863225-93-8Relevant academic research and scientific papers
Synthesis of cyclo-2,4,6-triarsa-1,3,5-triazanes from cyclo-2,4-diarsa-1,3- diazanes demonstrating the general influence of substituent steric strain on the relative stability of pnictazane oligomers
Burford, Neil,Landry, Jeff C.,Ferguson, Michael J.,McDonald, Robert
, p. 5897 - 5902 (2005)
2,4-Dichloro-1,3-diaryl-cyclo-2,4-diarsa-1,3-diazanes (aryl = 2,6-dimethylphenyl, Dmp, or 2,6-diisopropylphenyl, Dipp) have been transformed into the corresponding 2,4,6-trichloro-cyclo-2,4,6-triarsa-1,3,5-triazanes on reaction with GaCl3 followed by 4-(dimethylamino)pyridine (DMAP). The nitrogen bound Dmp and Dipp substituents impose medium substituent steric strain on the heterocycles influencing the relative thermodynamic stability of potential oligomers in favor of the trimers. This ring expansion disproportionation reaction is initiated by chloride ion abstraction, and the intermediate 2,4-dichloro-1,3,5-tris(2,6-diisopropylphenyl)-cyclo-2,4-diarsa-1, 3,5-triazane-6-arsenium tetrachlorogallate has been isolated and structurally characterized. Subsequent reaction with 4-(dimethylamino)pyridine (DMAP) effects release of chloride ion from the gallate anion and consequential formation of a covalent As-Cl bond in the trimer. The observations are analogous to those for the phosphorus derivatives demonstrating a general applicability of this new synthetic procedure for the development and diversification of cyclopnictazane chemistry.
