DINUCLEAR FE-MO-S COMPLEXES CONTAINING THE FES2MO CORE - SYNTHESES, GROUND-STATE ELECTRONIC-STRUCTURES, AND CRYSTAL AND MOLECULAR-STRUCTURES OF THE [(C6H5)4P]2[(C6H5S)2FES2MOS2], [(C2H5)4N]2[(C6H5S)2FES2WS2], AND [(C6H5)4P]2[(S5)FES2MOS2], [(C6H5)4P]2[(S5)FES2WS2) COMPLEXES

D Coucouvanis; P Stremple; E D Simhon; D Swenson; N C Baenziger; M Draganjac; L T Chan; A Simopoulos; V Papaefthymiou; A Kostikas; V Petrouleas

doi:10.1021/ic00144a020

The syntheses of the (C6H5)4P+ and (C2H5)4N+ salts of the [(C6H5S)2FeS2MS2]2- and [(S5)FeS2MS2]2- complex anions (M = Mo, W) are described in detail. The [(C6H5)4P]2[(PhS)2FeS2MoS2] salt (I) crystallizes in the monoclinic space group P21/n with four molecules in the unit cell. The cell dimensions are a = 12.985 (7) Å, b = 20.926 (3) Å, c = 20.980 (7) Å, and β = 100.26 (2)°. The (C2H5)4N+ salt of the [(C6H5S)2FeS2WS2]2- anion, II, crystallizes in the monoclinic space group P21/c with four molecules in the unit cell. The cell dimensions for II are a = 10.9823 (8) Å, b = 10.7867 (9) Å, c = 30.981 (3) Å, and 8 = 97.35 (1)°. The [(C6H5)4P]2[S5FeS2MS2] complexes are X-ray isomorphous and isostructural and crystallize in the triclinic space group [formula-omitted] with two molecules in the unit cell. In addition the unit cell in both structures contains one molecule of dimethylformamide. For M = Mo (III), the unit cell dimensions are a = 11.874 (3) Å, b = 22.486 (5) Å, c = 19.698 (3) Å, α = 107.3 (1)°, β = 79.07 (3)°, and γ = 106.86 (4)°. For M = W (IV), the unit cell dimensions are a = 11.882 (7) Å, b = 22.487 (20) Å, c = 10.707 (7) Å, α = 106.989 (1)°, β = 78.929 (5)°, and γ = 107.159 (7)°. Intensity data for I-IV were collected with a four-circle computer-controlled diffractometer with use of the θ-2θ scan technique. In all structures, all non-hydrogen atoms were refined with anisotropic temperature factors and the hydrogen atoms were included in the structure factor calculations but not refined. Refinement by full-matrix least squares of 391 parameters on 5887 data for I, 343 parameters on 4580 data for II, 563 parameters on 2862 data for III, and 570 parameters on 3262 data for IV gave final R values of 0.059, 0.035, 0.087, and 0.082, respectively. The structures of the dinuclear complexes are described in terms of the edge-sharing MS4 (M = Mo or W) and L2FeS2 tetrahedral units (L = PhS- or L2 = S52-). A common characteristic in all structures is the nearly planar MS2Fe rhombic core in which the M-Fe distances range from 2.737 (3) Å in III to 2.775 (1) Å in II. The Fe-S-M bridge angles in all complexes are found in the narrow range from 74.5 (3)° in I to 75.4 (3)° in II. Average values of selected structural parameters and the standard deviations from the mean are as follows. For I, Fe-Sb = 2.263 (3) Å, Fe-St = 2.297 (5) Å, Mo-St = 2.149 (6) Å, and Mo-Sb = 2.262 (9) Å the range in S(i)-Fe-S(i) angles is 100.7 (1)-117.9 (1)° and in S(i)-Mo-S(j) angles is 105.5 (1)-112.2 (1)°. For II, Fe-Sb = 2.290 (3) Å, Fe-St = 2.306 (11) Å, W-St = 2.156 (3) Å, and W-Sb = 2.247 (10) Å the range in S(i)-Fe-S(j) angles is 102.1 (1)-117.6 (1)° and in S(i)-W-S(j) angles is 105.8 (1)-110.5 (1)°. The distortions in the FeS4 tetrahedra for I and II arise from intramolecular, phenyl ortho hydrogen-sulfur and metal interactions. For III and IV, Fe-Sb = 2.249 (3) and 2.269 (17) Å, Fe-St = 2.33 (3) and 2.322 (11) Å, Mo(W)-St = 2.15 (2) and 2.16 (2) Å, and Mo(W)-Sb = 2.260 (2) and 2.26 (2) Å. Ranges in S(i)-Fe-S(j) angles are 99.2 (2)-118.0 (3)° and 99.3 (3)-117.6 (4)° for III and IV, respectively. Ranges in S(i)-Mo(W)-S(j) are 104.7 (3)-112.4 (3)° and 105.3 (3)-112.1 (3)°. Angular distortions in the S5FeS2 tetrahedral units are attributed to packing forces. The Mossbauer spectra of I-IV have been studied as a function of temperature and an externally applied magnetic field. Values of the fine and hyperfine parameters and the magnetic moments are interpreted in terms of Fe(II) (S = 2) centers in all complexes. The values of the 57Fe isomer shifts which are indicative of extensive Fe → S2MS2 charge transfer are slightly smaller for the WS42- complexes than for the corresponding MoS42- complexes. The less pronounced electron derealization in the WS42- complexes also is apparent in the electronic spectra and electrochemical properties of the complexes, which are discussed in detail.

DINUCLEAR FE-MO-S COMPLEXES CONTAINING THE FES2MO CORE - SYNTHESES, GROUND-STATE ELECTRONIC-STRUCTURES, AND CRYSTAL AND MOLECULAR-STRUCTURES OF THE [(C6H5)4P]2[(C6H5S)2FES2MOS2], [(C2H5)4N]2[(C6H5S)2FES2WS2], AND [(C6H5)4P]2[(S5)FES2MOS2], [(C6H5)4P]2[(S5)FES2WS2) COMPLEXES

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