Homogeneous CO Hydrogenation: Ligand Effects on the Lewis Acid ...

CHO signal of 2-P 2 in the 1 H NMR was significantly broadened, possibly signifying an
intermolecular interaction between these species. The precise speciation is unknown, as probably
fluxional, involving different species coordinating to the Re-CHO oxygen. Due to the broadness
and uncertainty in 31 P NMR delay times, rigorous integration was not pursued; K eq ~ 1 was
obtained by 31 P NMR integration. The equilibrium mixture was stable for at least 4.5 hours.
Figure S121. 31 P NMR after equilibrium.
Reaction of 2-P 2 with [1-E 2] + .
Boroxycarbene 2-P 2 was prepared by dropwise addition of 26.4 µL (0.0264 mmol) NaHBEt 3 (1.0
M in toluene) to a stirring ~0.6 mL C 6D 5Cl solution of 28.5 mg (0.0264 mmol) [1-P 2][BF 4]. The
solution was added to a J-Young NMR tube and multinuclear NMR spectroscopy showed clean
conversion to 2-P 2. The tube was returned to the glovebox, the contents poured onto 27.8 mg
S108