Catalytic Hydroarylation of Ethylene Using TpRu(L)(NCMe)Ph (L=2,6,7-Trioxa-1-phosphabicyclo[2,2,1]heptane): Comparison to TpRu(L′)(NCMe)Ph Systems (L′ = CO, PMe3, P(pyr)3, or P(OCH2)3CEt)

The Ru(11) complex TpRu[P(OCH2)(2)(OCCH3)] (NCMe)Ph (4; Tp = hydridotris(pyrazolyl)borate) has been synthesized and isolated. At 90 degrees C, TpRu[P(OCH2)(2)OCCH3](NCMe)Ph in C6D6 produces TpRu[P(OCH2)(2)(OCCH3)]-(NCMe)Ph-d(5) and C6H5D. TpRu[P(OCH2)(2)(OCCH3)](NCMe)Ph catalyzes the hydrophenylation of ethylene at 90 degrees C to produce ethylbenzene with 90 turnovers (TOs) after 50 h. Catalyst deactivation occurs by the formation of the eta(3)-allylcomplex TpRu[P(OCH2)(2)(OCCH3)](eta(3)-C3H4Me). Kinetic studies of stoichiometric C6D6 activation by TpRu(L)(NCMe)Ph (L = CO, P(OCH2)(3)CEt, PMe3 P(OCH2)(2)(OCCH3)) to give TpRu(L)(NCMe)Ph-d(5) and C6H5D reveal that the reactions occur with the following relative rates: PMe3 (k(obs) = [1.36(4)] X 10(-5) s(-1)) > P(OCH2)(3)CEt (k(obs) = 1.20(2) X 10(-5) s(-1)) > P(OCH2)(2)(OCCH3)(k(obs) = 7.2(5) X 10(-6) s(-1)) > CO (k(obs) = [4.62(3)] X 10(-6) s(-1)). These rates correlate linearly with Ru(III/II) potentials of the four TpRu(L)(NCMe)Ph complexes. DFT calculations have been used to model catalytic olefin hydroarylation by TpRu[P(OCH2)(2)(OCCH3)](NCMe)Ph (4) and to rationalize the observed differences in the various TpRu(L)(NCMe)Ph catalysts.