Cyanides and Other Carbon-Nitrogen Compounds

Stable thiocarbonyl complexes containing the elusive CS ligand are also now well established and known coordination modes, which include terminal, bridging and polyhaplo, are as shown at the top of the next column/  

Likewise complexes of CSe and CTe have been characterized/ The structure and reactivity of 

Jentsch, P. G. Jones, C, Thone and E. Schwarz-MANN, J. Chem. Soc., Chem. Commun., 1495 -6 (1989). 

CS complexes has been well reviewed and exciting work in this area continues.  

A useful theme for cohering much of the chemistry of compounds containing the CN group is the concept of pseudohalogens, a term introduced in 1925 for certain strongly bound, univalent radicals such as CN, OCN, SCN, SeCN, (and N3, etc.). These groups can form anions X , hydracids HX, and sometimes neutral species X2. 

The chemistry of compounds containing the CN group is both extensive and varied. The types of compound to be discussed arc listed in Table 8.7, which also summarizes some basic structural information. The names cyanide, cyanogen, etc., refer to the properly of forming deep-blue pigments such as Prussian blue (p. 1094) with iron salts (Greek Kuarjo, cyanos, dark blue). 

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Nitrogen (ca. 5 at. %) occurs as carbon-nitrogen bonds, probably mainly cyanamide (NCN ), although other C-N bonded compounds were also believed to be present. If cyanamide is present as the Cd salt, this would tie up 5% of the Cd. The Cd S ratio was found to be only slightly higher than unity (ca. 1.02), and some of the Cd may be bound to carbonate. Therefore other C-N species are likely also to be present, e.g., cyanide, several of which could adsorb to one Cd or even to a CdS moiety. By reducing the concentration of thiourea in the bath, C-N impurities in the CdS film could be reduced almost to zero [77]. Whatever the nature of the C-N impurity, much of it could be removed simply by dissolution in water at 60°C [78]... 

Of course, in all cases each carbon has a full octet of electrons. Carbon also forms double and triple bonds with several other elements that can exhibit a covalence of two or three. The carbon-oxygen (or carbonyl) double bond appears in carbon dioxide and many important organic compounds such as methanal (formaldehyde) and ethanoic acid (acetic acid). Similarly, a carbon-nitrogen triple bond appears in methanenitrile (hydrogen cyanide) and eth-anenitrile (acetonitrile). 

It is somewhat difficult to define what is meant by a toxic element. Some elements, such as white phosphorus, chlorine, and mercury, are quite toxic in the elemental state. Others, such as carbon, nitrogen, and oxygen, are harmless as usually encountered in their normal elemental forms. But, with the exception of those noble gases that do not combine chemically, all elements can form toxic compounds. A prime example is hydrogen cyanide. This extremely toxic compound is formed from three elements that are nontoxic in the uncombined form, and produce compounds that are essential constituents of living matter, but when bonded together in the simple HCN molecule constitute a deadly substance. 

Prussian blue — iron(III) hexacyanoferrate(II) is the archetype of sparingly soluble mixed valence polymeric metal hexacyanometalates with the formula Me Me(N) [Me c (CN)6] with (i), (N), and (C) indicating the position in the crystal lattice, where (i) means interstitial sites, (N) means metal coordinated to the nitrogen of the cyanides, and (C) means metal ions coordinated to the carbon of the cyanides. It is one of the oldest synthetically produced coordination compounds and was widely used as pigment in paints because of the intensive blue color. The compound has been studied extensively by electrochemical and other methods. The importance of Prussian blue in electrochemistry is related to the fact that it has two redox-active metal centers and that it has an open structure that allows small cations to... 

Nitrogen Linked to Carbon.—Now when the isomeric compound, formed with silver cyanide and the methyl halide, is decomposed with water the nitrogen of the cyanogen remains linked to the methyl carbon in the form of methyl amine and the other product contains the cyano-... 

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