Structure Salvarsan has long been assumed to have an As=As double bond, akin to the N=N linkage in azobenzene. However, in 2005, in an extensive mass spectrometric analysis, the arsenic–arsenic bonds in Salvarsan were shown to be single bonds rather than double bonds. Presumed to consist of RAs=AsR molecules, i.e. (RAs)2, Salvarsan was found to actually contain a mixture of cyclo-(RAs)3 and cyclo-(RAs)5 species, where R is the 3-amino-4-hydroxyphenyl moiety. According to Nicholson, these cyclic species slowly release an oxidised species, RAs(OH)2, that is likely responsible for Salvarsan's antisyphilis properties.
Structure Salvarsan has long been assumed to have an As=As double bond akin to the N=N linkage in azobenzene However in 2005 in an extensive mass spectrometric analysis the arsenic–arsenic bonds in Salvarsan were shown to be single bonds rather than double bonds Presumed to consist of RAs=AsR molecules ie (RAs)2 Salvarsan was found to actually contain a mixture of cyclo-(RAs)3 and cyclo-(RAs)5 species where R is the 3-amino-4-hydroxyphenyl moiety According to Nicholson these cyclic species slowly release an oxidised species RAs(OH)2 that is likely responsible for Salvarsan's antisyphilis properties