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

vessel was sealed and heated to 120 °C with stirring. The two mostly-insoluble white powders
dissolved quickly upon heating, and the solution turned pale yellow as the reaction proceeded.
After 18 hours, the reaction mixture was cooled and degassed under vacuum. After backfilling
with argon the vessel was sealed and re-heated to 120 °C. After 4 days the mixture was cooled,
degassed, put under argon, and re-heated again. After heating for another 48 hours, the reaction
mixture was allowed to cool, and the solvents were removed to dryness, yielding 2.2 g crude
product (90% pure by NMR). The crude material was purified by crystallization from a
toluene/pentane mixture at -35 °C. 1 H NMR (CD 2Cl 2, 500 MHz): δ 1.21-1.29 (m, 8H,
Ph 2PCH 2B(C 8H 14)), 1.64-1.84 (br m, 20H, Ph 2PCH 2B(C 8H 14)), 2.94 (m, 4H, Ph 2PCH 2B(C 8H 14)),
7.35-7.43 (m, 12H, Ph), 7.65 (m, 8H, Ph). 31 P{ 1 H} NMR (C 6D 5Cl, 121 MHz): δ 8.2. 13 C{ 1 H}
NMR (CD 2Cl 2, 126 MHz): δ 24.08 (Ph 2PCH 2B(C 8H 14)), 27.05 (br t, (Ph 2PCH 2B(C 8H 14)), 32.34
(br, (Ph 2PCH 2B(C 8H 14)), 34.72 (Ph 2PCH 2B(C 8H 14)), 128.81 (m, (m-Ph 2PCH 2B(C 8H 14)), 130.33
((p-Ph 2PCH 2B(C 8H 14)), 132.47 (m, (o-Ph 2PCH 2B(C 8H 14)), 139.04 (m, (ipso-Ph 2PCH 2B(C 8H 14)),
192.77 (t, J PC = 8.5 Hz, <strong>CO</strong>), 192.87 (t, J PC = 6.8 Hz, <strong>CO</strong>). 11 B NMR (CD 2Cl 2, 160 MHz): δ 67.8
(v br). IR (CD 2Cl 2): 2012 (w), 1958 (vs), 1899 (s) cm -1 . Anal. Calcd. for C 45H 52B 2BrO 3P 2Re: C,
54.56; H, 5.29. Found: C, 54.39; H, 5.05.
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