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The microwave spectra of twelve isotopic species of cis propanal (CH3CH2CHO) and six isotopic forms of the less stable gauche rotamer have been studied to determine accurate structural parame ters for both conformers. The following bond lengths (Ä) and angles (°) were derived: (9) 125.1 (9) 128.2 (3) Introduction Propanal (CH3CH2CHO) exists in the form of two rotational conformers in the gas phase, cis and gauche. Recently we reported [1] an extension to previous microwave work on propanal [2, 3, 4] which enabled us to compare the barriers to internal rotation of the methyl group in the two conformers. The purpose of the present paper is to present accurate structures for both conformers.The microwave spectrum of cis propanal is straight forward and has been extensively studied [2,4,5]. With the present work, isotopic data are now avail able for substitution at each atomic position in the molecule.The microwave spectrum of gauche propanal is more complicated because doublets, appear even in the ground state, due to + tunnelling. Study of the spectrum has also been limited because of the un Reprint requests to Dr. A. Peter Cox, School of Chemistry, Department of Physical Chemistry, University of Bristol, Bristol, England, BS8 ITS. favourable energy difference between the conformers, AH (gauche -cis) = 420(27) cm "1 [5], Recently we have obtained the A rotational constant for several species by the use of radiofrequency microwave dou ble resonance techniques. This information and data from assignment of carbon-13 spectra have been used to derive accurate structural information for the gauche conformer. ExperimentalThe microwave frequencies measured in the present work are given in Tables 1 and 2. The CH2DCH2CHO species were prepared and studied as described in Reference [6]. The cis car bon-13 species were studied in natural abundance using a pulsed molecular beam Fourier transform microwave spectrometer at Ann Arbor, details of which may be found in [7]. The high energy gauche form was not detected by this technique.The remaining cis and gauche species studied in this work were observed using the Bristol 100 kHz Stark 0932-0784 / 88 / 0300-283 $ 01.30/0. -Please order a reprint rather than making your own copy.

Three bacterial strains, Agrobacterium radiobacter, Klebsiella oxytoca, and Kluyvera ascorbata, isolated by enrichment culture for carbon to phosphorus bond cleavage ability, were analyzed for the mode of C-P bond fission. The cleavage of alkyl phosphonic acids to alkanes and inorganic phosphates proceeded both aerobically and anaerobically, and growth on trideuteromethylphosphonic acid yielded trideuteromethane as product. These data indicate that functionalization of the organic moiety does not precede carbon to phosphorus bond cleavage. As probes for radical intermediates, cyclopropylmethylphosphonic acid and cis-1,2-dideutero-1-propenylphosphonic acid were used in growth experiments and the gaseous hydrocarbon products were examined. With the cyclopropylmethylphosphonic acid probe, all three bacteria produced methylcyclopropane, but only K. oxytoca and K. ascorbata also generated the acyclic olefin I-butene, and then only in very low quantity (0.6 and 0.3% versus methylcyclopropane, respectively). With the propenylphosphonic acid probe, cis-1,Zdideuteropropene was formed with greater than 98% retention of configuration with each bacterial strain. Only for K. oxytoca was the alternate product, in this case trans-1,2dideuteropropene, clearly detected at 1.5%. Thus, C-P bond fission may yield radical intermediates that are trapped efficiently at the enzyme active site or, alternatively, homolysis of the C-P bond may occur as a minor reaction pathway. o 1987 Academic PESS, 1~. t Glyphosate is the commercial name for the broad-spectrum herbicide N-phosphonomethylglycine

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The complexes ofPF 3 with Ar and Kr, were studied by Fourier transform microwave spectroscopy. The force constants and amplitudes of vibration for the van der Waals modes of the complexes and the average moments of inertia and structural parameters were estimated from the centrifugal distortion constants. The distance (R e. m .)ave between the rare-gas atom and the center of mass of PF 3 is 3.959 A for the Ar complex and 4.077 A for Kr while the angle (8 e. m .)ave between the R e. m. vector and the C 3 axis of the PF 3 is 69.30° and 67.25°, respectively. The dipole moments of both complexes and of free PF 3 were determined. The induced dipole components estimated for the rare gas using electric fields from ab initio calculations of PF 3 agree with the experimental values for a conformation with the rare gas over a PF 2 face. The PF 2 face conformation is also consistent with the observed and ab initio estimates ofthe 83Kr nuclear quadrupole coupling constant for the 83Kr_PF3 species.