Selective meta-C–H Bond Activation of Substituted 1,3-Chlorobenzenes Promoted by an Osmium Pyridyl Complex

Ethylene displaces both the acetone and phosphine ligands of [OsTp­{κ1C-HNC5H3Me}­(κ1-OCMe2)­(PiPr3)]­BF4 (2; Tp = hydrydotris­(pyrazolyl)­borate). The reaction takes place by stages. Initially the replacement of acetone gives the mono­(olefin) derivative [OsTp­{κ1-C-[HNC5H3Me]}­(η2-CH2CH2)­(PiPr3)]­BF4 (3). The substitution of the phosphine occurs at 120 °C and leads to the bis­(olefin) complex [OsTp­{κ1-C[HNC5H3Me]}­(η2-CH2CH2)2]­BF4 (4). The NH wingtip of 3 and 4 undergoes deprotonation with tert-butoxide to afford the corresponding pyridyl compounds [OsTp­{κ1-C[NC5H3Me]}­(η2-CH2CH2)­(PiPr3)] (5) and [OsTp­{κ1-C[NC5H3Me]}­(η2-CH2CH2)2] (6). At 60 °C, the solvents chloro-3-fluorobenzene, 1,3-dichlorobenzene, and 3-chlorotoluene displace the pyridyl ligand of 6 to yield the haloaryl derivatives [OsTp­(3,5-C6H3ClX)­(η2-CH2CH2)2] (X = F (7), Cl (8), Me (9)) as a result of the selective meta-C–H bond activation of the haloarenes.