(C2N2H10)[FexV1-x(HPO3)F-3] (x = 0.44, 0.72) have been synthesized using mild solvothermal conditions under autogenous pressure and the ethylenediamine molecule as templating agent. The crystal structures have been determined from X-ray single-crystal diffraction data. The compounds crystallize in the orthorhombic P2(1)2(1)2(1) space group with Z = 4 and unit-cell parameters a = 12.8494(9), b = 9.5430(6), c = 6.4372(5) angstrom, and a = 12.8578(1), b = 9.5342(1), c = 6.4370(7) angstrom for (C2N2H10)[Fe0.44V0.56(H-PO3)F-3] and (C2N2H10)[Fe0.72V0.28(HPO3)F-3], (1) and (2), respectively. These isostructural compounds exhibit a monodimensional crystal structure formed by pillared double anionic chains with the formula [M(HPO3)F-3](2-), extended along the [0 0 1] direction. These doubled ionic chains are the result of the linking of two simple chains in which there are alternating octahedral [MO3F3] and tetrahedral groups [HPO3]. The ethylendiammonium cations are placed in the space delimited by three different chains. The metallic ions are interconnected by the pseudo-pyramidal (HPO3)(2-) phosphite oxoanions, adopting a slightly distorted octahedral geometry. The IR spectra show bands corresponding to the phosphite oxoanion and the ethylendiamonium cation at 2400 and 1600 cm(-1), respectively. The thermogravimetric analyses show that these phases are stable up to ca. 280 degrees C, at higher temperatures, the decomposition of the crystal structure begins by calcination of the organic cation and the elimination of the fluoride anions. The diffuse reflectance spectra show bands of the V3+ ion (d(2)) in octahedral symmetry. The values of the Dq (1540, 1540 cm(-1)), and Racah parameters, B (560, 535 cm(-1)) and C (3055, 3140 cm(-1)) for (1) and (2), respectively, correspond with those usually found for octahedrically coordinated V(III) compounds. Magnetic measurements, performed on a powered sample from 5.0 to 300 K at 1000 G, in the ZFC and FC modes, indicate the existence of antiferromagnetic interactions. (C) 2006 Elsevier Ltd. All rights reserved.