Molecular geometry of OC···AgI determined by broadband rotational spectroscopy and ab initio calculations

Pure rotational spectra of the ground vibrational states of six isotopologues of OC···AgI have been measured by chirped-pulse Fourier transform microwave spectroscopy. The spectra are assigned to determine the rotational constant, B(0), centrifugal distortion constant, D(J), and nuclear quadrupole coupling constant of the iodine atom, χ(aa)(I). The complex is linear. Isotopic substitutions at the silver, carbon, and oxygen atoms allow bond lengths to be established by the r(0), r(s), and r(m)((1)) methods of structure determination. The length of the C-O bond, r(CO), in the r(0) geometry for OC···AgI is 0.008 ? shorter than that found in the free CO molecule. The length of the Ag-I bond, r(AgI), is 0.013 ? shorter than in free AgI. χ(aa)(I) is determined to be -769.84(22) MHz for OC···(107)AgI implying an ionic character of 0.66 for the metal halide bond. Attachment of carbon monoxide to the isolated AgI molecule results in an increase of the ionic character of AgI of 0.12. The molecular structure and spectroscopic parameters determined from the experimental data are presented alongside the results of calculations at the explicitly correlated coupled-cluster singles, doubles and perturbative triples level. Vibrational frequencies, the electric dipole moment, the nuclear quadrupole coupling constant, and the dissociation energy of the molecule have been calculated.     

Alexander duality in experimental designs

If $F$ is a full factorial design and $D$ is a fraction of $F$ , then for a given monomial ordering, the algebraic method gives a saturated polynomial basis for $D$ which can be used for regression. Consider now an algebraic basis for the complementary fraction of $D$ in $F$ , built under the same monomial ordering. We show that the basis for the complementary fraction is the Alexander dual of the first basis, constructed by shifting monomial exponents. For designs with two levels, the Alexander dual uses the traditional definition for simplicial complexes, while for designs with more than two levels, the dual is constructed with respect to the basis for the design $F$ . This yields various new constructions for designs, where the basis and linear aberration can easily be read from the duality.     

The solubility of alkali-metal fluorides in non-aqueous solvents with and without crown ethers, as determined by flame emission spectrometry

The solubilities of LiF, NaF, KF, RbF and CsF in acetonitrile, acetone, tetrahydrofuran, dimethylformamide, benzene and cyclohexane have been determined with and without a crown ether (usually 0.1 M 18-crown-6) present. Flame emission spectrometry was the determination method. Three procedures, selected according to the miscibility of the solvent with water, and the solubility of the fluoride, are described. Samples, standards and blanks were matrix-matched. The precision varied between 1 and 10% RSD. Although extensive drying procedures were applied, moisture present in the solvents and salts had some effect on the results.     

Bonding in Halide and Interhalide Complexes with Ammonia: Studies by Microwave Spectroscopy and Density Functional Theory

Electron density redistribution and quadrupole coupling constants (QCC) in XY···NH₃ complexes were analyzed. Data on bond lengths and QCC calculated by the BHandHLYP/aug-cc-pVTZ were used to compare the results obtained with experimental data of rotational spectroscopy. Analysis of QCC values and of the results of approximation of the natural bonding orbitals reveals prevailing electrostatic nature of intermolecular interaction.     

Simultaneous analysis of cocaine,benzoylecgonine, methylecgonine,and ecgonine in plasma using an exchange resin and gas chromatography-mass spectrometry

Summary A gas chromatographic-mass spectrometric method is described for the simultaneous analysis of cocaine and the hydrolytic products benzoylecgonine, methylecgonine and ecgonine from plasma (0.25–2 g/ml). Isopropylecgonine was incorporated as an internal standard. Samples were extracted using a sulfonate cation exchange resin, then derivatized with pentafluoropropionic anhydride and pentafluoropropanol. Analytical separations were on a dimethylsilicone capillary column using a temperature program, and detection was by selected ion monitoring of the electron impact generated fragments m/z 94, 182, 210, and 300.Presented at the poster session of American Association of Pharmaceutical Scientists 1991 Southeast Regional Meeting, Charleston, South Carolina, USA, April 4–5