Physical Sciences and Mathematics Commons^™

(On The) Observability Of Cubic (P8) Octaphosphorus, Michael W. Schmidt, Mark S. Gordon

Mark S. Gordon

A recent MNDO calculation predicts that the hypothetical P8 is more stable than the observed gas-phase species P4. The ab initio calculations reported here predict just the opposite but do establish that P8 is more stable than another experimentally known form, P2. The relative enthalpies (kcaljmol) are found to be as follows: 4P2, 72.4; 2P 4, 0; P8, 30.4. A force field analysis proves P8 has a cubic structure. The bond length, vibrational frequencies, and photoelectron spectrum of P8 are predicted.

Advances In Synthetic Polymer Chemistry: New Polymer Types And New Directions, The Sixth Carl S. Marvel Symposium, Otto Vogl, Henry K. Hall

Otto Vogl

No abstract provided.

Polymer Science In Japan: The Hokuriku District And The Remaining Universities Of Japan, Otto Vogl, Kiichi Takemoto

Otto Vogl

No abstract provided.

Specialty Polymers -Present And Future, Otto Vogl, Roger Epton

Otto Vogl

No abstract provided.

Evaluation Of Electrochemical Kinetic Parameters Using The Bond-Henderson-Oldham Global Analysis, Dennis Evans, Mark Anderson

Mark R. Anderson

No abstract is currently available.

Studies Of Silicon-Phosphorus Bonding, Kenneth J. Dykema, Thanh N. Truong, Mark S. Gordon

Mark S. Gordon

Ab initio calculations are presented for several species containing a silicon-phosphorus bond. The types of bonding studied include "normal" single, double, and triple bonds, as well as an ylide-like structure. The latter is found to be much less strongly bound than the carbon analogue, with a smaller stretching force constant than that in silylphosphine. The insertions of silylene into the phosphine bond and of phosphinosilylene into H2 are discussed, with the former being illustrated using localized molecular orbitals along the intrinsic reaction coordinate (IRC). Silylene to silene isomerizations in both the closed-shell singlet and the lowest triplet states of SiPH3 …

A Theoretical Study Of Fluorine Atom And Fluoride Ion Attack On Methane And Silane, Larry P. Davis, Larry W. Burggraf, Mark S. Gordon, Kim K. Baldridge

Mark S. Gordon

We have performed MNDO and ab initio calculations for reactions of fluorine atom attack on methane and silane and, in addition, fluoride ion attack on the same molecules in the case of MNDO. We modeled both substitution and abstraction reactions in each case. Results were compared with experimental data, where available. Comparisons show that MNDO usually does as well as the ab initio methods in reproducing experimental values for D.E's of these reactions, but MNDO predicts activation barriers too high in most cases. Nevertheless, MNDO does qualitatively agree with the ab initio result that, while carbon undergoes abstraction much more …

Behavior Of An Electron In Helium Gas, John Bartholomew, Randall W. Hall, Bruce J. Berne

Randall W. Hall

The Intrinsic Reaction Coordinate And The Rotational Barrier In Silaethylene, Michael W. Schmidt, Mark S. Gordon, Michel Dupuis

Mark S. Gordon

The intrinsic reaction coordinate (IRC) is a minimum-energy pathway connecting reactants to products via the transition state. An improved algorithm for the determination of an IRC is presented. The method is illustrated for the rotation of the silicon-carbon double bond in silaethylene. This IRC shows all coordinates vary smoothly during the rotation from the planar to twisted structures, except for a slight pyramidalization at carbon. The rotational barrier is found to be about 37 kcaljmol, in good agreement with experimental estimates.

Glass Formation And High Conductivity In The Ternary System Silver Iodide + Silver Arsenate (Ag3aso4) + Silver Metaphosphate (Agpo3): Host To Glassy .Alpha.-Silver Iodide?, Steve W. Martin, Alberto Schiraldi

Steve W. Martin

Wide regions of glass formation have been found in the ternary system xAgI + yAg,As04 + (1 - x - y)AgPO,. Glasses containing up to 75 mol 7% AgI can be formed in sections greater than 2 cm thick without signs of devitrification. Glass transition temperatures as high as 175 OC for glasses containing - 10 mol % AgI fall to -45 OC at the highest AgI content. An equivalent ratio of Ag1:N is defined and it is found that, for all glass-forming compositions, the electrical data as expressed in the Arrhenius form, u = A exp(-E,,/RT), log (./(a cm)-’), …

Electronic Structure Of The Phosphoryl And Thiophosphoryl Bonds, Michael W. Schmidt, Mark S. Gordon

Mark S. Gordon

.The pho~phoryl bond is presented as a. resonan~e hybrid between singly and triply bound structures. The types of electromcally excited states and a number of their potential surfaces can be understood within the confines of a singly bound model: However, a detailed analysis of the electronic distribution within the ground state shows significant contribution from the tnpl~ bound structure. In fact, increasing the electronegativity of the ligands at phosphorus increases the contribution of t~e tnp~y bound structure, so that the. PO bond order approaches that of a double bond. The thiophosphoryl bond may be VIewed m much the same manner …

Molecular And Electronic Structures Of Metallaspiropentanes, Mark S. Gordon, Philip Boudjouk

Mark S. Gordon

Recent efforts in this laboratory have concentrated on synthesizing metallaspiropentane compounds (I) with M = C, Si, Ge, Sn, Ni, and Zn. To date, the molecule with M = Si and R = methyl has been successfully prepared, 1 while attempts to synthesize the corresponding carbon compound have not reached fruition. This paper presents initial ab initio calculations on the species with M = C and Si and with R = H. Geometries for all species were calculated with the

Predictors Of Grades In General Chemistry For Allied Health Students, Chris Craney, R. Armstrong

Chris L. Craney

Study searching for an effective predictor of student performance in the first term of a full-year general chemistry sequence for allied health students.

Electrochemical Reduction Of 1,1,4,4-Tetraphenylbutatriene In Dimethylformamid, Dennis Peters, Mark Anderson, Tsu-Yu Chen

Mark R. Anderson

No abstract is currently available.

Photothermal Lens Aberration Effects In Two Laser Thermal Lens Spectrometry, Stephen E. Bialkowski

Stephen E. Bialkowski

A comparison of theories describing two laser photothermal lens signals is given. The aberrant nature of this lens is accounted for in a theory which treats the propagation of a monitor laser in terms of a phase shift in this laser beam wave front. The difference between theories are discussed in terms of the predicted signal strengths and temporal behavior. The aberrant theory results in smaller theoretical signal strengths and different functional relationships between signal and analyte level.

Evaluation Of Electrochemical Kinetic Parameters Using The Bond-Henderson-Oldham Global Analysis, Dennis Evans, Mark Anderson

Mark R. Anderson

No abstract is currently available.