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Syntheses, structures and magnetic properties of mono- and di-manganese inclusion compounds

Authors
Journal
Inorganica Chimica Acta
0020-1693
Publisher
Elsevier
Publication Date
Volume
320
Identifiers
DOI: 10.1016/s0020-1693(01)00489-3
Keywords
  • Crystal Structures
  • Magnetic Properties
  • Manganese Complexes
  • Phthalate Complexes
  • Inclusion Complexes

Abstract

Abstract Mono- and di-manganese inclusion compounds 1 and 2 are reported. Two mono-manganese molecules Mn(bpy) 2(NO 3) 2 (bpy=2,2′-bipyridine) and [Mn(bpy) 2(NO 3)(H 2O)]·NO 3 coexist in the mole ratio of 1:1 in the structure of 1, while two di-manganese molecules [Mn 2O(bpy) 2(phtha) 2(H 2O) 2]·(NO 3) 2 (phtha=phthalate) and [Mn 2O(bpy) 2(phtha) 2(NO 3)(H 2O)]·NO 3 in the structure of 2. Refluxing Mn(NO 3) 2/bpy/phthalic acid reaction mixtures in CH 3CN leads to the isolation of 1, further concentration of the reaction solution in raising temperature results in 2. The Mn 1 and Mn 2 units in the inclusion compounds 1 and 2 are similar to other reported Mn 1 and Mn 2 analogs, respectively. The Jahn–Teller distortion was observed to give rise to the elongation along the O terminalMnO carboxyl axes for all the four Mn(III) sites in 2, leading to unexpected longer Mn(III)O aqua than Mn(II)O aqua in 1. Extensive hydrogen bonding interactions among H 2O, NO 3 − and COOH were observed in the two inclusion compounds. Cyclic voltammetry of 2 in DMF displays two quasi-reversible redox couples at +0.10/+0.22 and −0.43/−0.36 V assigned to the Mn(III)Mn(IV)/2Mn(III) and 2Mn(III)/Mn(III)Mn(II), respectively. Variable temperature magnetic susceptibilities of 1 and 2 were measured. The data were fit to a model including axial zero-field splitting term and a good fit was found with D=1.77 cm −1, g=1.98 and F=1.48×10 −5 for 1. For 2, the least-squares fitting of the experimental data led to J=2.37 cm −1, g=2.02 and D=0.75 cm −1 with R=1.45×10 −3.

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