Stibonium and bismuthonium ylides. A comparison with arsonium and other ylides, also including the crystal structure of triphenylarsonium bis(phenylsulphonyl)methylide and triphenylarsonium and triphenylstibonium 4,4-dimethyl-2,6-dioxocyclohexylides

The spectra, dipole moments, X-ray structures, and chemistry (stability, hydrolysis, reactivity in Wittig reactions) of a number of stibonium ylides are compared with similar properties of their arsonium analogues. There is a close resemblance between the stibonium and arsonium ylides; this is explained in terms of intramolecular interaction between substituent oxygen atoms and the antimony or arsenic atoms. Attempts to prepare stibonium ylides from dichlorotrphenylantimony (V) led always to ylides contaminated with oxybis(triphenylantimony) dichloride. Other oxybis(triphenylantimony) derivatives were obtained from acid hydrolyses of stibonium ylides. Two bismuthonium ylides were also studied. In their case also there appears to be an intramolecular bismuth–oxygen interaction.