Base-Controlled Directed Synthesis of Metal–Methyleneimidazoline (MIz) and Metal–Mesoionic Carbene (MIC) Compounds

Formation of CNHC∧Calkyl and CNHC∧Caryl κ2-Chelate Complexes through Competitive sp3- and sp2-CH Activations: An Experimental and Computational Study

Depending on the chelate ring present, cyclometalated complexes are useful catalysts for various reactions. The reactivity of IrIII and RhIII NHC complexes bearing aliphatic or aromatic N,N'-substituents and thus featuring various metalation sites toward cyclometalation has been investigated. The RhIII complex bearing an N-mesityl-N'-benzyl-NHC does not participate in any cyclometalation, while the IrIII complex reacts under metalation of an ortho-methyl group of the Mes substituent to give complex [3] with a six-membered chelate ring. The RhIII and IrIII complexes bearing an N-o-tolyl,N-benzyl-NHC undergo sp2-CH activation to yield the cyclometalated complexes [4] and [5] featuring a five-membered CNHC∧C chelate ring. Density functional theory (DFT) studies corroborated the experimental findings.

Palladium complexes with an annellated mesoionic carbene (MIC) ligand: catalytic sequential Sonogashira coupling/cyclization reaction for one-pot synthesis of benzofuran, indole, isocoumarin and isoquinolone derivatives

A Pd(ii) complex containing a mesoionic carbene and phosphine ligands is an efficient catalyst for tandem coupling/cyclization reaction.