A paradigm shift in the construction of heterobimetallic complexes: Synthesis of group 2 & 4 metal–calix[6]arene complexes

Abstract

Deprotonation of calix[6]arenes with barium in methanol followed by the addition of [Ti(OPri)4] or [Zr(OBun)4] is effective in the formation of novel dimeric 2 ∶ 1 barium–titanium(iv)/zirconium(iv) calix[6]arene complexes. In these complexes a central Ti(iv)/Zr(iv) coordinated in the exo-position connects the two calix[6]arenes in the 1,3-alternate conformation, each with an endo-barium sharing common phenolate groups with the titanium/zirconium centre and participating in cation–π interactions. A homometallic barium calix[6]arene dimer was also prepared wherein the calix[6]arenes are in the 1,3-alternate conformation with each coordinating one endo- and one exo-barium centre. The exo-barium..