Cyclometalation of 2-Vinylpyridine with MCl₂(PPh₃)₃ and MHCl(PPh₃)₃ (M = Ru, Os)

Treatment of RuCl₂(PPh₃)₃ in benzene at room temperature with 2-vinylpyridine produces the vinylpyridine complex RuCl₂(2-CH₂CHC₅H₄N)(PPh₃)₂. In the presence of Cs₂CO₃, RuCl₂(PPh₃)₃ reacts with 2-vinylpyridine at room temperature to give the cyclometalated complex RuCl(CHCHC₅H₄N)(CH₂CHC₅H₄N)(PPh₃), which is also produced from the reaction of RuHCl(PPh₃)₃ with 2-vinylpyridine. OsCl₂(PPh₃)₃ reacts with 2-vinylpyridine/Cs₂CO₃ at room temperature to give the analogous cyclometalated complex OsCl(CHCHC₅H₄N)(CH₂CHC₅H₄N)(PPh₃). In the presence of NaBF₄, the reaction produces [Os(CHCHC₅H₄N)(CH₂CHC₅H₄N)(PPh₃)₂]BF₄. The dihydrogen complex Os(H₂)Cl(CHCHC₅H₄N)(PPh₃)₂ is produced from the reaction of OsHCl(PPh₃)₃ with 2-vinylpyridine. The mechanism of the cyclometalation reactions has been investigated by computational chemistry.