The Crystal and Molecular Structure of Tris(tert-butyl thioxanthato)iron(III)

The structure of tris(tert-butyl thioxanthato)iron(III) has been determined in a single-crystal X-ray diffraction study. The coordination geometry of the iron atom is a distorted octahedron of sulfur atoms contributed by the three chelating thioxanthate ligands. The distortion may be expressed in terms of a twist angle α = 42°, compared to the value of α = 60° required for a regular octahedron. The mean iron-sulfur bond distance is 2.297 (7) å, and S-Fe-S intrachelate angle, 75.2 (2).° The geometries of coordinated 1,1-dithiolate ligands in the present and several related tris-chelate metal complexes are summarized. There is a significant amount (10^-30%) of double-bond character in the C-X bond for coordinated -S₂CX (X = OR, SR) ligands, although appreciably less than for analogous dithiocarbamate (X = NR2) compounds (40-50%). The complex Fe(S₂CSC₄H₉)₃crystallizes in the triclinic system, space group P$1B, with a = 19.44 (1) å, b = 5.917 (4) å, c = 11.016 (6) å, a = 100.36 (1)°, β = 86.30 (1)°, y-90.84 (2)°. The measured density of 1.48 ± 0.01 g/cm3 requires two molecules per unit cell (4rHealed 1.474 ± 0.001 g/cms). From 2330 independent, statistically significant reflections collected by diffractometer, the structure was solved by the usual Patterson and Fourier synthesis methods. Least-squares refinement of all atoms including hydrogen converged at values for R1 = 0.060 and = 0.085.