FeS and NiS show first order phase transitions with a change in electronic structure at Ta = 415 K and Tt = 265 K respectively, the latter depending sensitively on non-stoichiometry in the form of nickel vacancies. Extensive experimental data on NiS is reviewed which shows that the low-temperature phase is a semimetallic itinerant-electron antiferromagnet and the high temperature phase a weakly...

The synthesis and crystallographic characterization of a complex possessing a well-defined {2Fe3S(μ-H)} core gives access to a paramagnetic bridging hydride with retention of the core geometry. Chemistry of this 35-electron species within the confines of a thin-layer FTIR spectro-electrochemistry cell provides evidence for a unprecedented super-reduced Fe(I)(μ-H)Fe(I) intermediate.

Two hydrogenases from the methanogenic bacterium Methanobacterium thermoautotrophicum strain DeltaH have been purified and contain tightly bound nickel as well as the anticipated iron/sulfur atoms with a fixed ratio of 15-20 iron atoms per nickel. One hydrogenase reduces the 8-hydroxy-5-deazaflavin coenzyme factor 420 (F(420)), whereas the other has been purified as a methyl viologen-reducing h...

Double electron-electron resonance (DEER) spectroscopy can determine, from measurement of the dipolar interaction, the distance and orientation between two paramagnetic centres in systems lacking long-range order such as powders or frozen solution samples. In spin systems with considerable anisotropy, the microwave pulses excite only a fraction of the electron paramagnetic resonance (EPR) spect...

Real-time dynamics of native super-paramagnetic nanoparticles (SPMNPs) with different sizes were observed in a microchip at the single-particle level. Based on the optimized magnetic field conditions obtained in the single-nanoparticle study, the SPMNPs were successfully separated and detected within ~15 s from the model polydisperse mixture.

The conjugated iron-sulphur proteins are enzymes that contain iron-sulphur clusters, which are paramagnetic in certain oxidation states. Numerous enzymes of this type have been isolated (Palmer, 1975; Cammack, 1979; Yoch & Carithers, 1979), and whole books have been devoted to them (Lovenberg, 1977; Spiro, 1982). Most of them (aconitase being an exception) are oxidoreductases. By using e.p.r. (...

A number of oxidation-reduction proteins, containing iron and an acid-labile form of sulfide, have been shown to exhibit low-temperature electron paramagnetic resonance (EPR) signals near g = 1.94, on reduction.l-4 These proteins include oxidases of the xanthine type, ferredoxins, and nonheme-iron and iron flavoproteins from mitochondria and bacteria. By substitution with iron5 and sulfur6' I i...