Arsenic-oxygen rings

Phosphorus—phosphorus bonds, addition, to alkynes, 10, 751 Phosphorus rings, chromium carbonyl link arsenic rings, 5, 226 As, Sb, Se, Te, Sn rings, 5, 226 boron rings, 5, 222 carbon rings, 5, 224 characteristics, 5, 221 oxygen rings, 5, 227... 

Rings with Arsenic, Oxygen and Nitrogen Atoms... 

The relative affinities of various hydroxylic dithiols for arsenite were measured by Zahler and Cleland (33), but proved hard to understand (since seven-membered rings seemed to give the most stable complexes) until Cruse and James (34) showed that an oxygen atom of such a compound acted as a third ligand for arsenic, so that bicyclic complexes were formed. 

Inorganic arsenic complexes based on oxygen ligands is scarce. Simple esters of arsenic acid, As(0)(0R)3 (R = Me, Ft, n-Pr, n-Bu, CeHn) have tetragonal structures. Reaction of the diol ligand 2,4-dimethyl-2,4-pentanediol with AsCfr affords an arsenic chloride complex in which the As atom is part of a six-membered ring (37). ... 

It is not surprising that all but one of the known heterocyclic metallepin derivatives are those associated with the symmetrical structures (XVa) and (XVd). The Ring Index system describes each of the preceding isomers as follows (XVa), 10,ll-dihydro-5//-dibenzo[i,/]metallepin (XVb), 6,ll-dihydro-5//-dibenzo[i,e]metallepin (XVc), 6,7-dihydro-S//-dibenzo[6,d]metallepin (XVd), 5,7-dihydro-6/7-dibenzo[c,e]metallepin. The majority of the known derivatives are of type (XVa), but the bridged biphenyl (XVd) is known for arsenic and selenium. All four derivatives are known only for oxygen and sulfur heteroatoms. 

As in the case of monocyclic 1,3-azaphospholes/arsoles (Section 3.16.4.1.4) tris(trimethyl-silyl)phosphine/arsine provides the phosphorus/arsenic ring member by replacing the oxygen atom of an oxazolium ring. 

Rings with One Arsenic and One Oxygen or Sulfur Atom... 

Rings with One Arsenic, One Oxygen and One Nitrogen, or One Arsenic and Two Nitrogen Atoms... 

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