Crystal and Molecular Structure of (5, 10, 15, 20-Tetraphenylporphinato)indium(III) Chloride

The first crystal and molecular structure of an indium porphyrin has been determined by X-ray diffraction. (5, 10, 15, 20-Tetraphenylporphinato)indium(III) chloride crystallized in the space group P2\n, with unit cell dimensions of a = 10.099 (1) A, b = 16.117 (2) A, c = 21.090 (2) A, 0 = 90.70°, and four molecules per unit cell. The structure was solved by using heavy-atom methods and refined by full-matrix least-squares techniques on F, using 5096 independent reflections having F² > 3F²), to final agreement factors of R\ = 0.047 and R₂ = 0.064. The indium is five-coordinate in a square-pyramidal complex with chloride as the axial ligand. The average In-N bond length is 2.156 (6) A, with an In-Cl distance of 2.369 (2) A. The porphinato core is somewhat expanded with an average radius of 2.067 (3) A, and the macrocycle is nonplanar with some net doming toward the indium. The indium atom is located 0.61 A above the mean plane of the four pyrrole nitrogens. Inequivalence of the phenyl tilt angles is explained by crystal packing; all four phenyls are equivalent in solution. Reconstitution of indium porphyrins into apomyoglobin and apohemoglobin is proposed.