6533b828fe1ef96bd1287b02

RESEARCH PRODUCT

A polymeric two-dimensional mixed-metal network. Crystal structure and magnetic properties of {[P(Ph)4][MnCr(ox)3]}

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Abstract The mixed-metal ferromagnet {[P(Ph) 4 ][MnCr(ox) 3 ]} n , where Ph is phenyl and ox is oxalate, has been prepared and a two-dimensional network structure, extended by Mn(II)-ox-Cr(III) bridges, has been determined from single crystal X-ray data. Crystal data: space group R 3 c , a = b =18.783(3), c =57.283(24) A, α=β=90, γ=120°, Z =24 (C 30 H 20 O 12 PCrMn). The magnetic susceptibility data obey the Curie-Weiss law in the temperature range 260–20 K with a positive Weiss constant of 10.5 K. The temperature dependence of the molar magnetization exhibits a magnetic phase transition at T c =5.9 K. The structure is discussed in relation to the strategy for preparing molecular based ferromagnets and, in addition, it is a solution to the question of the dimensionality of the [MM′(ox) 3 ] n network, which in principle can extend two- or three-dimensionally to the crystal lattice. The optical absorption spectra of the single crystals are assigned to the ‘CrO 6 ’ chromophores. Their polarization patterns reflect the electric dipole selection rules for D 3 symmetry. A strong site selective luminescence from the chromium(III) 2 E states is observed at low temperature and the system may be suitable for studying energy transfer mechanisms.