Organometallics
Article
LiPPh2(THF)2,28 LiNEt2, and LiN(H)Ar29 were prepared as described
in the literature or by modified methods.
(w), 767.15 (s), 748.33 (s), 700.2 (w), 649.51 (vw), 566.5 (w), 462.44
(vw). Anal. Calcd for C33H47GeN3 (558.4): C, 70.98; H, 8.48; N, 7.53.
Found: C, 69.85; H, 8.43; N, 7.49.
LGeCl (1). At −18 °C nBuLi (0.42 mL, 2.4 M, 1 mmol) was added
drop by drop to a solution of LH (0.310 g, 1 mmol) in Et2O (30 mL).
The mixture was stirred and warmed to room temperature. Additional
stirring for 12 h ensured complete formation of LLi. To a solution of
GeCl2·(dioxane) (0.232 g, 1 mmol) in Et2O (20 mL) was added the
above solution of LLi at −18 °C. After stirring for another 12 h at
room temperature, the formed precipitate was filtered off and the
solvent was removed in vacuo. The residue was treated upon quick
washing with cold n-hexane (2 × 2 mL) and then dried under vacuum
to afford a pale yellow solid (0.26 g, 62%). Mp: 107 °C. 1H NMR (500
MHz, C6D6): δ 7.35 (s, 1H, CHN), 7.00−7.12 (m, 3H, Ar), 6.76 (d,
J = 3.9 Hz, 1H, pyrrole CH), 6.26 (d, J = 3.9 Hz, 1H, pyrrole CH),
3.57 (septet, 1H, CHMe2), 3.12 (septet, 1H, CHMe2), 1.38 (s, 9H,
CMe3), 1.34 (d, J = 6.7 Hz, 3H, CHMe2), 1.12 (d, J = 6.9 Hz, 3H,
CHMe2), 1.00 (d, J = 6.9 Hz, 3H, CHMe2), 0.91 (d, J = 6.8 Hz, 3H,
CHMe2) ppm. 13C NMR (126 MHz, C6D6): δ 163.80 (Ar), 155.59
(CHN), 144.81, 143.06, 138.64, 135.39, 124.86, 123.45 (Ar),
122.54, 113.39 (pyrrole CH), 33.50 (CMe3), 30.66 (CMe3), 29.32,
28.03 (CHMe2), 25.77, 24.42, 24.18, 23.91 (CHMe2) ppm. IR (Nujol
LAlMe(Cl) (4). Method a. To a solution of in situ formed LLi
(1 mmol) in Et2O (30 mL) was added a solution of MeAlCl2 (1
mL, 1.0 M, 1 mmol) at −18 °C with continuous stirring. The
resulting mixture was slowly warmed to room temperature and
stirred for 12 h. After workup, the LiCl precipitate was filtered
off and the solvent was removed in vacuo to give an off-white
solid. From the concentrated n-hexane extract at −18 °C,
colorless crystals of 4 were obtained (0.22 g, 56%).
Method b. A mixture of LH (1.552 g, 5 mmol) and Me2AlCl (5 mL,
1.0 M, 5 mmol) in toluene was heated under reflux for 2 h. After
workup, the volatile components were removed under vacuum to
afford a crystalline solid. From the concentrated n-hexane extract,
crystals of 4 were afforded (1.76 g, 91%). Mp: 147 °C. 1H NMR (500
MHz, C6D6): δ 7.36 (s, 1H, CHN), 7.00−7.12 (m, 3H, Ar), 6.70 (d,
J = 3.8 Hz, 1H, pyrrole CH), 6.27 (d, J = 3.8 Hz, 1H, pyrrole CH),
3.58 (septet, 1H, CHMe2), 3.03 (septet, 1H, CHMe2), 1.36 (s, 9H,
CMe3), 1.34 (d, J = 6.5 Hz, 3H, CHMe2), 1.13 (d, J = 6.8 Hz, 3H,
CHMe2), 0.94 (d, J = 6.9 Hz, 3H, CHMe2), 0.88 (d, J = 6.8 Hz, 3H,
CHMe2), −0.13 (s, 3H, AlMe) ppm. 13C NMR (125 MHz, C6D6): δ
165.20 (Ar), 159.88 (CHN), 144.41, 143.20, 139.36, 133.96, 124.52
(Ar), 124.41 (pyrrole CH), 123.68 (Ar), 113.63 (pyrrole CH), 33.53
(CMe3), 30.58 (CMe3), 28.20, 28.11 (CHMe2), 25.54, 25.54, 23.35,
22.49 (CHMe2), −6.1 (br, AlMe) ppm. 27Al NMR (130 MHz, C6D6):
mull, cm−1): ν
̃
1627 (m), 1592.72 (m), 1574.94 (vs), 1266.51 (s),
1231.34 (s), 1179.89 (m), 1099.65 (m), 1056.1 (s), 960.49 (m), 933.1
(m), 896.02 (m), 801.85 (m), 769.76 (m), 754.01 (m), 650.69 (w),
570.18 (w). Anal. Calcd for C21H29ClGeN2 (417.6): C, 60.4; H, 7.00;
N, 6.71. Found: C, 61.72; H, 7.02; N, 6.58.
LGeOtBu (2). To a solution of LGeCl (0.418 g, 1 mmol) in Et2O
(30 mL) was added a suspension of KOtBu (0.112 g, 1 mmol) in Et2O
at −18 °C with rigorous stirring. The reaction mixture was slowly
warmed to room temperature and stirred for an additional 12 h. After
filtration, the solvent was removed in vacuo to leave an oily paste. The
residue was extracted with a small portion of n-hexane (5 mL) and
then dried again under vacuum overnight to afford a light yellow solid
(0.31 g, 68%). Mp: 78 °C. 1H NMR (500 MHz, C6D6): δ 7.51 (s, 1H,
CHN), 7.00−7.11 (m, 3H, Ar), 6.82 (d, J = 3.8 Hz, 1H, pyrrole
CH), 6.37 (d, J = 3.8 Hz, 1H, pyrrole CH), 3.53 (septet, 1H, CHMe2),
3.32 (septet, 1H, CHMe2), 1.48 (s, 9H, OCMe3), 1.34 (s, 9H, CMe3),
1.26 (d, J = 6.6 Hz, 3H, CHMe2), 1.19 (d, J = 6.9 Hz, 3H, CHMe2),
0.96 (d, J = 6.9 Hz, 3H, CHMe2), 0.88 (d, J = 6.8 Hz, 3H, CHMe2)
ppm. 13C NMR (126 MHz, C6D6): δ 161.59 (Ar), 154.82 (CHN),
144.02, 142.87, 140.52, 135.16, 123.66, 123.44 (Ar), 120.10, 112.14
(pyrrole CH), 70.74 (OCMe3), 33.53 (CMe3), 33.43 (CMe3), 30.46
(OCMe3), 28.71, 27.57 (CHMe2), 26.45, 24.52, 24.31, 23.56 (CHMe2)
δ 62.21 ppm. IR (Nujol mull, cm−1): ν
̃
1593.28 (m), 1573.69 (s),
1397.21 (w), 1326.38 (w), 1268.18 (m), 1233.47 (m), 1199.87 (w),
1186.91 (w), 1108.2 (vw), 1061.08 (s), 1031.65 (w), 933.8 (vw),
910.29 (w), 804.96 (w), 779.05 (w), 758.81 (w), 694.49 (vw), 664.08
(w), 572.57 (vw), 473.74 (w). Anal. Calcd for C22H32AlClN2 (386.9):
C, 68.29; H, 8.34; N, 7.24. Found: C, 67.94; H, 8.13; N, 7.08.
LH·AlMe2Cl (5). To a solution of LH (0.310 g, 1 mmol) in Et2O (5
mL) was added a solution of Me2AlCl (1 mL, 1.0 M, 1 mmol) at −18
°C with stirring. The resulting mixture was stored at −18 °C in a
freezer for 2 days. Colorless crystals of 5 were formed (0.19 g, 48%).
1
Mp: 146 °C. H NMR (500 MHz, C6D6): δ 8.49 (s, 1H, NH) 6.93−
7.07 (br, 3H, Ar), 6.98 (s, 1H, CHN), 6.19 (d, J = 3.8 Hz, 1H,
pyrrole CH), 5.56 (d, J = 3.8 Hz, 1H, pyrrole CH), 3.37 (septet, 2H,
CHMe2), 1.24 (d, J = 6.8 Hz, 6H, CHMe2), 0.68 (d, J = 6.7 Hz, 6H,
CHMe2), 0.62 (s, 9H, CMe3), −0.14 (s, 6H, AlMe) ppm. 13C NMR
(125 MHz, C6D6): δ 160.46, 156.45, 142.33 (Ar), 128.17 (CHN),
125.02 (Ar), 129.07, 107.58 (pyrrole CH), 31.30 (CMe3), 28.57
(CMe3), 28.24 (CHMe2), 23.61 (CHMe2), −8.07 (br, AlMe) ppm. 27Al
ppm. IR (Nujol mull, cm−1): ν
̃
1623.44 (vs), 1592.43 (vs), 1574.95
(vs), 1509.25 (vs), 1485.82 (vs), 1382.26 (vs), 1328.99 (s), 1298.8
(vs), 1268.21 (vs), 1232.98 (vs), 1181.89 (vs), 1106.02 (s), 1054.15
(vs), 1024.08 (s), 935.39 (vs), 892.73 (s), 858.22 (s), 800.73 (vs),
765.96 (vs), 754.34 (vs), 744.9 (s), 727.89 (s), 710.12 (s), 652.11 (s),
613.53 (vs), 567.46 (s). Anal. Calcd for C25H38GeN2O (455.2): C,
65.96; H, 8.41; N, 6.15. Found: C, 65.5; H, 8.51; N, 5.99.
NMR (130 MHz, C6D6): δ 61.48 ppm. IR (Nujol mull, cm−1): ν
̃
3424.18 (vw, NH), 1605.62 (w), 1584.16 (w), 1528.81 (w), 1258.68
(w), 1237.76 (w), 1186.47 (w), 1055.17 (w), 995.38 (w), 961.66 (w),
934.53 (vw), 895.05 (w), 807.85 (w), 785.41 (w), 675.19 (w), 569.17
(vw), 530.43 (vw), 470.15 (vw), 435.04 (vw). Anal. Calcd for
C23H36AlClN2 (403.0): C, 68.55; H, 9.00; N, 6.95. Found: C, 66.62;
H, 8.84; N, 6.85.
LGeN(H)Ar (3). The preparation of 3 is similar to that of 2 using
LiN(H)Ar (0.183 g, 1 mmol) and LGeCl (0.418 g, 1 mmol) as starting
materials. Compound 3 was obtained as pale yellow crystals from n-
LH·AlCl3 (5′). The preparation of 5′ was carried out as for 5 using
1
LH (0.310 g, 1 mmol) and AlCl3 (0.133 g, 1 mmol) to afford a
hexane extract at −18 °C (0.40 g, 71%). Mp: 91 °C. H NMR (500
1
colorless crystalline solid (0.21 g, 48%). Mp: 208 °C. H NMR (500
MHz, C6D6): δ 7.52 (s, 1H, CHN), 7.00−7.12 (m, 6H, Ar), 6.81 (d,
J = 3.8 Hz, 1H, pyrrole CH), 6.36 (d, J = 3.8 Hz, 1H, pyrrole CH),
4.70 (s, 1H, NH), 3.42 (septet, 1H, CHMe2), 3.31 (septet, 1H,
CHMe2), 3.11 (septet, 2H, CHMe2), 1.37 (s, 9H, CMe3), 1.31 (d, J =
6.8 Hz, 3H, CHMe2), 1.19 (d, J = 6.8 Hz, 6H, CHMe2), 1.09 (d, J = 6.9
Hz, 3H, CHMe2), 1.01 (d, J = 6.7 Hz, 6H, CHMe2), 0.94 (d, J = 6.8
Hz, 3H, CHMe2), 0.92 (d, J = 6.8 Hz, 3H, CHMe2) ppm. 13C NMR
(126 MHz, C6D6): δ 161.62 (Ar), 154.39 (CHN), 144.03, 143.37,
143.07, 140.51, 135.06, 134.84, 124.26, 123.43, 123.37 (Ar), 120.75
(pyrrole CH), 118.08 (Ar), 112.57 (pyrrole CH), 33.30 (CMe3), 30.99
(CMe3), 29.23 (CHMe2), 29.02, 28.54 (CHMe2), 24.50, 23.09
(CHMe2), 26.03, 24.74, 23.41, 23.41 (CHMe2) ppm. IR (Nujol
MHz, C6D6): δ 8.42 (s, 1H, NH), 6.96−7.06 (br, 3H, Ar), 6.98 (s, 1H,
CHN), 6.17 (m, 1H, pyrrole CH), 5.55 (m, 1H, pyrrole CH), 3.41
(septet, 2H, CHMe2), 1.32 (d, J = 6.8 Hz, 6H, CHMe2), 0.67 (d, J =
6.8 Hz, 6H, CHMe2), 0.59 (s, 9H, CMe3) ppm. 13C NMR (125 MHz,
C6D6): δ 157.75, 156.79, 143.60 (Ar), 129.33 (CHN), 125.43 (Ar),
132.59, 109.26 (pyrrole CH), 31.53 (CMe3), 28.57 (CHMe2), 28.33
(CMe3), 23.76, 23.56 (CHMe2) ppm. 27Al NMR (130 MHz, C6D6): δ
61.79 ppm. IR (Nujol mull, cm−1): ν
̃
3361.64 (m, NH), 1600.64 (s),
1584.41 (s), 1417.07 (s), 1405.08 (s), 1262.97 (s), 1206.68 (m),
1098.26 (w), 1067.21 (m), 1028.68 (w), 988.36 (m), 963.98 (m),
915.61 (s), 819.21 (w), 804.64 (m), 796.15 (s), 781.73 (m), 695.25
(w), 653.83 (w), 549.95 (m), 530.04 (m), 495.93 (m), 438.12 (m),
417.52 (m). Anal. Calcd for C21H30AlCl3N2 (443.8): C, 56.83; H, 6.81;
N, 6.31. Found: C, 57.01; H, 6.72; N, 6.45. Crystals of 5′ suitable for
single-crystal X-ray analysis were grown from Et2O solution.
mull, cm−1): ν
̃
3399.42 (vw, −NH), 1593.51 (s), 1575.52 (vs),
1509.74 (m), 1335.28 (s), 1268.37 (s), 1231.75 (s), 1203.47 (m),
1178.45 (m), 1153.71 (m), 1108.15 (m), 1054.2 (vs), 1023.05 (m),
961.47 (w), 932.31 (m), 884.94 (m), 842.97 (m), 801.69 (m), 784.99
1962
dx.doi.org/10.1021/om201252k | Organometallics 2012, 31, 1958−1964