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.