Carbohydride Explained

Carbohydrides (or carbide hydrides) are solid compounds in one phase composed of a metal with carbon and hydrogen in the form of carbide and hydride ions. The term carbohydride can also refer to a hydrocarbon.[1]

Structure and bonding

Many of the transition metal carbohydrides are non-stochiometric, particularly with respect to the hydrogen that can vary in proportion up to a theoretical balanced proportion. The hydrogen and carbon occupy holes in the metal crystalline lattice. The carbon takes up octahedral sites (surrounded by six metal atoms) and the hydrogen takes up tetrahedral sites in the metal lattice. The hydrogen atoms go to sites away from the carbon atoms, and away from each other, at least 2 Å apart, so there are no covalent bonds between the carbon or hydrogen atoms. Overall the lattice retains a high symmetry of the original metal.[2]

Nomenclature

A carbodeuteride (or carbo-deuteride) is a compound where the hydrogen is of the isotope deuterium.[3] [4]

Properties

Reactions

Metal carbide hydrides give off hydrogen when heated, and are in equilibrium with a partial pressure of hydrogen that depends on the temperature.

When Ca2LiC3H is heated with ammonium chloride, the gas C3H4 (methylacetylene-propadiene) is produced.[5]

Comparisons

There are also metal cluster molecules and ions that contain both carbon and hydrogen. Methylidyne complexes contain the CH group with three bonds to a metal e.g. NiCH+ or PtCH+.

Natural occurrence

Iron carbide hydrides do not appear to be stable at the conditions present in the Earth's inner core, even though carbon or hydrogen have been proposed as alloying light elements in the core.[6]

Applications

Carbohydrides are studied for their ability in hydrogen storage. Carbohydrides may be made when carbides are manufactured by milling, using hydrocarbons as a carbon source. Since the carbohydride is not the desired outcome, other material like graphite is added to try to maximise carbide production.

Preparation

Transition metal carbohydrides can be produced by heating a metal carbide in hydrogen, for example at 2000 °C and 3 bars. This reaction is exothermic, and just needs to be ignited at a much lower temperature. The process is called self-propagating high-temperature synthesis or SHS.[7] A hydrocarbide may be formed when the metal is milled in a hydrocarbon, for example in the manufacture of titanium carbide.[8]

Rare earth carbohydrides can be prepared by heating a metal hydride with graphite in a closed metal container, with a hydrogen atmosphere.[9]

List

Nameformulaformspace groupunit cellappearancedensitystructureref
Lithium dicalcium tricarbide hydrideCa2LiC3HtetragonalP4mbma=6.8236 c=3.7518 Z=2silver2.36has C34−
Titanium carbo-deuterideTiC0.48D0.60cubicFm3ma=4.30963[10]
Titanium carbo-deuterideTiC0.48D0.60trigonalFm31a=3.08208 c=5.0405
Zirconium carbohydrideZrC0.3H[11]
Hafnium carbohydrideHf2CH2a=3.427 c=5.476[12]
thorium carbohydrideThCH2is cubic under 380°, and above is hexagonal.[13] [14]
Th2CH2hexagonala=3.083 c=5.042
Th3CH4monoclinic
Niobium carbohydrideNbC0.76H0.18[15]
Barium indium allenylide hydrideBa12InC18H4cubicIma=11.1447InBa12 icosahedrons[16]
Y5Si3C0.5H7.33[17]
La2C3H1.5[18]
La2CH4a=5.642[19]
La2CH2monoclinicC2/ma = 7.206, b = 3.932, c = 6.739, β = 94.66 °
La15(FeC6)4HhexagonalPa=8.7764 c=10.7355 Z=1 V=720.42silver[20]
Ytterbium carbide hydrideYb2CH2hexgonala=3.575 c=5.786
Ytterbium dicarbide hydrideYb2C2Hcubica=4.974fcc
Pr3Fe27.5Ti1.5CxH monoclinicA2/m[21]
Dy2Co17C0.2H2.8P63/mmca=8.418 c=8.165 V=501.1[22]
Dy2Ni17C0.4H2.7P63/mmca=8.3789 c=8.054 V=489.7
Gd2ICHP63/mmca = 3.8128 c = 14.844 grey8.071[23]
Gd2BrCHP63/mmcgrey
Gd2ClCHP63/mmcgrey
Tb2ICHP63/mmcgrey
Tb2BrCHP63/mmcgrey

Notes and References

  1. Book: Ure . Andrew . Ures̓ Dictionary of Arts, Manufactures and Mines: Containing a Clear Exposition of Their Principles and Practice . 1867 . Longmans, Green and Company . 648–649 . en.
  2. Rundqvist . Stig . Tellgren . Roland . Andersson . Yvonne . Hydrogen and deuterium in transition metal-p element compounds: Crystal chemical aspects of interstitial solid solubility and hydride phase formation . Journal of the Less Common Metals . August 1984 . 101 . 145–168 . 10.1016/0022-5088(84)90092-4.
  3. Makovec . M. . Ban . Z. . The crystal structure of thorium carbohydrides . Journal of the Less Common Metals . June 1970 . 21 . 2 . 169–180 . 10.1016/0022-5088(70)90115-3.
  4. Renaudin . G. . Yvon . K. . Dolukhanyan . S.K. . Aghajanyan . N.N. . Shekhtman . V.Sh. . Crystal structures and thermal properties of titanium carbo-deuterides as prepared by combustion synthesis . Journal of Alloys and Compounds . August 2003 . 356-357 . 120–127 . 10.1016/S0925-8388(03)00107-5.
  5. Lang. David A.. Zaikina. Julia V.. Lovingood. Derek D.. Gedris. Thomas E.. Latturner. Susan E.. 2010-12-15. Ca 2 LiC 3 H: A New Complex Carbide Hydride Phase Grown in Metal Flux. Journal of the American Chemical Society. en. 132. 49. 17523–17530. 10.1021/ja107436n. 21090715. 0002-7863.
  6. Litasov . K. D. . Shatskiy . A. F. . Ohtani . E. . Interaction of Fe and Fe3C with hydrogen and nitrogen at 6–20 GPa: a study by in situ X-ray diffraction . Geochemistry International . 12 October 2016 . 54 . 10 . 914–921 . 10.1134/S0016702916100074. 2016GeocI..54..914L . 100503929 .
  7. Dolukhanyan . S.K . Aghajanyan . N.N . Hakobyan . H.G . Shekhtman . V.Sh . Ter-Galstyan . O.P . The structural peculiarities of the transition metals carbohydrides produced by combustion synthesis . Journal of Alloys and Compounds . December 1999 . 293-295 . 452–457 . 10.1016/S0925-8388(99)00335-7.
  8. Eryomina . M.A. . Lomayeva . S.F. . Demakov . S.L. . Yurovskikh . A.S. . SPS of "Titanium Carbide/Carbohydride – Copper" Composites . KnE Engineering . 15 April 2019 . 1 . 1 . 246 . 10.18502/keg.v1i1.4416. free . 10995/82850 . free .
  9. Haschke. John M.. April 1975. Preparation and some properties of ytterbium carbide hydrides. Inorganic Chemistry. en. 14. 4. 779–783. 10.1021/ic50146a016. 0020-1669.
  10. Renaudin . G. . Yvon . K. . Dolukhanyan . S.K. . Aghajanyan . N.N. . Shekhtman . V.Sh. . Crystal structures and thermal properties of titanium carbo-deuterides as prepared by combustion synthesis . Journal of Alloys and Compounds . August 2003 . 356-357 . 120–127 . 10.1016/S0925-8388(03)00107-5.
  11. Book: 10.1016/B978-0-12-804173-4.00071-5. Hydridonitrides and Carbohydrides of Transition Metals. Concise Encyclopedia of Self-Propagating High-Temperature Synthesis. 2017. Dolukhanyan. Seda K.. 159–160. 9780128041734.
  12. Ternary metal-carbon-hydrogen compounds of some transition metals. Rexer. Joachim. 1962. Iowa State University.
  13. Makovec . M. . Ban . Z. . The crystal structure of thorium carbohydrides . Journal of the Less Common Metals . June 1970 . 21 . 2 . 169–180 . 10.1016/0022-5088(70)90115-3.
  14. Makovec . M. . Ban . Z. . The crystal structure of thorium carbohydrides part II. Hexagonal thorium carbohydride . Journal of the Less Common Metals . December 1970 . 22 . 4 . 383–388 . 10.1016/0022-5088(70)90125-6.
  15. Skripov . A.V. . Wu . H. . Udovic . T.J. . Huang . Q. . Hempelmann . R. . Soloninin . A.V. . Rempel . A.A. . Gusev . A.I. . Hydrogen in nonstoichiometric cubic niobium carbides: Neutron vibrational spectroscopy and neutron diffraction studies . Journal of Alloys and Compounds . June 2009 . 478 . 1–2 . 68–74 . 10.1016/j.jallcom.2008.12.012.
  16. Blankenship. Trevor V.. Dickman. Matthew J.. van de Burgt. Lambertus J.. Latturner. Susan E.. 2015-02-02. Ca 12 InC 13– x and Ba 12 InC 18 H 4 : Alkaline-Earth Indium Allenylides Synthesized in AE/Li Flux (AE = Ca, Ba). Inorganic Chemistry. en. 54. 3. 914–921. 10.1021/ic502315m. 25375309. 0020-1669.
  17. Hassen. M.A.. McColm. I.J.. December 2000. The preparation of high hydrogen content yttrium silicide carbides with reversible storage potential. Journal of Alloys and Compounds. en. 313. 1–2. 95–103. 10.1016/S0925-8388(00)01174-9.
  18. Kienle . L. . García García . F.J. . Duppel . V. . Simon . A. . Direct observation of crystallographic and chemical changes during dehydrogenation of oxygen contaminated La2C3H1.5 . Journal of Solid State Chemistry . April 2006 . 179 . 4 . 993–1002 . 10.1016/j.jssc.2005.12.019 . 2006JSSCh.179..993K . en.
  19. Simon. Arndt. Gulden. Thomas. November 2004. La2C3 und seine Reaktion mit Wasserstoff. Zeitschrift für anorganische und allgemeine Chemie. de. 630. 13–14. 2191–2198. 10.1002/zaac.200400226. 0044-2313.
  20. Engstrand. Tate O.. Cope. Emily M.. Vasquez. Guillermo. Haddock. Jo W.. Hertz. Mary B.. Wang. Xiaoping. Latturner. Susan E.. 2020-08-17. Flux Synthesis of a Metal Carbide Hydride Using Anthracene As a Reactant. Inorganic Chemistry. en. 59. 16. 11651–11657. 10.1021/acs.inorgchem.0c01505. 32799481. 1771895. 225348956. 0020-1669.
  21. Psycharis . V . Gjoka . M . Kalogirou . O . Niarchos . D . Papaefthymiou . V . Christodoulou . Ch . Magnetic properties of interstitial modified Pr3(Fe,Ti)29 hydrocarbide . Journal of Alloys and Compounds . July 2000 . 307 . 1–2 . 234–239 . 10.1016/S0925-8388(00)00741-6.
  22. Chemistry of Metals and Alloys. 7. 26–31. Crystal structure and hydrogenation properties of the hexagonal Dy2M17 and Dy2M17Cx. Levytskyy. Volodymyr. Volodymyr. Babizhetskyy1. Oksana. Myakush1. Bogdan. Kotur1. Ihor. Koval’chuk. 2014. 10.30970/cma7.0264. en. 2020-05-14. free.
  23. Ruck. M.. Simon. A.. November 1992. Ln2XCHy: Kondensierte Cluster mit zwei verschiedenen interstitiellen Atomen. Zeitschrift für anorganische und allgemeine Chemie. de. 617. 11. 7–18. 10.1002/zaac.19926170102. 0044-2313.

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