Supporting Information
© Wiley-VCH 2008
69451 Weinheim, Germany
Supporting Information
for
The Low Basicity of Phosphabenzenes: First
Examples of Protonation, Alkylation and Silylation
Reactions
by
Yun Zhang, Fook S. Tham, John F. Nixon, Charlotte Taylor, Jennifer C. Green, and
Christopher A. Reed
(9 pages)
Synthetic Procedures
General. Air sensitive materials were handled in a He atmosphere Vac. Atm. Corp. glove box (O2, H2O < 2 ppm). All
reactions outside of the dry box were carried out under dry nitrogen in Schlenk tubes with Teflon stopcocks. High purity
dichloromethane (Omisolv), benzene, o-dichlorobenzene, and n-hexane were purchased from EM science. Solvents were dried
over Na/K, P2O5, or CaH and distilled prior to use. NMR spectra were record on a Varian Inova 400, 500 or Bruker 300
spectrometers for 1H, 13C, and 31P (referenced externally to 85% H3PO4).
All carborane reagents were freshly prepared. Et3Si(CHB11Me5Br6),1 Et3Si(CHB11Me5Cl6),1 arenium ion salts
[H(arene)][CHB11Me5Cl5] (arene = mesitylene, o-xylene and toluene),1 and CH3(CHB11Me5Br6)2 were prepared by literature
methods.
(1) Reed, C. A.; Kim, K-C.; Stoyanov, E. S.; Stasko, D.; Tham, F. S.; Mueller, L.
J.; Boyd, P. D. W. J. Am. Chem. Soc. 2003, 125, 1796-1804.
(2) Kato, T.; Stoyanov, E.; Geier, J.; Grutzmacher, H.; Reed, C. A. J. Am. Chem.
Soc. 2004, 126, 12451.
[H(C3P3tBu3)][CHB 11Me5Br6], 6. Freshly prepared Et3Si(CHB11Me5Br6) (148 mg, 0.185 mmol) was combined with
(C3P3tBu3), 4 (55.4 mg, 0.185 mmol), in a 5 mL vial with a stir bar. Approximately 1 mL of benzene was added to yield a pale
yellow solution. A white powdery precipitate was formed when 3 drops of TfOH (~2 eq) was added to this solution. Dry nhexane (~2 mL) was added to ensure complete precipitation of the product. The resulting white precipitate was filtered off,
washed with dry n-hexane (~2 mL) and dried under vacuum (153 mg, 84 %). The final product was re-dissolved in CH2Cl2
and layered with n-hexane to yield X-ray quality crystals. 1H NMR (Figure S1) in (300 MHz, δ, CD2Cl2, 25 ºC): 0.11 (s, 15H,
BCH3), 1.54 (bs, 1H, BCH), 1.84 (s, 27H, tBu), 9.46 (d, 1H, 1JH-P = 595 Hz, PH). 31P NMR (Figure S2) (122 MHz, δ, CD2Cl2,
25 ºC): 85.11 (dt, 1P, 2JP-P = 49.0 Hz, 1JP-H = 592 Hz), 304.49 (d, 2P, 2JP-P = 49.2 Hz). ). 31P NMR (1H-Dec, 122 MHz, δ,
CD2Cl2, 25 ºC): 85.07 (t, 1P, 2JP-P = 48.7 Hz), 304.47 (d, 2P, 2JP-P = 48.9 Hz).
[H(C3P3tBu3)][CHB 11Cl11]. This was prepared in an analogous manner to 6 from 4 and Et3Si(CHB11Me5Cl6). 1H NMR
(Figure S3) (300 MHz, δ, d4-o-dichlorobenzene, 25 ºC): 1.54 (s, 18H, tBu), 1.60 (s, 9H, tBu), 2.98 (bs, 1H, BCH), 9.22 (d, 1H,
1
JH-P = 586 Hz, PH). 31P NMR (122 MHz, δ, CD2Cl2, 25 ºC): 81.68 (dt, 1P, 2JP-P = 48.3 Hz, 1JP-H = 590 Hz), 302.69 (d, 2P,
2
JP-P = 48.3 Hz). 31P NMR (1H-Dec, 122 MHz, δ, d4-o-dichlorobenzene, 25 ºC): 81.88 (t, 1P, 2JP-P = 48.8 Hz), 302.91 (d, 2P,
2
JP-P = 48.5 Hz).
[H(PC5H2t-Bu3)][CHB 11Me5Cl6], 7. This was prepared in an analogous manner to 6 from 5 and Et3Si(CHB11Me5Cl6). X-ray
crystals were grown from CD2Cl2/hexanes. 1H NMR (Figure S5) (300 MHz, δ, CD2Cl2 25 °C): 0.13 (15HMe, s), 1.48 (9HBut, s),
1.61 (18HBut, s), 8.45 (1H, dd, 3JPH = 36, 4JHH = 4.6 Hz), 9.32 (1H, dt, 4JHH = 4.6Hz, 1JPH = 627 Hz) ppm). 31P NMR (Figure
S6) (122 MHz, δ, CD2Cl2, 25 ºC) 60.2 (dt, 1JPH = 625 Hz, 3JPH = 36 Hz). 31P NMR (1H-Dec, 122 MHz, δ, CD2Cl2, 25 ºC): 60.2
(s).
[Me(C3P3tBu3)][CHB11Me5Br6], 8. Freshly prepared CH3(CHB11Me5Br6) (50.1 mg, 0.073 mmol) was combined with
(C3P3tBu3) 5 (19.5 mg, 0.065 mmol) in a 5 mL vial with a stir bar. The reaction vial was cooled down to dry ice temperature
before addition of 2 mL cold CH2Cl2 (-90 ºC). The reaction was allowed to warm up to room temperature with stirring before
all volatiles were removed by vacuum. The resulting pale yellow solid (59 mg, 83 %) was re-dissolved in CD2Cl2 for NMR
spectroscopic analysis. 1H NMR (400 MHz, δ, 25 ºC): 0.11 (s, 15H, BCH3), 1.55 (bs, 1H, CH), 1.82 (s, 27H, tBu), 3.50 (d,
3H, CCH3, 2JH-P = 18.6 Hz). 31P NMR (Figure S7) (122 MHz, δ, 25 ºC): 133.8 (tq, 1P, 2JP-P = 52.0 Hz, 2JP-H = 19.0 Hz), 302.6
(d, 2P, 2JP-P = 52.0 Hz). ). 31P NMR (1H-Dec, 122 MHz, δ, CD2Cl2, 25 ºC): 133.4 (t, 1P, 2JP-P = 52.2 Hz), 302.2 (d, 2P, 2JP-P =
52.0 Hz).
Figure S1. 1H NMR spectrum of [H(C3P3tBu3)][CHB11Me5Br6] 6 in CD2Cl2.
tBu
BCH3
1
JHP = 595 Hz
CD2Cl2
CH
31
Figure S2.
P and 31P{1H} NMR spectrum of [H(C3P3tBu3)][CHB11Me5Br6] 6 in CD2Cl2.
31
P NMR
doublet of triple
85.11 ppm
2
JPP = 49.0 Hz
1
JPH = 592 Hz
doublet
304.49 ppm
2
JPP = 49.2 Hz
306.5
306.0
305.5
305.0
304.5
304.0
304.0
303.5
303.0
302.5
302.0
301.5
90
89
88
87
86
85
2P
325
84
83
82
81
1P
300
275
250
225
31
2
P NMR
H Dec
200
175
150
125
100
75
50
JPP = 48.9 Hz
1
2
306.5
306.0
305.5
305.0
304.5
304.0
304.0
303.5
303.0
302.5
87.5
325
300
275
250
225
302.0
87.0
JPP = 48.7 Hz
301.5
86.5
200
86.0
85.5
175
85.0
84.5
150
84.0
84.0
83.5
125
83.0
83.0
82.5
82.0
100
75
50
Figure S3. 1H NMR spectrum of [H(C3P3tBu3)][CHB11Cl11] in d4-ODCB.
1H NMR
1.54 ppm
1.60 ppm
tBu
9.22 ppm
1JPH = 586.3 Hz
2.98 ppm
CH
d4-ODCB
10
9
27 H
1H
1H
8
7
6
5
4
3
2
1
0
Figure S4.
31
31
P and 31P{1H} NMR spectrum of [H(C3P3tBu3)][CHB11Cl11] in d4-ODCB.
302.89 ppm
302.49 ppm
2
JPP = 48.3 Hz
P
304.2
325
304.0
304.0
303.8
303.8
303.6
300
303.4
303.2
302.8
302.6
302.4
302.2
302.0
302.0
301.8
250
301.6
301.4
301.2
301.0
301.0
87
225
200
86
85
84
175
83
304.2
300
304.0
304.0
303.8
303.8
303.6
303.4
275
303.2
303.0
302.8
302.6
302.4
250
302.2
302.0
302.0
79.67 ppm
79.26 ppm
18.86 ppm
1
JPH = 590.0 Hz
82
81
80
150
79
78
77
125
76
100
75
50
82.28 ppm
81.88 ppm
81.48 ppm
2
JPP = 48.8 Hz
303.10 ppm
302.71 ppm
2
JPP = 48.5 Hz
P
H-Dec
325
303.0
275
31
1
84.48 ppm
84.09 ppm
83.70 ppm
2
JPP = 48.3 Hz
301.8
301.6
301.4
225
301.2
83.4
301.0
301.0
200
175
83.2
83.0
82.8
150
82.6
82.4
82.2
82.0
81.8
81.6
125
81.4
81.2
81.0
80.8
80.6
100
80.4
80.2
75
50
Figure S5. 1H NMR spectrum of [H(PC5 H2tBu3)][CHB11Me5Cl6], 7, in CD2Cl2.
0.5
10.4
1.9
10.2
10.0
9.8
9.6
9.4
9.2
9.0
8.8
8.6
8.4
0.5
8.2
8.0
2.0
11
10
9
27.4
8
7
6
5
4
3
2
15.0
1
0
-1
Figure S6.
31
P and 31P{1H} NMR spectrum of [H(PC5H2tBu3)][CHB11Me5Cl6], 7, in CD2Cl2.
31P
70
31
68
66
64
62
60
58
56
54
52
50
68
66
64
62
60
58
56
54
52
50
P{1H}
70
Figure S7.
31
31
P and 31P{1H} NMR spectrum of [Me(C3P3tBu3)][CHB11Me5Br6], 8, in CD2Cl2 at room temperature.
doublet
302.6 ppm
2
JPP = 52.0 Hz
P
Triplet of quartet
133.8 ppm
2
JPP = 52.0 Hz
2
JPH = 19.0 Hz
135.4
303.6
303.4
303.2
300
302.8
302.6
302.4
275
302.2
302.0
301.8
250
301.6
135.2 135.0
135.0
P
H-Dec
303.6
300
303.4
303.2
303.0
302.8
302.6
302.4
275
302.2
302.0
301.8
301.6
134.8 134.6 134.4 134.2 134.0
133.8 133.6
133.4 133.2 133.0 132.8 132.6 132.4 132.2 132.0
301.4
225
200
doublet
302.2 ppm
2
JPP = 52.0 Hz
31
1
303.0
175
150
125
triplet
133.4 ppm
2
JPP = 52.2 Hz
301.4
301.2
250
301.0
300.8
135.2 135.0
135.0 134.8 134.6 134.4 134.2 134.0 133.8 133.6 133.4 133.2 133.0 132.8 132.6 132.4 132.2 132.0
132.0 131.8
225
200
175
150
125