Half-Sandwich Rhodium Amido Complexes
Organometallics, Vol. 28, No. 5, 2009 1445
(s, C5Me5), 31.40 (s, CMe3), 69.75 (s, C5), 71.90 (s, C10), 99.48 (d,
JRhC ) 9 Hz, C5Me5), 124.60 (s, C2), 126.96 (s, C9), 127.53 (s,
C8), 127.84 (s, C12), 127.86 (s, C3), 128.76 (s, C13 or C14), 128.96
(s, C13 or C14), 129.35 (s, C7), 139.72 (s, C6 or C11), 140.12 (s, C6
or C11), 143.02 (s, C4), 152.53 (s, C1). 15N NMR (50.7 MHz,
CD2Cl2, 300 K): δ -263.7 (d, JRhN ) 17 Hz, NH2), -208.6 (d,
JRhN ) 20 Hz, NTs). MS (FAB, m/z): 681 ([MH+]). IR (KBr/cm-1):
3287 (νNH), 3233 (νNH). Anal. Calcd for C34H42ClN2O2RhS: C,
59.95; H, 6.22; N, 4.11. Found: C, 59.70; H, 6.25; N, 4.16.
aromatic), 7.56 (m, 1H, NH), 7.78 (d, JHH ) 8 Hz, 1H, NH).
13C NMR (75 MHz, CD2Cl2, 300 K): δ 9.06 (s, C5Me5), 9.30 (s,
C5Me5), 21.16 (s, Me), 60.72 (s, CH), 60.84 (s, CH), 63.55 (s,
CH), 64.10 (s, CH), 106.24 (d, JRhC ) 5 Hz, C5Me5), 106.55 (d,
JRhC ) 5 Hz, C5Me5), 124.86 (s), 126.90 (s), 127.26 (s), 127.59
(s), 127.66 (s), 127.78 (s), 127.83 (s), 128.44 (s), 128.68 (s),
129.10 (s), 129.32 (s), 137.30 (s), 137.46 (s), 137.95 (s), 138.24
(s), 138.36 (s), 138.43 (s), 142.77 (s), 142.98 (s), 181.58 (d,
JRhC ) 27 Hz, NCO), 181.75 (d, JRhC ) 27 Hz, NCO), 188.08
(d, JRhC ) 77 Hz, CO), 188.14 (d, JRhC ) 77 Hz, CO). 13C NMR
(125 MHz, CD2Cl2, 300 K): δ 181.6 (d, JRhC ) 27 Hz, NCO),
181.7 (d, JRhC ) 27 Hz, NCO), 188.1 (d, JRhc ) 77 Hz, CO),
188.2 (d, JRhc ) 77 Hz, CO). MS (FAB, m/z): 603 ([M - 2CO]+).
IR (CH2Cl2/cm-1): 2056 (νCO), 1600 (νCO).
[Cp*Rh(tBuNC)(TsNCHPhCHPhNH2)][PF6] (4a). 4a was
prepared by addition of tBuNC (13 mg, 0.16 mmol) to a solution
of 2a (100 mg, 0.16 mmol) in CH3OH (5 mL), stirring for 1 h,
removing the solvent under reduced pressure, and extracting into
toluene. The addition of KPF6 (59 mg, 0.32 mmol) to the toluene
solution resulted in the precipitation of a yellow solid. The yellow
solid was extracted into THF, filtered, and crystallized from THF/
hexane to give 4a (102 mg, 76%) as yellow needles. 1H NMR (500
MHz, CD3CN, 300 K): δ 1.70 (s, 9H, tBu), 1.91 (s, 15H, C5Me5),
2.15 (s, 3H, Me), 3.75 (ddd, JHH ) 3, 12, 14 Hz, 1H, H10), 4.09 (br
d, JHH ≈ 11 Hz, 1H, NHa), 4.15 (d, JHH ) 11 Hz, 1H, H5), 4.29 (br
apparent t, JHH ≈ 11, 11 Hz, 1H, NHb), 6.60 (d, JHH ) 7 Hz, 2H,
Ph), 6.65 (t, JHH ) 8 Hz, 2 H, Ph), 6.74 (d, JHH ) 8 Hz, 2H, H2),
6.74-6.76 (m, 1H, H9, or H14), 7.03-7.04 (m, 2H, Ph), 7.12 (d,
JHH ) 8 Hz, 2H, H3), 7.18 (m, 3H, Ph). 13C NMR (125 MHz,
CD3CN, 300 K): δ 10.33 (s, C5Me5), 21.50 (s), 30.64 (s, CMe3),
60.37 (s, CMe3), 71.74 (s, C10), 73.84 (s, C5), 102.26 (d, JRhC ) 7
Hz, C5Me5), 127.60 (s, Ph), 128.52 (s, Ph), 128.77 (s, Ph), 129.03
(s, C2), 129.33 (s, C3), 129.62 (s, Ph), 130.00 (s, Ph), 134.8 (d,
JRhC ) 69, CN), 139.69 (s, Ph), 140.11 (s, Ph), 141.40 (s, C1 or
C4), 141.91 (s, C1 or C4). 31P NMR (202 MHz, CD3CN, 300 K): δ
-144.61 (sept, JFP ) 702 Hz). MS (ESI, m/z): 686 ([M+]). IR (KBr/
cm-1): 3336 (νNH), 3292 (νNH); 2212 (νCN). Anal. Calcd for
C36H45F6N3O2PRhS: C, 51.99; H, 5.42; N, 5.05. Found: C, 51.68;
H, 5.48; N, 4.99.
1H NMR (500 MHz, CD3CN, 300 K): δ 1.24 (9H, s, CMe3),
1.80 (15H, s, C5Me5), 3.64 (1H, br apparent t, JHH ) 11, 11 Hz,
NHb), 3.78 (1H, ddd, JHH ) 3, 12, 14 Hz, H10), 4.00 (1H, d, JHH
11 Hz, H5), 4.42 (1H, br d, JHH ) 9 Hz, NHa), 6.63 (2H, d, JHH
)
)
7 Hz, H7), 6.68 (2H, d, JHH ) 7 Hz, H8), 6.73-6.76 (1H, m),
6.90-6.92 (2H, m), 7.04 (2H, d, JHH ) 9 Hz), 7.12-7.13 (3H, m),
7.27 (2H, d JHH ) 9 Hz).
Cp*RhCl(4-FC6H4SO2NCHPhCHPhNH2) (2c). [Cp*RhCl2]2
(0.83 g, 1.35 mmol), 4-FC6H4SO2DPEN (1.0 g, 2.7 mmol), and
NEt3 (0.75 mL,5.4 mmol) were reacted in CH2Cl2 (50 mL) to give
2c (1.35 g, 78%). Crystals suitable for X-ray analysis were grown
by slow diffusion of hexane into a concentrated solution of 2c in
1
CH2Cl2. H NMR (500 MHz, CDCl3, 300 K): δ 1.80 (15H, s,
C5Me5), 3.54 (1H, br d, JHH ≈ 10 Hz, NHb), 3.70 (1H, ddd, JHH
)
2, 12, 14 Hz, H10), 3.84 (1H, br apparent t, JHH ≈ 11, 11 Hz, NHa),
3.96 (1H, d, JHH ) 11 Hz, H5), 6.62 (2H, d, JHH ) 9 Hz, H7 or H8),
6.65-6.68 (2H, m, H7 or H8), 6.78 (2H, apparent t, JHH ) 8, 8 Hz,
H2), 6.82-6.85 (3H, m, H9 and H12), 7.10 (3H, m, H13 and H14),
7.40 (2H, dd, JHH ) 8 Hz, JHF ) 5 Hz, H3). 13C (125 MHz, CD2Cl2,
300 K): δ 9.96 (s, C5Me5), 69.85 (s, C5), 71.87 (s, C10), 94.92 (d,
JRhC ) 8 Hz, C5Me5), 113.9 (C2,d, JFC ) 22 Hz), 127.09 (s, C9 or
C12), 127.55 (s, C9 or C12), 127.66 (s, C7 or C8), 128.79 (s, C13 or
C14), 128.96 (s, C13 or C14), 129.32 (s, C7 or C8), 130.79 (d, JFC
)
6 Hz, C3), 139.87 (s, C5 or C10), 139.94 (s, C5 or C10), 141.70 (s,
C4), 163.43 (d, JFC ) 250 Hz,C1). 19F NMR (480 MHz, CD2Cl2,
300 K): δ -112.76 (s). 1H–15N HMQC NMR (50.7 MHz, CD2Cl2,
300 K): δ -263.8 (d, JRhN ) 16 Hz, NH2), -210.2 (d, JRhN ) 21
Hz, NTos). 1H-103Rh HMQC (22.18 MHz, CDCl3, 300 K): δ
2036.5. MS (FAB, m/z): 643 ([MH]+). IR (KBr/cm-1): 3292 (νNH),
3234 (νNH). Anal. Calcd for C30H33ClFN2O2RhS: C, 56.04; H, 5.17,
N, 4.36. Found: C, 55.70; H, 5.39; N 4.39.
[(Cp*Rh)2(µ-H)(µ-Cl)(µ-HCO2)][BPh4] ([5a][BPh4]). 2a (200
mg, 0.32 mmol) was dissolved in CH3OH (10 mL) with the aid of
sonication, and HCO2H (150 mg, 3.26 mmol) was added via
microsyringe. The solution turned from orange to red and was
stirred for a further 15 min before stirring was stopped and NaBPh4
(220 mg, 0.64 mmol) was added as a solid, and the flask was swirled
to afford mixing, causing a red precipitate to settle from the solution
upon standing. The solid was removed by filtration, dried under
reduced pressure, and crystallized from acetone/Et2O (1:1) at -20
°C to give [5a][BPh4] as red crystals (121 mg, 43%). Crystals
suitable for X-ray analysis were grown from a solution of
[5a][BPh4] in (CH3)2CO/Et2O (1:1) at -20 °C. 1H NMR (500 MHz,
(CD3)2CO, 300 K): δ -8.59 (t, JRhH ) 27.4 Hz, 1H, Rh-H-Rh),
1.94 (s, 30H, C5Me5), 6.77 (t, JHH ) 7.2 Hz, 4H, BPh4), 6.92 (t,
JHH ) 7.5 Hz, 8H, BPh4), 7.33-7.35 (m, 8H, BPh4), 7.46 (t, JHH
) 3.5 Hz, 1H, HCO2). 13C NMR (125 MHz, (CD3)2CO, 300 K): δ
10.09 (s, C5Me5), 98.93-98.99 (m, C5Me5), 122.29 (s, BPh4),
126.01-126.08 (q, JBC ) 3 Hz, BPh4), 137.07-137.08 (m, BPh4),
164.40-165.58 (q, JBC ) 49 Hz, BPh4), 173.84 (s, HCO2). IR (KBr/
cm-1): 1556 (νCO). MS (ESI, m/z): 557 ([M]+). Anal. Calcd for
C45H52BClO2Rh2: C, 61.63; H, 5.98. Found: C, 61.21; H, 6.12.
1H NMR (500 MHz, CD3CN, 300 K): δ 1.80 (15H, s, C5Me5),
3.61 (1H, br apparent t, JHH ≈ 11, 11 Hz, NHb), 3.80 (1H, ddd,
JHH ) 3, 12, 14 Hz, H10), 3.94 (1H, d, JHH ) 11 Hz, H5), 4.44 (1H,
br d, JHH ≈ 8 Hz, NHa), 6.69 (2H, d, JHH ) 7 Hz), 6.75-6.79 (4H,
m), 6.83-6.85 (1H, m), 6.89-6.91 (2H, m) 7.12-7.14 (3H, m),
7.44 (2H, dd JHH ) 9 Hz, JFH ) 5 Hz).
15N-Labeled Cp*RhCl(TsNCHPhCHPhNH2) (2a-15N). [Cp*Rh-
Cl2]2 (36.0 mg, 58 µmol), TsDPEN (41.0 mg, 112 µmol), and NEt3
(33 µL, 237 µmol) were reacted in CH2Cl2 (5 mL), to give 15N-
enriched 2a (54 mg, 71%). 1H NMR (500 MHz, CDCl3, 300 K): δ
1.80 (15H, s, C5Me5), 2.21 (3H, s, Me), 3.48 (1H, dd, JNH ) 72
Hz, JHH ) 10 Hz), 3.70 (1H, ddd, JHH ) 14, 12, 3 Hz), 3.86 (1H,
d of apparent t, JNH ) 82 Hz, JHH ) 11, 11 Hz), 3.96 (1H, d, JHH
)11 Hz), 6.63 (2H, d, JHH ) 7 Hz), 6.75 (2H, t, JHH ) 7 Hz),
6.80-6.85 (5H, m), 7.06-7.14 (3H, m), 7.28 (2H, d, JHH ) 7 Hz).
15N{1H} NMR (50.7 MHz, CD2Cl2, 300 K): δ -263.6 (d, JRhN
)
14 Hz, NH2), -210.6 (d, JRhN ) 18 Hz, NTs). MS (FAB, m/z):
639 ([MH+] 14N/14N isotopomer), 640 ([MH]+ 14N/15N isotopomer),
641 ([MH]+ 15N/15N isotopomer).
Synthesis of [Cp*Rh(CO)(CONTsCHPhCHPhNH2)][Cl] (3a).
3a was prepared by adding CO (3 atm) to an NMR tube fitted
with a Young’s tap containing a degassed solution of 2a in dry
CD2Cl2, CD3OD, or a mixture of CD2Cl2/CD3OD (1%). 1H NMR
(500 MHz, CD2Cl2, 300 K): δ 1.68 (s, 15H, C5Me5), 1.83 (s,
15H, C5Me5), 2.28 (s, 3H, Me), 2.31 (s, 3H, Me), 4.49-4.51
(m, 2H, CH), 5.04-5.09 (m, 2H, CH), 6.02 (d, JHH ) 6 Hz, 1H,
NH), 6.07 (d, JHH ) 6 Hz, 1H, NH), 6.82-7.40 (m, 28H,
Transfer Hydrogenation of d6-Acetone with d15-NEt3/Formic
Acid Catalyzed by 2a. (S,S)-2a (4.4 mg, 6.8 µmol) was dissolved
in CD3CN; d6-acetone (10 µL, 0.14 mmol) was added to the tube
via microsyringe followed by d15-NEt3 (35 µL, 0.27 mmol). At each
1
stage of addition, a H NMR spectrum was recorded. The sample
was cooled to 250 K, HCO2H (26 µL, 0.680 mmol) was added to