CHARACTERIZATION OF THE ADMIXED INTERMEDIATE-SPIN COMPLEX BIS(3-CYANOPYRIDINE)(OCTAETHYLPORPHINATO)IRON(III) PERCHLORATE

The preparation of bis(3-cyanopyridine)(octaethylporphinato)iron(III) perchlorate is described. The molecular structure has been determined by an X-ray crystal structure determination. The centrosymmetric complex has coplanar axial pyridine ligands that are close to eclipsing an Fe-N(p) bond (phi = 4-degrees). The average equatorial bond distance is 2.012(3) angstrom. The axial Fe-N(Py) bond distance is 2.269(6) angstrom. The complex has been further characterized by EPR and Mossbauer spectroscopy and temperature dependent magnetic susceptibility measurements between 1.8 and 300 K. The complex has an axial EPR spectrum with g perpendicular-to = 4.28 and g parallel-to = 1.97. The Mossbauer spectrum in zero field at 77 K has an isomer shift of 0.38 mm/s and a quadrupole split doublet of 2.61 mm/s. The Mossbauer has also been studied in an applied magnetic field (6 T) at 4.2 K and fitted with a crystal field model. The structure and spin state of this compound serve to emphasize an emerging pattern in the relationship of axial ligand orientation (phi-angles) and spin state. Crystal data: [Fe(OEP)(3-CNPy)2]ClO4.3CHCl3: a = 10.463(7), b = 24.805(26), c = 11.661(4) angstrom, and beta = 109.60(6)-degrees, monoclinic, space group P2(1)/m, V = 2851.0 angstrom 3, Z = 2, observed data = 3118, R1 = 0.099, R2 = 0.102.