Triply bridged bis-iminodioxolene dinuclear metal complexes of general formula M-2(diox-diox)(3), with M = Co, Fe, have been synthesized using the bis-bidentate ligand N,N'-bis(3,5-di-tert-butyl-2-hydroxyphenyl)-1,3-phenylenediamine. These complexes were characterized by means of X-ray, HF-EPR, and magnetic measurements. X-ray structures clearly show that both complexes can be described as containing three bis-iminosemiquinonato ligands acting in a bis-bidentate manner toward tripositive metal ions. The magnetic data show that both of these complexes have singlet ground states. The observed experimental behavior indicates the existence of intraligand antiferromagnetic interactions between the three pairs of m-phenylene units linked iminosemiquinonato radicals (J = 21 cm(-1) for the cobalt complex and J = 11 cm(-1) for the iron one). It is here suggested that the conditions for the ferromagnetic coupling that is expected to characterize the free diradical ligand are no longer satisfied because of the severe torsional distortion induced by the metal coordination.
Dinuclear Iron(III) and Cobalt(III) Complexes Featuring a Biradical Bridge: Their Molecular Structures and Magnetic, Spectroscopic, and Redox Properties
units was used to synthesize novel binuclearcomplexes [(LR)MIII(•LB•)MIII(LR)](ClO4)2, M = Fe (1) and Co (2, 3), with HLR (R = CH3, Cl) being the facially coordinating tetradentate coligands. Upon the synthesis, the fully reduced amidophenolate form of the ligand (LB)4– becomes oxidized, resulting in the formation of a rare example of a biradical (•LB•)2– bridge connecting two metal ions, as supported
使用具有两个邻氨基苯酚非清纯单元的双双配体H 4 L B来合成新型双核络合物[(L R)M III(•L B •)M III(L R)](ClO 4)2,M =的Fe(1)和Co(2,3)中,用HL - [R(R = CH 3,Cl)的作为表面式地协调四齿共配体。合成后,完全还原的酰胺基苯酚配体形式(L B)4–会被氧化,导致形成X射线晶体学支持的连接两个金属离子的双自由基(•L B •)2–桥的罕见例子。配合物的电子结构已通过Mössbauer光谱,磁化率测量和电子顺磁共振(EPR)光谱进行了探测。物种1包含两个高自旋的Fe(III)离子(小号= 5/2),每个耦合强反铁磁(| Ĵ |>150厘米-1 ; H ^ = - 2J S ^ 1 S ^ 2)配有一个半醌的π基团(小号= 1/2)桥接形式(•L B•)2 –配体。每个[Fe(III)+ R ● ]单体单元的有效S = 2自旋,然后与J
A unique series of dinuclear transition metal–polyradical complexes with a m-phenylenediamine spacer and their catalytic reactivity
A series of dinuclear transition metal complexes with either six or four iminosemiquinone radicals, in which the metal centres are separated by a distance of â¼6.8 Ã , together with their catalytic reactivity is reported.
报告了一系列含有六个或四个亚氨基喹啉酮自由基的双核过渡金属配合物及其催化反应性。
Dinuclear ruthenium bipyridine complexes with a bis(iminodioxolene)-meta-phenylene ligand: magnetic coupling and mixed valence character of the semiquinonato species
作者:Fabrizia Fabrizi De Biani、Andrea Dei、Claudio Sangregorio、Lorenzo Sorace
DOI:10.1039/b508401f
日期:——
strong ferromagnetic interaction (H=JS(1) x S(2), J=-85(5) cm(-1)). This result is the theoretically expected one and it is contrasting with the antiferromagneticinteraction observed in previously investigated complexes containing the same ligand. It is suggested that the different behaviour is determined by the different coordination requirements occurring in these complexes. The spectroelectrochemical
The reaction of Mn(II) salts with N,N'-bis(3,5-di-tert-butyl-2-hydroxyphenyl)-1,3-phenylenediamine yields a dinuclear Mn2L3 complex, which on the basis of its structural and magnetic characterisation can be formulated as a Mn(IV) derivative of both dinegative bis-iminosemiquinonato and mixed valence trinegative iminosemiquinonato-iminocatecholato forms of the reacting ligand. HF-EPR spectra at various frequencies suggest that the electron transfer process in this mixed valence species is frozen on the time scale of EPR at high frequency, whereas is still dynamic at lower frequencies. This spectral behaviour therefore indicates a thermally activated character of the electron transfer process, as expected in a class 11 mixed valence system. (C) 2002 Elsevier Science B.V. All rights reserved.
Dinuclear and mononuclear manganese(<scp>iv</scp>)-radical complexes and their catalytic catecholase activity
of the radicals without redox participation of the metal center is proposed for the catalytic oxidation process. Complex 1 is found to be a good catalyst for oxidative C-C coupling of hindered phenols to diphenoquinones.