the interlayer space and in the windows within the layers. Crystal data for 2: orthorhombic, space group Pna2 1 (no. 33), a=13.1812(6), b=15.2918(8), c=6.2821(3) Å, V=1266.25 Å 3, Z=2, and R1=0.0367. Compound 2 is a mixed-valence V IV/V V vanadium phosphate as was confirmed by magnetic susceptibility measurements. V IVO 6 octahedra connected via HPO 4 groups form a double chain, which alternates with a chain of trans-corner-shared square pyramids containing an infinite V IV–O–V V–O motif. Both chains are connected through phosphate groups to form a layer, which contains 14-membered empty windows. Piperazinium dications are anchored in the interlayer space.