Bis-diimidazolylidine complexes of nickel: Investigations into nickel catalyzed coupling reactionsElectronic supplementary information (ESI) available. CCDC reference numbers 697184697187. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c1dt10858a

Air and moisture stable homoleptic bis(diimidazolylidine)nickel( ii ) complexes, ([(diNHC) 2 Ni] 2+ ) 3a,b and their corresponding silver( i ) 4a,b and palladium( ii ) 5a,b complexes were synthesized and characterized by NMR and single crystal X-ray analysis. The catalytic potential of complex 3a was assessed in MizorokiHeck and SuzukiMiyaura coupling reactions. In the SuzukiMiyaura coupling reaction, nickel precatalyst 3a was active for the coupling of aryl chlorides as well as aryl fluorides. The analogously synthesized Pd( ii ) complexes resulted in formation of (diNHC)PdCl 2 species which were not active for the coupling of aryl fluorides. For the MizorokiHeck reaction, it was found that aryl iodides could be activated in the absence of nickel or palladium precatalysts when using Na 2 CO 3 or NEt 3 as base while aryl iodides and aryl bromides could be activated in the SuzukiMiyaura reaction sans precatalyst when K 3 PO 4 was used as base. Bis(diimidazolylidine)nickel( ii ) complexes were synthesized via a transmetallation route using (diNHC)Ag( i ) complexes and investigated as possible substitutes for palladium-based precatalysts in MizorokiHeck and SuzukiMiyaura coupling reactions.