Chłopek Krzysztof, Bill Eckhard, Weyhermüller Thomas, Wieghardt Karl
Max-Planck-Institut für Bioanorganische Chemie, Mülheim an der Ruhr, Germany.
Inorg Chem. 2005 Oct 3;44(20):7087-98. doi: 10.1021/ic050829k.
The reaction of the ligand N-phenyl-1,2-benzenediamine (N-phenyl-o-phenylenediamine), H2[L(PDI)], in dry acetonitrile with FeIII(dmf)63 (dmf = N,N-dimethylformamide) affords the dimer (mu-NH,NH)[FeIII(L(ISQ))(L(PDI))]2 (1), where (L(ISQ))- represents the pi radical monoanion N-phenyl-o-diiminobenzosemiquinonate and (L(PDI))2- is its one-electron-reduced, closed-shell form. Complex 1 possesses a diamagnetic ground-state St = 0. Addition reactions of tri-n-butylphosphane, tert-butyl isocyanide, cyclohexyl isocyanide, 4,5-diphenylimidazole, and 4-(1-phenylpentyl)pyridine with 1 in acetonitrile or toluene yields [FeII(L(ISQ))2(PBu3)] (2), [Fe(II)(L(ISQ))2(CN-tBu)] (4), [FeII(L(ISQ))2(CNCy)] (5), [FeIII(L(ISQ))2(Ph2Im)] (6), and [FeIII(L(ISQ))(L(PDI))(BuPhCH-py)].BuPhCH-py (7). Oxidation of 1 with iodine affords [FeIII(L(ISQ))2I] (3), and oxidation of 2 with ferrocenium hexafluorophosphate yields FeIII(L(ISQ))2(PBu3) (2ox). The structures of complexes 2, 2ox, 3, 5, 6, and 7 have been determined by X-ray crystallography at 100(2) K. Magnetic susceptibility measurements and EPR, UV-vis, and Mössbauer spectroscopy have established that mononuclear complexes containing the [FeII(L(ISQ))2X] chromophore (2, 4, 5) are diamagnetic (St = 0) whereas those with an [FeIII(L(ISQ))2X]n chromophore (3, 2(ox), 6) are paramagnetic (St = 1/2) and those with an [FeIII(L(ISQ))(L(PDI))X] chromophore (7) possess an St = 1 ground state. It is established that all ferric species have an intrinsic intermediate spin (SFe = 3/2) which is intramolecularly antiferromagnetically coupled to one or two (L(ISQ))- ligand radicals yielding an St = 1 (7) or St = 1/2 (2ox, 3, 6) ground state, respectively. In the ferrous complexes 2, 4, and 5 the intrinsic spin at the iron ion is either low spin (SFe = 0) or intermediate spin (SFe = 1). Antiferromagnetic coupling between two radicals (L(ISQ))*- or, alternatively, between the intermediate spin ferrous ion and two radicals yields then the observed diamagnetic ground state. In 1 two [FeIII(L(ISQ))(L(PDI))] halves with S = 1 couple antiferromagnetically affording an St = 0 ground state.
配体N-苯基-1,2-苯二胺（N-苯基-邻苯二胺），即H2[L(PDI)]，在干燥乙腈中与FeIII(dmf)63（dmf = N,N-二甲基甲酰胺）反应，得到二聚体(μ-NH,NH)[FeIII(L(ISQ))(L(PDI))]2（1），其中(L(ISQ))* - 代表π自由基单阴离子N-苯基-邻二亚氨基苯半醌，(L(PDI))2 - 是其一电子还原的闭壳层形式。配合物1具有抗磁性基态St = 0。三正丁基膦、叔丁基异腈、环己基异腈、4,5-二苯基咪唑和4-(1-苯基戊基)吡啶与1在乙腈或甲苯中发生加成反应，生成[FeII(L(ISQ))2(PBu3)]（2）、[Fe(II)(L(ISQ))2(CN-tBu)]（4）、[FeII(L(ISQ))2(CNCy)]（5）、[FeIII(L(ISQ))2(Ph2Im)]（6）和[FeIII(L(ISQ))(L(PDI))(BuPhCH-py)].BuPhCH-py（7）。用碘氧化1得到[FeIII(L(ISQ))2I]（3），用六氟磷酸二茂铁氧化2得到FeIII(L(ISQ))2(PBu3)（2ox）。配合物2、2ox、3、5、6和7的结构已在100(2)K下通过X射线晶体学确定。磁化率测量以及电子顺磁共振、紫外可见和穆斯堡尔光谱表明，含有[FeII(L(ISQ))2X]发色团的单核配合物（2、4、5）是抗磁性的（St = 0），而含有[FeIII(L(ISQ))2X]n发色团的配合物（3、2(ox)、6）是顺磁性的（St = 1/2），含有[FeIII(L(ISQ))(L(PDI))X]发色团的配合物（7）具有St = 1的基态。已确定所有铁物种都具有固有的中间自旋（SFe = 3/2），其在分子内与一个或两个(L(ISQ))* - 配体自由基发生反铁磁耦合，分别产生St = 1（7）或St = 1/2（2ox、3、6）的基态。在亚铁配合物2、4和5中，铁离子处的固有自旋要么是低自旋（SFe = 0）要么是中间自旋（SFe = 1）。两个自由基(L(ISQ))* - 之间，或者中间自旋亚铁离子与两个自由基之间的反铁磁耦合，进而产生观察到的抗磁性基态。在配合物1中，两个S = 1的[FeIII(L(ISQ))(L(PDI))]半体发生反铁磁耦合，得到St = 0的基态。
