Cadmium hydride

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Cadmium hydride
Other names
Cadmium(II) hydride
Cadmium dihydride
3D model (JSmol)
  • InChI=1S/Cd.2H/q+2;2*-1 X mark.svgN
  • InChI=1/Cd.2H/q+2;2*-1
  • [H-].[H-].[Cd+2]
Molar mass 113.419 g mol−1
NIOSH (US health exposure limits):
PEL (Permissible)
[1910.1027] TWA 0.005 mg/m3 (as Cd) [1]
REL (Recommended)
Ca [1]
IDLH (Immediate danger)
Ca [9 mg/m3 (as Cd)] [1]
Related compounds
Related compounds
Mercury(II) hydride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Cadmium hydride (systematically named cadmium dihydride) is an inorganic compound with the chemical formula (CdH
(also written as ([CdH
or CdH
). It is a solid, known only as a thermally unstable, insoluble white powder.



The systematic name cadmium dihydride, a valid IUPAC name, is constructed according to the compositional nomenclature. Cadmium dihydride is also used to refer to the related molecular compound dihydridocadmium and its oligomers. Care should be taken to avoid confusing the two compounds.

Cadmium hydride is also used as a compositional IUPAC name for the compound with the chemical formula CdH.


In 1950 a research group led by Glenn D. Barbaras, synthesized cadmium hydride for the first time. This reaction sequence consisted of demethylation [ dubious ] of dimethylcadmium in diethyl ether at −78 °C, to cadmium hydride. [2]

Chemical properties

Solid cadmium hydride, on the basis of its infrared spectrum, is believed to contain hydrogen-bridge bonds. [3] Other lower metal hydrides polymerize in a similar fashion. Unless cooled below −20 °C (−4 °F), cadmium hydride rapidly decomposes to produce cadmium and hydrogen: [2]

n Cd + nH


Dihydridocadmium is the monomeric, molecular form with the chemical formula CdH
(also written [CdH
). It is a colorless gas that does not persist undiluted. Dihydridocadmium has a low activation barrier toward autopolymerisation into the standard form of cadmium hydride and would rapidly do so in undiluted concentrations. Since the activation barrier for the reverse reaction is much greater than that of the decomposition reaction, autopolymerisation of dihydridocadmium may be considered as irreversible for most intents and purposes. It was produced by the gas phase reaction of excited cadmium atoms with dihydrogen, H2, and the structure determined high-resolution infrared emission spectra. The molecule is linear, with a bond length of 168.3 pm. [4]

Chemical properties

The two-coordinate hydridocadmium group (-CdH) in hydridocadmiums such as dihydridocadmium can accept an electron-pair donating ligand into the molecule by adduction: [3]

] + L → [CdH

Because of this acceptance of the electron-pair donating ligand (L), dihydridocadmium has Lewis-acidic character. Dihydridocadmium can accept two electron-pairs from ligands, as in the case of the tetrahydridocadmate(2−) anion (CdH2−

The compound, Cs3CdH5, prepared by the reaction of caesium hydride, CsH, and cadmium metal powder at high temperature contains the CdH2−
ion, along with caesium cations, Cs+, and hydride anions, H. The tetrahedral anion is an example of an ionic complex of CdH2. The average Cd-H bond length in CdH2−
is 182pm. [5]

In gaseous dihydridocadmium, the molecules form groups (trimers), being connected by van der Waals forces. The dissociation enthalpy of the dimer is estimated at 8.8 kJ mol−1. [3]

Related Research Articles

Inorganic chemistry deals with synthesis and behavior of inorganic and organometallic compounds. This field covers chemical compounds that are not carbon-based, which are the subjects of organic chemistry. The distinction between the two disciplines is far from absolute, as there is much overlap in the subdiscipline of organometallic chemistry. It has applications in every aspect of the chemical industry, including catalysis, materials science, pigments, surfactants, coatings, medications, fuels, and agriculture.

The oxidation state, or oxidation number, is the hypothetical charge of an atom if all of its bonds to different atoms were fully ionic. It describes the degree of oxidation of an atom in a chemical compound. Conceptually, the oxidation state may be positive, negative or zero. While fully ionic bonds are not found in nature, many bonds exhibit strong ionicity, making oxidation state a useful predictor of charge.

In chemistry, a hydride is formally the anion of hydrogen, H. The term is applied loosely. At one extreme, all compounds containing covalently bound H atoms are called hydrides: water (H2O) is a hydride of oxygen, ammonia is a hydride of nitrogen, etc. For inorganic chemists, hydrides refer to compounds and ions in which hydrogen is covalently attached to a less electronegative element. In such cases, the H centre has nucleophilic character, which contrasts with the protic character of acids. The hydride anion is very rarely observed.

Diborane Chemical compound

Diborane(6), generally known as diborane, is the chemical compound consisting of boron and hydrogen with the formula B2H6. It is a colorless, pyrophoric gas with a repulsively sweet odor. Synonyms include boroethane, boron hydride, and diboron hexahydride. Diborane is a key boron compound with a variety of applications. It has attracted wide attention for its electronic structure. Its derivatives are useful reagents.

Cadmium sulfide Chemical compound

Cadmium sulfide is the inorganic compound with the formula CdS. Cadmium sulfide is a yellow solid. It occurs in nature with two different crystal structures as the rare minerals greenockite and hawleyite, but is more prevalent as an impurity substituent in the similarly structured zinc ores sphalerite and wurtzite, which are the major economic sources of cadmium. As a compound that is easy to isolate and purify, it is the principal source of cadmium for all commercial applications. Its vivid yellow color led to its adoption as a pigment for the yellow paint "cadmium yellow" in the 18th century.

Borderline hydrides typically refer to hydrides formed of hydrogen and elements of the periodic table in group 11 and group 12 and indium (In) and thallium (Tl). These compounds have properties intermediate between covalent hydrides and saline hydrides. Hydrides are chemical compounds that contain a metal and hydrogen acting as a negative ion.

Beryllium hydride Chemical compound

Beryllium hydride is an inorganic compound with the chemical formula n. This alkaline earth hydride is a colourless solid that is insoluble in solvents that do not decompose it. It is used in rocket fuels Unlike the ionically bonded hydrides of the heavier Group 2 elements, beryllium hydride is covalently bonded.

Magnesium hydride Chemical compound

Magnesium hydride is the chemical compound with the molecular formula MgH2. It contains 7.66% by weight of hydrogen and has been studied as a potential hydrogen storage medium.

Zinc hydride is an inorganic compound with the chemical formula ZnH2. It is a white, odourless solid which slowly decomposes into its elements at room temperature; despite this it is the most stable of the binary first row transition metal hydrides. A variety of coordination compounds containing Zn-H bonds are used as reducing agents, however ZnH2 itself has no common applications.

Chemical compound Substance composed of multiple elements that are chemically bonded

A chemical compound is a chemical substance composed of many identical molecules composed of atoms from more than one element held together by chemical bonds. A molecule consisting of atoms of only one element is therefore not a compound.

Compounds of zinc are chemical compounds containing the element zinc which is a member of the group 12 of the periodic table. The oxidation state of most compounds is the group oxidation state of +2. Zinc may be classified as a post-transition main group element with zinc(II). Zinc compounds are noteworthy for their nondescript behavior, they are generally colorless, do not readily engage in redox reactions, and generally adopt symmetrical structures.

Cobalt tetracarbonyl hydride Chemical compound

Cobalt tetracarbonyl hydride is an organometallic compound with the formula HCo(CO)4. It is a volatile, yellow liquid that forms a colorless vapor and has an intolerable odor. The compound readily decomposes upon melt and in absentia of high CO partial pressures forms Co2(CO)8. Despite operational challenges associated with its handling, the compound has received considerable attention for its ability to function as a catalyst in hydroformylation. In this respect, HCo(CO)4 and related derivatives have received significant academic interest for their ability to mediate a variety of carbonylation (introduction of CO into inorganic compounds) reactions.

Iron tetracarbonyl dihydride Chemical compound

Iron tetracarbonyl dihydride is the organometallic compound with the formula H2Fe(CO)4. This compound was the first transition metal hydride discovered. The complex is stable at low temperatures but decomposes rapidly at temperatures above –20 °C.

Binary compounds of hydrogen are binary chemical compounds containing just hydrogen and one other chemical element. By convention all binary hydrogen compounds are called hydrides even when the hydrogen atom in it is not an anion. These hydrogen compounds can be grouped into several types.

Mercury(I) hydride is an inorganic compound with the chemical formula HgH. It has not yet been obtained in bulk, hence its bulk properties remain unknown. However, molecular mercury(I) hydrides with the formulae HgH and Hg
have been isolated in solid gas matrices. The molecular hydrides are very unstable toward thermal decomposition. As such the compound is not well characterised, although many of its properties have been calculated via computational chemistry.

Titanium(IV) hydride is an inorganic compound with the empirical chemical formula TiH
. It has not yet been obtained in bulk, hence its bulk properties remain unknown. However, molecular titanium(IV) hydride has been isolated in solid gas matrices. The molecular form is a colourless gas, and very unstable toward thermal decomposition. As such the compound is not well characterised, although many of its properties have been calculated via computational chemistry.

Mercury(II) hydride Chemical compound

Mercury(II) hydride is an inorganic compound with the chemical formula HgH
. It is both thermodynamically and kinetically unstable at ambient temperature, and as such, little is known about its bulk properties. However, it known as a white, crystalline solid, which is kinetically stable at temperatures below −125 °C (−193 °F), which was synthesised for the first time in 1951.

Cadmium tetrafluoroborate Chemical compound

Cadmium tetrafluoroborate is an ionic, chemical compound with the formula Cd(BF4)2. It is an ionic, crystalline solid, which is colorless and odorless. Cadmium tetrafluoroborate is most frequently used in the industrial production of high-strength steels, its purpose being to prevent hydrogen absorption, a source of post-production cracking of the metal, in the treated steels. Another application of the chemistry of cadmium tetrafluoroborate is fine tuning of the size of cadmium telluride nanomaterials.

Chromium(II) hydride, systematically named chromium dihydride and poly(dihydridochromium) is pale brown solid inorganic compound with the chemical formula (CrH
. Although it is thermodynamically unstable toward decomposition at ambient temperatures, it is kinetically metastable.

Iron(II) hydride, systematically named iron dihydride and poly(dihydridoiron) is solid inorganic compound with the chemical formula (FeH
. ). It is kinetically unstable at ambient temperature, and as such, little is known about its bulk properties. However, it known as a black, amorphous powder, which was synthesised for the first time in 2014.


  1. 1 2 3 NIOSH Pocket Guide to Chemical Hazards. "#0087". National Institute for Occupational Safety and Health (NIOSH).
  2. 1 2 Barbaras, Glenn D.; Dillard, Clyde; Finholt, A. E.; Wartik, Thomas; Wilzbach, K. E.; Schlesinger, Hermann I. (October 1951). "The Preparation of the Hydrides of Zinc, Cadmium, Beryllium, Magnesium and Lithium by the Use of Lithium Aluminum Hydride". Journal of the American Chemical Society. ACS Publications. 73 (10): 4585–4590. doi:10.1021/ja01154a025.
  3. 1 2 3 Wang, Xuefeng; Andrews, Lester (December 2004). "Infrared Spectra of Zn and Cd Hydride Molecules and Solids". The Journal of Physical Chemistry A. ACS Publications. 108 (50): 11006–11013. Bibcode:2004JPCA..10811006W. doi:10.1021/jp046414m.
  4. Shayesteh, Alireza; Yu, Shanshan; Bernath, Peter F. (2005). "Gaseous HgH2, CdH2, and ZnH2". Chemistry: A European Journal. 11 (16): 4709–4712. doi:10.1002/chem.200500332. ISSN   0947-6539. PMID   15912545.
  5. Bortz, M.; Gutmann, M.; Yvon, K. (1999). "Synthesis and structure determination of the first ternary cadmium hydride, Cs3CdH5". Journal of Alloys and Compounds. 285 (1–2): L19–L21. doi:10.1016/S0925-8388(99)00031-6. ISSN   0925-8388.