The Organization of Two Soft (Cu2Ө, Ni2Ө) Metal Centers in Heterotrinuclear Complexes of a Macrocyclic Ligand by Cocomplexation with Ba2Ө

The short distances between the two transitionmetal centers in the trinuclear complexes 3 are caused by cocomplexation of Ba2Ө: Cu2Ө:...Cu2Ө 3.50, Ni2Ө ...Ni2Ө 3.42 Å. The macrocyclic ligand is formed as the complex 2 from o-phenylenediamine and 1 in the presence of Ba2Ө. Complexes 3, in turn, are obtained by treatment of 2 with copper or nickel acetate

The atomic surface structure of SrTiO3 (001) studied with synchrotron X-rays

The atomic surface structure of single terminated SrTiO3(0 0 1) (1 × 1) is investigated employing surface X-ray diffraction. In order to obtain these surfaces a special treatment is needed consisting of chemical etching and annealing. Since this is done in an aqueous and subsequently oxygen environment, after which the crystals are kept at ambient conditions, the surface is studied in air. Crystal truncation rods are measured and several models that are proposed in literature in recent years are tested against the experimental data. These models include surface rumpling, low temperature-like distortions, strontium adatom and lateral displacement distortions for both TiO2 and SrO-terminated surfaces. None of these models represents the data very accurately. A much better fit to the experimental results is obtained by using a model in which a TiO2-terminated crystal is covered by an oxygen layer