Phenanporphodimethene (1) is a porphyrin analogue which has a dipyrromethene unit replaced by a 1,10-phenanthroline moiety. This modification effectively coverts a dianionic porphyrin to a monoanionic porphyrin analogue with a porphyrin-like N4 coordination sphere. The ligand 1 forms copper and nickel hexafluorophosphate complexes, Cu-1 and Ni-1, respectively. X-ray crystallographic analysis of Cu-1 indicates that the Cu(ii) complex istetracoordinated by two pyrrolic nitrogen atoms and two phenanthrolic nitrogen atoms and includes a non-bondingPF6 counter-anion. The Ni-1 complex has similar geometry with a tetracoordinate square-planar structure in non-coordinating solvents such as CHCl3. In coordinating solvents such as MeOH, the coordinationstructure adopts an octahedral geometry. These results indicate that Ni-1 can be converted from a low-spin tohigh-spin configuration by the coordination of two solvent molecules to the nickel center. This solvatochromic conversion of Ni-1 is accompanied by thermochromic behavior resulting from the transformation between square planar and octahedral configurations in THF solution. The redox peak responsible for the nickel-centered redox reactionof Ni-1 is observed at −0.66 V (vs. Fc/Fc+) in CH2Cl2 solution, which indicates generation of low valent Ni(i) species. Thus, Ni-1 may be useful for future investigations as a novel structural model of the active site of cofactor F430 in methyl-coenzyme M reductase.
|Number of pages||9|
|Journal||Journal of the Chemical Society. Dalton Transactions|
|Publication status||Published - Feb 23 2010|
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