COORDINATION CHEMISTRY OF MICROBIAL IRON TRANSPORT COMPOUNDS .17. PREPARATION AND STRUCTURAL CHARACTERIZATION OF TRIS(N-METHYLTHIOBENZOHYDROXAMATO)COBALT(III), TRIS(N-METHYLTHIOBENZOHYDROXAMATO)CHROMIUM(III), TRIS(N-METHYLTHIOBENZOHYDROXAMATO)IRON(III), AND TRIS(N-METHYLTHIOBENZOHYDROXAMATO)MANGANESE(III)

The preparation and isolation of tris(N-methylthiobenzohydroxamato)cobalt(III), -chromium(III), -iron(III), and -manganese(III) are reported. The structures of these four compounds have been determined by single-crystal X-ray diffraction using automated-counter methods. The complexes are isostructural in the cis configuration, with the metal environment being a trigonally distorted octahedron, though the manganese complex displays considerable tetragonal distortion. The twist angle (the projection of the top trigonal face on the bottom one) averages 54.9° for the Co complex, 48.7° for the Cr, 42.9° for the Fe, and 46.0° for the Mn; these are 60° and 0° for octahedral and trigonal-prismatic structures, respectively. The M-S bond lengths average 2.203 (3) Å for Co, 2.367 (8) Å for Cr, and 2.445 (14) Å for Fe, while the M-O bond lengths average 1.935 (5), 1.976 (6), and 1.990 (5) Å, respectively. The axial (tetragonal axis) and equatorial bond lengths for the Mn-S bonds are 2.584 (1) and 2.339 (15) Å and for Mn-O are 2.132 (2) and 1.950 (9) Å, respectively. The average S-M-O chelate angles are 87.3 (3), 82.6 (1), 80.1 (2), and 80.6 (11)° for M = Co, Cr, Fe, and Mn. The changes in M-S bond lengths and trigonal twist angles of the complexes are ascribed to ligand field effects. The structure of Cr(MTB)3 (MTB = N-methylthiobenzohydroxamate anion) was solved by direct phasing methods followed by full-matrix least-squares and Fourier techniques, while the other structures were refined by using atomic coordinates from the Cr complex. Green crystals of Co(MTB)3 conform to the space group P21/n with a = 11.805 (2), b - 12.182 (2), c = 18.230 (4) Å, and β = 92.12 (2)°; V= 2620 (2) Å3; Z = 4; = 1.41 and pobsd = 1.41 (1) g cm-3. Refinement using the 3862 reflections with F2 > 3σ(F2), with all nonhydrogen atoms given anisotropic temperature factors, gave R = 3.4% and Rw = 4.2%. Green crystals of Cr(MTB)3 have a = 11.698 (4), b = 12.080 (3), c = 18.851 (6) Å, and β = 93.81 (3)°; K= 2658 (3) Å3; pcalcd = 1.38 and pobsd = 1.36 (1) g cm-3. The 3207 reflections with F2 > 3σ(F2) gave R = 3.2 and Rw = 4.2%. Violet crystals of Fe(MTB)3 have a = 11.668 (2), b = 12.037 (2), c - 19.013 (4) Å, and β = 94.94 (2)°; V= 2661 (2) Å3; pcalcd = 1.38 and pobsd = 1.36 (1) g cm-3. The 3070 reflections with F2 > 3σ(F2) gave R = 3.3% and Rw = 3.8%. Green crystals of Mn(MTB)3 have a = 11.604 (3), b = 12.044 (3), c = 18.990 (6) Å, and β = 94.87 (2)°; V- 2644 (3) Å3; pcalcd = 1.39 and pobsd = 1.38 (1) g cm-3. The 3452 reflections with F2 > 3σ(F2) gave R = 3.5% and Rw = 3.8%. © 1979, American Chemical Society. All rights reserved.