Preparation of Complexes Bearing N-Alkylated, Anionic or Protic CAACs Through Oxidative Addition of 2-Halogenoindole
Sebastian Termühlen1, Jonas Blumenberg1, Alexander Hepp1
1Institut für Anorganische und Analytische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstrasse 30, 48149, Münster, Germany.
Abstract:
CAAC precursors 2-chloro-3,3-dimethylindole 1 and 2-chloro-1-ethyl-3,3-dimethylindolium tetrafluoroborate 2BF4 have been prepared and oxidatively added to [M(PPh3 )4 ] (M=Pd, Pt). Salt 2BF4 reacts with [Pd(PPh3 )4 ] in toluene at 25 °C over 4 days to yield complex cis-[3]BF4 featuring an N-ethyl substituted CAAC, two cis-arranged phosphines and a chloro ligand. Compound trans-[3]BF4 was obtained from the same reaction at 80 °C over 1 day. Salt 2BF4 reacts with [Pt(PPh3 )4 ] to give cis-[4]BF4 . The neutral indole derivative 1 adds oxidatively to [Pt(PPh3 )4 ] to give trans-[5] featuring a CAAC ligand with an unsubstituted ring-nitrogen atom. This nitrogen atom has been protonated with py⋅HBF4 to give trans-[6]BF4 bearing a protic CAAC ligand. The PdII complex trans-[7]BF4 bearing a protic CAAC ligand was obtained in a one-pot reaction from 1 and [Pd(PPh3 )4 ] in the presence of py⋅HBF4 .
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