Azide group structure

It is not only the activity that can be altered by incorporation of noncoded amino acids. Introduction of structures possessing certain chemical functions leads to the possibility of highly regioselective modification of enzymes. For example, selective enzymatic modification of cystein residues with compounds containing azide groups has led to the preparation of enzymes that could be selectively immobilized using click chemistry methods [99]. 

A further interesting X-ray structural study has been that of (AsPh4)2-[Pd2(N3)6] (66). This reveals similar asymmetry in the two N—N bond lengths for the bridging (1.239 and 1.142 A) and terminal (1.205 and 1.139 A) azide groups. Such structural equivalence indicates that there is no appreciable change in electronic character when a terminal azide co-ordinates to a second Pd via a normally unshared electron pair on the trigonal N atom (see Table... 

The structure is in part inferred from the observation that in boiling tetrahydrofuran the substance loses nitrogen and sulfur and gives pentyl cyanide. The absence of absorption in the neighbourhood of 2150 cm-1 indicative of an azide group excludes the thioacyl azide structure.17... 

In a DTA study of 14 anthraquinone dyes, most had high flash points (225—335°C) and ignition points (320—375°C). Purpurin dianilide [107528-40-5] was exceptional with the much lower values of 110 and 155°C, respectively [1]. A similar study of indigo type dyes and vat solubilised modifications is reported. The basic dyes decompose over 350°C, destabilised to around 200°C for solubilised dyes. The relation between functional groups, structure and flammability is discussed [2]. Sulfonyl azides have been employed for attachment of reactive dyes, it is claimed they are safer used in supercritical carbon dioxide than in water [3]. 

Letter, W. H. Bragg to Sir Richard Gregory, 3 July 1934, W. H. Bragg Archives, The Royal Institution. The note was published as Bragg, W. H. (1934). Structure of the azide group. Nature 134 138. 

The related pseudohahdes AgCN, AgNCO, and AgSCN all have infinite chain structures. The Ag+ ion in AgN3 is coordinated tetrahedraUy by four azide groups, each being surrounded in turn by four Ag+ ions in a pseudotetrahedral arrangement. 

In salts of [Zn(NCS)4], the thiocyanate ligand is N-bonded, whereas it is S-bonded to cadmium in [Cd(SCN)4] salts, reflecting the respective hard and soft characters of the respective metal ions. Zinc complexes with the azide ion are well known crystallographic determinations of the structures of the compounds M2Zn(N3)4 (M = K or Cs) show the presence of discrete [Zn(N3)4] tetrahedra with linear azide groups. Some of the complexes in this category, such as those with hydrazine and azide, for example [Zn(N2H4)2(N3)2], are of interest as primary explosives and care is needed in their manipulation. The 2,2 -dipyridylamine-azide complexes [Zn(dpa)(N3)2] and [Zn(dpa)(N3)(N03)], which have infinite 2D and 3D structures respectively, display fluorescence and phosphorescence. ... 

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