Reactions of an Osmium Bis(dihydrogen) Complex under Ethylene: Phosphine Addition to a C–C Double Bond and C–H Bond Activation of Fluoroarenes

The bis(dihydrogen) complex [OsTp(η 2 -H 2 ) 2 (P i Pr 3 )]BF 4 ( 1; Tp = hydridotris(pyrazolyl)borate) reacts with ethylene under 2 atm of the gas to afford [OsTp(CH 2 CH 2 P i Pr 3 )(η 2 -CH 2 ═CH 2 ) 2 ]BF 4 ( 2 ), which promotes the CH bond activation of fluorobenzene and 1,3-difluorobenzene to give OsTp(3-C 6 H 4 F)(η 2 -CH 2 ═CH 2 ) 2 ( 3 ) and OsTp(3,5-C 6 H 3 F 2 )(η 2 -CH 2 ═CH 2 ) 2 ( 4 ), respectively, releasing [EtP i Pr 3 ]BF 4 . The formation of 2 takes place via [OsTp(η 2 -CH 2 ═CH 2 ) 2 (P i Pr 3 )]BF 4 ( 5 ), which has been isolated and characterized by X-ray diffraction analysis.