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At least 253 records · Page 14
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DOE OSTI2019

O -Functionalization of a cobalt carbonyl generates a terminal cobalt carbyne

Despite efforts toward extending multiple bonding motifs to late metal systems, examples of late transition metal carbynes remain scarce. Herein, we describe the synthesis of a series of L 3 Co(CO) complexes supported by a trisphosphine ligand framework, with the most reduced of these complexes being amenable to O-functionalization. Furthermore, this transformation provides access to the second reported example of a terminal Co-carbyne complex, in this case stabilized in a pseudotetrahedral geometry (i.e., L 3 Co≡C-OSiR 3 ). Its geometry makes its electronic structure suitable for comparison to structurally-related examples of terminal Co-imido and oxo species.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1975

Fast metastable fragments produced by dissociative excitation of carbonyl sulfide

Dissociative excitation of OCS by electron impact has been studied using the method of translational spectroscopy. Time-of-flight distributions and excitation functions of the fast metastable fragments have been measured. The results are compared with similar measurements on CO2 and show that a variety of metastable fragments including CO(a 3Pi), S(5S), O(5S) as well as long-lived high-lying atomic and molecular Rydberg fragments can contribute to dissociation.

Van Brunt, R. J.↗
NASA NTRS1980

Ab initio projected-unrestricted Hartree-Fock calculation of some potential energy curves for carbonyl fluoride

Some potential energy curves for CF2O were calculated using projected-unrestricted Hartree-Fock (PUHF) theory. The calculations employed a contracted (4s 3p) Gaussian-type atomic orbital basis set. Bound states were found for the X-tilde 1A1 and 1,3A2 states while the 1,3B1 and 1,3B2 states were repulsive in the valence representation. The merits of the PUHF treatment for excited states are discussed. The results are discussed in terms of available experimental information and previous calculations with particular emphasis on the question of the photolysis channels open in the solar spectral region.

Brewer, D. A.↗
NASA NTRS1981

Long wavelength carbonyl sulfide photodissociation

The aeronomic implications of a preliminary observation of weak OCS photoabsorption above 270 nm are investigated. It is argued that the measured cross section is consistent with a forbidden transition in this wavelength region. Model calculations are made for the OCS photodissociation rates in daylight, the OCS and SO2 distributions in the upper atmosphere, and the budgets of sulfur in the stratosphere and OCS in the troposphere, assuming various extrapolations of the measured OCS absorption cross sections and quantum yields to longer wavelengths. It is shown that weak OCS absorption above 300 nm can have important consequences for all of these quantities. Laboratory and field experiments are identified which might lead to a better understanding of the atmospheric OCS cycle.

Turco, R. P.↗
NASA NTRS1994

Ultraviolet absorption cross-sections of some carbonyl compounds and their temperature dependence

Ultraviolet absorption cross-section of phosgene (CCl2O), trichloroacetylchloride (CCl3-CClO) and trichloroacetaldehyde (CCl3-CHO) have been measured between 170 and 320 nm for temperature ranging from 210 to 295 K with classical double beam equipment. These data are compared with other available determinations performed at room temperature. Photodissociation coefficients are estimated and their temperature dependence is discussed. Impact of the photodissociation on the total atmospheric destruction of these compounds is illustrated.

Gillotay, D.↗
NASA NTRS1994

Southern hemisphere ground based measurements of Carbonyl Fluoride (COF2) and Hydrogen Fluoride (HF): Partitioning between Fluoride reservoir species

We report infrared ground based total column measurements of the stratospheric fluorine reservoir gases COF2 and HF above Lauder, New Zealand (45 deg S, 167.8 deg E) obtained between April 1993 and January 1994. The average retrieved COF2 and HF total columns are 2.81(+/- 0.56) x 10(exp 14) and 9.91(+/- 1.09) x 10(exp 14) molecules/sq cm respectively. The daily average COF2 and HF columns are correlated; this correlation is likely the result of dynamics. The average HF/COF2 column ratio on days with measurements of both HF and COF2 is 3.63 (+/- 0.55). Comparison of this ratio with model calculations implies that the quantum yield for COF2 photolysis is near unity. Our measured COF2 columns are higher than all previously reported values, but inconsistencies among the earlier measurements and uncertainty in the latitudinal gradient of the COF2 column preclude an accurate determination of the long-term COF2 trend.

Reisinger, Andreas R.↗