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A new manganese(II) phosphite templated by ethylenediamine has been prepared by hydrothermal synthesis and characterized by X-ray diffraction data and spectroscopic techniques. A study of the evolution of the synthetic process suggests the presence of a manganese(II) phosphite as intermediate in the first steps of the reaction. The (C 2 H 10 N 2 )-[Mn 3 (HPO 3 ) 4 ] compound crystallizes in the triclinic space group P-1 with a ) 5.459 and Z ) 1. The compound exhibits a layered structure along the c axis with the ethylenediammonium cations located between the sheets. Within the layers the face-sharing MnO 6 octahedra give rise to trimeric entities which are interconnected by HPO 3 tetrahedra. Studies of luminescence and diffuse reflectance spectroscopies have been carried out. The values of the Dq ) 875 cm -1 and Racah parameters, B ) 660 and C ) 3160 cm -1 , have been calculated. The ESR spectra at different temperatures show isotropic signals with a g value of 2.01, which remains unchanged with variation in temperature. The thermal evolution of both the intensity and the line width of the ESR signals shows an increase from room temperature to 4.2 K. From the magnetic measurements the presence of antiferromagnetic interactions in the compound can be observed. The high-temperature magnetic data have been fitted to a model for linear isolated trimers of Mn(II) with a J exchange parameter of -17 K. At temperatures lower than ca. 80 K a long magnetic order, propagated via phosphite anions along the sheets, is established.

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A new manganese(II) phosphate templated by ethylenediamine, (C 2 H 10 N 2 )[Mn 2 (HPO 4 ) 3 -(H 2 O)], has been prepared by hydrothermal synthesis and characterized by single-crystal diffraction data and spectroscopic and magnetic techniques. The compound crystallizes in the monoclinic space group P2 1 /n with a ) 21.961(7), b ) 9.345(1), c ) 6.639(2) Å; β ) 91.06(2)°; V ) 1362.3(6) Å 3 ; and Z ) 4. The structure consists of anionic sheets of formula [Mn 2 (HPO 4 ) 3 ] 2-, being the charge compensated by ethylendiammonium cations. The sheets are constructed by edge-sharing MnO 6 octahedra, MnO 5 trigonal bipyramids, and hydrogen phosphate tetrahedra. Within a layer, the edge-sharing octahedra and the trigonal bipyramids are linked in an alternating way, forming zigzag chains along the [001] direction. The ethylenediammonium cations and the water molecules are located in the interlayer space. The compound has been characterized by IR spectroscopy. A study of the compound by luminescence and diffuse reflectance spectroscopies is carried out. The Dq and Racah parameters have been calculated for Mn(II) ions in octahedral sites. The ESR spectra at different temperatures of the compound show isotropic signals, with a g value that remains unchanged with variation in temperature. The intensity and the line width of the ESR signals increase continuously from room temperature to 4.2 K. Magnetic measurements from room temperature to 1.8 K indicate the presence of antiferromagnetic interactions. A value of J/k ) -0.75 K for the exchange parameter has been calculated by fitting the experimental magnetic data to a triangular lattice antiferromagnet of S ) 5 / 2 spins.