Competitive reactions among three monomers over a catalytic surface

We studied in this work a three-monomer reaction model on one- and two-dimensional lattices. We have taken different reactivity rates among pairs of monomers and the reaction between two selected monomers was forbidden. We have employed the mean field and the pair approximation to decouple the equations of motion for the densities of single and pairs of monomers. We found the stationary states and the phase diagram of the model. We have shown that, in two dimensions and within the pair approximation, there is a first-order transition line between active and poisoned steady states.     

Gamma decay of particle-core states in 209Pb

A γ-decay scheme for levels in ²⁰⁹Pb up to 4.13 MeV of excitation has been established by means of the reaction ²⁰⁸Pb(d, pγ)²⁰⁹Pb. In high efficiency p-γ coincidence measurements γ-cascades have been observed from the single-particle states and from core-excited states with very small single-particle strength. Assuming a qualitative validity of the weak-coupling model spins and main configurations of particle-core states can be deduced from their γ-decay. The $\text{J}{}^{\mathrm{\pi }}\text{= (}\text{3}\text{2}{}^{\mathrm{?}}\text{,}\text{5}\text{2}{}^{\mathrm{?}}\text{or}\text{7}\text{2}{}^{\mathrm{?}}\text{,}\text{11}\text{2}{}^{\mathrm{?}}\text{,}\text{15}\text{2}{}^{\mathrm{?}}\text{)}$ members of the $\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}\text{?3}{}^{\mathrm{?}}$ multiplet could be located. A systematic manner of doublet splitting is found for the lowest states with main configuration $\text{(}\text{p}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{)}{}^{\mathrm{?1}}\text{?3}{}^{210}\text{Pb}\text{(0}{}^{\mathrm{+}}\text{, 2}{}^{\mathrm{+}}\text{, 4}{}^{\mathrm{+}}\text{, 6}{}^{\mathrm{+}}\text{, 8}{}^{\mathrm{+}}\text{)}$. A new decay branch of the $\text{g}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}$ single-particle state is attributed to an admixture of quadrupole core vibration.     

4-Cyanopyridine and amide-N and amide-O linkage isomers of 4-pyridinecarboxamide on trans-chloro(1,4,8,11-tetraazacyclotetradecane)ruthenium(II/III)

The synthesis, UV-vis spectra, and electrochemical behavior of the nitrile-bonded trans-[Ru(II)Cl(cyclam)(4-NCpyH(+))](BF(4))(2) (4-Ncpy = 4-cyanopyridine; cyclam = 1,4,8,11-tetraazacyclotetradecane) and of trans-[Ru(III)Cl(cyclam)(NHC(O)-4-pyH(+))](2+) are described. The UV-vis spectrum of the Ru(II) nitrile complex shows a MLCT band at 548 nm at pH 1, which is shifted to 440 nm at pH approximately 6, for the unprotonated species. trans-[Ru(II)Cl(cyclam)(4-NCpyH(+))](2+) was electrolytically oxidized (+600 mV vs Ag/AgCl) at pH 1 to Ru(III), followed by hydrolysis (k = 0.25 s(-1)) of the coordinated nitrile to give trans-[Ru(III)Cl(cyclam)(NHC(O)-4-pyH(+))](2+), in which the amide is deprotonated and coordinated through nitrogen. The identity of the species is pH dependent, the nitrogen-bonded amide prevailing at low pH (< 7), but the oxygen-bonded amide is formed through linkage isomerization at higher pH (>8). Reduction of trans-[Ru(III)Cl(cyclam)(NHC(O)-4-pyH)](2+) in acidic media does not result in fast aquation (k = approximately 2.4 x 10(-5) s(-1)) as for other amides on ruthenium(II) pentaammine, but instead linkage isomerization occurs, resulting in the oxygen-bonded species, with an estimated rate constant of approximately 2 x 10(-2) s(-1), smaller than in the pentaammine analogues.