Polymorphism of the dinuclear CoIII–Schiff base complex [Co2(o‐van‐en)3]·4CH3CN (o‐van‐en is a salen‐type ligand) |
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Authors: | Anna Vrblov Juraj ernk Larry R Falvello Milagros Toms |
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Institution: | Anna Vráblová,Juraj Černák,Larry R. Falvello,Milagros Tomás |
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Abstract: | Reactions of Co(OH)2 with the Schiff base bis(2‐hydroxy‐3‐methoxybenzylidene)ethylenediamine, denoted H2(o‐van‐en), under different conditions yielded the previously reported complex aquabis(3‐methoxy‐2‐oxidobenzylidene)ethylenediamine]cobalt(II), Co(C18H18N2O4)(H2O)], 1 , under anaerobic conditions and two polymorphs of μ‐bis(3‐methoxy‐2‐oxidobenzylidene)ethylenediamine]bis{bis(3‐methoxy‐2‐oxidobenzylidene)ethylenediamine]cobalt(III)} acetonitrile tetrasolvate, Co2(C18H18N2O4)3]·4CH3CN, i.e. monoclinic 2 and triclinic 3 , in the presence of air. Both novel polymorphs were chemically and spectroscopically characterized. Their crystal structures are built up of centrosymmetric dinuclear Co2(o‐van‐en)3] complex molecules, in which each CoIII atom is coordinated by one tetradentate dianionic o‐van‐en ligand in an uncommon bent fashion. The pseudo‐octahedral coordination of the CoIII atom is completed by one phenolate O and one amidic N atom of the same arm of the bridging o‐van‐en ligand. In addition, the asymmetric units of both polymorphs contain two acetonitrile solvent molecules. The polymorphs differ in the packing orders of the dinuclear Co2(o‐van‐en)3] complex molecules, i.e. alternating ABABAB in 2 and AAA in 3 . In addition, differences in the conformations, the positions of the acetonitrile solvent molecules and the pattern of intermolecular interactions were observed. Hirshfeld surface analysis permits a qualitative inspection of the differences in the intermolecular space in the two polymorphs. A knowledge‐based study employing Full Interaction Maps was used to elucidate possible reasons for the polymorphism. |
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Keywords: | dinuclear cobalt(III) crystal structure polymorphism full interaction map Schiff base ligand |
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