The synthesis and spectroscopic characterization of the [Fe2S2L4]2- clusters (L2 = o,o'-C12HG02 2-, -O-o-C6H4CH(n-BU)- NHC6H4-o-S-; L = -OC6H4-P-CH3, C4H4N-) are reported. The crystal and molecular structures of (Et4N)2[Fe2S2(o,o'-C12H8O2)2] (I), (Et4N)2[Fe2S2(C4H4N)4] (II), (Et4N)2[Fe2S2(O-o-C6H4CH(n-Bu)NHC6H4-o-S)2] (III), and (Ph4P)2[Fe2S2(OC6H4-p-CH3).] (IV) are described in detail. I crystallizes in the monoclinic space group C2/c, with cell dimensions a = 11.500 (2) Å, i = 13.541 (3) Å, c = 26.612 (5) Å, β = 92.25 (1)°, and Z = 4. II crystallizes in monoclinic space group P21/n, with cell dimensions a = 9.689 (3) Å, b = 16.362 (2) Å, c = 11.910 (5) Å, β = 97.74 (3)°, and Z = 2. Ill crystallizes in the monoclinic space group P21/c, with cell dimensions a = 14.878 (4) Å, b = 9.585 (3) Å, c = 18.950 (6) Å, β = 95.59 (2)°, and Z = 2, and IV crystallizes in the monoclinic space group P21/a, with cell dimensions a = 16.308 (5) Å, b= 16.674 (6) Å, c = 24.456 (9) Å, β = 91.13 (3)°, and Z = 4. Intensity data for I-IV were collected on a four-circle computer-controlled diffractometer with use of the 8-26 scan technique. All four structures were solved by conventional methods from 2739, 1736, 2086 and 3632 reflections for I-IV, respectively. The structures were refined by full-matrix least-squares techniques (310 parameters for I, 173 parameters for II, 280 parameters for III, and 385 parameters for IV) to final R values of 0.033 (I), 0.069 (II), 0.065 (III), and 0.074 (IV). Complexes I-IV contain the planar [Fe2S2]2+ cores coordinated fully or partially by non-sulfur terminal ligands. The Fe...Fe distance in the centrosymmetric dianions ranges from 2.677 (3) Å in II to 2.749 (24) Å in IV. The Fe-O distances are 1.894 (2) (I), 1.921 (11) (III), and 1.870 (12) A (IV), and the Fe-N distance in II is 1.97 (5) Å. Structural comparisons with the already reported thiolate dimers [Fe2S2L4]2- (L = -SAr; L2 = Sro-xyl2-) are reported. The electronic, Mossbauer, cyclic voltammetric, and proton magnetic resonance properties of the new dimers are discussed in detail. A comparison of these properties with the available data on the Rieske [Fe2S2] centers is presented and certain conclusions are drawn concerning future design of synthetic analogues.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry