Stepwise Formation of a Molecular Square with Bridging NH,O-Substituted Dicarbene Building Blocks

The β,β′-bis(triisopropylsiloxy)phenyl-1,4-diisocyanide 3 and [Ir(Cp*)Cl₂]₂ were used for the stepwise assembly of the [Ir(Cp*)Cl] cornered molecular square [6](Cl)₄. Synthesis of the tetrakis(diisocyanide) bridged molecular square [Ir(Cp*)Cl(3)]₄(BF₄)₄ [5](BF₄)₄ followed by cleavage of the O–Si(i-Pr)₃ bonds of the diisocyanide bridges with HCl/i-PrOH led to an intramolecular attack of the liberated hydroxyl groups at the isocyanide carbon atoms with formation of molecular square [6](Cl)₄ featuring four dicarbene linkers.