Single-Step Synthesis of Organometallic Molecular Squares from NR,NR',NR'',NR'''-Substituted Benzobiscarbenes

摘要

The single-step multicomponent self-assembly of molecular squares featuring four bridging benzobiscarbenes and four Pd~(II)(allyl) or Ir~I(COD) vertices is presented. Four equivalents of the linear benzobisimidazolium salt [1](PF_6)_2 react with two equivalents of [Pd(allyl)Cl]_2 or [IrCl(COD)]_2 in the presence of Cs_2CO_3 to yield the tetranuclear octacarbene molecular squares [2](PF_6)_4 (M=Pd) and [3](PF_6)_4 (M=Ir), respectively. Compounds [2](PF_6)_4 and [3](PF_6)_4 feature exclusively M-carbon bonds making them the first purely organometallic molecular squares.