Hubert Winter

Characterisation of New Organic Ligand-Based Magnets: [MNTTP] [TCNE] and [MNTTP][TCNQ]

Abstract We analysed the temperature and field dependence of the magnetisation of the electron transfer salts meso-(Tetratolylporphinato)manganese(III)-tetracyanoethenide, [MnIIITTP]:: +[TCNE]− and meso-(Tetratolylporphinato)manganese(III)-7,7,8,8-tetracyano-p-quinodimethane [MnIIITTP]:: +[TCNQ]−. They show cooperative magnetic behaviour for temperatures below 10 K.

Magnetic properties of 1,3,5,6-tetraphenyl- and related verdazyls

Abstract The magnetic properties of 1,3,5,6-tetraphenyl-verdazyl and related verdazyls were characterized by static magnetic susceptibility measurements (1.8K ≤ T ≤ 300K, H ≤ 55 kOe), ESR (10 GHz, solid and solution) and proton NMR (360 MHz, dilute solution). Concentration of radical spins, asymptotic Curie temperature, 1d-exchange integral, ESR linewidth (and thus the strength of exchange narrowing) and spin densities (from proton paramagnetic shifts) were derived. The onedimensional antiferromagnetic exchange interaction is increased by a factor larger than 3 if one additional phenyl unit is added to 1,3,5–6-triphenyl-verdazyl (TPV). The unsymmetrical substitution of TPV by 3-trifluoromethylphenyl reduces the 1d antiferromagnetic exchange drastically, in contrast to the symmetrical substitution by 4-trifluoromethylphenyl.

2-Dicyanomethylene-1,3-Dithiole-4,5- Dithlolate-A New Dithiolene Ligand and Its Metal Complexes

Abstract 2-Dicyanomethylene-1,3-dithiole-4,5-dithiolate (DCDD) has been prepared and used for the synthesis of transition metal complexes (Bu4N)2[M(DCDD)2], M = Ni, Cu, Zn. The redox properties of the nickel complex are similar to that of (Bu4N)2[Ni(dmit)2] (dmit: 1,3-dithiole-2-thione-4,5 dithiolate). Oxidation of (Bu4N)2[Ni(DCDD)2] yields the monoanionic complex Bu4N[Ni(DCDD)2] the electron spectrum of which is characterized by a strong NIR absorption at 1135 nm. The crystal structure of Bu4N[Ni(DCDD)2] shows the anion to be almost planar. Face-to-face stacking of the anions with alternating Ni-Ni distances results in a columnar structure of dimeric anions. The spins of the anions within a dimer are anti-ferromagnetically coupled. The complex Fc*[Ni(DCDD)2] (Fc*: decamethyl-ferrocene) has been prepared by a metathesis reaction using Fc*BF4.

Characterisation of new organic magnetic materials

Abstract Magnetic interactions of organic solids are currently a topic of intense research activity. We analysed the temperature and field dependence of the magnetic moment for the electron transfer salt meso-(Tetratolylporphinato)manganese(III)-TCNQ [Mn III TTP] ::+ [TCNQ] ·− . It shows cooperative magnetic behaviour for temperatures below 10 K.

Novel Dithiolene Complexes and Tetrathiafulvalenes

Abstract Novel dithiolene metal complexes, some of which absorb in the near infrared, and tetrathiafulvalenes, in particular tetraiodotetrathia- fulvalene, have been prepared, and their magnetic properties studied.

Magnetic properties of the new conducting radical cation salt (trans-1,2-bis(2-naphthyl)ethene)SbF6

Abstract In the 1:1 radical cation salt, (trans-1,2-bis(2-naphthyl)ethene)SbF6, the naphthalene stacks of the corresponding 2:1 stoichiometric naphthalene salt are chemically bridged. The magnetic properties of this new organic semiconductor are analysed. The role of defects related to the disordered crystal structure and the influence of sample ageing have been discerned.