Selective formation of the [PhP(H)-PPh]- anion in the reaction of PhPHLi with MeAlCl(2); synthesis and structure of the unusual tetramer [(PhP(H)-PPh)Li.thf]4

The reaction of PhPHLi with MeAlCl(2)(3:1 equivalents) gives the tetramer [(PhP(H)-PPh)Li.thf]4, and provides the first direct evidence of a link between the reactivity patterns observed for Group 14 and 15 phosphanenides and those of Group 13.     

Special Lagrangian Submanifolds with Isolated Conical Singularities. III. Desingularization,The Unobstructed Case

This is the third in a series of five papers studying special Lagrangian submanifolds(SLV m-folds) X in (almost) Calabi–Yau m-folds M with singularities x ₁, ..., x _n locally modelled on special Lagrangian cones C ₁, ..., C _n in ^m with isolated singularities at 0. Readers are advised to begin with Paper V.This paper and Paper IV construct desingularizations of X, realizing X as a limitof a family of compact, nonsingular SL m-folds ^t in M for small t > 0.Suppose L ₁, ..., L _n are Asymptotically Conical SL m-folds in ^m , with L _i asymptotic to the cone C _i at infinity. We shrink L _i by a small t > 0, and glue tL _i into X at x _i for i= 1, ..., nto get a 1-parameter family of compact, nonsingular Lagrangian m-folds N ^t for small t > 0.Then we show using analysis that when t is sufficiently small we can deform N ^t to a compact,nonsingular special Lagrangian m-fold ^t , via a small Hamiltonian deformation.This ^t depends smoothly on t, and as t 0 it converges to the singular SL m-fold X, in the sense of currents.This paper studies the simpler cases, where by topological conditions on X and L _i we avoid various obstructions to existence of ^t . Paper IV will consider more complex cases when these obstructions are nontrivial, and also desingularization in families of almost Calabi–Yau m-folds.     

Cross-metathesis between ethane and toluene catalyzed by [([triple bond, length as m-(SiO)(2)TaH]: the first example of a cross-metathesis reaction between an alkane and an aromatic

The silica-supported tantalum hydride [([triple bond, length as m-dash]SiO)(2)TaH] catalyzes at moderate temperature (150-250 degree C) the cross-metathesis reaction between toluene and ethane, to form mainly ethylbenzene and xylenes.     

New approach for measuring properties of rp-process nuclei

A new experimental approach was developed that can reduce the uncertainties in astrophysical rapid proton capture (rp) process calculations due to nuclear data. This approach utilizes neutron removal from a radioactive ion beam to populate the nuclear states of interest. Excited states were deduced by the gamma-decay spectra measured in a semiconductor Ge-detector array. In the first case studied, 33Ar, excited states were measured with uncertainties of several keV. The 2 orders of magnitude improvement in the uncertainty of the level energies resulted in a 3 orders of magnitude improvement in the uncertainty of the calculated 32Cl(p,gamma)33Ar rate that is critical to the modeling of the rp process. This approach has the potential to measure key properties of almost all interesting nuclei on the rp-process path.     

Half-life of the doubly magic r-process nucleus 78Ni

Nuclei with magic numbers serve as important benchmarks in nuclear theory. In addition, neutron-rich nuclei play an important role in the astrophysical rapid neutron-capture process (r process). 78Ni is the only doubly magic nucleus that is also an important waiting point in the r process, and serves as a major bottleneck in the synthesis of heavier elements. The half-life of 78Ni has been experimentally deduced for the first time at the Coupled Cyclotron Facility of the National Superconducting Cyclotron Laboratory at Michigan State University, and was found to be 110(+100)(-60) ms. In the same experiment, a first half-life was deduced for 77Ni of 128(+27)(-33) ms, and more precise half-lives were deduced for 75Ni and 76Ni of 344(+20)(-24) ms and 238(+15)(-18) ms, respectively.     

A flexible nudged elastic band program for optimization of minimum energy pathways using ab initio electronic structure methods

A driver program for carrying out nudged elastic band optimizations of minimum energy reaction pathways is described. This approach allows for the determination of minimum energy pathways using only energies and gradient information. The driver code has been interfaced with the GAUSSIAN 98 program. Applications to two isomerization reactions and to a cluster model for H(2) desorption from the Si(100)-2 x 1 surface are presented.     

Non-aggregating octasubstituted dendritic phthalocyanines

Eight poly(aryl) ether dendritic wedges attached to the periphery of a phthalocyanine significantly decreases self-association of these chromophores in solution and the condensed state.