- Imidazole Complexes of Iron and Manganese Tetraphenylporphyrins
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The possible importance of partially or completely deprotonated imidazole ligation in the hemoproteins has led us to investigate imidazolate, Im-, complexes of iron(II,III) and manganese(II,III) meso-tetraphenylporphyrin (TPP).Tetrabutylammonium imidazolate is a convenient reagent for the synthesis of isolable complexes.By steric and stoichiometric control the stereochemistry can be manipulated to give complexes with most possible coordination numbers and spin states. - is the first example of a low-spin Mn(III) porphyrin complex and demonstrates the greater ligand field strength of imidazolate over imidazole.The X-ray crystal structure of the polymer n is reported.It shiws layers of parallel chains with alternate layers having their quasi-linear chains approximately orthogonal to each other.There is a short-short/long-long alternation of Mn-N(Im) bond lengths (2.186 (5) and 2.280 (4) Angstroem) interpreted as reflecting alternating predominantly low- and high-spin Mn(III) atoms along the polymeric chain.The average Mn-N(porph) bond distance is 2.019 (4) Angstroem.Crystal data: a = 20.073 (3) Angstroem, b = 16.885 (3) Angstroem, c = 22.590 (5) Angstroem, β = 104.36 (2) deg, space group C2/c, Z = 8 (Mn(Im)(TPP) units).
- Landrum, John T.,Hatano, K.,Scheidt, W. Robert,Reed, Christopher A.
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p. 6729 - 6735
(2007/10/02)
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