Stabilization of an unusual conformation of an encapsulated metal ion cobalt(methylarsasarcophagine): synthesis and structure

Abstract

Base-catalysed condensation of [Co(sen)]³⁺(1)[sen = 4,4′,4″-ethylidyne-tris(3-azabutan-1-amine)] with formaldehyde yields the stable tri-imine [Co(sim)]³⁺(2)[sim = 6,6′,6″-ethylidyne-tris(2,5-diazahex-1-ene)] that is converted into the arsenic capped cage molecule [Co(Mearsasar)]³⁺(3)(Mearsasar = 8-methyl-1,3,6,10,13,16,19-arsahexa-azabicyclo[6.6.6]icosane) by reaction with AsH₃; an X-ray crystallographic analysis of (3) reveals an unusual oblique conformation of the encapsulating ligand, which affects the properties of the complex in a marked manner.