Preparation of Complexes Bearing N‐Alkylated, Anionic or Protic CAACs Through Oxidative Addition of 2‐Halogenoindole Derivatives

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).