Synthesis and Study of Palladium(II) and Platinum(II) Complexes Supported by a Common “Wingtip” N‐Heterocyclic Carbene

Two annulated imidazolium salts, 2‐(phenyl)imidazo[1,5‐ a ]pyridin‐4‐ylium hexafluorophosphate 1⋅ H(PF 6 ) and 1‐methyl‐2‐(phenyl)imidazo[1,5‐ a ]pyridin‐4‐ylium hexafluorophosphate 2⋅ H(PF 6 ), were synthesized via formylative cyclization of the corresponding Schiff bases followed by anion metathesis with KPF 6 . Independently treating 1⋅ H(PF 6 ) or 2⋅ H(PF 6 ) with silver oxide and then palladium chloride in acetonitrile led to the formation of the complexes [Pd( 1 ) 2 Cl(CH 3 CN)]PF 6 ( 1 a ) and [Pd( 2 ) 2 Cl(CH 3 CN)]PF 6 ( 2 a) , respectively. Likewise, [Pt( 1 ) 2 Cl(CH 3 CN)]PF 6 ( 1 b) and [Pt( 2 ) 2 Cl(CH 3 CN)]PF 6 ( 2 b) were synthesized using similar transmetallation chemistry. The complexes were characterized using various spectroscopic techniques and the solid state structures of 1‐ H(PF 6 ) as well as 2 a were elucidated using X‐ray diffraction analyses. A series of DFT calculations were also performed to gain further insight into the respective structures of the complexes. Complexes 1 a and 2 a were found to facilitate Suzuki coupling reactions under relatively mild conditions.