5192 Organometallics, Vol. 16, No. 24, 1997
Coles et al.
Li[tBu C(NiP r )2] (3a ). This compound was prepared by the
procedure described for 2a , using 5.00 g of 1,3-diisopropylcar-
bodiimide (39.6 mmol) and 23.3 mL of BuLi (1.7 M solution
{tBu C(NSiMe3)2}AlCl2 (5c). A solution of 1,3-bis(trimeth-
ylsilyl)carbodiimide (1.0 g, 5.4 mmol) in Et2O (35 mL) was
cooled to 0 °C. tBuLi (3.2 mL of a 1.7 M solution in hexanes,
5.4 mmol) was added slowly by syringe. The resulting mixture
was allowed to warm to room temperature and was stirred
for 30 min. The mixture was cooled to -78 °C, and a solution
of AlCl3 (0.71 g, 5.4 mmol) in Et2O (15 mL) was added. The
resulting solution was allowed to warm to room temperature
over 5 h. After a further 16 h, the volatiles were removed and
the product was extracted from the LiCl with pentane. The
pentane extract was concentrated and cooled to -30 °C to
afford {tBuC(NSiMe3)2}AlCl2 as white crystals, which were
isolated by filtration (1.02 g, 56% based on AlCl3). 1H NMR
t
in pentane, 39.6 mmol). After 30 min, the solvent was removed
under vacuum, affording a yellow oily solid, which was dried
under vacuum (18 h, 23 °C) to give a pale yellow solid.
Trituration with hexane gave Li[tBuC(NiPr)2] as an off-white
3
powder (4.56 g, 61%). 1H NMR (THF-d8): δ 3.84 (sept, J HH
3
) 5.7, 2H, CHMe2), 1.13 (s, 9H, CMe3), 0.96 (d, J HH ) 6.1,
12H, CHMe2). 13C NMR (THF-d8): δ 168.5 (s, CCMe3), 46.6
(d, 1J CH ) 122.3, CHMe2), 39.4 (s, CMe3), 31.0 (q, 1J CH ) 116.1,
1
CHMe2), 26.3 (q, J CH ) 116.1, CMe3).
Li[tBu C(NCy)2] (3b). This compound was prepared by the
procedure described for 3a , using 5.00 g of 1,3-dicyclohexyl-
carbodiimide (24.2 mmol) and 14.3 mL of tBuLi (1.7 M solution
in pentane, 24.2 mmol). Trituration with hexane gave Li-
[tBuC(NCy)2] as a pale yellow powder (4.91 g, 75%). 1H NMR
(THF-d8): δ 3.50 (m, 2H, Cy), 1.81-0.93 (m, 20H, Cy), 1.10 (s,
9H, CMe3). 13C NMR (THF-d8): δ 168.3 (s, CCMe3), 55.9 (d,
(CD2Cl2): δ 1.33 (s, 9H, CMe3), 0.34 (s, 18H, SiMe3). 13C NMR
1
(CD2Cl2): δ 195.4 (s, CCMe3), 41.0 (s, CMe3), 29.5 (q, J CH
)
1
121.7, CMe3), 3.3 (q, J CH ) 113.9, SiMe3). Anal. Calcd for
11H27AlCl2N2Si2: C, 38.70; H, 7.97; N, 8.21. Found: C, 38.82;
C
H, 8.10; N, 8.17.
{tBu C(NiP r )2}AlMe2 (6a ). This compound was prepared
by the procedure described for 4a , using 0.25 mL of AlMe2Cl
(2.7 mmol) in 25 mL of Et2O and 0.50 g of Li[tBuC(NiPr)2] (2.6
mmol) in 30 mL of Et2O. The extract was evaporated to
dryness under vacuum, yielding {tBuC(NiPr)2}AlMe2 as a pale
yellow solid (0.57 g, 87%). Analytically pure samples of {tBuC-
(NiPr)2}AlMe2 were obtained by sublimation (50 °C, 0.005
1
1J CH ) 119.8, Cy-C1), 39.5 (s, CMe3), 37.7 (t, J CH ) 118.9,
1
Cy), 31.1 (q, J CH ) 117.7, CMe3), 28.2 (t, partially obscured,
1
Cy), 26.8 (t, J CH ) 119.4, Cy).
[Li(tBu CN){µ-N(SiMe3)2}]2 (3d ). This compound was
prepared by the procedure described for 3a , using 3.00 g of
1,3-bis(trimethylsilyl)carbodiimide (16.1 mmol) and 9.50 mL
3
mmHg). 1H NMR (CD2Cl2): δ 4.07 (sept, J HH ) 6.2, 2H,
t
of BuLi (1.7 M solution in pentane, 16.1 mmol). Recrystalli-
CHMe2), 1.38 (s, 9H, CMe3), 1.06 (d, 3J HH ) 6.1, 12H, CHMe2),
zation from pentane yielded [Li(tBuCN){µ-N(SiMe3)2}]2 as
white crystals (2.74 g, 68%). 1H NMR (THF-d8): δ 1.29 (s,
18H, CMe3), -0.11 (br s, 36H, SiMe3). 13C NMR (THF-d8): δ
-0.81 (s, 6H, AlMe2). 13C NMR (CD2Cl2): δ 178.4 (s, CCMe3),
1
1
45.8 (d, J CH ) 135.3, CHMe2), 40.0 (s, CMe3), 29.7 (q, J CH
)
127.0, CHMe2), 26.3 (q, 1J CH ) 125.5, CMe3), -9.06 (br q, 1J CH
) 105.4, AlMe2). Anal. Calcd for C13H29AlN2: C, 64.96; H,
12.16; N, 11.65. Found: C, 64.46; H, 11.90; N, 11.90.
1
125.8 (s, CtN), 28.7 (q, J CH ) 125.8, CMe3), 28.8 (s, CMe3),
1
6.1 (q, J CH ) 123.9, SiMe3).
{MeC(NiP r )2}AlCl2 (4a ). A solution of AlCl3 (1.80 g, 13.5
mmol) in Et2O (20 mL) at -78 °C was added dropwise to a
slurry of Li[MeC(NiPr)2] (2.00 g, 13.5 mmol) in Et2O (50 mL)
at -78 °C. The reaction mixture was allowed to warm to room
temperature and was stirred for 16 h, resulting in a slurry of
a white solid in a yellow solution. The volatiles were removed
under vacuum, the crude product was extracted with pentane,
and the extract was concentrated to dryness under vacuum.
Pure samples of {MeC(NiPr)2}AlCl2 were obtained by sublima-
tion (50 °C, 0.005 mmHg) (1.71 g, 52%). 1H NMR (CD2Cl2): δ
{tBu C(NCy)2}AlMe2 (6b). This compound was prepared
by the procedure described for 4a , using 0.71 mL of AlMe2Cl
(7.7 mmol) in 30 mL of Et2O and 2.0 g of Li[tBuC(NCy)2] (7.4
mmol) in 40 mL of Et2O. Concentration of the pentane extract
afforded {tBuC(NCy)2}AlMe2 (2.00 g, 83%) as large colorless
crystals, which were collected by filtration. 1H NMR
(CD2Cl2): δ 3.56 (m, 2H, Cy), 1.80-1.69 (m, 8H, Cy), 1.61-
1.57 (m, 2H, Cy), 1.36 (s, 9H, CMe3), 1.27-1.03 (m, 8H + 2H,
Cy), -0.83 (s, 6H, AlMe2). 13C NMR (CD2Cl2): δ 178.5 (s,
CCMe3), 54.2 (d, 1J CH ) 125.9, Cy-C1), 39.9 (s, CMe3), 37.3 (t,
3
3.56 (br sept, J HH ) 6.1, 2H, CHMe2), 2.09 (s, 3H, CMe), 1.14
1J CH ) 119.3, Cy), 29.7 (q, 1J CH ) 117.3, CMe3), 26.1 (t, 1J CH
)
(d, 3J HH ) 6.4, CHMe2). 13C NMR (CD2Cl2): δ 178.2 (s, CMe),
119.3, Cy), 26.0 (t, 1J CH ) 119.3, Cy), -9.1 (br q, 1J CH ) 103.9,
AlMe2). Anal. Calcd for C19H37AlN2: C, 71.20; H, 11.64; N,
8.74. Found: C, 71.18; H, 11.88; N, 8.73.
1
1
45.6 (d, J CH ) 134.9, CHMe2), 24.8 (q, J CH ) 127.1, CHMe2),
1
12.0 (q, J CH ) 129.7, CMe). Anal. Calcd for C8H17AlCl2N2:
C, 40.18; H, 7.17; N, 11.71. Found: C, 40.48; H, 7.49; N, 11.50.
{tBu C(NiP r )2}AlCl2 (5a ). This compound was prepared by
the procedure described for 4a , using 1.40 g of AlCl3 (10.5
mmol) and 2.00 g of Li[tBuC(NiPr)2] (10.5 mmol). The pentane
extract was concentrated and cooled to 0 °C to afford {tBuC-
(NiPr)2}AlCl2 as white crystals, which were collected by
{tBu C(NSiMe3)2}AlMe2 (6c). This compound was pre-
pared by the procedure described for 5c, using 2.00 mL of 1,3-
bis(trimethylsilyl)carbodiimide (10.7 mmol) in 50 mL of Et2O,
t
6.30 mL of BuLi (1.7 M solution in hexanes, 10.7 mmol) and
1.00 mL of AlMe2Cl (10.7 mmol) in 15 mL of Et2O. The yellow
pentane extract was taken to dryness under vacuum, yielding
a yellow waxy solid. Pure samples of {tBuC(NSiMe3)2}AlMe2
were obtained by sublimation (50 °C, 0.005 mmHg) (2.16 g,
67% based on AlMe2Cl). 1H NMR (CD2Cl2): δ 1.27 (s, 9H,
filtration (2.01 g, 68%). 1H NMR (CD2Cl2): δ 4.12 (br sept,
3
3J HH ) 5.9, 2H, CHMe2), 1.43 (s, 9H, CMe3), 1.18 (d, J HH
)
6.2, 12H, CHMe2). 13C NMR (CD2Cl2): δ 184.3 (s, CCMe3),
1
1
46.6 (d, J CH ) 135.7, CHMe2), 40.1 (s, CMe3), 29.2 (q, J CH
)
CMe3), 0.23 (s, 18H, SiMe3), -0.79 (s, 6H, AlMe2). 13C NMR
1
125.7, CMe3), 25.9 (q, J CH ) 124.1, CHMe2). Anal. Calcd for
11H23AlCl2N2: C, 46.98; H, 8.24; N, 9.96. Found: C, 46.84;
1
(CD2Cl2): δ 189.5 (s, CCMe3), 40.9 (s, CMe3), 29.6 (q, J CH
)
)
C
1
1
126.7, CMe3), 3.4 (q, J CH ) 109.3, SiMe3), -9.4 (br q, J CH
H, 8.12; N, 9.85.
{tBu C(NCy)2}AlCl2 (5b). This compound was prepared by
the procedure described for 4a , using 1.0 g of AlCl3 (7.4 mmol)
in 25 mL of Et2O and 2.0 g of Li[tBuC(NCy)2] (7.4 mmol) in 50
mL of Et2O. The product was extracted from the LiCl with
toluene. Concentration and cooling of the toluene extract to
0 °C afforded {tBuC(NCy)2}AlCl2 as colorless crystals, which
were collected by filtration (1.84 g, 69%). 1H NMR (CD2Cl2):
δ 3.62 (br m, 2H, Cy), 1.41 (s, 9H, CMe3), 1.91-1.71 (m, 4H,
Cy), 1.62 (m, 2H, Cy), 1.30-1.09 (m, 8H + 2H, Cy). 13C NMR
108.4, AlMe2). Anal. Calcd for C13H33AlSi2N2: C, 51.95; H,
11.07; N, 9.32. Found: C, 51.90; H, 11.29; N, 9.28.
{tBu C(NiP r )2}Al(CH 2P h )2 (7a ). A solution of {tBuC-
(NiPr)2}AlCl2 (0.50 g, 1.8 mmol) in Et2O (25 mL) was cooled
to -78 °C, and PhCH2MgCl (3.6 mL of a 1.0 M solution in
Et2O, 3.6 mmol) was added dropwise. The reaction mixture
was allowed to warm to room temperature and was stirred
for 15 h. The volatiles were removed under vacuum, and the
residue was extracted with pentane. The extract was evapo-
rated to dryness under vacuum, affording pure {tBuC(NiPr)2}-
Al(CH2Ph)2 as a viscous oil (0.55 g, 79%) that solidified after
1
(CD2Cl2): δ 184.4 (s, CCMe3), 54.6 (d, J CH ) 138.7, Cy-C1),
40.1 (s, CMe3), 36.9 (t, 1J CH ) 127.9, Cy), 29.3 (q, 1J CH ) 127.7,
1
1
3
CMe3), 25.7 (t, J CH ) 125.7, Cy), 25.6 (t, J CH ) 125.7, Cy).
Anal. Calcd for C17H31AlCl2N2: C, 56.51; H, 8.65; N, 7.75.
Found: C, 56.22; H, 8.70; N, 7.67.
storage at -40 °C. 1H NMR (CD2Cl2): δ 7.11 (t, J HH ) 7.6,
3
3
4H, m-Ph), 7.02 (d, J HH ) 6.9, 4H, o-Ph), 6.88 (t, J HH ) 7.3,
3
2H, p-Ph), 4.00 (sept, J HH ) 6.2, 2H, CHMe2), 1.75 (s, 4H,