PRELIMINARY REPORT ON THE THERMODYNAMIC PROPERTIES OF SELECTED LIGHT-ELEMENT AND SOME RELATED COMPOUNDS.
Contributor(s)NATIONAL BUREAU OF STANDARDS GAITHERSBURG MD
KeywordsCeramics, Refractories and Glass
Atomic and Molecular Physics and Spectroscopy
(*ALKALINE EARTH COMPOUNDS
HEAT OF FORMATION
EQUATIONS OF STATE
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AbstractThermodynamic and related properties of substances important in current high-temperature research and development activities are being investigated. This report describes in detail a variety of recent NBS experimental results and their interpretation. The vibrational spectra of different isotopic varieties of MgF2, MgCl2, CaF2, SrF2, and BaF2 molecules trapped in solid rare-gas matrices were determined and analyzed; this technique particularly defines the bending vibrations, heretofore unreliable but a major factor in the thermodynamic properties of such gases. Preliminary microwave studies of the CsOH molecule indicate it to be linear and with highly anharmonic bending vibrations; these pioneering results important implications for the spectroscopically little investigated hydroxides of all the elements of Groups 1, 2, and 3. Further infrared studies of the borohydrides of aluminum and beryllium show, between the solid and gaseous forms of the beryllium compound, a great difference which is tentatively interpreted. Spectroscopic time histories of aluminum wires exploding in vacuum and controlled atmospheres of nitrogen and oxygen were obtained. Several literature reviews with critical data analysis are included. The present status of the heats of formation of CF4 and selected fluorides of nitrogen, carbon, chlorine, and oxygen is described, with a report of recent NBS flame calorimetry on OF2.
Supplement to Rept. no. NBS-9028 dated 1 Jan 66, AD-485 872L.
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THE TRANSITION METAL HYDRIDE COMPLEXESAEROSPACE CORP EL SEGUNDO CALIF; SIEGEL,BERNARD (1961-10-05)The status of present-day knowledge concerning transition metal hydrides that are stabilized by ligand molecules is summarized. Particular emphasis is given to he structures and chemical properties of such complex molecules and to conjectures about the possible structures of complexes as yet unknown. The literature survey on which this report is based was intended to provide background infor ation for the experimental program on transition metal hydrides. (Author)
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COMPLEX TRANSITION METAL HYDRIDES,AEROSPACE CORP EL SEGUNDO CALIF; Gibbins,S. G. (1963-11-12)A review of the properties of complex transition metal hydrides and a discussion of the probable mechanism requisite for stability are given. The absence of stoichiometric binary transition metal hydrides coupled with features common to the complex ones indicates that the primary stabilization mechanism of the transition metalhydrogen bond is one involving multiple bonding between the metal and the stabilizing ligand. The multiple bond comprises of a sigma bond, the electron pair being provided by the ligand, and a pi bond, the electron pair being provided by the metal. Thus, negative charge that would have accumulated on the metal, if only a sigma bond existed, is diminished. From a molecular orbital point of view, the pi bond permits formerly metal non-bonding d orbitals to become bonding. Thus, the total energy of the system is reduced and the stability is increased. (Author)