Dinuclear manganese(III,IV) and (IV,IV) complexes, [Mn2(N4-py)2(O)2](ClO4)3·H2O (1) and [Mn2 (N4-py)2(O)2](ClO4)4·CH3CN·H2O (2), were prepared, where N4-py represents tris(2-pyridylmethyl)amine. Both complexes 1 and 2 exhibited strong antiferromagnetic interaction with J≈−159 and −137 cm−1, respectively. ESR spectrum of 1 showed a sixteen 55Mn hyperfine pattern at g=2, which is indicative of a Mn(III,IV) trapped valence state.

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The effect of H2O2 on ferrous human haemoglobin subunits (alphash-, betash-, alphapmb- and betapmb-chains) was studied. These chains were easily transformed to haemichrome by the addition of H2O2 or H2O2-generating systems, including glucose oxidase (EC 1.1.3.4) AND XANTHINE OXIDASE (EC 1.2.3.2), and this was ascertained by e.p.r. measurements and by absorption spectra. The changes in these haemoglobin subunits were not inhibited by superoxide dismutase (EC 1.15.1.1), but were decreased by catalase (EC 1.11.1.6). The rate of oxidation of alphapmb-chains was higher than that of alphash-chains, and the rate of oxidation of betapmb-chains was higher than that of betash-chains. Haemichrome was demonstrated to be formed directly from these ferrous chains by the attack by H2O2, and this process did not involve formation of methaemoglobin. On the basis of these findings the kinetics of the reaction between the haemoglobin subunits and H2O2 was studied, and the pathological significance of H2O2 in disorders of erythrocytes such as thalassaemia was discussed.

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The temperature dependences of the 2 H nuclear magnetic resonance (NMR) spectra and the spin-lattice relaxation time T 1 were measured forThe motional modes for both compounds were discussed on the basis of the spectral simulation. The temperature variations of the 2 H NMR spectra at high temperatures could be explained by threehowever, six-site jumps of [Fe(H 2 O) 6 ] 2+ about the C 3 axis were found to be most probable form of motion at high temperatures. At low temperatures, the 2 H NMR spectra of both compounds could be explained by 180 • flips of the water molecule. The 2 H NMR T 1 was dominated by the fluctuations of the electric field gradient caused by the molecular motion and of the magnetic interaction between the 2 H nucleus and the unpaired electron spin in the metal ion. T 1 was analysed in terms of the motional modes predicted from the spectral simulation. The activation energies, the jumping rates at infinite temperature for each form of motion and the quadrupole interaction parameters (e 2 Qq/ h, η) were obtained from the 2 H NMR spectra and T 1 . The conclusions from the spectral simulation are in good agreement with the results for T 1 . These results suggest that [Fe(H 2 O) 6 ][SiF 6 ] possesses dynamic disorder structure in the high-temperature phase.