temperature unless otherwise noted and referenced to either SiMe4
of 89% (191 mg, 0.159 mmol). The material was found to contain
87% 2b and 13% 4, by integration of the ortho methyl groups in
the 1H NMR spectrum.
1
through the residual solvent resonance(s) (1H and 13C{ H}), or an
1
external standard (85% H3PO4 (31P{ H}), trifluorotoluene (19F),
1
or boron trifluoride diethyl etherate (11B)). 1H and 13C{ H} NMR
Method B: a slight excess of dimethylzinc (0.050 mL of a 1.2 M
solution in toluene, 0.060 mmol) was added to a suspension of 1c
(80.7 mg, 0.0559 mmol) in bromobenzene (1 mL). All material
dissolved within 1 min, and the resulting yellow solution was
left to stand for 30 min. Within this time, the reaction products
crystallized from solution. The mother liquor was decanted from
the resulting white crystalline material, which was then washed
with benzene (3 ¥ 1 mL) and pentane (2 ¥ 1 mL), and dried in
vacuo, affording an overall 64% yield (42.7 mg, 0.0355 mmol). The
material was found to contain 55% 2b and 45% 4, by integration
of the ortho methyl groups in the 1H NMR spectrum.
peak assignments were facilitated by COSY, DEPT-90, and HSQC
experiments. X-Ray crystal structures were collected using a
Bruker AXS SMART APEX II single crystal X-ray diffractometer
˚
(Mo Ka (l = 0.71073 A)). Elemental analyses were performed
using an Elementar Vario Microcube instrument. GPC data were
collected on a Viscotek Triple Detector GPC System outfitted with
a model 270 Dual Detector Platform (Four Capillary Viscometer
and Light Scattering Detector) and a Refractive Index Detector.
Samples were run in THF at a concentration of 1 mg mL-1.
MALDI-TOF data were collected using an Applied BioSystems
Voyager Elite instrument.
NMR data are reported for material isolated from method B
(55% 2b, 45% 4). 1H NMR (C6D5Br): d 7.83 (br m, 8H, o-BPh4),
7.70 (d, 2H, 3JHH = 7.8 Hz, 1,9-dbf), 7.25–7.00 (ov m, 20H, o-Ph
+ p-Ph + m-BPh4, partially obscured by solvent resonance), 7.00–
6.83 (ov m, 14H, p-BPh4 + m-Ph + 2,8-dbf, partially obscured by
solvent resonances), 6.70 (dd, 2H, 3JPH = 12.0 Hz, 3JHH = 7.5 Hz,
3,7-dbf), 6.40 (s, 2.2H, m-mesityl of 2b), 6.37 (s, 1.8 H, m-mesityl of
4), 2.08 (s, 2.7H, p-CH3 mesityl of 4), 2.04 (s, 3.3H, p-CH3 mesityl
of 2b), 1.33 (s, 6.6H, o-CH3 mesityl of 2b), 1.03 (s, 5.4H, o-CH3
Synthesis
+
-
=
[4,6-(MesN PPh2)2dibenzofuran·ZnMe] [B(C6F5)4] , 2a. An
excess of 1.2 M dimethylzinc in toluene (65 mL, 0.0780 mmol) was
added to a solution of 1a (100 mg, 0.0674 mmol) in bromobenzene
(2 mL). Effervescence of methane was immediately observed. After
allowing the mixture to stand for 30 min at ambient temperature,
the product was precipitated as a red/orange oil by addition of
pentane (5 mL). The mother liquor was decanted, the resulting oil
was washed twice with 1 mL of pentane, then once with 2 mL
of a 1 : 2 benzene–pentane mixture and dried in vacuo, giving
the material as a pale yellow powder in 92.0% yield (96.6 mg,
0.0618 mmol). 1H NMR (C6D5Br): d 7.87 (d, 2H, 3JHH = 7.6 Hz,
1,9-dbf), 7.32–7.19 (ov m, 4H, p-Ph obscured by solvent), 7.19–
1
mesityl of 4), -0.49 (s, 1.65H, ZnCH3); 31P{ H} NMR (C6D5Br): d
1
23.6 (2b), 24.2 (4); 11B{ H} NMR (C6D5Br): d -5.55. Compound
solubility and purity did not permit the collection and assignment
1
of 13C{ H} NMR data.
+
-
=
[4,6-(MesN PPh2)2dibenzofuran·ZnOAc] [BPh4] , 3. Com-
plex 3 was prepared similarly to 2a, by reaction of 1b (200 mg,
0.178 mmol) and MeZnOAc (25 mg, 0.179 mmol). After com-
bining the reagents in bromobenzene (1 mL), the resulting
cloudy solution promptly clarified to give a yellow solution.
After standing for 15 min at ambient temperature the product
crystallized. The mother liquor was decanted, the white crystalline
material was washed with benzene and pentane, and after drying
under vacuum for 24 h, complex 3 was isolated in 99% yield
(220 mg, 0.176 mmol). 1H NMR (C6D5Br): d 7.83 (br s, 8H,
o-BPh4), 7.68 (d, 2H, 3JHH = 7.9 Hz, 1,9-dbf), 7.27–7.09 (m, 12H,
o-Ph + p-Ph, partially obscured by solvent signal), 7.05 (t, 8H,
3JHH = 7.3 Hz, m-BPh4), 7.01–6.93 (m, 10H, m-Ph + 2,-8-dbf,
partially obscured by solvent signal), 6.93–6.84 (m, 4H, p-BPh4,
3
7.06 (ov m, 10H, o-Ph + 2,8-dbf), 6.99 (td, 8H, JHH = 7.6 Hz,
4JPH = 3.2 Hz, m-Ph), 6.77 (dd, 2H, 3JPH = 11.8 Hz, 3JHH = 7.6 Hz,
3,7-dbf), 6.41 (s, 4H, m-mesityl), 2.05 (s, 6H, p-CH3 mesityl),
1.34 (s, 12H, o-CH3 mesityl), -0.48 (s, 3H, CH3Zn); 11B{ H}
1
NMR (C6D5Br): d -17.7; 19F NMR (C6D5Br): d 133.22 (d, 8F,
o-C6F5), 163.68 (t, 4F, p-C6F5), 167.47 (t, 8F, m-C6F5); 31P{ H}
1
NMR (C6D5Br): d 23.4 (s); 13C{ H} NMR (C6D5Br): d 157.60
1
(s, aromatic C), 150.23 (br s, C6F5), 147.06 (br s, C6F5), 139.99
(br s, C6F5), 138.29 (d, JPC = 7.9 Hz, aromatic C), 136.55 (d,
JPC = 6.0 Hz, aromatic C), 135.00 (br s, C6F5), 134.39 (d, JPC
=
4
4.1 Hz, aromatic C), 134.12 (d, JCP = 2.6 Hz, p-Ph), 132.84 (d,
2JCP = 10.0 Hz, o-Ph), 132.36 (d, 2JCP = 6.8 Hz, 3,7-dbf), 129.81
3
(s, m-mesityl), 129.49 (d, 3JCP = 12.4 Hz, m-Ph), 127.13 (d, 4JCP
=
partially obscured by solvent), 6.71 (dd, 2H, JPH = 12.2 Hz,
3JHH = 7.9 Hz, 3,7-dbf), 6.41 (s, 4H, m-mesityl), 1.97 (d, 6H,
4JHH = 2.0 Hz, p-CH3 mesityl), 1.80 (s, 3H, CO2CH3), 1.40 (s,
3
2.3 Hz, 1,9-dbf), 124.09 (d, JCP = 10.5 Hz, 2,8-dbf), 123.96 (d,
1
JCP = 8.9 Hz, aromatic C), 114.75 (d, JPC = 92.0 Hz, 4,6-dbf),
12H, o-CH3 mesityl); 31P{ H} NMR (C6D5Br): d 28.34; 11B{ H}
1
1
20.75 (s, p-CH3 mesityl), 19.04 (s, o-CH3 mesityl); ipso-Ph not
observed. Anal. Calcd. (%) for C79H51BF20N2OP2Zn·C6H5Br: C:
59.38; H: 3.28; N: 1.63; found: C: 59.44; H: 3.29; N: 1.71.
NMR (C6D5Br): d -5.55; 13C{ H} NMR (C6D5Br): d 185.02 (s,
1
CO2CH3), 164.80 (q, 1JBC = 49.2 Hz, ipso-BPh4), 138.46 (d, JCP
=
2
8.0 Hz, aromatic C), 136.89 (q, JBC = 1.3 Hz, o-BPh4), 136.42
(d, JCP = 5.7 Hz, aromatic C), 134.66 (d, JCP = 3.8 Hz, aromatic
C), 134.26 (s, p-Ph), 133.41 (d, 3JCP = 10.3 Hz, m-Ph), 132.38 (d,
2JCP = 10.4 Hz, 3,7-dbf), 131.45 (d, obscured by solvent, o-Ph),
+
-
=
[4,6-(MesN PPh2)2dibenzofuran·Zn(Me/Ph)] [BPh4] , 2b/4.
Method A: a small excess of dimethylzinc (0.160 mL of a 1.2 M
solution in toluene, 0.192 mmol) was added to a solution of
1b (200 mg, 0.178 mmol) in bromobenzene (1 mL). Immediate
evolution of methane gas was observed, with a concomitant colour
change of the solution from pale yellow to pale orange. Within
15 min at ambient temperature, the reaction products crystallized
from solution. The mother liquor was decanted from the white
crystalline material, which was washed with benzene (3 ¥ 1 mL)
and pentane (2 ¥ 1 mL), and dried in vacuo, giving an overall yield
3
130.04 (s, m-mesityl), 129.44 (d, JCP = 12.9 Hz, m-Ph), 128.27
3
(s, 1,9-dbf), 125.86 (q, JBC = 2.7 Hz, m-BPh4), 121.93 (s, p-
1
BPh4), 113.76 (d, JPC = 92.6 Hz, 4,6-dbf), 21.20 (s, CO2CH3),
20.80 (s, p-CH3 mesityl), 18.59 (s, o-CH3 mesityl). Signals for
four quaternary carbons were not observed. Anal. Calcd. (%) for
C80H71BN2O3P2Zn·2 C6H6: C: 78.77; H: 5.96; N: 2.00; found: C:
78.58; H: 5.94; N: 2.11.
This journal is
The Royal Society of Chemistry 2010
Dalton Trans., 2010, 39, 3861–3869 | 3867
©