Organostannoxanes and Cyclophosphazenes as Scaffolds for Multi-Ferrocene Assemblies

Abstract

The reactions of n-butylstannonic acid and di n-butyltinoxide with ferrocene monocarboxylic acid have been studied. In the former reaction a hexameric compound, [n-BuSn(O)OC(O)C₅H₄FeC₅H₅]₆ has been isolated in a quantitative yield. In the latter reaction a tetrameric compound [{n-Bu₂SnO₂C(C₅H₄FeC₅H₅}₂O}]₂ has been isolated. In contrast to the drum like structure of the former compound, the latter has a ladder like arrangement. Both [n-BuSn(O)OC(O)C₅H₄FeC₅H₅]₆ and [{n-Bu₂SnO₂C(C₅H₄FeC₅H₅)}₂O]₂ are electro-chemically robust and show a single oxidation peak in the cyclic voltammetric experiment corresponding to the simultaneous oxidation of six and four ferrocene substituents respectively. The hydrazine substituted cyclophosphazenes, N₃P₃[N(Me)NH₂]₆, gem-N₃P₃Ph₂[N(Me)NH₂]₄, and gem-N₃P₃(O₂C₁₂H₈)₂[N(Me)NH₂]₂, are readily condensed with ferrocene carboxaldehyde, C₅H₅FeC₅H₄CHO, to afford the corresponding cyclophosphazenes linked to the ferrocenyl moiety through the hydrazone linkage, N₃P₃[N(Me)N=CHC₅H₄FeC₅H₅]₆, gem-N₃P₃Ph₂[N(Me)N=CHC₅H₄FeC₅H₅]₄, and gem-N₃P₃(O₂C₁₂H₈)₂]N(Me)N=CHC₅H₄FeC₅H₅]₂.

Keywords::

• stannoxanes
• cyclophosphazenes
• ferrocene
• cyclic voltammetry
• multi-metallocene
• ladder
• drum