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

Figure S165. 1 H- 13 C gHMBC, with 2-bond correlation to acyl carbon highlighted.
Reaction of trans-[(PPh 3)(Ph 2P(CH 2) 2B(C 8H 14))Re(<strong>CO</strong>) 4][OTf] ([1-E 1Ph 1][OTf]) with 2 equiv
[HPt][PF 6] (with and without triethylborane).
A vial was charged with 31.9 mg (0.0306 mmol) [1-E 1Ph 1][OTf] and ~0.6 mL THF-d 8. With
stirring, solid [HPt][PF 6] (39.2 mg, 0.0611, 2 equiv) was added, and the mixture was transferred
to a J-Young NMR tube. Before monitoring by NMR could begin, most of the Re-containing
material had precipitated as boroxycarbene (see above). No further reduction or C-C bond
formation products were observed by NMR or when the precipitates were extracted with
pyridine.
Separate experiments were carried out under similar conditions, only with 1 and 10 equiv
BEt 3 (1.0 M in hexanes) added after the hydride had been added to the Re. Precipitation still
occurred, although in the case of 1 equiv, trace C-C coupled products were observed after ~4
hours.
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