Synthesis and characterization of indenyl-functionalized N-heterocyclic carbene complex of Ni(II)

A new type of Ind-NHC ligand precursor (Ind = indenyl), [C9H7-(CH2)3-(CH{NCHCHNiPr})]Br (HL·HBr, 1), was designed and prepared. The reaction of in situ generated anionic indenyl-functionalized NHC ligand LLi with (DME)NiCl2 affords a novel mono-ligand Ni(II) bromide, [C9H6-(CH2)3-(C{NCHCHNiPr})]NiBr (2), which was characterized by elemental analysis, NMR and X-ray crystal determination. Complex 2 in combination with NaBPh4 can catalyze the polymerization of styrene at 80 °C.