S-, X-, Q- und W-Band-Pulver-EPR-Untersuchungen an Tetra-n -butylammonium-bis( 1,2-dicyanoethen-1,2-dithiolato)aurat(II), [(n-C4H9)4N]2[AuII(mnt)2] / S, X, Q and W Band Powder-EPR Investigations on Tetra-n-butylammoniumbis( 1,2-dicyanoethylene-1,2-dithiolato)aurate(II), [(n-C4H9)4N]2 [AuII(mnt)2]

Powder-EPR studies at T = 295 K and T = 12 K on the unstable gold(II) complex [(n- C4H9)4N]2[AuII(mnt)2] diamagnetically diluted by the corresponding NiIIcomplex are reported. Due to (i) the small anisotropy of the g and the 197Au hyperfine tensor AAu, and (ii) the large 197Au quadrupole interaction the powder spectra possess a very complex pattern. Using different EPR frequencies - S band (2.4 GHz), X band (9.5 GHz), Q band (35 GHz) and W band (94 GHz) - the spectra could be analyzed successfully. All spectra were simulated with a computer program which diagonalizes the spin-Hamiltonian matrix exactly.

EPR Characterisation of Bis(dimethylglyoximato)-Cobalt(II) Complexes and Their Oxygen Adducts Synthesised in an X-Zeolite Matrix

The synthesis of bis(dimethylglyoximato)-cobalt(II) (CoII(dmgH)2) in the α-cages of a cobalt-exchanged sodium X-zeolite is described. A simple hydration/oxygenation sequence culminating in a superoxo complex, CoIII(dmgH )2 · H2O · O2- has been studied using X-band EPR spectroscopy. The identification of the precursor species: square-planar CoII(dmgH)2, distorted CoII(dmgH)2 and CoII(dmgH)2 · 2H2O was aided by comparison of their g- and 59Co hyperfine tensor principal values with those o f model complexes. On the basis of this identification the reaction sequence is discussed.