Phospha-capped cobalt(III) cage molecules: synthesis, properties, and structure

Abstract

Base-induced condensation of [Co(sen)]³⁺[sen = 4,4′,4″-ethylidynetris(3-azabutan-1-amine)] with paraformaldehyde and phosphine leads to the phospha-capped bicyclic cage complexes [Co(Mephosphasar)]³⁺(Mephosphasar = 8-methyl-3,6,10,13,16,19,1-hexa-azaphosphabicyclo[6.6.6]icosane) and its phosphine oxide derivative [Co(Me, Ophosphasar)]³⁺; the complexes have surprisingly different spectral and electrochemical properties which are attributed to their different conformations and the X-ray crystal structure of [Co(Me, Ophosphasar)][ZnCl₄]Cl has been determined.