Isolation and chemistry of aluminum compounds containing (S)-3,3′-bis(triphenylsilyl)-1,1′-bi-2,2′-naphthoxide ligands

Article abstract of DOI:10.1021/om030011b

The reaction of the resolved, bulky binol (S)-3,3′-bis(triphenylsilyl)-2,2′-dihydroxy-1,1′-binaphthyl, (S)-H₂O₂C₂₀H₁₀ {SiPh₃}₂-3,3′ (1), with a variety of alkyl and amide compounds has been investigated. Reaction of 1 with [Al₂Me₆] initially proceeds only in a 1:1 ratio to produce dinuclear [Al₂(O₂C₂₀H₁₀{SiPh₃} ₂-3,3′)(CH₃)₄], (S)-2. Compound 2 contains a [Al(μ-C)(μ-O)] core, Al-Al = 2.739(2) A, with the binaphthoxide ligand oxygen atoms occupying terminal and bridging positions. In the presence of pyridine, 2 reacts further with 1 to produce [Al(O₂C₂₀H₁₀{SiPh₃}₂- 3,3′)(CH₃)(py)], (S)-4. The ethyl analogue of 4, [Al(O₂C₂₀H₁₀{SiPh₃}₂- 3,3′)(CH₃)(py)], (S)-5, was obtained from [Et₂AlCl]. Both 4 and 5 were shown to adopt tetrahedral geometries in the solid state with O-Al-O angles of ～ 107°. Reaction of [LiAl-(NMe₂)₄] with 1 produced a dinuclear compound, [LiAl(O₂C₂₀H₁₀{SiPh₃}₂-3, 3′)(NHMe₂)- (NMe₂)₂], (S)-6, containing a terminal and bridging amino group. The lithium-bound HNMe₂ ligand could be substituted by pyridine to produce [LiAl(O₂C₂₀H₁₀{SiPh₃}₂-3, 3′) (NC₆H₅)-(NMe₂)₂], (S)-7. In the solid state the formally three-coordinated lithium atoms in 6 and 7 are pyramidalized. The sum of the three angles for the LiN₂O core is 305° and 322° for 6 and 7, respectively. This is due to an interaction of the lithium with one arene ring of an SiPh₃ group. In 6 the carbon atoms involved are an ipso- and ortho-carbon, while for 7 the ortho- and meta-carbon atoms of a Ph-Si ring are in close contact.

Full text of DOI:10.1021/om030011b

2318
Organometallics 2003, 22, 2318-2324
Isola tion a n d Ch em istr y of Alu m in u m Com p ou n d s
Con ta in in g
(S)-3,3′-Bis(tr ip h en ylsilyl)-1,1′-bi-2,2′-n a p h th oxid e
Liga n d s
Au J i Ru Son, Matthew G. Thorn, Phillip E. Fanwick, and Ian P. Rothwell*
Department of Chemistry, Purdue University, 560 Oval Drive,
West Lafayette, Indiana 47907-2038
Received J anuary 7, 2003
The reaction of the resolved, bulky binol (S)-3,3′-bis(triphenylsilyl)-2,2′-dihydroxy-1,1′-
binaphthyl, (S)-H2O2C20H10{SiPh3}2-3,3′ (1), with a variety of alkyl and amide compounds
has been investigated. Reaction of 1 with [Al2Me6] initially proceeds only in a 1:1 ratio to
produce dinuclear [Al2(O2C20H10{SiPh3}2-3,3′)(CH3)4], (S)-2. Compound 2 contains a [Al(µ-
C)(µ-O)] core, Al-Al ) 2.739(2) Å, with the binaphthoxide ligand oxygen atoms occupying
terminal and bridging positions. In the presence of pyridine, 2 reacts further with 1 to produce
[Al(O2C20H10{SiPh3}2-3,3′)(CH3)(py)], (S)-4. The ethyl analogue of 4, [Al(O2C20H10{SiPh3}2-
3,3′)(CH3)(py)], (S)-5, was obtained from [Et2AlCl]. Both 4 and 5 were shown to adopt
tetrahedral geometries in the solid state with O-Al-O angles of ∼107°. Reaction of [LiAl-
(NMe2)4] with 1 produced a dinuclear compound, [LiAl(O2C20H10{SiPh3}2-3,3′)(NHMe2)-
(NMe2)2], (S)-6, containing a terminal and bridging amido group. The lithium-bound HNMe2
ligand could be substituted by pyridine to produce [LiAl(O2C20H10{SiPh3}2-3,3′)(NC6H5)-
(NMe2)2], (S)-7. In the solid state the formally three-coordinated lithium atoms in 6 and 7
are pyramidalized. The sum of the three angles for the LiN2O core is 305° and 322° for 6
and 7, respectively. This is due to an interaction of the lithium with one arene ring of an
SiPh3 group. In 6 the carbon atoms involved are an ipso- and ortho-carbon, while for 7 the
ortho- and meta-carbon atoms of a Ph-Si ring are in close contact.
In tr od u ction
easily obtained by adding the corresponding phenol to
AlMe3 and can be generated “in situ” for use. Significant
structural and chemical studies have also been reported
from the Barron group.9 A continuing challenge centers
on the development of chiral analogues for the synthesis
of optically pure compounds.10 A series of aluminum
reagents containing C2-symmetric, chiral aryloxides
were also synthesized and have been applied to asym-
metric Claisen rearrangements, 2 aldol reactions,11 and
aldehyde alkylations. Over the years many studies have
also dealt with the utilization of 2,2′-dihydroxy-1,1′-
binaphthyl ligands (BINOLS) in conjunction with alu-
minum reagents. Despite this extensive literature and
demonstrated utility, there are still few structural
studies of isolated binaphthoxide derivatives of alumi-
num.12 An extensive study of “Noyori’s reagent” did lead
to the structures of a number of LiAl binaphthoxide
compounds.13 As an extension of our work with early
transition metal aryloxide compounds, we have begun
to study resolved 3,3′-disubstituted-1,1′-bi-2,2′-naph-
thoxide compounds of these metals. This work is being
The application of aluminum reagents has made some
significant contributions to organic synthesis. Besides
their application as Lewis acids, aluminum compounds
have also been important as reducing and alkylating
agents.1 In all three areas the reactivity of aluminum
reagents can be modified by the addition of suitable
oxygen donor (typically alkoxide or aryloxide) ligation
into the metal coordination sphere. More recently the
use of bulky aryloxide ligands attached to aluminum to
generate monomeric, “designer” Lewis acid catalysts has
been pioneered by Yamamoto and co-workers.2,3 Impor-
tant examples include the compounds [Al(Me)(OC6H2-
But -2,6-X-4)2] (X ) Me, acronym “MAD”,4,5 and X ) Br,
2
“MABR”6), [Al(Me)(OC6H3Ph2-2,6)2] (“MAPH”7), and [Al-
(OC6H3Ph2-2,6)3] (“ATPH”8). These compounds are all
* Corresponding author. E-mail: rothwell@purdue.edu.
(1) Ooi, T.; Maruoka, K. Lewis Acids Org. Synth. 2000, 1, 191.
(2) Bradley, D. C.; Mehrotra, R. C.; Rothwell, I. P.; Singh, A. Alkoxo
and Aryloxo Derivatives of Metals; Academic Press: London, 2001.
(3) Saito, S.; Yamamoto, H. J . Chem. Soc., Chem. Commun. 1997,
1585.
(4) Maruoka, K.; Itoh, T.; Sakurai, M.; Nonoshita, K.; Yamamoto,
H. J . Am. Chem. Soc. 1988, 110, 3588.
(5) Power, M. B.; Bott, S. G., Atwood, J . L.; Barron, A. R. J . Am.
Chem. Soc. 1990, 112, 3446.
(6) Maruoka, K.; Ooi, T.; Yamamoto, H. J . Am. Chem. Soc. 1989,
111, 6431.
(7) Maruoka, K.; Conception, A. B.; Murase, N.; Oishi, M.; Hirayama,
N.; Yamamoto, H. J . Am. Chem. Soc. 1993, 115, 3943.
(8) Maruoka, K.; Imoto, H.; Saito, S.; Yamamoto, H. J . Am. Chem.
Soc. 1994, 116, 4131.
(9) Healy, M. D.; Power, M. B.; Barron, A. R. Coord. Chem. Rev.
1994, 130, 63.
(10) Wulff, W. D. Lewis Acids Org. Synth. 2000, 1, 283.
(11) Saito, S.; Hatanaka, K.; Kano, T.; Yamamoto, H. Angew. Chem.,
Int. Ed. 1998, 37, 3378.
(12) (a) Arai, T.; Sasai, H.; Yamaguchi, K. C.; Shibasaki, M. J . Am.
Chem. Soc. 1998, 120, 441. (b) Arai, T.; Sasai, H.; Aoe, K.; Okamura,
K.; Date, T.; Shibasaki, M. Angew. Chem., Int. Ed. Engl. 1996, 35, 104.
(13) Noth, H.; Schlegel, A.; Suter, M. J . Organomet. Chem. 2001,
621, 231.
10.1021/om030011b CCC: $25.00 © 2003 American Chemical Society
Publication on Web 04/29/2003

Aluminum Compounds Containing Naphthoxide
Organometallics, Vol. 22, No. 11, 2003 2319
Sch em e 1
Ta ble 1. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for [Al2(O2C20H10{SiP h 3}2-3,3′)(CH3)4], (S)-2
extended to cover a variety of chiral, main group
derivatives of this ligand set. Recent publications have
dealt with germanium compounds.14 In this paper we
report on the synthesis and structures of a series of
aluminum compounds containing the bulky (S)-3,3′-bis-
(triphenylsilyl)-1,1′-bi-2,2′-naphthoxide ligand, 1.
Al(1)-O(2)
Al(2)-O(1)
Al(1)-C(2)
Al(2)-C(2)
Al(1)-Al(2)
1.748(3)
1.854(3)
2.064(5)
2.175(5)
2.739(2)
Al(1)-O(1)
Al(1)-C(1)
Al(2)-C(4)
Al(2)-C(3)
1.857(3)
1.926(4)
1.940(5)
1.986(5)
O(2)-Al(1)-C(1)
O(2)-Al(1)-C(2)
C(1)-Al(1)-C(2)
O(1)-Al(2)-C(3)
O(1)-Al(2)-C(2)
C(3)-Al(2)-C(2)
Al(1)-O(1)-C(11)
Al(1)-C(2)-Al(2)
114.7(2)
108.5(2)
114.1(2)
114.3(2)
89.8(2)
98.7(2)
118.8(2)
80.5(2)
O(2)-Al(1)-O(1)
O(1)-Al(1)-C(1)
O(1)-Al(1)-C(2)
O(1)-Al(2)-C(4)
C(4)-Al(2)-C(3)
C(4)-Al(2)-C(2)
Al(2)-O(1)-C(11)
Al(2)-O(1)-Al(1)
105.8(1)
118.3(2)
93.2(2)
112.8(2)
123.6(2)
110.7(2)
135.6(2)
95.1(1)
Resu lts a n d Discu ssion
Syn th esis a n d Ch a r a cter iza tion of Meth yl Com -
p ou n d s. Reaction of a toluene solution of [Al2Me6] with
(S)-H2O2C20H10{SiPh3}2-3,3′, 1 (1 binol per 2Al), leads
to the formation of a single new organometallic product,
2 (Scheme 1). Compound 2 does not react further with
1 under ambient conditions. In fact when a solution of
2 and excess 1 is heated at 100 °C for several hours in
C6D6, very little noticeable change (as determined by
NMR) is observed. The solid state structure of 2 (Figure
1, Table 1) shows the presence of an edge-shared, bis-
tetrahedral structure related to that of the [Al2Me6]
substrate. The binol ligand has two protonated methyl
groups and occupies one terminal and one bridging
position. Hence the two tetrahedral aluminum atoms
in 2 have different coordination environments. In con-
trast the addition of monophenols (1 HOAr per Al) to
[Al2Me6] leads to the more symmetric structural motif
with both oxygen atoms bridging and the four remaining
methyl groups being terminal. This is highlighted by
the reaction with 2,6-diphenylphenol, which leads to
compound 3 (Scheme 1), which we have structurally
characterized (Figure 2, Table 2). Compound 3 has been
used as a Lewis acid catalyst/reagent in a number of
organic synthesis applications.15 A ubiquitous stoichi-
ometry, [R2M(µ2-OAr)]2, is well known for all of the
F igu r e 1. Molecular structure of [Al2(O2C20H10{SiPh3}2-
3,3′)(CH3)4], (S)-2.
group 13 (M ) Al, Ga, In, Tl) metals,2 although the
metal coordination number varies from 4 with simple
aryloxides16 to 5 for chelating ligands.17 The only other
structurally characterized compound related to 2 con-
taining a [Al(µ-R)(µ-OX)Al] core is that reported by Scott
et al.18 This also contains a chelating bis(aryloxide)
ligand, although a pair of such units are linked by an
anthracene spacer, resulting in
methanediyl-tetraphenoxide ligand.
a 1,8-anthracene-
(15) (a) Maruoka, K.; Concepcion, A. B.; Murase, N.; Oishi, M.;
Hirayama, N.; Yamamoto, H. J . Am. Chem. Soc. 1993, 115, 3943. (b)
Denmark, S. E.; Cottell, J . S. J . Org. Chem. 2001, 66, 4276. (c)
Denmark, S. E.; Seierstad, M. S. J . Org. Chem. 1999, 64, 1610.
(14) Weinert, C. S.; Fanwick, P. E.; Rothwell, I. P. J . Chem. Soc.,
Dalton Trans. 2002, 2948.

2320 Organometallics, Vol. 22, No. 11, 2003
Son et al.
F igu r e 3. Molecular structure of [Al(O2C20H10{SiPh3}2-
3,3′)(CH3)(NC5H5)], (S)-4.
Ta ble 3. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for [Al(O2C20H10{SiP h 3}2-3,3′)(CH3)(p y)], (S)-4
Al-O(2)
Al-C(4)
1.75(2)
1.94(2)
Al-O(1)
1.76(1)
1.98(2)
F igu r e 2. Molecular structure of [Al2(µ-OC6H3Ph2-2,6)2-
(CH3)4], 3.
Al-N(31)
O(2)-Al-O(1)
O(1)-Al-C(4)
O(1)-Al-N(31)
C(11)-O(1)-Al
C(36)-N(31)-Al
106.83(7)
115.36(9)
105.25(7)
113.8(1)
121.5(2)
O(2)-Al-C(4)
O(2)-Al-N(31)
C(4)-Al-N(31)
C(21)-O(2)-Al
C(32)-N(31)-Al
119.63(9)
102.39(7)
105.6(1)
123.5(1)
121.3(2)
Ta ble 2. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for [Al2(µ-OC6H3P h 2-2,6)2(CH3)4], 3
Al-O(1)
Al-Al′
1.879(1)
2.898(2)
Al-C(1)
1.935(2)
Sch em e 2
C(1)-Al-C(1)′
Al-O(1)-Al′
116.9(2)
100.90(8)
O(1)-Al-O(1)′
79.10(8)
The Al-Al distances in [Al2Me6] have been reported
as 2.600(4)19 and 2.606(2) Å,20 whereas a neutron study
of [Al2(CD3)6] yielded 2.700(8) Å.21 This elongates to
2.739(2) Å in (S)-2 and 2.898(2) Å in 3 as µ-Me groups
are replaced by µ-O. The value in 2 compares favorably
to the distance of 2.757(2) Å found in the Scott com-
pound.18
Although the molecular structure of 2 contains four
nonequivalent methyl groups, only one signal is ob-
1
served in both the H and 13C NMR spectra even at low
temperatures (-60 °C, toluene-d8). Hence the molecules
are undergoing fast bridge/terminal exchange on the
NMR time scale. Again a similar situation was reported
for the 1,8-anthracenemethanediyl-tetraphenoxide com-
pound.18
(16) (a) Burke, P. J .; Gray, L. A.; Hayward, P. J . C.; Matthews, R.
W.; McPartiln, M.; Gillies, D. G. J . Organomet. Chem. 1977, 136, C7.
(b) Kumar, R.; Sierra, M. L.; Mel, V. S. J .de.; Oliver, J . P. Organome-
tallics 1990, 9, 484. (c) Firth, A. V.; Stewart, J . C.; Hoskin, A. J .;
Stephan, D. W. J . Organomet. Chem. 1999, 591, 185. (d) Giesbrecht,
G. R.; Gordon, J . C.; Brady, J . T.; Clark, D. L.; Keogh, D. W.;
Michalczyk, R.; Scott, B. L.; Watkin, J . G. Eur. J . Inorg. Chem. 2002,
723. (e) Saied, O.; Simard, M.; Wuest, J . D. Inorg. Chem. 1998, 37,
2620. (f) Hendershot, D. G.; Kumar, R.; Barber, M.; Oliver, J . P.
Organometallics 1991, 10, 1917. (g) Weber, M.; Browning, D. J .; Corker,
J . M.; Acta Crystallogr., Sect. C: Cryst. Struct. Commun. 1996, 52,
2439. (h) Saied, O.; Simard, M.; Wuest, J . D. Organometallics 1996,
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(j) Benn, R.; J anssen, E.; Lehmkuhl, H.; Rufinska, A.; Angermud, K.;
Betz, P.; Goddard, R.; Kruger, C. J . Organomet. Chem. 1991, 411, 37.
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Polyhedron 1994, 13, 2831.
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Carvalho, A. B.; Peppe, C. J . Organomet. Chem. 2001, 637, 631. (b)
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65, 782. (c) Dzugan, S. T.; Goedken, V. L. Inorg. Chim. Acta 1998, 154,
169. (d) Francis, J . A.; Bott, S. G.; Barron, A. R. J . Chem. Soc., Dalton
Trans. 1998, 3305. (e) Hendershot, D. G.; Barber, M.; Kumar, R.;
Oliver, J . P. Organometallics 1991, 10, 3302. (f) Alcock, N. W.; Gegnan,
I. A.; Roe, S. M.; Wallbridge, M. G. H. J . Organomet. Chem. 1991, 414,
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18, 2211.
Addition of pyridine to 2 leads, as determined by
NMR, to a mixture of products. We assume one of these
is the adduct [AlMe3(py)],22 while the other product was
identified as [Al(O2C20H10{SiPh3}2-3,3′)(CH3)(py)], (S)-
4. Compound (S)-4 was obtained in moderate yield by
the reaction of [Al2Me6] with 2 equiv of (S)-1 in the
presence of added pyridine (Scheme 1). The compound
adopts a pseudo-tetrahedral geometry about the Al
metal center in the solid state (Figure 3, Table 3). The
ethyl analogue of (S)-4, (S)-5, was also obtained via
reaction of a hydrocarbon solution of [EtAlCl2] with (S)-1
in the presence of pyridine (Scheme 2). The solid state
structures of (S)-4 and (S)-5 (Figure 4, Table 4) can be
compared with previously reported [MeAl(OC6H2Me3-
2,4,6)2(pyMe2-3,5)].23 The Al-O, Al-C, and Al-N(py)
distances are very similar in all three compounds.
However, the chelate rings in (S)-4 and (S)-5 lead to
(22) For structurally characterized pyridine adducts of trialkylalu-
minum see: (a) Lalama, M. S.; Kampf, J .; Dick, D. G.; Oliver, J . P.
Organometallics 1995, 14, 495. (b) Steiner, A.; Stalke, D. Organome-
tallics 1995, 14, 2422. (c) Wang, X, M.; Sun, H, S.; Wang, S. X.; Huang,
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1996, 52, 35.
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(21) McGrady, G. S.; Turner, J . F. C.; Ibberson, R. M.; Prager, M.
Organometallics 2000, 19, 4398.
(23) Healy, M. D.; Ziller, J . W.; Barron, A. R. J . Am. Chem. Soc.
1990, 112, 2949.

Aluminum Compounds Containing Naphthoxide
Organometallics, Vol. 22, No. 11, 2003 2321
(OPPh3)] has also been structurally characterized.27
What makes compounds (S)-6 and (S)-7 interesting is
the coordination environment about the lithium atoms.
In each case they are bound to a bridging binaphthoxide
oxygen, a bridging NMe2 nitrogen, and the nitrogen of
a terminal dimethylamine or pyridine ligand (Figures
5 and 6). The formally three-coordinate Li atom is
severely pyramidalized. The sum of the three angles for
the LiN2O core is 305° and 322° for (S)-6 and (S)-7,
respectively. The coordination environment about the
electron-deficient Li atom is completed by an interaction
with a phenyl ring of a Ph3Si group. This type of
interaction is absent in trigonal planar, three-coordinate
amine and pyridine adducts of lithium. Examples
include [(Pri HN)Li(µ-NPhCy)2Li(NHPri )] (Cy ) cyclo-
F igu r e 4. Molecular structure of [Al(O2C20H10{SiPh3}2-
3,3′)(C2H5)(NC5H5)], (S)-5.
2
2
Ta ble 4. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for [Al(O2C20H10{SiP h 3}2-3,3′)(C2H5)(p y)], (S)-5
hexenyl)28 and [(py)Li(µ-X)2Li(py)] (X ) NR2, OR).29 Of
particular relevance are the two mixed metal species
[(py)Li{µ-N(CH2Ph)2}2AlMe2]30 and [(py-4NMe2)Li{µ-
NMe(SiMe3)}2Al{NMe(SiMe3}2].31 In these last two
cases the three angles about Li sum to 347° and 359°,
respectively. There are many examples of π-arene
interactions with alkali metals.32 In the case of (S)-6
and (S)-7 there are two close contacts, 2.66-2.74 Å, with
an arene ring. In (S)-6 the carbon atoms involved are
an ipso- and ortho-carbon, while for (S)-7 the ortho- and
meta-carbon atoms of a Ph-Si ring are in close contact.
Al-O(2)
Al-C(1)
1.762(1)
1.944(2)
Al-O(1)
Al-N(31)
1.754(1)
1.987(2)
O(1)-Al-O(2)
O(1)-Al-C(1)
O(1)-Al-N(31)
Al-O(1)-C(11)
106.65(6) O(2)-Al-C(1)
122.36(8) O(2)-Al-N(31)
101.66(6) C(1)-Al-N(31)
113.28(7)
106.43(6)
104.76(7)
114.2(1)
121.2(1)
124.2(1)
Al-O(2)-C(21)
Al-N(31)-C(32)
Al-N(31)-C(36) 121.6(1)
Al-C(1)-C(2) 120.9(1)
C(36)-N(31)-C(32) 117.2(2)
O-Al-O angles of 107° compared to slightly larger
angles, 111°, in the bis(aryloxide). The methyl signal
in (S)-4 appears as a single resonance at δ -1.20 ppm
and -14.8 ppm in the 1H and 13C NMR spectra. The
ethyl group in (S)-5 appears as an ABX3 pattern due to
the presence of the chiral binaphthoxide ligand.
Exp er im en ta l Section
Gen er a l Rem a r k s. All manipulations were carried out
using standard syringe, Schlenk line, and glovebox tech-
niques.33 Benzene, toluene, ether, THF, and hexane were dried
over sodium benzophenone ketyl and were freshly distilled
before use. Pentane was dried over sodium ribbon. The 3,3′-
bis(triphenylsilyl)-2,2′-dihydroxy-1,1′-binaphthyl ligand (S)-
H2O2C20H10{SiPh3}2-3,3′ (1) was prepared according to litera-
ture procedures or slight variations thereof.34,35 1H NMR
spectra were recorded on a Varian INOVA-300 NMR spec-
Syn t h esis a n d Ch a r a ct er iza t ion of Dim et h yl-
a m id o Com p ou n d s. Metal dialkylamido compounds
have proven extremely useful substrates for the syn-
thesis of the corresponding alkoxides and aryloxides. In
fact we have found that there are many synthetic
advantages to the use of transition metal dimethyl-
amides for the sunthesis of binaphthoxide derivatives
over the use of more traditional halide starting materi-
als.24 The reaction of the compound [LiAl(NMe2)4] with
(S)-1 leads to a new mixed metal product containing (as
(25) (a) Ouzounis, K.; Riffel, H.; Hess, H.; Kohler, U.; Weidlein, J .
Z. Anorg. Allg. Chem. 1983, 504, 67. (b) Waggoner, K. M.; Olmstad,
M. M.; Power, P. P. Polyhedron 1990, 9, 257. (c) J anik, J . F.; Wella, R.
L.; Rheingold, A. L.; Guzei, I. A. Polyhedron 1998, 17, 4101. (d) J anik,
J . Fr.; Duesler, E. N.; Paine, R. T. J . Organomet. Chem. 1987, 323,
149. (e) J egier, J . A.; Luo, B.; Buss, C. E.; Gladfelter, W. L. Inorg. Chem.
2001, 40, 6017. (f) J anik, J . F.; Wells, R. L.; Coffer, J . L.; St. J ohn, J .
V.; Pennington, W. T.; Schimek, G. L. Chem. Mater. 1998, 10, 1613.
(g) Atwood, D. A.; Cowley, A. H.; J ones, R. A.; Mardones, M. A.; Atwood,
J . L.; Bott, S. G. J . Coord. Chem. 1992, 26, 285. (h) Neumayer, D. A.;
Cowlwy, A. H.; Decken, A.; J ones, R. A.; Lakhotia, V.; Ekerdt, J . G. J .
Am. Chem. Soc. 1995, 117, 5893.
1
determined by H NMR) both dimethylamido and di-
methylamino groups. The product was identified as
[LiAl(O2C20H10{SiPh3}2-3,3′)(NHMe2)(NMe2)2], (S)-6, by
X-ray diffraction studies. A directly related pyridine
compound (S)-7 was obtained by carrying out the
reaction in the presence of pyridine (Scheme 3), and this
was also structurally characterized.
(26) Bock, S.; Noth, H.; Rahm, P. Z. Naturforsch., Teil B 1988, 43,
53.
The molecular structures of (S)-6 and (S)-7 (Figures/
Tables 5 and 6) are of some interest. The aluminum
atom in both compounds is pseudo-tetrahedral. The
binaphthoxide ligand has one terminal oxygen atom,
while the other is bridging between aluminum and
lithium. In this respect the binding of the (S)-1 ligand
resembles that seen in (S)-2 above (Figure 1). The
aluminum atom is also bound to one terminal and one
bridging dimethylamido ligand. There are numerous
examples of dinuclear compounds of aluminum and the
other group 13 metals that contain terminal and bridg-
ing NMe2 groups.25 The compound [(THF)2Li(µ-NMe2)2-
Al(NMe2] has an Li-Al distance of 2.742 Å with
tetrahedral Li and Al.26 A simple adduct [Al(NMe2)3-
(27) Pinkas, J .; Wessel, H.; Yang, Y.; Monteron, M. L.; Noltemeyer,
M.; Froba, M.; Roesky, H. W. Inorg. Chem. 1998, 37, 2450.
(28) Wanat, R. A.; Collum, D. B.; Duyne, G.van; Clardy, J .; Depue,
R. T. J . Am. Chem. Soc. 1986, 108, 3415.
(29) (a) Clegg, W.; Liddle, S. T.; Henderson, K. W.; Keenan, F. E.;
Kennedy, A. R.; McKeown, A. E.; Mulvey, R. E. J . Organomet. Chem.
1999, 572, 283. (b) Clegg, W.; Henderson, K. W.; Mulvy, R. E.; O’Neil,
P. A. Chem. Commun. 1994, 769. (c) Forbes, G. C.; Kennedy, A. R.;
Mulvey, R. E.; Rodger, P. J . A.; Rowlings, R. B. J . Chem. Soc., Dalton
Trans. 2001, 1477. (d) Boyle, T. J .; Pedrotty, D. M.; Alam, T. M.; Vick,
S. C.; Rodriguez, M. A. Inorg. Chem. 2000, 39, 5133.
(30) Clegg, W.; Liddle, S. T.; Henderson, K. W.; Keenan, F. E.;
Kennedy, A. R.; McKeown A. E.; Mulvey, R. E. J . Organomet. Chem.
1999, 572, 283.
(31) Kim, J .; Bott, S. G.; Hofman, D. M. Inorg. Chem. 1998, 37, 3835.
(32) Ref to group 1 arene interactions.
(33) Shriver, D. F.; Drezdzon, M. A. The Manipulation of Air-
Sensitive Cmpounds, 2nd ed.; J ohn Wiley & Sons: New York, 1986.
(34) Buisman, G. J . H.; van der Veen, L. A.; Klootwijk, A.; de Lange,
W. G. J .; Kamer, P. C. J .; van Leeuwen, P. W. N. M.; Vogt, D.
Organometallics 1997, 16, 2929.
(35) Cox, P. J .; Wang, W.; Snieckus, V. Tetrahedron Lett. 1992, 33,
2253.
(24) (a) Thorn, M. T.; Moses, J . E.; Fanwick, P. E.; Rothwell, I. P. J .
Chem. Soc., Dalton Trans. 2000, 2659. (b) Weinert, C. S.; Fanwick, P.
E.; Rothwell, I. P. Organometallics 2002, 21, 484.

2322 Organometallics, Vol. 22, No. 11, 2003
Son et al.
Sch em e 3
Ta ble 5. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for
[LiAl(O2C20H10{SiP h 3}2-3,3′)(NMe2)2(NHMe2)], (S)-6
Al-O(2)
Al-N(3)
Al-Li
Li-N(3)
Li-C(111)
1.764(3)
1.864(5)
2.774(9)
2.13(1)
Al-O(1)
Al-N(4)
Li-O(1)
Li-N(9)
Li-C(116)
1.802(3)
1.790(5)
1.893(9)
2.11(1)
2.73(9)
2.66(1)
O(2)-Al-N(4)
N(4)-Al-O(1)
O(2)-Al-Li
106.9(2)
118.6(2)
122.8(2)
42.6(2)
105.0(4)
118.0(5)
137.9(4)
81.8(3)
O(2)-Al-O(1)
O(2)-Al-N(3)
N(4)-Al-Li
103.8(1)
116.5(2)
129.0(2)
50.0(2)
82.1(4)
89.2(4)
102.9(4)
111.8(4)
30.3(2)
122.0(4)
94.5(3)
O(1)-Al-Li
N(3)-Al-Li
O(1)-Li-N(9)
N(9)-Li-N(3)
N(9)-Li-C(116)
O(1)-Li-C(111)
N(3)-Li-C(111)
Al-Li-O(1)
O(1)-Li-N(3)
O(1)-Li-C(116)
N(3)-Li-C(116)
N(9)-Li-C(111)
C(116)-Li-C(111)
Al-Li-N(9)
130.1(4)
40.1(2)
42.2(2)
Al-Li-N(3)
Al-Li-C(111)
Al-Li-C(116)
106.2(3)
Ta ble 6. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for [LiAl(O2C20H10{SiP h 3}2-3,3′)(NMe2)2(p y)],
(S)-7
Al-O(2)
Al-N(3)
Al-Li
Li-N(4)
Li-C(232)
1.813(3)
1.790(4)
2.759(8)
2.103(9)
2.63(1)
Al-O(1)
1.766(3)
1.849(4)
1.923(8)
2.016(9)
2.738(9)
Al-N(4)
Li-O(2)
F igu r e 5. Molecular structure of [LiAl(O2C20H10{SiPh3}2-
3,3′)(NHMe2)(NMe2)2], (S)-6.
Li-N(911)
Li-C(233)
O(2)-Al-N(4)
N(4)-Al-O(1)
O(2)-Al-Li
92.5(2)
118.3(2)
43.97(2) N(4)-Al-Li
127.4(2)
116.2(4)
124.2(4)
O(2)-Al-O(1)
O(2)-Al-N(3)
102.9(1)
117.2(2)
49.6(2)
123.1(2)
82.1(4)
93.0(3)
107.0(4)
90.3(4)
123.9(3)
138.2(4)
92.4(3)
95.2(3)
O(1)-Al-Li
N(3)-Al-Li
O(2)-Li-N(911)
N(911)-Li-N(4)
O(2)-Li-N(4)
O(2)-Li-C(42)
N(4)-Li-C(232)
N(911)-Li-C(42)
C(42)-Li-C(233)
Al-Li-N(911)
Al-Li-C(232)
Al-O(2)-Li
N(911)-Li-C(232) 125.2(4)
O(2)-Li-C(233)
115.0(4)
Li-N(911)-C(911) 128.5(4)
Al-Li-O(2)
Al-Li-N(4)
Al-N(4)-Li
40.9(2)
42.1(2)
88.3(3)
trometer or a Bruker DRX-500 NMR spectrometer and were
referenced to residual protio solvent. 13C NMR spectra were
recorded on a Bruker DRX-500 NMR spectrometer at 125.7
MHz and were internally referenced to the solvent signal.
Syn th esis of [Al2(O2C20H10{SiP h 3}2-3,3′)(CH3)4], (S)-2. To
a 50 mL solvent seal round-bottom flask containing benzene
(30 mL) was added a toluene solution of AlMe3 (2.0 M, 1.1 mL,
2.2 mmol). One equivalent of (S)-1 (1.798 g 2.24 mmol)
dissolved in benzene (10 mL) was slowly added to the stirring
reaction mixture. This mixture was stirred for 1 h and
evaporated to dryness. The crude red solid was dissolved in a
minimal amount of toluene and carefully layered with hexane
to afford red crystals of product. Yield: 0.45 g (24%). Anal.
Calcd for Al2C60H52O2Si2: C, 78.74; H, 5.72. Found: C, 78.70;
H, 5.62. 1H NMR (C6D6): δ 8.31 (s, 2H, meta-H); 6.80-7.91
(aromatics); -1.21 (s, 12H, CH3). 13C NMR (C6D6, 25 °C):
157.16 (ipso-C); -7.84 (CH3).
F igu r e 6. Molecular structure of [LiAl(O2C20H10{SiPh3}2-
3,3′)(NC5H5)(NMe2)2], (S)-7.
Syn th esis of [Al(O2C20H10{SiP h 3}2-3,3′)(CH3)(p y)], (S)-
4. To a 50 mL solvent seal round-bottom flask containing
benzene (30 mL) was added a toluene solution of AlMe3 (2.0
M, 0.48 mL, 0.96 mmol). Two equivalents of (S)-1 (1.55 g 1.93
mmol) dissolved in benzene (10 mL) was slowly added to the
stirring reaction mixture. Pyridine (2.5 equiv, 0.195 mL, 2.4
mmol) was also added to the reaction mixture. This mixture
was stirred for 17 h and then evaporated to dryness. The crude
white solid was dissolved in a minimal amount of toluene and
carefully layered with hexane to afford white crystals of

Aluminum Compounds Containing Naphthoxide
Organometallics, Vol. 22, No. 11, 2003 2323
Ta ble 7. Cr ysta l Da ta a n d Da ta Collection P a r a m eter s
(S)-2
3
(S)-4
(S)-5
formula
fw
Al2C66H57O2Si2
992.32
Al2C40H38O2
604.71
AlC69H56NO2Si2
1014.37
AlC70H58NO2Si2
1028.40
space group
a, Å
b, Å
P21 (No. 4)
13.4646(3)
14.6264(4)
14.1823(4)
90
98.5360(10)
90
2762.1(2)
2
Ccca (No. 68)
15.2476(9)
19.486(2)
11.4194(12)
90
P212121 (No. 19)
11.9573(2)
17.3102(2)
26.4682(4)
90
90
90
5478.5(2)
4
1.230
150.
P212121 (No. 19)
12.10690(10)
17.35720(10)
26.2629(3)
90
90
90
5518.94(8)
4
1.238
150.
c, Å
R, deg
â, deg
γ, deg
V, Å
90
90
3392.8(10)
4
1.184
Z
F
calc, g cm-3
1.193
150.
temperature, K
203
radiation (wavelength)
R
Mo KR (0.71073Å)
0.048
Mo KR (0.71073Å)
0.045
Mo KR (0.71073Å)
0.044
Mo KR (0.71073Å)
0.039
Rw
0.114
0.103
0.092
0.086
(S)-6
(S)-7
formula
fw
space group
a, Å
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å
AlLiC62H59N3O2Si2
968.27
P212121 (No. 19)
12.9970(3)
18.2917(5)
22.4617(7)
90
90
AlLiC65H57N3O2Si2
1002.29
P212121 (No. 19)
13.3931(4)
18.2342(6)
22.4204(9)
90
90
90
90
5340.0(4)
4
1.204
5475.3(3)
4
1.216
Z
F
calc, g cm-3
temperature, K
radiation (wavelength)
R
Mo KR (0.71073Å)
0.053
Mo KR (0.71073Å)
0.055
Rw
0.131
0.124
product. Yield: 0.45 g (46%). Anal. Calcd for AlNC69H56O2Si2:
C, 81.69; H, 5.56; N, 1.38. Found: C, 81.68; H, 5.66; N, 1.37.
1H NMR(C6D6): δ 8.24 (s, 2H, meta-H); 6.91-7.79 (aromatics);
6.49 (t, meta H of coordinating pyridine); 5.92 (t, para-H of
coordinating pyridine); -1.20 (s, 3H, CH3). 13C NMR (C6D6,
25 °C): 161.69 (ipso-C); -14.75 (CH3).
P r epar ation of [LiAl(O2C20H10{SiP h 3}2-3,3′)(py)(NMe2)2],
(S)-7. A 50 mL solvent seal round-bottom flask containing
benzene (30 mL) was charged with LiAl(NMe2)4 (0.31 g, 1.43
mmol). One equivalent of (S)-1 (1.14 g, 1.43 mmol) dissolved
in benzene (10 mL) was slowly added to the stirring reaction
mixture. Then 2.5 equiv of pyridine (0.29 mL, 2.4 mmol) was
also added to the reaction mixture. This mixture was stirred
for 17 h and evaporated to dryness. The crude brown solid was
dissolved in a minimal amount of hot toluene to afford pale
brown crystals of product. Yield: 0.65 g (48%). Anal. Calcd
for AlLiC62H59O2N3Si2: C, 77.88; H, 5.73; N, 4.19. Found: C,
Syn th esis of [Al(O2C20H10{SiP h 3}2-3,3′)(C2H5)(p y)], (S)-
5. To a 50 mL solvent seal round-bottom flask containing
benzene (30 mL) was added a toluene solution of AlEtCl2 (1.8
M, 1.60 mL, 2.88 mmol). One equivalent of (S)-1 (1.55 g 1.93
mmol) dissolved in benzene (10 mL) was slowly added to the
stirred reaction mixture. Pyridine (3 equiv, 0.46 mL, 5.5 mmol)
was also added to the reaction mixture. This mixture was
stirred for 17 h and evaporated to dryness. The resulting crude
product was dissolved in a minimum of toluene and carefully
layered with hexane to afford transparent crystals of product.
Yield: 1.12 g (42%) Anal. Calcd for AlNC63H50O2Si2: C, 81.82;
1
75.22; H, 5.67; N, 3.20. H NMR (C6D6): δ 8.27 (s, 2H, meta-
H); 6.80-7.93 (aromatics); 6.68 (t, meta-H of coordinating
pyridine); 6.26 (t, para-H of coordinating pyridine); 2.076 (s,
NMe2); 2.016 (s, NMe2). 13C NMR (C6D6, 25 °C): 149.07 (ipso-
C); 41.56 (NMe2); 37.79 (NMe2).
X-r a y Da ta Collection a n d Red u ction . Crystal data and
data collection parameters are contained in Table 7. A suitable
crystal was mounted on a glass fiber in a random orientation
under a cold stream of dry nitrogen. Preliminary examination
and final data collection were performed with Mo KR radiation
(λ ) 0.71073 Å) on a Nonius Kappa CCD. Lorentz and
polarization corrections were applied to the data.36 An empiri-
cal absorption correction using SCALEPACK was applied.37
Intensities of equivalent reflections were averaged. The struc-
ture was solved using the structure solution program PATTY
in DIRDIF92.38 The remaining atoms were located in succeed-
ing difference Fourier syntheses. Hydrogen atoms were in-
cluded in the refinement but restrained to ride on the atom to
which they are bonded. The structure was refined in full-
1
H, 5.68; N, 1.36. Found: C, 81.17; H, 5.37; N, 1.58. H NMR
(C6D6): δ 8.22 (s, 2H, meta-H); 6.84-7.84 (aromatics); 6.61 (t,
meta-H of coordinating pyridine); 6.03 (t, para-H of coordinat-
ing pyridine); -0.59 (m, 2H, CH2); 0.67 (t, 3H, CH3). 13C NMR
(C6D6, 25 °C): 161.76 (ipso-C); 8.86 (CH2); -3.68 (CH3).
P r ep a r a tion of [LiAl(O2C20H10{SiP h 3}2-3,3′)(NHMe2)-
(NMe2)2], (S)-6. To a 50 mL solvent seal round-bottom flask
containing benzene (30 mL) was added LiAl(NMe2)4 (0.31 g,
1.43 mmol). One equivalent of (S)-1 (1.14 g, 1.43 mmol)
dissolved in benzene (10 mL) was slowly added to the stirring
reaction mixture. This mixture was stirred for 17 h and
evaporated to dryness. The crude yellow solid was dissolved
in a minumum of toluene and carefully layered with hexane
to afford pale yellow crystals of product. Yield: 0.61 g (44%).
Anal. Calcd for AlLiC62H59O2N3Si2: C, 76.90; H, 6.14; N, 4.34.
(36) McArdle, P. C. J . Appl. Crystallogr. 1996, 239, 306.
(37) Otwinowski, Z.; Minor, W. Methods Enzymol. 1996, 276.
(38) Beurskens, P. T.; Admirall, G.; Beuskens, G.; Bosman, W. P.;
Garcia-Granda, S.; Gould, R. O.; Smits, J . M. M.; Smykalla, C. The
DIRDIF92 Program System, Technical Report; Crystallography Labo-
ratory, University of Nijmegen: The Netherlands, 1992.
1
Found: C, 76.83; H, 6.17; N, 3.96. H NMR (C6D6): δ 8.32 (s,
2H, meta-H); 6.80-8.00 (aromatics); 2.066 (s, AlNMe2); 1.213
(br, NMe2); 1.070 (br, NHMe2); -1.211 (t, H, NMe2H). 13C NMR
(C6D6, 25 °C): 162.1 (ipso-C); 41.49 (NMe2); 37.24 (NMe2).

2324 Organometallics, Vol. 22, No. 11, 2003
Son et al.
matrix least-squares where the function minimized was
using SHELX-97.40 Crystallographic drawings were done using
the programs ORTEP.41
2
2
2
∑w(|Fo| - |Fc| )2 and the weight w is defined as w ) 1/[σ2(Fo
)
+ (0.0585P)2 + 1.4064P] where P ) (Fo + 2Fc2)/3. Scattering
factors were taken from the International Tables for Crystal-
lography.39 Refinement was performed on a AlphaServer 2100
2
Ack n ow led gm en t. We thank the National Science
Foundation (Grant CHE-0078405) for financial support
of this research.
(39) International Tables for Crystallography; Kluwer Academic
Publishers: Dordrecht, The Netherlands, 1992; Vol. C, Tables 4.2.6.8
and 6.1.1.4.
(40) Sheldrick, G. M. SHELXS97. A Program for Crystal Structure
Refinement; University of Gottingen: Germany, 1997.
(41) J ohnson, C. K. ORTEPII, Report ORNL-5138; Oak Ridge
National Laboratory: Oak Ridge, TN, 1976.
Su p p or tin g In for m a tion Ava ila ble: This material is
available free of charge via the Internet at http://pubs.acs.org.
OM030011B