Organometallics
Article
3
ppm) for 13C NMR. Herein, numbered proton and carbon atoms refer
to the positions of the xanthene backbone, as shown in Scheme 1.
Inequivalent o-isopropyl protons are labeled A and B, while
inequivalent aryl ring protons and inequivalent methyl groups are
labeled with ′ and ″, so that the corresponding carbon resonances can
be identified. X-ray crystallographic analyses were performed on
suitable crystals coated in Paratone oil and mounted on a SMART
APEX II diffractometer with a 3 kW sealed-tube Mo generator in the
McMaster Analytical X-ray (MAX) Diffraction Facility. In all cases,
non-hydrogen atoms were refined anisotropically and hydrogen atoms
were generated in ideal positions and then updated with each cycle of
refinement.
GC-MS analyses were performed by Dr. Kirk Green and Dr. Fan
Fei at the McMaster Regional Centre of Mass Spectrometry
(MRCMS) using an Agilent 6890N gas chromatograph (Santa
Clara, CA, USA), equipped with a DB-17ht column (30 m × 0.25
mm i.d. × 0.15 μm film, J & W Scientific) and a retention gap
(deactivated fused silica, 5 m × 0.53 mm i.d.) and coupled to an
Agilent 5973 MSD single-quadrupole mass spectrometer. A 1 μL
portion of the sample was injected using the Agilent 7683 autosampler
in splitless mode. The injector temperature was 230 °C, and the carrier
gas (helium) flow was 0.7 mL/min. The transfer line was heated to
280 °C, and the MS source temperature was 230 °C. The column
temperature started at 50 °C and was raised to 300 °C at 8 °C/min
and held at 300 °C for 15 min for a total run time of 46.25 min. Full-
scan mass spectra between m/z 50 and 800 were acquired after a 5 min
solvent delay.
1.49 (d, 6H, JH,H 7 Hz, A-o-CHMe2″), 1.27 (s, 18H, CMe3), 1.12 (d,
3 3
6H, JH,H 7 Hz, B-o-CHMe2′), 1.21 (d, 12H, JH,H 7 Hz, p-CHMe2),
0.99 (d, 6H, 3JH,H 7 Hz, B-o-CHMe2″), 0.84 (s, 4H, THF-C3,4H2), 0.36
(s, 9H, YCH2SiMe3), − 0.22 (d, 2H, JY,H 3.6 Hz, YCH2SiMe3). 13C
2
NMR (C6D6, 126 MHz): δ 147.66 (Xanth-C2), 147.21 (A-o-
CCHMe2), 146.33 (B-o-CCHMe2), 145.34 (p-CCHMe2), 141.33
(Xanth-C11), 140.83 (Ar-Cipso), 130.49 (Xanth-C10), 122.23 (Ar-
CH′), 121.90 (Ar-CH″), 108.68 (Xanth-C3H), 106.52 (Xanth-C1H),
70.27 (THF-C2,5H2), 35.57 (Xanth-C9Me2), 35.41 (CMe2′), 35.03
1
(CMe3), 34.52 (p-CHMe2), 34.02 (d, JY,H 51.12 Hz, YCH2SiMe3),
31.91 (CMe3), 28.38 (B-o-CHMe2), 27.90 (A-o-CHMe2), 27.17 (A-o-
CHMe2″), 26.06 (B-o-CHMe2″), 25.36 (B-o-CHMe2′), 25.14 (CMe2″),
24.90 (THF-C3,4H2), 24.60 (A-o-CHMe2′), 24.49 (p-CHMe2), 4.09
(YCH2SiMe3). Anal. Calcd for C67H111N2O3YSi3: C, 69.02; H, 9.59; N,
2.40. Found: C, 68.61; H, 9.40; N, 2.82.
[(XN2)Y(CH2SiMe2Ph)(THF)]·O(SiMe3)2 (1b·O(SiMe3)2). A sol-
ution of H2XN2 (0.100 g, 0.132 mmol) in benzene (7 mL) was added
to [Y(CH2SiMe2Ph)3(THF)2] (0.098 g, 0.145 mmol), and the
solution was stirred for 14 days in the glovebox at 24 °C. Solvent
was removed in vacuo, and the dark yellow solid was recrystallized
from O(SiMe3)2 at −30 °C, yielding 1b·O(SiMe3)2 as a yellow-brown
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solid (0.079 g, 49%). H NMR (C6D6, 600 MHz): δ 7.84 (m, 2H,
4
YCH2SiMe2Ph), 7.22 (d, 2H, JH,H 1.68 Hz, Ar-H′), 7.20 (m, 3H,
YCH2SiMe2Ph), 7.13 (d, 2H, 4JH,H 1.68 Hz, Ar-H″), 6.82 (d, 2H, 4JH,H
2 Hz, Xanth-CH3), 6.23 (d, 2H, JH,H 2 Hz, Xanth-CH1), 4.13 (sept,
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2H, 3JH,H 7 Hz, A-o-CHMe2), 3.34 (sept, 2H, 3JH,H 7 Hz, B-o-CHMe2),
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2.80 (sept, 2H, JH,H 7 Hz, p-CHMe2), 2.66 (s, 4H, 1 equiv of THF-
H2XN2. 4,5-Dibromo-2,7-di-tert-butyl-9,9-dimethylxanthene (5.0 g,
10.41 mmol), NaOtBu (2.8 g, 29.14 mmol), Pd(OAc)2 (86.48 mg,
0.38 mmol), and DPEPhos (307.0 mg, 0.57 mmol) were dissolved in
toluene (100 mL) followed by the addition of 2,4,6-triisopropylaniline
(4.56 g, 20.8 mmol) via syringe. The reaction mixture was heated to
100 °C for 5 days, over which time a color change to chocolate brown
was observed. The reaction mixture was then quenched with water,
extracted into toluene (3 × 50 mL), dried over MgSO4, filtered, and
concentrated to approximately 10 mL. Recrystallization from hot
ethanol yielded H2XN2 as an off-white solid (4.76 g, 60%). To remove
excess moisture, the solid was stirred at room temperature with NaH
(452 mg, 18.84 mmol) in toluene (35 mL) for 24 h followed by
filtration, and concentration of the mother liquor yielded an off-white
solid, which was then dissolved in hexanes (20 mL), centrifuged to
remove a small amount of insoluble material, and evaporated to
dryness in vacuo to yield H2XN2 as an off-white solid (4.08 g, 52%
2,5H2), 1.89 (s, 3H, CMe2′), 1.73 (s, 3H, CMe2″), 1.41 (d, 6H, 3JH,H
7
3
Hz, A-o-CHMe2′), 1.34 (d, 6H, JH,H 7 Hz, A-o-CHMe2″), 1.28 (s,
3
18H, CMe3), 1.24 (d, 6H, JH,H 7 Hz, B-o-CHMe2′), 1.18 (d, 12H,
3JH,H 7 Hz, p-CHMe2), 1.00 (d, 6H, 3JH,H 7 Hz, B-o-CHMe2″), 0.84 (s,
4H, THF-C3,4H2), 0.57 (s, 6H, YCH2SiMe2Ph), − 0.07 (d, 2H, 2JY,H3.6
Hz, YCH2SiMe2Ph). 13C NMR (C6D6, 126 MHz): δ 147.79 (Xanth-
C2), 147.66 (A-o-CCHMe2), 147.20 (YCH2SiMe2Phipso), 146.19 (B-o-
CCHMe2), 145.40 (p-CCHMe2), 141.23 (Xanth-C11), 140.66 (Ar-
Cipso), 133.89 (YCH2SiMe2Ph), 130.46 (Xanth-C10), 127.50
(YCH2SiMe2Ph), 122.28 (Ar-CH′), 121.87 (Ar-CH″), 108.77
(Xanth-C1H), 106.72 (Xanth-C3H), 70.37 (THF-C2,5H2), 35.59
(CMe2′), 35.06 (Xanth-C9Me2), 34.87 (CMe3), 34.50 (p-CHMe2),
31.92 (CMe3), 30.25 (YCH2SiMe2Ph), 28.42 (B-o-CHMe2), 27.92 (A-
o-CHMe2), 27.19 (A-o-CHMe2″), 26.06 (B-o-CHMe2″), 25.41 (B-o-
CHMe2′), 25.20 (CMe2″), 24.91 (THF-C3,5H2), 24.57 (A-o-CHMe2′),
24.49 (p-CHMe2), 2.39 (YCH2SiMe2Ph). Anal. Calcd for
C72H113N2O3YSi3: C, 70.43; H, 9.27; N, 2.28. Found: C, 70.28; H,
8.99; N, 2.29.
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from starting materials). H NMR (C6D6, 600 MHz): δ 7.25 (s, 4H,
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Ar-H), 6.98 (d, 2H, JH,H 2 Hz, Xanth-CH1), 6.57 (d, 2H, JH,H 2 Hz,
Xanth-CH3), 5.90 (s, 2H, NH), 3.52 (sept, 4H, 3JH,H 7 Hz, o-CHMe2),
2.86 (sept, 2H, JH,H 7 Hz, p-CHMe2), 1.69 (s, 6H, CMe2), 1.264 (d,
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[(XN2)Y(μ-Me)2AlMe2(THF)]·O(SiMe3)2 (2·O(SiMe3)2). A solu-
tion of [(XN2)Y(CH2SiMe3)(THF)]·O(SiMe3)2 (1a·O(SiMe3)2) in
benzene (8 mL) was added to an excess of AlMe3 (0.05 g, 0.686
mmol), and the resulting solution was stirred at 24 °C for 1 h. Solvent
was removed in vacuo, and the yellow solid was recrystallized from
O(SiMe3)2 at −30 °C, yielding 2·O(SiMe3)2 as colorless crystals
(0.008 g, 20%). Note: by 1H NMR spectroscopy, compound 2 is
formed cleanly in the reaction between 1a and AlMe3; thus, the low
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12H, JH,H 7 Hz, o-CHMe2), 1.260 (d, 12H, JH,H 7 Hz, p-CHMe2),
1.23 (s, 18H, CMe3), 1.188 (d, 12H, JH,H 7 Hz, o-CHMe2) 13C NMR
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(C6D6, 126 MHz): δ 148.12 (p-CCHMe2), 147.78 (Ar-Cipso), 146.14
(Xanth-C2), 136.56 (Xanth-C11), 133.62 (o-CCHMe2), 129.27 (Xanth-
C10), 122.15 (Ar-CH), 111.68 (Xanth-C1H), 107.82 (Xanth-C3H),
35.07 (Xanth-C9 Me2), 34.81 (CMe3), 34.78 (p-CHMe2), 32.96
(CMe2), 31.71 (CMe3), 28.89 (o-CHMe2), 24.82 (o-CHMe2), 24.41
(p-CHMe2), 23.64 (o-CHMe2). Anal. Calcd for C53H76N2O: C, 84.06;
H, 10.12; N, 3.69. Found: C, 83.88; H, 10.45; N, 3.28.
1
yield is due to losses during recrystallization. H NMR (C6D6, 600
MHz): δ 7.23 (s, 4H, Ar-H), 6.81 (d, 2H, JH,H 2 Hz, Xanth-CH1),
4
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6.18 (d, 2H, JY,H 2 Hz, Xanth-CH3), 3.30 (sept, 4H, JH,H 7 Hz, o-
[(XN2)Y(CH2SiMe3)(THF)]·xO(SiMe3)2 (1a·xO(SiMe3)2; x = 1−
1.5). A solution of H2XN2 (0.150 g, 0.198 mmol) in benzene (5 mL)
was added to [Y(CH2SiMe3)3(THF)2] (0.107 g, 0.217 mmol), and the
solution was stirred for 24 h at 24 °C in the glovebox. Solvent was
removed in vacuo, and the yellow solid was recrystallized from
O(SiMe3)2 at −30 °C, yielding 1a·xO(SiMe3)2 as a yellow solid (0.120
g, 52%). The amount of O(SiMe3)2 in samples of 1a varied from 1.0 to
1.5; the sample used for elemental analysis contained 1.0 O(SiMe3)2
by NMR spectroscopy. 1H NMR (C6D6, 600 MHz): δ 7.27 (s, 2H, Ar-
CHMe2), 3.29 (m, 4H, THF-C2,5H2), 2.83 (sept, 2H, JH,H 7 Hz, p-
3
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CHMe2), 1.64 (s, 6H, CMe2), 1.30 (d, 12H, JH,H 7 Hz, A-o-CHMe2),
3
1.28 (d, 12H, JH,H 7 Hz, p-CHMe2), 1.23 (s, 18H, CMe3), 1.22 (d,
12H, JH,H 7 Hz, B-o-CHMe2), 0.93 (m, 4H, THF-C3,4H2), − 0.56 (d,
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12H, JY,H 3.8 Hz, AlMe4). 13C NMR (C6D6, 126 MHz): δ 148.06
2
(Xanth-C2), 146.84 (p-CCHMe2), 146.25 (Xanth-C4), 145.55 (o-
CCHMe2), 140.47 (Xanth-C11), 138.05 (Ar-Cipso), 129.81 (Xanth-C10),
122.89 (Ar-CH), 109.56 (Xanth-C3H), 108.78 (Xanth-C1H), 70.11
(THF-C2,5H2), 35.07 (CMe3), 35.04 (Xanth-C9Me2), 34.72 (p-
CHMe2), 31.79 (CMe3), 31.46 (CMe2), 29.43 (o-CHMe2), 27.28 (B-
o-CHMe2), 24.83 (THF-C3,4H2), 24.39 (p-CHMe2), 23.67 (A-o-
CHMe2), 3.22 (AlMe4). Anal. Calcd for C67H112N2O3YAlSi2: C,
69.03; H, 9.68; N, 2.41. Found: C, 68.51; H, 9.27; N, 2.53.
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H′), 7.14 (s, 2H, Ar-H″), 6.80 (d, 2H, JH,H 2 Hz, Xanth-CH1), 6.23
4
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(d, 2H, JH,H 2 Hz, Xanth-CH3), 4.28 (sept, 2H, JH,H 7 Hz, A-o-
3
CHMe2), 3.32 (sept, 2H, JH,H 7 Hz, B-o-CHMe2), 2.83 (sept, 2H,
3JH,H 7 Hz, para−CHMe2), 2.68 (s, 4H, THF-C2,5H2), 1.89 (s, 3H,
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CMe2′), 1.74 (s, 3H, CMe2″), 1.50 (d, 6H, JH,H 7 Hz, A-o-CHMe2′),
F
Organometallics XXXX, XXX, XXX−XXX