97170-98-4Relevant academic research and scientific papers
Structural and electronic properties of six-coordinate manganese(III) porphyrin cations. Crystal and molecular structure of bis(N,N-dimethylformamide)(tetraphenylporphinato)manganese(III) perchlorate, [MnIIITPP(DMF)2]+ClO4-
Hill, Craig L.,Williamson, Michael M.
, p. 2836 - 2841 (2008/10/08)
In toluene or chloride-free chloroform solutions of Mn-TPP(ClO4) in the presence of the neutral ligands L = dimethylformamide, dimethylacetamide, 1-methylimidazole, dimethyl sulfoxide, and tetrahydrofuran the six-coordinate cationic complexes [MnIIITPP(L)2]+ClO4- form. One of these complexes, bis(N,N-dimethylformamide)(tetraphenylporphinato)manganese(m) perchlorate [MnIIITPP(DMF)2]+ClO4- (1), was isolated, purified, and characterized in detail. The electronic spectra, H NMR spectra and magnetic properties of 1 in solution establish that this complex contains a high-spin S = 2 MnIII atom with a (dxzπ,dyzπ)2(dxy) 1(d z2σ)1 electronic configuration. The variable-temperature 1H NMR data furthermore rule out any change in ground electronic state over the temperature range -30 to +55 °C. All the cationic MnIII porphyrin complexes undergo fast exchange of the neutral axial ligands, L, on the NMR time scale even at -40 °C. Complex 1 forms solvate-free crystals in space group C2/c. The unit cell has a = 17.7386 (43) A?, b = 17.7182 (60) A?, c = 15.9477 (56) A?, β = 118.693 (22)° and Z = 4. The structure was solved by the heavy-atom method and converged with a final R = 0.0841. The six-coordinate S = 2 MnIII atom displays the predicted tetragonal elongation with very long MnIII-O(DMF) bonds (2.217 (4) A?). Complex 1 shows a temperature-dependent alteration of coordination geometry in solution with the six-coordinate species predominating below -10 °C and a five-coordinate species predominating above +10 °C.
