| Abstract
| - The electronic structures of four members of the electron-transfer series [Fe2(1L)4]n (n = 2−, 1−, 0, 1+) have beenelucidated in some detail by electronic absorption, IR, X-band electron paramagnetic resonance (EPR), and Mössbauerspectroscopies where (1L)2- represents the ligand 1,2-bis(4-tert-butylphenyl)-1,2-ethylenedithiolate(2−) and (1L•)-is its π-radical monoanion. It is conclusively shown that all redox processes are ligand-centered and that high-valent iron(IV) is not accessible. The following complexes have been synthesized: [FeIII2(1L•)2(1L)2]0 (1), [FeIII2(2L•)2(2L)2]·2CH2Cl2 (1‘) where (2L)2- is 1,2-bis(p-tolyl)-1,2-ethylenedithiolate(2−) and (2L•)- represents its π-radicalmonoanion, [Cp2Co][FeIII2(1L•)(1L)3]·4(toluene)·0.5Et2O (2), and [Cp2Co]2[FeIII2(1L)4]·2(toluene) (3). The crystal structuresof 1‘ and 2 have been determined by single-crystal X-ray crystallography at 100 K. The ground states of complexeshave been determined by temperature-dependent magnetic susceptibility measurements and EPR spectroscopy: 1‘ and 1 are diamagnetic (St = 0); 2 (St = 1/2); 3 (St = 0); the monocation [FeIII2(1L•)3(1L)]+ possesses an St =1/2 ground state (St = total spin ground state of dinuclear species). All species contain pairs of intermediate-spinferric ions (SFe = 3/2), which are strongly antiferromagnetically coupled (H = −2JS1·S2, where S1 = S2 = 3/2 andJ = ∼−250 cm-1).
- The electronic structures of four members of the electron-transfer series [FeIII2(1L)4]n (n = 2−, 1−, 0, 1+) have been elucidated, where (1L)2- represents the dianion and (1L•)- its radical monoanion of 1,2-bis(4-tert-butylphenyl)-1,2-ethylenedithiolate. The four dinuclear species are interrelated by three successive one-electron-transfer steps that are ligand-centered. In all four species, there are two central ferric ions (SFe = 3/2).
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