Energy of the 5− isomer and (πg 9/2⊗vg 9/2) states in82Rb

Excited states in the doubly-odd nucleus⁸²Rb have been investigated via the reactions⁷⁹Br(,n) and⁷⁸Se(⁷Li,3n) using in-beam-ray spectroscopy. The level energy of the longlived 5^– isomer has been determined to 68.3 keV which is below the energy of the 2^– state found at 88.9 keV with a lifetime of=2.4(2) ns. A sequence of positive-parity states beginning with a 6⁺ level at 191.3 keV (=20(3) ns) and extending to a (10⁺) level has been interpreted to contain the two-particle configuration (g ₉/2 _9/2) and collective excitations.     

The application of novel methodology for the synthesis of o-, m-, and p-(SF5-perfluoroethyl) benzene derivatives

The reaction of o-, m-, and p-F₂CCFC₆H₄X with SF₅Br produces an intermediate adduct, F₅SCF₂CFBrC₆H₄X, which, on treatment with AgBF₄, affords the first useful, high yield preparation of o-, m-, and p-F₅SCF₂CF₂C₆H₄X.     

Backbone modified small bite-angle diphosphines: Synthesis and molecular structures of [M(CO)4{X2PC(RR)PX2}] (M = Mo, W; X = Ph, Cy; R = H, Me, Et, Pr, allyl, R = Me, allyl)

A range of new small bite-angle diphosphine complexes, [M(CO)₄{X₂PC(R¹R²)PX₂}] (M = Mo, W; X = Ph, Cy; R¹ = H, Me, Et, Pr, allyl, R² = Me, allyl), have been prepared via elaboration of the methylene backbones in [M(CO)₄(X₂PCH₂PX₂)] as a result of successive deprotonation and alkyl halide addition. When X = Ph it proved possible to replace both methylene protons but for X = Cy only one substitution proved possible. This is likely due to the electron-releasing nature of the cyclohexyl groups but may also be due to steric constraints. Attempts to prepare the bis(allyl) substituted complex [Mo(CO)₄{Ph₂PC(allyl)₂PPh₂}] were only moderately successful. The crystal structures of nine of these complexes are presented.     

Evidence of Shear Rate Dependence on Restructuring and Breakup of Latex Aggregates

Small-angle static light scattering has been used to probe the evolution of aggregate size and structure in the shear-induced aggregation of latex particles. The size of aggregates obtained from the particle-sizing instrument (Coulter LS230) was compared with the size of those obtained with another approach utilizing the Guinier equation on the scattering data. Comparison of the two methods for studying the effects of mixing on the evolution of the aggregate size with time revealed similar trends. The aggregate structures were quantified in terms of their fractal dimensions on the grounds of the validity of Rayleigh-Gans-Debye scattering theory for the fractal aggregates. Analysis of the scattering patterns of aggregates verified that restructuring of the aggregates occurred as the aggregates were exposed to certain shear environments, resulting in a scale-dependent structure that could not be quantified by a fractal dimension. The effect of restructuring on aggregate size was particularly noticeable when the aggregates were exposed to average shear rates of 40 to 80 s(-1), whereas no significant restructuring occurred at lower shear rates. At 100 s(-1), the fragmentation of aggregates appeared to be more significant than aggregate compac-tion. Copyright 2001 Academic Press.     

Alignment ofH(2P) after beam-foil excitation

The alignment of foil-excited hydrogen was determined by measuring the polarization of Ly- radiation in the particle energy region 23E190 keV. A change of sign at 45 keV is observed.     

Diastereoselective synthesis of the 5-hydroxy-pyrrolidinone amino acid of the microsclerodermins and model studies for an end-game strategy for microsclerodermin B

The first diastereoselective synthesis of the 5-hydroxy-pyrrolidinone amino acid common to eight members of the microsclerodermin family is presented. Our strategy involves formal hydration of an unsaturated precursor via the use of a two-step hydroxybromination-debromination protocol; this procedure provides exclusively the requisite 4,5-cis-pyrrolidinone. Furthermore model studies are presented that indicated the potential viability of this hydration strategy in the context of a synthesis of microsclerodermin B.