ABSTRACT:The reductive preparation of poly(thiophene) and copolymers from 2,5-dibromothiophene and tetrabromothiophene is described. In this reaction, hydrazine and palladium catalysts were used. Yield of the polymer was 65% when 2,5-dibromothiophene was used as a monomer. Electric conductivity of the polymer was 1 x 10-5 S cm -1 (1 2 20 wt¾) and 1 x 10-3 S cm -1 (12 50 wt¾). The polymer had 1.6 wt¾ of bromine residue. As the mixing ratio of 2,5-dibromothiophene to tetrabromothiophene decreased, yield of the polymer decreased. A polymer from tetrabromothiophene gave yield of 41 %. As for electric conductivity, the polymer prepared from only 2,5-dibromothiophene gave a higher value than copolymers of 2,5-dibromothiophene and tetrabromothiophene. Increasing the a mixing ratio of tetrabromothiophene caused a decrease of the conductivity. The polymer from tetrabromothiophene gave electric conductivity of -10-6 -10-7 Scm-1 (1 2 20wt%).KEY WORDS Poly(thiophene) / 2,5-Dibromothiophene / Tetrabromothiophene / Palladium / Reductive Polymerization / of these polymers were measured.

We present a technique for building itinerant electron states as approximate ground states to the spin half Anderson lattice Hamiltonian. We choose one fermionic state per site from amongst the two initial states, in the most general mathematical manner. Restricting the application of the Hamiltonian to states where only this special state is non-empty, we minimise the restricted energy in the Hartree-Fock approximation. Treating the initial choice of the relevant fermion as a variable, we then minimise the Hartree-Fock energy over this choice. The resulting energy is an upper bound on the ground state energy because the variational principle underpins our technique. Since we are forcing an itinerant solution onto the problem, this technique fails when the solution involves localised electrons behaving as spins together with non-interacting electrons. There are however large regions of parameter space where the energy found is less than the best localised solutions. We treat on-site hybridisation, nearest-neighbour hybridisation and Coulomb repulsion between the two types of electron with equal ease. Finally we consider speculative applications to the u-Ce to 7-Ce phase transition and a more reasonable application to the magnetic phase transitions in CeNi,Ptl-, and CeNi,Pdl-, and the similar systems CeSiz-, and CeSi2-,Ge,y.

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We studied platinum-zinc alloy plating by adding zinc to an alkaline platinum bath that used hexahydroxoplatinate.