(OCTAETHYLAZAPORPHYRINATO)IRON(III) CHLORIDE - ITS STRUCTURE IN THE SOLID-STATE AND IN SOLUTION

The structure of (OEAP) Fe(III)Cl (where OEAP is the dianion of octaethylazaporphyrin), which was obtained from verdohemochrome by treatment with ammonia, was determined by X-ray crystallography. Red blocks of C35H43N5-FeCl.CH2Cl2.N2 form in the triclinic space group P1 with a = 10.051 (2) angstrom, b = 13.746 (3) angstrom, c = 14.712 (3) angstrom, alpha = 66.50 (3)-degrees, beta = 80.72 (3)-degrees, and gamma = 75.93 (3)-degrees at 130 K with Z = 2. Refinement of 424 parameters with 3056 reflections gave R = 0.071, R(w) = 0.089. The structure shows a typical high-spin five-coordinate iron with Fe-N(av) = 2.044 angstrom and the iron 0.49 angstrom out of the N4 plane. A dichloromethane molecule is hydrogen bonded to the meso nitrogen in the solid. This interaction plays a role in ordering the structure of this symmetrically substituted, core-modified porphyrin. (OEAP)Fe(III)Cl reacts with hydrogen chloride in dichloromethane to form high-spin, six-coordinate (HOEAP)Fe(III)Cl2. In this transformation, the ability of the meso nitrogen to accept a proton triggers a significant change in the coordination geometry of the iron. In dimethylsulfoxide, (OEAP)Fe(III)Cl reacts with silver nitrate to form high-spin [(OEAP)Fe(III)(DMSO)2]NO3. These reactions have been monitored by UV/vis absorption and H-1 NMR spectroscopy.