Hydroxylamine complexes, osmium

Examples of the osmium and iridium complexes are Os(PPh3)2Cl(NO) and Ir(PPh3)3(NO), respectively [216]. The osmium compound gave, on reaction with HC1, the first characterized complex with the feature of an N-coordinated HNO, Os(PPh3)2Cl2(HNO), which was confirmed by X-ray crystallography. On the other hand, the nitrosylated iridium compound gave the hydroxylamine complex [216]. 

Nitrosating agents, 22 144, 145 Nitrosation, electrophilic, 22 144-152 Nitrosoarene complexes, osmium, 37 254 iV-Nitrosobis(trifluoromethyl) amine, 16 29, 30 )-Nitrosobis(trifluoromethyl) hydroxylamine, 16 46... 

It seems strange that no hydroxylamine complexes of osmium are established. There is a brief report of a deprotonated complex Os(NO)(NHOH)Cl2(PPh3)2, made from Os(NO)2(PPh3)2 and HC1. The vNO band is at 1860 cm-1.247... 

The distortions induced in the DNA double helix by the interstrand cross-links have been characterized by several techniques. As judged by chemical probes (diethyl pyrocarbonate, hydroxylamine, osmium tetroxide), antibodies to cisplatin-modified poly(dG-dC)-poly(dG-dC), natural (DNase I) and artificial (1,10-phenanthroline-copper complex) nucleases, the cytosine residues are accessible to the solvent, and the distortions are located at the level of the adduct [48-50]. From the electrophoretic mobility of the multimers of double-stranded oligonucleotides containing a single interstrand cross-link [50] it is deduced that the DNA double helix is unwound (79°) and its axis is bent (45°). 

---