Infrared intensities of some SiH-containing compounds in the gas-phase.

Infrared intensities measured in the gas-phase are reported for CH3SiH3, CH3SiD3, (CH3)2SiH2, (CH3)2SiD2, (SiH3)2CH2, (SiD3)2CH2, Si2H6, SiH2Cl2 and (SiH3)2O. These are compared with theoretical estimates from HF, MP2 and B3LYP calculations with the 6-311G** basis set. Literature values of nuCH intensities per bond from 18 compounds correlate linearly with the values calculated at MP2 and B3LYP levels: the corresponding HF plot is slightly curved. The new HC(Si) data fit these correlations adequately. In similar plots for SiH stretching intensity, the point for SiH2Cl2 is displaced, especially at the HF level. The lack of relation of nuCH or nuSiH intensity to Mulliken atomic charge points to the effect of varying atomic charge flux in the parameter thetamu/thetar. Anomalies associated with nuSiH intensities influenced by chlorine or OR substitution and previously explained by d(pi)-p(pi) bonding are attributed instead to charge flux variation. For silyl groups, deformation band intensities are roughly additive according to the number of such groups. However, this is not the case for the methyl symmetric deformation bands in methyl and dimethyl silanes.

Infrared and quantum-chemical studies of the structure and vibrations of trisilylamine.

New infrared spectra are reported for variously labelled trisilylamines. Quantum-chemical (QC) calculations of structure and force field have been made at HF, MP2 and B3LYP levels, each with the 6-31G* and 6-311G** basis sets. At each level, a minimum in the potential surface occurs at the C3h configuration. No evidence was found for a significant variation in SiH bond length with orientation. The appearance of two bands in the infrared spectrum of N(SiH3)3 in the 2nuSiH region is explained by local mode theory in terms of transitions to (200) and (110) levels. In the gas phase, signal averaging appears to occur in the nuSiH region in the infrared spectrum, but not in the Raman. In solid films, both IR and Raman spectra indicate the presence of a range of SiH bond strengths, corresponding to an absence of any site symmetry. Each complete QC calculated force field was fitted to the frequencies observed for N(SiH3)3 and N(SiD3)3, using nine independent scale factors. An interaction force constant between nu(as)NSi3 and delta(s)SiH3 motions required further adjustment. Unobserved frequencies in the d0 and d9 species are predicted. The out-of-plane skeletal bending mode is expected to lie between 170 and 200 cm(-1). Unscaled SiH3 torsional frequencies vary from 64 cm(-1) upwards. The effect of the presence of three internal rotors on the spectra throughout calls for theoretical study.

Pharmaceutical services at the Tenth Pan American Games.

The pharmaceutical services provided by volunteers, including more than 100 pharmacists, at the 1987 Pan American Games in Indianapolis, Indiana, are described. Pharmacists at a local hospital were given responsibility for doping control and operation of the medical clinic pharmacy at the games. Barracks at a U.S. Army facility within the games' boundaries were converted into the clinic; an area on the second floor was equipped as the pharmacy. The pharmacy secured the necessary licensure and obtained drug products and supplies. Volunteer pharmacists were recruited and instructed about responsibilities, procedures, and security. The formulary was based on the 1983 Pan American Games formulary, the 1988 Olympic Games formulary, and requests from the Pan American Sports Organization. In the 26 days that the pharmacy was open, 968 prescriptions were filled. The drugs most commonly prescribed were ibuprofen, terfenadine, acetaminophen, penicillin V potassium, clotrimazole cream, and naproxen. A doping control center located at each competition venue was staffed by a physician, pharmacists, nurses, medical technologists, and nonmedical personnel. After an event, selected athletes were escorted to a doping control center, where a medical history and urine sample were obtained. The urine was tested for pH and specific gravity, and the coded specimen bottles were sealed for transport to the laboratory. Each step was documented on special forms. A total of 981 athletes were tested; six athletes had positive test results. The 1987 Pan American Games provided a unique opportunity for pharmacists to assist in providing medical services at a large athletic event and to become involved in doping control.