Structures of similar accuracy have been computed for the cis,cis, trans,trans, and cis,trans isomers of octatetraene at the CCSD(T) level with a basis set of wCVQZ(ae) quality adjusted in accord with the experience gained with trans-hexatriene. The accuracy of this structure is 0.001 Å and 0.1 °. In the mixed estimation method bond parameters are fit concurrently to moments of inertia of various isotopologues and to theoretical bond parameters, each data set carrying appropriate uncertainties.

CRAIG, Department of Chemistry and Biochemistry, Oberlin College, Oberlin, OH, USA JEAN DEMAISON, Laboratoire PhLAM, UMR 8523 CNRS - Université Lille 1, Villeneuve d'Ascq, France PETER GRONER, Department of Chemistry, University of Missouri - Kansas City, Kansas City, MO, USA HEINZ DIETER RUDOLPH, NATALJA VOGT, Section of Chemical Information Systems, Universität Ulm, Ulm, Germany Īn accurate equilibrium structure of trans-hexatriene has been determined by the mixed estimation method with rotational constants from 8 deuterium and carbon isotopologues and high-level quantum chemical calculations. P840: ACCURATE EQUILIBRIUM STRUCTURES FOR trans-HEXATRIENE BY THE MIXED ESTIMATION METHOD AND FOR THE THREE ISOMERS OF OCTATETRAENE FROM THEORY STRUCTURAL CONSEQUENCES OF ELECTRON DELOCALIZATION All the experimental data is in good agreement with the calculated data. SOOHYUN KA, JIHYUN KIM, HEESU JANG, JUNG JIN OH, Research Institute of Global Environment, Sookmyung Women's University, Seoul, Korea Ĭonsequentially, the rotational constants, nuclear quadrupole constants, and centrifugal distortion constants were determined and the dipole moment of the aa conformer with 79Br were measured. P1080: MICROWAVE SPECTRA OF 1- AND 2-BROMOBUTANE Other aspects of this joint work, including the bond order inferred from the eQq(N) coupling constants, and the issue of planarity in substituted derivatives of the form R 1R 2NNO, will be discussed. These findings are consistent with new CCSD(T) calculations which predict that the equilibrium geometry of H 2NNO is planar, but that it possesses an extremely flat H 2N-X potential, like NH 3. By correcting the experimental rotational constants for vibrational corrections calculated theoretically, a precise semi-experimental structure has been derived. For each isotopic species, all three rotational constants have been determined to a fractional accuracy of 10 ppm or better nitrogen quadrupole coupling constants have also been derived to very high accuracy. Due to its perceived instability, H 2NNO has never been isolated and spectroscopically characterized in the gas phase, but, by means of Fourier transform microwave spectroscopy in combination with millimeter-wave double resonance techniques, the rotational spectrum of the normal and six of its rare isotopic species have been measured to high accuracy between 15 and 90 GHz. As the simplest N-nitrosamine, it is also the basis for understanding how specific substituents subtly change the structure of the NNO unit in larger nitrosamines, an important set of compounds that can be produced in foods by nitrites, but which are commonly carcinogenic to humans. H 2NNO plays a central role as the initial intermediate in the NH 2 + NO reaction. STANTON, Department of Chemistry, The University of Texas, Austin, TX, USA MICHAEL C McCARTHY, Atomic and Molecular Physics, Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, USA KELVIN LEE, School of Chemistry, UNSW, Sydney, NSW, Australia JOHN F.

P1165: DETECTION AND STRUCTURAL CHARACTERIZATION OF NITROSAMIDE H 2NNO: A CENTRAL INTERMEDIATE IN deNO x PROCESSES A precise empirical molecular equilibrium structure was derived from a combination of theory and experiment. Once formed, HSNO appears quite stable, as evidenced by its high steady-state concentration. Surprisingly, HSNO is readily produced in a gas expansion of H 2S and NO, i.e. Here we report the first detection of both cis- and trans-HSNO by means of Fourier-transform microwave spectroscopy and double resonance experiments. The simplest S-nitrosothiol, thionitrous acid (HSNO), is a reactive molecule of both biological and astronomical interest.

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