A new layered inorganic-organic hybrid manganese(II) phosphite: (C2H10N2) [Mn-3(HPO3)(4)]. Hydrothermal synthesis, crystal structure, and spectroscopic and magnetic properties

A new manganese(II) phosphite templated by ethylenediamine has been prepare d by hydrothermal synthesis and characterized by X-ray diffraction data and spectroscopic techniques. A study of the evolution of the synthetic proces s suggests the presence of a manganese(II) phosphite as intermediate in the first steps of the reaction. The (C2H10N2)-[Mn-3(HPO3)(4)] compound crysta llizes in the triclinic space group P-l with a = 5.459(1) Angstrom, b = 5.4 60(2) Angstrom, c = 14.194(5) Angstrom, alpha = 80.65(2)degrees, beta = 85. 41(1)degrees, gamma = 60.04(2)degrees, V = 361.7(2) Angstrom(3), and Z = 1. The compound exhibits a layered structure along the c axis with the ethyle nediammonium cations located between the sheets. Within the layers the face -sharing MnO6 octahedra give rise to trimeric entities which are interconne cted by HPO3 tetrahedra. Studies of luminescence and diffuse reflectance sp ectroscopies have been carried out. The values of the Do = 875 cm(-1) and R acah parameters, B = 660 and C = 3160 cm(-1), have been calculated. The ESR spectra at different temperatures show isotropic signals with ag value of 2.01, which remains unchanged with variation in temperature. The thermal ev olution of both the intensity and the line width of the ESR signals shows a n increase from room temperature to 4.2 K. From the magnetic measurements t he presence of antiferromagnetic interactions in the compound can be observ ed. The high-temperature magnetic data have been fitted to a model for line ar isolated trimers of Mn(II) with a J exchange parameter of -17 K. At temp eratures lower than ca. 80 K a long magnetic order, propagated via phosphit e anions along the sheets, is established.