Magnetic spin crossover

ID coordination polymer assemblies have attracted much attention in the development of new functional materials owing to such properties as zeolitic behavior, conductivity, luminescence, magnetism, spin-crossover, and nonlinear optical effects [76]. ID coordination chains in solution were obtained from Fe and ditopic bis-terpyridines on graphite [109]. Also, polymeric ro-taxane chains consisting of cyclodextrins-dipyridine units connected by coordination with Ni ions [259], and [CuBr-(isoniconitic acid)] polymeric chains [260] were investigated regarding their surface assembly behavior. 

There will exist an equilibrium between the two states. If the ener between the two states, E, is of the order of kT, then the relative populations of the two states will vary with the temperature of the sample. In the Fe(III) dithiocarbamate series of complexes, [FeCRiRgdtcla], AE can be varied by suitable choice of substituents Ri and Rj. Although these are well removed from the FeSg molecular core, they can appreciably affect the electronic parameters of the central iron atom and of the surrounding crystal field of the sulfur atom by way of the conjugated system of the ligand (237). The results of the spin crossover are reflected in magnetic susceptibility data. 

Bousseksou A, Varret F, Goiran M, Boukheddaden K, Tuchagues J-P (2004) The Spin Crossover Phenomenon Under High Magnetic Field. 235 65-84 Bousseksou A, see Tuchagues J-P (2004) 235 85-103 Bowers MT, see Wyttenbach T (2003) 225 201-226... 

Murray KS, Kepert CJ (2004) Cooperativity in Spin Crossover Systems Memory, Magnetism and Microporosity. 233 195-228... 

Abstract Metal complexes including the dmit2- (1,3-dithio-2-thione-4,5-dithiolato) ligand are the only class of metal bis-dithiolenes to give rise to superconductive molecular materials. This chapter first focuses on the description of these superconductive phases. Further sections describe the association of M(dmit)2 moieties with three types of magnetic molecules, i.e., metalloceniums, radical cations, and spin crossover complexes. 

Keywords M(dmit)2, Metal bis(dithiolene), Metallocenium, Radical cations, Spin crossover, Magnetic properties, Superconductor... 

The Spin Crossover Phenomenon under High Magnetic Field... 

Keywords Spin crossover Magnetism Mossbauer spectroscopy Coooperativity Hysteresis... 

The formation of diimine systems by Schiff -base-type condensation of suitable aldehydes and primary amines has been widely applied. Those reported are mostly strong field systems and their relevance to the spin crossover field is generally in systems of the kind [Fe(diimine)2(NCS)2]. The effect of the incorporation of substituents likely to hinder coordination has been studied. Robinson and Busch noted a fundamental difference at room temperature in the electronic properties of the [Fe N6]2+ derivatives of 2-pyridi-nalmethylhydrazone and 2-pyridinal-dimethylhydrazone, those of the former being low spin and those of the latter high spin [49]. The temperature-dependence of the magnetism of the latter complex was not reported but may well be of interest. However, spin crossover [Fe(diimine)3]2+ systems have been characterised for systems where the incorporation of appropriate substituents has reduced the ligand field. 

Keywords Iron(II) spin crossover complexes Multidentate ligands Ligand design Synthesis Magnetic properties... 

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