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.