Search

The wave function-based method namely the CASSCF/MS-CASPT2 method was used to study the Creutz-Taube complex [[[(N[H.sub.3]).sub.5]-Ru-pyrazine-Ru-[(N[H.sub.3]).sub.5]].sup.5+]. The g-factors of the CT ion are shown to be independent of the coupling between the centers and to be the same as in the monomer, because the coupling acts in symmetry different from the one of the ground state.

The reaction of the electronically unsaturated tetrahedral cluster [[Re.sub.4][([mu].sub.3]-H).sub.4][(CO).sub.12] with pyridazine (pydz) has provided the main initial product the tetranuclear cluster [[Re.sub.4][([mu]-H).sub.4]([mu].pydz)[(pydz).sub.2][(CO).sub.12]], with 64 ve and four hydrogen-bridged metal-metal interactions, with a spiked-triangle geometry. The quantum yields are [[Re.sub.4][([mu].sub.3]-H).sub.4][(CO).sub.12] order of magnitude higher for the squares than for the dinuclear complexes.

An OFF-OFF-ON fluorescence sensor is described for metal ions by stepwise complex formation equilibria of 2,3,5,6-tetrakis(2-pyridyl)pyrazine (TPPZ) with metal ions. The OFF-OFF-ON fluorescence sensor can be used in biological applications because its concept should be general enough to be applied to other probe molecules that display stepwise complex formation with metal ions.

The preparation of tetrahydropyrazines, dihydropyrazines, pyrazines, piperazinones, and quinoxalines by 1,4-addition of 1,2-diamines to 1,2-diaza-1,3-butadienes bearing carboxylate, carboxylate, carboxamide or phosphorylated groups at the terminal carbon and subsequent internal heterocyclization is described. The solid-phase reaction of polymer-bound 1,2-diaza-1,3-butadienes with 1,2-diamines has produced pyrazines.