Abstract
CAAC precursors 2-chloro-3,3-dimethylindole 1 and 2-chloro-1-ethyl-3,3-dimethylindolium tetrafluoroborate 2BF(4) have been prepared and oxidatively added to [M(PPh(3) )(4) ] (M=Pd, Pt). Salt 2BF(4) reacts with [Pd(PPh(3) )(4) ] in toluene at 25 °C over 4 days to yield complex cis-[3]BF(4) featuring an N-ethyl substituted CAAC, two cis-arranged phosphines and a chloro ligand. Compound trans-[3]BF(4) was obtained from the same reaction at 80 °C over 1 day. Salt 2BF(4) reacts with [Pt(PPh(3) )(4) ] to give cis-[4]BF(4) . The neutral indole derivative 1 adds oxidatively to [Pt(PPh(3) )(4) ] to give trans-[5] featuring a CAAC ligand with an unsubstituted ring-nitrogen atom. This nitrogen atom has been protonated with py⋅HBF(4) to give trans-[6]BF(4) bearing a protic CAAC ligand. The Pd(II) complex trans-[7]BF(4) bearing a protic CAAC ligand was obtained in a one-pot reaction from 1 and [Pd(PPh(3) )(4) ] in the presence of py⋅HBF(4) .