| Abstract
| - A new manganese gallium phosphate, Mn3(H2O)6Ga4(PO4)6, has been synthesized under hydrothermal conditionsat 150 °C and characterized by single-crystal X-ray diffraction, thermogravimetric analysis, magnetic susceptibility,and electron paramagnetic resonance (EPR) spectroscopy. It crystallized in the monoclinic space group, P21/n,with a = 8.9468(4) Å, b = 10.1481(5) Å, c = 13.5540(7) Å, β = 108.249(1)°, and Z = 2. The compound isunusual in that it is not only the first nonorganically templated MnGaPO phase but also the first instance whereedge-shared trinuclear manganese−oxygen clusters are encapsulated in a metal phosphate lattice. The trimer involvesa central Mn(H2O)4O2 octahedron, which links to two Mn (H2O)2O4 octahedra at trans edges. The Mn3(H2O)6O8clusters reside in tunnels built from GaO5 trigonal bipyramids and PO4 tetrahedra. Our magnetic study revealedthat superexchange interactions occurred between the neighboring MnII centers. A good fit of the magneticsusceptibility data for the isolated trimers was obtained by using a derived expression based on Van Vleck'sequation. Unlike all existing linear trinuclear MnII complexes, the χΜT product in the range 8−4 K remains at aconstant value corresponding to one spin S = 5/2 per three MnII centers. The Curie behavior at such low temperatureshas been confirmed by EPR data. According to the thermogravimetric analysis/differential thermal analysis (TGA/DTA) results, the title compound is thermally stable up to ca. 200 °C.
- The synthesis and characterization of the first nonorganically templated MnIIGaPO phase is described. The 3-D framework consists of discrete GaO5 trigonal bipyramids connected via PO4 tetrahedra to generate intersecting tunnels where the trinuclear Mn3(H2O)6 cluster cations reside.
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