Alpha-decay of 39.3 h 254mEs isomer

Mass-separated samples of ^254mEs were used to investigate its α-decay scheme. Twelve α-groups were identified in a spectrum measured with the Argonne magnetic α-spectrometer. The favored α-transition populates a 211.8 keV level in ²⁵⁰Bk and four members of its rotational band were observed. A three-parameter α-γ time coincidence experiment showed that the 211.8 keV level decayed by three routes: two were prompt and one was delayed. The delayed γ-rays (50.07, 71.30, 90.7, 104.0, 126.0 and 175.7 keV) decayed with a 42±2ns half-life. The energies of the prompt γ-rays were 79.90, 96.3, 177.3 and 211.8 keV. From an α-ce^? coincidence experiment the multipolarity of the 211.8 keV transition was deduced to be E1. The α-branching was determined from an α-singles spectrum and was found to be 0.33±0.01%. From the results of the present investigation and the known properties of ²⁵⁰Bk and ^254mEs, the 211.8 keV state in ²⁵⁰Bk and the ^254mEs ground state were given $\text{{}\text{n}\text{[622]}\text{3}\text{2}{}^{\mathrm{+}}\text{;}\text{p}\text{[633]}\text{7}\text{2}{}^{\mathrm{+}}\text{2}{}^{\mathrm{+}}$ assignment. Other levels in ²⁵⁰Bk were postulated at 104.0 (and its rotational member at 125.3), 131.9 and 175.3 keV and these were given tentative assignments of $\text{n}\text{[620]}\text{1}\text{2}{}^{\mathrm{+}}\text{;}\text{p}\text{[521]}\text{3}\text{2}{}^{\mathrm{?}}\text{1}{}^{\mathrm{?}}\text{,}\text{n}\text{[620]}\text{1}\text{2}{}^{\mathrm{+}}\text{;}\text{p}\text{[633]}\text{7}\text{2}{}^{\mathrm{+}}\text{3}{}^{\mathrm{+}}$ and $\text{n}\text{[613]}\text{7}\text{2}{}^{\mathrm{+}}\text{;}\text{p}\text{[633]}\text{7}\text{2}\text{O}{}^{\mathrm{+}}$ (with I = 1), respectively. The splitting energies between the parallel and antiparallel coupled states were calculated with a Gaussian potential for the residual neutron-proton interaction and were found to be in agreement with the experimental values. A precise measurement of the energies and intensities of γ-rays and K X-rays associated with the ^254mEs β^? decay was also made. The Fm K_α2 and K_α1 energies were found to be 115.280±0.015 and 121.065±0.015 keV, respectively.     

Antibody-catalyzed aminolysis of a chloropyrimidine derivative

We have generated antibody FTB8E9 by immunization with the designed hapten to catalyze the aminolysis reaction of a chloropyrimidine derivative.     

Identity of a purple dye formed by peroxidic oxidation of p-aminophenol at low pH

The structure of a colored intermediate commonly formed in the oxidation of p-aminophenol at low pH is established by analysis of H NMR and UV/vis spectra, kinetics, and molecular modeling, following a new method for synthesizing the dye in high concentrations. The chromogen is shown to consist of two compounds with absorption maxima at 540-560 and 375-385 nm. The 2,6-dimethyl and 3,5-dimethyl analogues of p-aminophenol are found to undergo N- rather than C-substitution under similar conditions.     

Mixed A p -A r Inequalities for Classical Singular Integrals and Littlewood–Paley Operators

We prove mixed A _p -A _r inequalities for several basic singular integrals, Littlewood–Paley operators, and the vector-valued maximal function. Our key point is that r can be taken arbitrarily big. Hence, such inequalities are close in spirit to those obtained recently in the works by T. Hytönen and C. Pérez, and M. Lacey. On one hand, the “A _p -A _∞” constant in these works involves two independent suprema. On the other hand, the “A _p -A _r ” constant in our estimates involves a joint supremum, but of a bigger expression. We show in simple examples that both such constants are incomparable. This leads to a natural conjecture that the estimates of both types can be further improved.     

Crystal Structures and Chemical Properties of Dimesitylcadmium and Dimesitylmercury

Mesityllithium was used to synthesize dimesitylcadmium and dimesitylmercury from CdCl₂ and HgCl₂, respectively. X‐ray‐crystallographic data show that the group 12 metal compounds M[Mes]₂ (M = Zn, Cd, Hg) are isomorphous (monoclinic, P2₁/n). The asymmetric unit of M[Mes]₂ (M = Zn, Cd, Hg) consists of one mesityl group bonded to the metal atom, which is related to the second substituent by an inversion center. In addition we have investigated the reaction of BBr₃ with M[Mes]₂ (M = Cd, Hg) for our understanding of the reactivity of donor‐free group 12 mesityl compounds. The reaction of M[Mes]₂ (M = Cd, Hg) with an excess of BBr₃ produces MesBBr₂. UV‐induced conversion of Hg[Mes]₂ in benzene yielded quantitatively mesitylene and mercury whereas irradiation of a chloroform solution of Hg[Mes]₂ for 1290 min (λ_max = 510 nm) gave mesitylene, Hg[Mes]Cl, and HgCl₂ in a ratio of 6:4:1. Slow concentration of the reaction solution led to the deposition of X‐ray quality crystals of the addition compound of two Hg[Mes]Cl molecules and HgCl₂ (monoclinic space group P2₁/n).     

Efficient Access to Substituted Silafluorenes by Nickel‐Catalyzed Reactions of Biphenylenes with Et2SiH2

The reaction of biphenylene ( 1 ) with Et₂SiH₂ in the presence of [Ni(PPhMe₂)₄] results in the formation of a mixture of 2‐diethylhydrosilylbiphenyl [ 2 (Et₂HSi)] and 9,9,‐diethyl‐9‐silafluorene ( 3 ). Silafluorene 3 was isolated in 37.5 % and 2 (Et₂HSi) in 36.9 % yield. The underlying reaction mechanism was elucidated by DFT calculations. 4‐Methyl‐9,9‐diethyl‐9‐silafluorene ( 7 ) was obtained selectively from the [Ni(PPhMe₂)₄]‐catalyzed reaction of Et₂SiH₂ and 1‐methylbiphenylene. By contrast, no selectivity could be found in the Ni‐catalyzed reaction between Et₂SiH₂ and the biphenylene derivative that bears tBu substituents in the 2‐ and 7‐positions. Therefore, two pairs of isomers of tBu‐substituted silafluorenes and of the related diethylhydrosilylbiphenyls were formed in this reaction. However, a subsequent dehydrogenation of the diethylhydrosilylbiphenyls with Wilkinson’s catalyst yielded a mixture of 2,7‐di‐tert‐butyl‐9,9‐diethyl‐9‐silafluorene ( 8 ) and 3,6‐di‐tert‐butyl‐9,9‐diethyl‐9‐silafluorene ( 9 ). Silafluorenes 8 and 9 were separated by column chromatography.     

One- and three-dimensional infinite arrays of Cu(I) ions exhibited by [Cu(NH3)2]Br and [Cu(NH3)Cl] in the solid state

In the solid state, [Cu(NH3)Cl] forms a three-dimensional network with each Cu(I) ion being surrounded by three other Cu(I) centres in a trigonal-planar fashion [Cu...Cu = 2.979(1) A; cubic space group I2(1)3], whereas in [Cu(NH3)2]Br the cations establish infinite linear (Cu...Cu) chains spanning the crystal lattice [Cu...Cu = 2.931(1) A; monoclinic space group C2/c].