Single‐Step Synthesis of Organometallic Molecular Squares from NR,NR′,NR′′,NR′′′‐Substituted Benzobiscarbenes

Abstract 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 2 CO 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.