Compounds of carbon
Compounds of carbon are defined as chemical substances containing carbon. More compounds of carbon exist than any other chemical element except for hydrogen. Organic carbon compounds are far more numerous than inorganic carbon compounds. In general bonds of carbon with other elements are covalent bonds. Carbon is tetravalent but carbon free radicals and carbenes occur as short-lived intermediates. Ions of carbon are carbocations and carbanions are also short-lived. An important carbon property is catenation as the ability to form long carbon chains and rings.
Allotropes of carbon
The known inorganic chemistry of the allotropes of carbon (diamond, graphite, and the fullerenes) blossomed with the discovery of buckminsterfullerene in 1985, as additional fullerenes and their various derivatives were discovered. One such class of derivatives is inclusion compounds, in which an ion is enclosed by the all-carbon shell of the fullerene. This inclusion is denoted by the "@" symbol in endohedral fullerenes. For example, an ion consisting of a lithium ion trapped within buckminsterfullerene would be denoted Li+@C60. As with any other ionic compound, this complex ion could in principle pair with a counterion to form a salt. Other elements are also incorporated in so-called graphite intercalation compounds.
It was once thought that organic compounds could only be created by living organisms. Over time, however, scientists learned how to synthesize organic compounds in the lab. The number of organic compounds is immense and the known number of defined compounds is close to 10 million. However, an indefinitely large number of such compounds are theoretically possible.
|Core organic chemistry||Many uses in chemistry|
|Academic research, but no widespread use||Bond unknown|
By definition, an organic compound must contain at least one atom of carbon, but this criterion is not generally regarded as sufficient. Indeed, the distinction between organic and inorganic compounds is ultimately a matter of convention, and there are several compounds that have been classified either way, such as: COCl2, CSCl2, CS(NH2)2, CO(NH2)2. With carbon bonded to metals the field of organic chemistry crosses over into organometallic chemistry.
There are many oxides of carbon (oxocarbons), of which the most common are carbon dioxide (CO2) and carbon monoxide (CO). Other less known oxides include carbon suboxide (C3O2) and mellitic anhydride (C12O9). There are also numerous unstable or elusive oxides, such as dicarbon monoxide (C2O), oxalic anhydride (C2O4), and carbon trioxide (CO3).
There are several oxocarbon anions, negative ions that consist solely of oxygen and carbon. The most common are the carbonate (CO32−) and oxalate (C2O42−). The corresponding acids are the highly unstable carbonic acid (H2CO3) and the quite stable oxalic acid (H2C2O4), respectively. These anions can be partially deprotonated to give the bicarbonate (HCO3−) and hydrogenoxalate (HC2O4−). Other more exotic carbon–oxygen anions exist, such as acetylenedicarboxylate (O2C–C≡C–CO22−), mellitate (C12O96−), squarate (C4O42−), and rhodizonate (C6O62−). The anhydrides of some of these acids are oxides of carbon; carbon dioxide, for instance, can be seen as the anhydride of carbonic acid.
Carbonyls are coordination complexes between transition metals and carbonyl ligands. Metal carbonyls are complexes that are formed with the neutral ligand CO. These complexes are covalent. Here is a list of some carbonyls: Cr(CO)6, Co2(CO)8, Fe(CO)5, Mn2(CO)10, Mo(CO)6, Ni(CO)4, W(CO)6.
Important inorganic carbon-sulfur compounds are the carbon sulfides carbon disulfide (CS2) and carbonyl sulfide (OCS). Carbon monosulfide (CS) unlike carbon monoxide is very unstable. Important compound classes are thiocarbonates, thiocarbamates, dithiocarbamates and trithiocarbonates.
|carbon monosulfide||carbon disulfide||carbonyl sulfide|
|Inorganic carbon-sulfur compounds|
|composition||Molar mass (g/mole)||Boiling point °C||Melting point °C|
|hydrogen cyanide||HCN||27.03||25-26||-12 - -14|
|Inorganic carbon-nitrogen compounds|
Other types of inorganic compounds include the inorganic salts and complexes of the carbon-containing cyanide, cyanate, fulminate, thiocyanate and cyanamide ions. Examples of cyanides are copper cyanide (CuCN) and potassium cyanide (KCN), examples of cyanates are potassium cyanate (KNCO) and silver cyanate (AgNCO), examples of fulminates are silver fulminate (AgOCN) and mercury fulminate (HgOCN) and an example of a thiocyanate is potassium thiocyanate (KSCN).
A carborane is a cluster composed of boron and carbon atoms such as H2C2B10H10.
Its use in alloys
There are hundreds of alloys that contain carbon. The most common of these alloys is steel, sometimes called "carbon steel" (see Category:Steels). All kinds of steel contain some amount of carbon, by definition, and all ferrous alloys contain some carbon.
Whether it was placed there deliberately or not, some traces of carbon is also found in these common metals and their alloys: aluminum, chromium, magnesium, molybdenum, niobium, thorium, titanium, tungsten, uranium, vanadium, zinc, and zirconium. For example, many of these metals are smelted with coke, a form of carbon; and aluminum and magnesium are made in electrolytic cells with carbon electrodes. Some distribution of carbon into all of these metals is inevitable.
- Organic Chemistry by Abraham William Simpson
- Encyclopedia of Inorganic Chemistry Bruce King Ed. Second Edition
- Advanced Inorganic Chemistry Cotton, F. Albert / Wilkinson, Geoffrey
- Chemistry Operations (December 15, 2003). "Carbon". Los Alamos National Laboratory. Retrieved 2007-11-21.