Hydrothermal synthesis, crystal structure and spectroscopic and magnetic properties Of (C2H10N2)[Mn2.09Co0.91(HPO3)4]

(C2H10N2)[Mn2.09Co0.91(HPO3)(4)] has been synthesized using mild hydrothermal conditions under autogeneous pressure. The compound crystallizes in the triclinic P-1 space group. The unit-cell parameters are a = 5.4061(8), b = 5.4150(7), c = 14.136(2) Angstrom, alpha = 80.84(1), beta = 85.41(1), gamma = 60.00(1) and Z = 1. The compound shows a layered structure constructed from M3O12 trimer units linked thorough the (HPO3)(2-) phosphite oxoanions with the ethylenediammonium cations located between the sheets compensating the anionic charge of the inorganic framework. The IR and Raman spectra confirm the presence of the ethylenediammonium cation and phosphite anion. The diffuse reflectance spectrum is in accordance with the presence of Co(II) and Mn(II) high spin cations in slightly distorted octahedral symmetry. The calculated Dq and Racah parameters for the Co(II) cations are Dq = 710, B = 870 and C = 4100 cm(-1). The magnetic measurements indicate the existence of antiferromagnetic interactions as the major interactions. Hysteresis observed at low temperature indicates a weak ferromagnetic component, due to a non-cancellation of spins, with coercitive field of 900 G and magnetization of 700 emu/mol. (C) 2004 Elsevier Ltd. All rights reserved.