Synthesis and reactions of aluminum sulfonamide alkyls and hydride

Article abstract of DOI:10.1021/om0611296

Aluminum compounds supported by a sulfonamide ligand are described. Reaction of AlEt₃ with 1 equiv of the sulfonyl amine ArNH(SO ₂-p-Tol) (Ar = 2,6-iPr₂C₆H₃, Toi = 4-MeC₆H₄) yielded the dimeric aluminum species [ArN(SO₂-p-Tol)AlEt₂]₂ (1), and reactions of AlEt₃ and AlH₃·NMe₃ with 2 equiv of ArNH(SO₂-p-Tol) yielded the aluminum bis(sulfonamide) species [ArN(SO₂-p-Tol)]₂AlEt (2) and [ArN(SO₂-p-Tol)] ₂AlH (3). The iodide species [ArN(SO₂-p-Tol)AlI ₂]₂ (4) and [ArN(SO₂-p-Tol)]₂AlI (5) were prepared by the reaction of 1 and 2 with iodine. Reaction of 3 with PhNH₂, HCCPh, and Ph₂CO yielded [ArN(SO ₂-p-Tol)]₂AlNHPh (6), [ArN(SO₂-p-Tol)] ₂AlCCPh (7), and [ArN(SO₂-p-Tol)]₂AlOCHPh ₂ (8). Treatment of 6 with BuⁿLi in n-hexane led to a ligand transfer reaction to give the dimeric lithium salt [ArN(SO ₂-p-Tol)Li(THF)₂]₂ (9). Compounds 1-4 and 7-9 have been characterized by X-ray single-crystal analysis, which disclosed that the aluminum mono(sulfonamide) compounds adopt a dimeric NSOAlNSOAl eight-membered-ring structure while the aluminum bis(sulfonamide) species are monomeric species with a five-coordinate aluminum center. Interestingly, the lithium salt 9 has a dimeric structure with an OSOLiOSOLi eight-membered-ring core. Compounds 3 and 8 are found to be active for lactide polymerization at high temperature.

Full text of DOI:10.1021/om0611296

Organometallics 2007, 26, 1947-1954
1947
Synthesis and Reactions of Aluminum Sulfonamide Alkyls and
Hydride
Jian Zhao, Haibin Song, and Chunming Cui*
State Key Laboratory of Elemento-Organic Chemistry, Nankai UniVersity, Tianjin 300071,
People’s Republic of China
ReceiVed December 14, 2006
Aluminum compounds supported by a sulfonamide ligand are described. Reaction of AlEt3 with 1
equiv of the sulfonyl amine ArNH(SO2-p-Tol) (Ar ) 2,6-iPr2C6H3, Tol ) 4-MeC6H4) yielded the dimeric
aluminum species [ArN(SO2-p-Tol)AlEt2]2 (1), and reactions of AlEt3 and AlH3‚NMe3 with 2 equiv of
ArNH(SO2-p-Tol) yielded the aluminum bis(sulfonamide) species [ArN(SO2-p-Tol)]2AlEt (2) and
[ArN(SO2-p-Tol)]2AlH (3). The iodide species [ArN(SO2-p-Tol)AlI2]2 (4) and [ArN(SO2-p-Tol)]2AlI (5)
were prepared by the reaction of 1 and 2 with iodine. Reaction of 3 with PhNH2, HCCPh, and Ph2CO
yielded [ArN(SO2-p-Tol)]2AlNHPh (6), [ArN(SO2-p-Tol)]2AlCCPh (7), and [ArN(SO2-p-Tol)]2AlOCHPh2
(8). Treatment of 6 with BunLi in n-hexane led to a ligand transfer reaction to give the dimeric lithium
salt [ArN(SO2-p-Tol)Li(THF)2]2 (9). Compounds 1-4 and 7-9 have been characterized by X-ray single-
crystal analysis, which disclosed that the aluminum mono(sulfonamide) compounds adopt a dimeric
NSOAlNSOAl eight-membered-ring structure while the aluminum bis(sulfonamide) species are monomeric
species with a five-coordinate aluminum center. Interestingly, the lithium salt 9 has a dimeric structure
with an OSOLiOSOLi eight-membered-ring core. Compounds 3 and 8 are found to be active for lactide
polymerization at high temperature.
Diels-Alder reactions.3 Several main-group elements,4 tita-
nium,5 and lanthanide complexes6 supported by disulfonamide
ligands have also been reported recently, and their structures
have been investigated by X-ray single-crystal analysis. In view
of the potential application of metal sulfonamide complexes in
catalytic applications, we are interested in exploring the
coordination behavior of this ligand family, since the corre-
sponding structural data are still very limited. Herein we report
on the synthesis and structures of aluminum and lithium
complexes incorporating the bulky sulfonamide ligand [ArN(SO2-
p-Tol)]- (Ar ) 2,6-Pri2C6H3, Tol ) toluene)7 and the subsequent
reaction of the aluminum bis(sulfonamide) hydride with PhNH2,
Ph2CO, and HCCPh.
Introduction
Aluminum complexes supported by monoanionic bidentate
ligands have been extensively investigated recently, since they
are excellent precursors for the generation of well-defined
cationic alkyls and low-valent aluminum species.1 The key
features of these ligands include electron delocalization in the
ligand backbone to form chelating complexes and tunable
electronic and steric properties by modification of substituents
on the ligand backbone. Monoanionic sulfonamide ligands are
also potential bidentate ligands, since the electron may be
delocalized over oxygen, sulfur, and nitrogen atoms. In addition,
because of the electron-withdrawing nature of sulfonyl groups,
the derivatives of their amides are more acidic, similar to the
case for phenols. As a result, metal sulfonamide complexes may
display enhanced Lewis acidity compared to the normal amide
complexes. In recent years, there has been growing interest in
using chiral disulfonamide ligands as auxiliaries for the prepara-
tion of metal complexes as catalysts for organic transformations.2
The first well-defined disulfonamide aluminum complex was
reported in 1992 by Corey and co-workers and has been
successfully applied as a catalyst for high enantioselective
Results and Discussion
Synthesis of Aluminum Sulfonamide Alkyls and Hydride.
Reaction of the bulky sulfonamide ligand ArNH(SO2-p-Tol)
with 1 equiv of AlEt3 in toluene at room temperature yielded
(LAlEt2)2 (1; L ) [ArN(SO2-p-Tol)]-) (Scheme 1). The ethane
and hydrogen elimination reactions of AlEt3 and AlH3‚NMe3
with 2 equiv of ArNH(SO2-p-Tol) afforded the aluminum ethyl
complex L2AlEt (2) and the hydride L2AlH (3), respectively.
Alternatively, 2 can be also prepared quantitatively by the
* To whom correspondence should be addressed. E-mail: cmcui@
nankai.edu.cn.
(1) For leading references, see: (a) Coles, M. P.; Jordan, R. F. J. Am.
Chem. Soc. 1997, 119, 8125. (b) Coles, M. P.; Swenson, D. C.; Jordan, R.
F.; Young, V. G., Jr. Organometallics 1997, 16, 5183. (c) Radzewich, C.
E.; Guzei, I. A.; Jordan, R. F. J. Am. Chem. Soc. 1999, 121, 8673. (d)
Aeilts, S. L.; Coles, M. P.; Swenson, D. C.; Jordan, R. F.; Young, V. G.,
Jr. Organometallics 1998, 17, 3265. (e) Qian, B.; Ward, D. L.; Smith, M.
R., III. Organometallics 1998, 17, 3070. (f) Cui, C.; Roesky, H. W.; Schmidt,
H.-G.; Noltemeyer, M.; Hao, H.; Cimpoesu, F. Angew. Chem., Int. Ed. 2000,
39, 4274. (g) Schmidt, J. A. R.; Arnold, J. Organometallics 2002, 21, 2306.
(2) For examples, see: (a) Pritchett, S.; Woodmansee, D. H.; Gantzel,
P.; Walsh, P. J. J. Am. Chem. Soc. 1998, 120, 6423. (b) Ackermann, L.;
Bergman, R. G.; Loy, R. N. J. Am. Chem. Soc. 2003, 125, 11956. (c) Evans,
D. A.; Nelson, S. G. J. Am. Chem. Soc. 1997, 119, 6452. (d) Seidel, S. W.;
Deming, T. J. Macromolecules 2003, 36, 969.
(3) (a) Corey, E. J.; Sarshar, S.; Bordner, J. J. Am. Chem. Soc. 1992,
114, 7938. (b) Corey, E. J.; Sarshar, S.; Lee, D.-H. J. Am. Chem. Soc. 1994,
116, 12089.
(4) (a) Blaschette, A.; Michalides, A.; Jones, P. G. J. Organomet. Chem.
1991, 411, 57. (b) Kavallieratos, K.; Rosenberg, J. M.; Bryan, J. C. Inorg.
Chem. 2005, 44, 2573.
(5) Royo, E.; Betancort, J. M.; Davis, T. J.; Carroll, P.; Walsh, P. J.
Organometallics 2000, 19, 4840.
(6) Gorlitzer, H. W.; Spiegler, M.; Anwander, R. Eur. J. Inorg. Chem.
1998, 1009.
(7) Carver, F. J.; Hunter, C. A.; Livingstone, D. J.; McCabe, J. F.; Seward,
E. M. Chem. Eur. J. 2002, 8, 2848.
10.1021/om0611296 CCC: $37.00 © 2007 American Chemical Society
Publication on Web 03/15/2007

1948 Organometallics, Vol. 26, No. 8, 2007
Scheme 1. Synthesis of Aluminum Complexes
Zhao et al.
Table 1. Crystallographic Details for 1-3
just out of the range reported for aluminum mono(amidinate)
alkyls (1.912-1.940 Å) but shorter than those found in the
dimeric amidato species {Me2Al[µ,η2-ArNC(Ph)O]}2 (1.973(1)
Å).9 The Al-O bond lengths (1.882(3) Å) are significantly
longer than those in {Me2Al[µ,η2-ArNC(Ph)O]}2 (1.811(1) Å).10
The S1-O1 (1.480(3) Å) and S1-N1 distances (1.581(3) Å)
are longer than those of normal SdO (1.40-1.44 Å) and SdN
double bonds (ca. 1.50 Å).11 The lengthening of the S-O and
S-N distances indicates the delocalized bonding of the N-S-O
backbone to the aluminum atoms.
1
2
3‚2C7H8
formula
C46H74Al2N2
O6S2
C40H53AlN2
O4S2
C52H65AlN2
O4S2
formula wt
temp (K)
cryst syst
space group
a (Å)
869.15
293(2)
triclinic
P1h
10.5056(15)
10.8810(15)
12.6463(18)
96.918(2)
99.860(2)
107.204(2)
1337.9(3)
1
716.94
294(2)
triclinic
P1h
11.1065(14)
16.532(2)
22.444(3)
89.462(2)
78.601(2)
88.062(2)
4037.4(9)
4
873.16
294(2)
monoclinic
C2/c
30.430(6)
9.810(2)
21.250(4)
90
126.940(8)
90
5070.1(17)
4
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
Single crystals of 2 and 3 suitable for X-ray analysis were
obtained from toluene. The structure of 2 is crystallographically
centrosymmetric. Both compounds are monomeric, and the
central aluminum atom is five-coordinated. The geometry of
the aluminum atom can be best described as distorted trigonal
bipyramids (tbp) in which the two bonded oxygen atoms of the
sulfonamide ligands occupy axial sites and equatorial sites are
occupied by the methylene carbon atom and two nitrogen atoms
of the ligands. The sum of the equatorial atomic angles (357.96°
in 2) is close to 360°, but the O-Al-O angles (155.21(10)° in
2 and 160.83(16)° in 3) markedly deviate from the ideal linearity
for a tbp because of the acute N-Al-O angles (from 71.84(9)
to 72.56(10)°). The wide O-Al-O angles and high coordination
number of 2 and 3 lead to the relatively longer Al-O bond
lengths (1.975(2) and 1.982(2) Å in 2 and 2.000(2) Å in 3)
compared to those found in 1. The Al-N bond lengths in 2
(1.930(3) and 1.933(2) Å) are longer than the corresponding
Al-N distances in 3 (1.899(3) Å) but are in the reported range
for aluminum bis(amidinate) alkyl complexes (1.914-1.986
Å).1b The Al-C bond length (1.954(3) Å) in 2 is typical for an
Al-C bond found in the five-coordinate aluminum alkyls. The
N-S (1.589-1.619 Å) and O-S bond lengths (1.491-1.4996
Å) in the bonding backbone are slightly lengthened compared
to those found in 1. These structural parameters indicate the
charge delocalization in the N-S-O subunit and the bonding
mode of the sulfonamide ligand can be rationalized as a
chelating coordination.
Z
cryst dimens
(mm)
0.14 × 0.12 ×
0.38 × 0.32 ×
0.24 × 0.22 ×
0.08
0.26
0.18
d
calcd, (g/cm3)
1.079
1.179
1.144
no. of rflns
no. of obsd rflns
GOF
7322
4661
1.078
22 763
16 125
0.985
10 364
4424
1.051
R1 (I > 2σ(I))
0.0753
0.2742
0.0540
0.1523
0.0619
0.2091
wR2 (all)
reaction of 1 with 1 equiv of ArNH(SO2-p-Tol) in toluene at
room temperature. It is noteworthy that reaction of ArNH(SO2-
p-Tol) with 1 equiv of AlH3NMe3 did not give the desired
(LAlH2)2; instead, L2AlH was isolated alone with an excess of
sulfonamine under various conditions. Compounds 1-3 were
isolated as colorless crystals by crystallization from toluene.
They have been characterized by IR, 1H and 13C NMR spectra,
and elemental analysis. The structures of these compounds were
determined by X-ray single-crystal analysis. Crystal data for
1-3 are summarized in Table 1. The molecular structures of
1-3 are shown in Figures 1-3, respectively.
The structure of 1 has a crystallographically required center
of symmetry with a bimetallic Al2N2O2S2 eight-membered ring
in a chair conformation. The two bridging sulfonamide ligands
link the two AlEt2 units. The central aluminum atoms are four-
coordinated and adopt a distorted-tetrahedral geometry, being
bonded to two ethyl groups and to one of the two oxygen atoms
and the nitrogen atom in the ligand. The Al-C bond lengths
(1.949(5) Å) are in the range for an Al-C single bond. The
structure may be comparable to those of the dimeric amidinate
complex {[MeC(NMe)2]AlMe2}28 and amide complex {Me2Al-
[µ,η2-ArNC(Ph)O]}2.9 The Al-N bond length (1.944(3) Å) is
(8) Hausen, H.-D.; Gerstner, F.; Schwartz, W. J. Organomet. Chem. 1978,
145, 277.
(9) Huang, B. H.; Yu, T. L.; Huang, Y. L.; Ko, B. T.; Lin, C. C. Inorg.
Chem. 2002, 41, 2987.
(10) Huang, Y. L.; Huang, B. H.; Ko, B. T.; Lin, C. C. Dalton Trans.
2001, 1390.
(11) Blais, P.; Brask, J. K.; Chivers, T.; Schatte, G. Inorg. Chem. 2001,
40, 384.

Aluminum Sulfonamide Alkyls and Hydride
Organometallics, Vol. 26, No. 8, 2007 1949
Figure 3. Ortep drawing of 3 (30% probability). Hydrogen atoms,
except that attached to the aluminum atom, have been omitted for
clarity. Selected bond distances (Å) and angles (deg): Al1-N1 )
1.899(3), Al1-O1 ) 2.000(2), Al1-S1 ) 2.6153(10), Al1-H1
) 1.86(5), S1-O1 ) 1.491(2), S1-O2 ) 1.409(2), S1-N1 )
1.619(3); N1*-Al1-N1 ) 121.70(17), N1-Al1-O1* ) 97.90(11),
N1-Al1-O1 ) 72.56(10), O1*-Al1-O1 ) 160.83(16), O1-S1-
N1 ) 95.75(13), S1-N1-Al1 ) 95.71(13), S1-O1-Al1 )
95.92(12).
Figure 1. Ortep drawing of 1 (30% probability). Hydrogen atoms
have been omitted for clarity. Selected bond distances (Å) and
angles (deg): Al1-O1 ) 1.882(3), Al1-N1* ) 1.944(3), Al1-
C22 ) 1.949(5), Al1-C20 ) 1.962(5), S1-O1 ) 1.480(3), S1-
N1 ) 1.581(3); O1-Al1-N1* ) 101.37(14), O1-Al1-C22 )
103.81(19), N1*-Al1-C22 ) 109.90(19), O1-Al1-C20 )
108.71(18), C22-Al1-C20 ) 117.9(2), O1-S1-N1 ) 104.48(16),
S1-O1-Al1 ) 137.64(19), S1-N1-Al1* ) 122.22(18).
Figure 2. Ortep drawing of 2 (30% probability). Hydrogen atoms
have been omitted for clarity. Selected bond distances (Å) and
angles (deg): Al1-N2 ) 1.930(3), Al1-N1 ) 1.933(2), Al1-
C39 ) 1.954(3), Al1-O3 ) 1.975(2), Al1-O1 ) 1.982(2), S1-
O1 ) 1.487(2), S1-O2 ) 1.422(2), S1-N1 ) 1.589(2), S2-O3
) 1.492(2), S2-O4 ) 1.423(2), C39-C40 ) 1.495(5); N2-Al1-
N1 ) 123.74(11), N2-Al1-C39 ) 112.01(13), N1-Al1-C39 )
124.22(13), N2-Al1-O3 ) 72.24(10), N1-Al1-O3 ) 94.97(10),
N2-Al1-O1 ) 97.25(10), N1-Al1-O1 ) 71.84(9), O3-Al1-
O1 ) 155.21(10), O1-S1-N1 ) 96.57(12), S1-N1-Al1 )
94.90(12), S2-N2-Al1 ) 94.68(12), S1-O1-Al1 ) 96.30(11),
S2-O3-Al1 ) 95.92(11).
Figure 4. Ortep drawing of 4 (30% probability). Hydrogen atoms
have been omitted for clarity. Selected bond distances (Å) and
angles (deg): Al1-O1* ) 1.808(4), Al1-N1 ) 1.872(5), Al1-
I2 ) 2.4858(19), Al1-I1 ) 2.5065(19), S1-O1 ) 1.501(4), S1-
N1 ) 1.595(5), O1-Al1* ) 1.808(4), N1-C1 ) 1.483(7), S1-
C13 ) 1.744(16); O1*-Al1-N1 ) 105.1(2), O1*-Al1-I2 )
104.73(16), N1-Al1-I2 ) 112.23(16), O1*-Al1-I1 ) 110.15(15),
N1-Al1-I1 ) 113.26(17), I2-Al1-I1 ) 110.88(7), O1-S1-
N1 ) 101.5(2), S1-O1-Al1* ) 140.0(3).
Reaction of 1 and 2 with Iodine. It is known that aluminum
iodides can be prepared by the reaction of the corresponding
aluminum methyl species with iodine.12 The reaction of the
aluminum mono- and bis(sulfonamide) ethyl species with the
appropriate amount of iodine in toluene afforded the expected
iodides (LAlI2)2 (4) and L2AlI (5) in good yield. Both
compounds were isolated as colorless crystals from toluene.
Reduction of 4 with potassium did not give the desired low
valent species but resulted in the formation of 5. Similar
reduction of 5 yielded a complicated mixture, which could not
be separated and characterized.
The molecular structure of 4 has been determined by X-ray
single crystal analysis, which is shown in Figure 4 alone with
selected bond parameters. Crystal data for 4 are summarized in
Table 2. Compound 4 is dimeric, and the overall structure is
similar to that of 1. The Al-O and Al-N bond lengths (1.808(4)
and 1.872(5) Å) in 4 are much shorter than those found in 1
(1.882(3) Å) because of the electron-withdrawing nature of the
1
The H NMR spectra of 2 and 3 contain four doublets for
the resonances of the CHMe2 groups. One of the doublets is
shifted significantly upfield (δ 0.25 in 2 and 0.26 ppm in 3)
because of the close intramolecular contact (the closest H-CPh
distance is 2.937 Å) of one of the methyl groups with the
S-bound phenyl rings, as observed in the crystal structures of 2
and 3. The broad Al-C resonance of 2 was found at δ 0.60
ppm in the 13C NMR spectrum. The terminal hydride resonance
in 3 was not observed in the 1H NMR spectrum, but its existence
was unambiguously verified by the solid-state IR spectrum, in
which the strong band centered at 1865 cm-1 is characteristic
of Al-H vibration absorptions.12
(12) (a) Wang, X.; Andrews, L.; Tam, S.; DeRose, M. E.; Fajardo, M.
E. J. Am. Chem. Soc. 2003, 125, 9218. (b) Himmel, H.-J.; Vollet, J.
Organometallics 2002, 21, 5972. (c) Chang, J.-C.; Hung, C.-H.; Huang,
J.-H. Organometallics 2001, 20, 4445.

1950 Organometallics, Vol. 26, No. 8, 2007
Table 2. Crystallographic Details for 4 and 7-9
Zhao et al.
4
7
8‚C7H8
9
formula
formula weight
temp (K)
cryst syst
space group
a (Å)
C26H32AlI2NO2S
703.37
294(2)
triclinic
P1h
10.2632(17)
12.263(2)
12.986(2)
89.811(3)
76.040(3)
69.851(3)
1483.4(4)
2
C46H53AlN2O4S2
789.00
113(2)
tetragonal
I41/a
40.2284(5)
40.2284(5)
10.69300(10)
90
C58H67AlN2O5S2
963.24
113(2)
trigonal
R3h:H
46.107(3)
46.107)3)
13.1715(12)
90
90
120
24 250(3)
18
C54H64Li2N2O8S2
947.07
293(2)
triclinic
P1h
11.270(3)
11.371(3)
12.802(3)
77.355(4)
75.431(4)
65.187(4)
1429.2(6)
1
b (Å)
c (Å)
R (deg)
â (deg)
90
90
γ (deg)
V (Å3)
17 304.7(3)
16
Z
cryst dimens, mm
d
0.40 × 0.38 × 0.34
0.32 × 0.28 × 0.24
0.12 × 0.06 × 0.04
0.26 × 0.24 × 0.18
calcd (g/cm3)
1.575
1.211
1.187
1.100
no. of rflns
no. of obsd rflns
GOF
8403
5982
1.025
74 564
10 273
1.085
61 704
9491
1.285
7297
5020
1.035
R1 (I > 2σ(I))
wR2 (all)
0.0501
0.1654
0.0482
0.1193
0.1206
0.2192
0.0620
0.2138
Scheme 2. Reactions of the Hydride 3
iodide ligands. As a result, the S1-O1 (1.501(4) Å) bond length
in 4 is lengthened by 0.021 Å compared to those in 4 (1.480(3)
Å). The O1-S1-N1 angle (104.48(16)°) in 1 is also slightly
more open than those (101.5(2)°) in 4.
Reaction of 3 with NH2Ph, HCCPh, and Ph2CO. Alumi-
num hydrides are highly reactive and have been used as reducing
agents for carbonyls, imines, and other unsaturated functional
groups because of the nucleophilic nature of hydride ligands.
Aluminum hydrides also undergo hydrogen elimination reactions
with alcohols, amines, and terminal acetylenes.13,14 The five-
coordinate aluminum hydride 3 is thermally stable in solution
and in the solid state and does not decompose in refluxing
toluene within 2 h and in the melt (ca. 245 °C). The high thermal
stability of 3 is comparable to that of the amidinate hydride
[ArNC(H)NAr]2AlH.13a However, it has been shown that the
monomeric aluminum hydrides [C4H3N(CH2NMe2-2)2AlH and
(OCCMeCHCMeNAr)2AlH with five- and six-membered rings
are not stable in solution and decompose at 70-80 °C. 3 is
highly reactive and could be used as a precursor for the
preparation of the amide L2AlNHPh (6), alkynyl L2AlCCPh (7),
and alkoxide L2AlOCHPh2 (8) by reactions with PhNH2,
HCCPh, and Ph2CO, respectively (Scheme 2). All of these
1
compounds have been characterized by IR, H and 13C NMR,
and elemental analysis. The molecular structures of 7 and 8
have been determined by X-ray single-crystal analysis. These
five-coordinate aluminum species show NMR patterns in the
ligand region similar to those observed in the NMR spectra of
(13) (a) Wehmschulte, R. J.; Power, P. P. Inorg. Chem. 1998, 37, 6906.
(b) Cole, M. L.; Jones, C.; Junk, P. C.; Kloth, M.; Stasch, A. Chem. Eur.
J. 2005, 11, 4482. (c) Lin, C.-Y.; Tsai, C.-F.; Chen, H.-J.; Hung, C.-H.;
Yu, R.-C.; Kuo, P.-C.; Lee, H. M.; Huang, J.-H. Chem. Eur. J. 2006, 12,
3067. (d) Kuo, P.-H.; Chen, I.-C.; Chang, J.-C.; Lee, M.-T.; Hu, C.-H.;
Hung, C.-H.; Lee, H. M.; Huang, J.-H. Eur. J. Inorg. Chem. 2004, 4898.
(14) (a) Zheng, W.; Hohmeister, H.; Mo¨sch-Zanetti, N. C.; Roesky, H.
W.; Noltemeyer, M.; Schmidt, H.-G. Inorg. Chem. 2001, 40, 2363. (b)
Zheng, W.; Mo¨sch-Zanetti, N. C.; Roesky, H. W.; Hewitt, M.; Cimpoesu,
F.; Schneider, T. R.; Stasch, A.; Prust, J. Angew. Chem., Int. Ed. 2000, 39,
3099. (c) Himmel, H.-J. Organometallics 2003, 22, 2679.
1
L2AlH (3). The H NMR spectrum of 6 displayed a singlet at
δ 3.57 ppm, attributed to the resonance of the amide proton,
which was further supported by its IR spectrum, in which the
N-H stretching vibration appeared at 3440 cm-1. The 13C NMR
spectrum of 7 shows characteristic resonances at δ 109.8 and
106.5 ppm for the CtC moiety, comparable to those found in
But2pzAlCCPh (3,5-But2pz ) 3,5-di-tert-butylpyrazolate).14

Aluminum Sulfonamide Alkyls and Hydride
Organometallics, Vol. 26, No. 8, 2007 1951
Figure 5. Ortep drawing of 7 (30% probability). Hydrogen atoms
have been omitted for clarity. Selected bond distances (Å) and
angles (deg): S1-O1 ) 1.4996(12), S1-O2 ) 1.4279(12), S1-
N1 ) 1.5947(14), S2-O3 ) 1.4933(12), S2-O4 ) 1.4321(12),
S2-N2 ) 1.5967(13), Al1-N1 ) 1.8942(14), Al1-N2 )
1.8980(14), Al1-C39 ) 1.9332(18), Al1-O1 ) 1.9591(12), Al1-
O3 ) 1.9817(12), C39-C40 ) 1.210(2); O1-S1-N1 ) 96.08(7),
O3-S2-N2 ) 96.23(7), N1-Al1-N2 ) 120.80(6), N1-Al1-
O1 ) 73.35(5), N1-Al1-O3 ) 93.89(5), N2-Al1-O3 )
72.73(5), C39-Al1-O3 ) 97.54(6), S1-O1-Al1 ) 95.48(6), S2-
O3-Al1 ) 95.54(6), S2-N2-Al1 ) 95.47(7), C40-C39-Al1 )
167.43(15), C39-C40-C41 ) 173.23(18).
Figure 6. Ortep drawing of 8 (30% probability). Hydrogen atoms
have been omitted for clarity. Selected bond distances (Å) and
angles (deg): S1-O1 ) 1.499(3), S1-O2 ) 1.433(4), S1-N1 )
1.593(4), S2-O3 ) 1.496(4), S2-O4 ) 1.430(4), S2-N2 )
1.591(4), Al1-N1 ) 1.899(4), Al1-N2 ) 1.914(4), Al1-O5 )
1.699(4), Al1-O1 ) 1.966(4), Al1-O3 ) 1.963(4), O5-C39 )
1.372(7); O1-S1-N1 ) 95.9(2), O3-S2-N2 ) 96.5(2), N1-
Al1-N2 ) 126.51(19), N1-Al1-O1 ) 72.90(16), N1-Al1-O3
) 95.03(16), N2-Al1-O3 ) 72.90(16), O5-Al1-O3 ) 101.97(18),
S1-O1-Al1 ) 95.82(18), S2-O3-Al1 ) 95.77(18), S2-N2-
Al1 ) 94.6(2), C39-O5-Al1 ) 146.3(4).
Single crystals of 7 were obtained from toluene. The
molecular structure of 7 is shown in Figure 5 along with selected
bond lengths and angles. Compound 7 is monomeric in the solid
state. The overall structure is comparable to those of 2 and 3.
Compound 7 features a terminal acetylide ligand. The Al-C
bond length in 7 (1.9332(18) Å) is longer than those found in
the four-coordinate aluminum acetylide species [3,5-But2pz(µ-
Al)2(CCPh)2]2 (1.913(3) and 1.929 Å). The short C30-C40
bond distance (1.210(2) Å) indicates a C-C triple bond. The
Al1-C39-C40 bond angle (167.43(15)°) significantly deviates
from linearity compared to those in a few known terminal
actetylide aluminum compounds (174.3-178.2°), probably
caused by the hydrogen bonding of one of the 2-H atoms of
the S-bound phenyl ring with the C40 (the H-C39 and H-C40
distances are 2.724 and 2.734 Å). This kind of abnormal
deviation, however, has been previously observed in the
structure of [3,5-But2pz(µ-Al)2(CCPh)2]2.14
Compound 8 is stable in solution and in the solid state at
ambient temperature. However, it slowly decomposes (ca. 10%
within 6 h) in refluxing toluene, leading to the formation of the
free ligand. Single crystals of 8 suitable for X-ray analysis were
obtained from toluene. The structure is shown in Figure 6.
Compound 8 also has a monomeric structure with a five-
coordinate aluminum center (Figure 6) similar to those of 2, 3,
and 7. The Al1-O5 bond length (1.699(4) Å) is short and
consistent with the corresponding distances found in terminal
aluminum alkoxides.15
Scheme 3. Synthesis of Lithium Complex 9
(Scheme 3). Colorless crystals of the product were grown from
THF, and its structure was determined by X-ray single-crystal
analysis. The lithium mono(sulfonamide) salt 9 has a dimeric
structure with a Li2O4S2 eight-membered ring having a crystal-
lographic central symmetry (Figure 7). In this case, the lithium
ion is coordinated to the two oxygen atoms in the ligand. The
central lithium atoms in 9 are four-coordinated. The average
Li-O bond length in the eight-membered ring is 1.881(6) Å,
which is very close to those found in polymeric [Li(THF)2{Al-
[SO2(NBut)2]2}]∞.11 The S-O bond length of 1.463(2) Å is
slightly longer than a typical SdO double bond. The S-N bond
length (1.520(3) Å) indicates a double-bond character. Very few
lithium sulfonamides have been structurally characterized.16 The
closely related mono((trifluoromethyl)sulfonyl)amide [Li(CF3-
SO2N(CH2)3OCH3)]2‚CH3CN adopts a dimeric structure with
µ2(O,N) coordination.16a The unusual bridging µ2(O,O) coor-
dination in the structure of 9 may result from the sterically
demanding Ar groups.
Generation of Lithium Sulfonamide. Compound 6 has a
terminal hydroamino group. We reasoned that deprotonation
with BuLi might yield the corresponding binuclear species. The
reaction of 6 with BunLi in n-hexane at room temperature gave
a white precipitate, which is not soluble in hydrocarbon solvents
Lactide Polymerization Reactions. Aluminum alkoxides are
known to be excellent initiators for lactide polymerization
reactions.17 The stereoselectivity of aluminum precursors de-
pends largely on the ligand systems employed. Therefore,
catalytic behaviors of the hydride 3 and alkoxide 8 for lactide
(15) (a) Wengrovius, J. H.; Garbauskas, M. F.; Williams, E. A.; Going,
R. C.; Donahue, P. E.; Smith, J. F. J. Am. Chem. Soc. 1986, 108, 982. (b)
Healy, M. D.; Power, M. B.; Barron, A. R. Coord. Chem. ReV. 1994, 130,
63. (c) Lewin´ski, J.; Horeglad, P.; Dranka, M.; Justyniak, I. Inorg. Chem.
2004, 43, 5789. (d) Amgoune, A.; Lavanant, L.; Thomas, C. M.; Chi, Y.;
Welter, R.; Dagorne, S.; Carpentier, J.-F. Organometallics 2005, 24, 6279.
(16) (a) Dillon, R. E. A.; Stern, C. L.; Shriver, D. F. Chem. Mater. 2000,
12, 1122. (b) Brouillette, D.; Irish, D. E.; Taylor, N. J.; Perron, G.;
Odziemkowski, M.; Desnoyers, J. E. Phys. Chem. Chem. Phys. 2002, 4,
6063.

1952 Organometallics, Vol. 26, No. 8, 2007
Zhao et al.
Experimental Section
General Remarks. All operations were carried out under an
atmosphere of dry argon or nitrogen by using modified Schlenk
line and glovebox techniques. All solvents were freshly distilled
from Na and degassed immediately before use. The chemicals used
in this study were purchased from Aldrich or Acros and used as
received. ArNH(SO2-p-Tol) was prepared as described in the
literature.7 The 1H and 13C NMR spectroscopic data were recorded
on a Varian Mercury Plus 400 spectrometer. IR spectra were
recorded on a Bio-Rad FTS 6000 spectrometer. Elemental analyses
were carried out on an Elemental Vario EL analyzer.
[ArN(SO2-p-Tol)AlEt2]2 (1). To a stirred solution of ArNH-
(SO2-p-Tol) (9.93 g, 30.0 mmol) in toluene (50 mL) was added
AlEt3 (4.5 mL, 32.9 mmol) over a period of 10 min. The mixture
was stirred at room temperature for 4 h. The clear solution was
concentrated (to 10 mL) and stored at -25 °C overnight, affording
colorless crystals of 1 (11.46 g, 92%). Mp: 224-226 °C. Anal.
Calcd for C46H68Al2N2O4S2 (830.43): C, 66.47; H, 8.25; N, 3.37.
Found: C, 66.09; H, 7.80; N, 3.37. 1H NMR (400.15 MHz,
DMSO): δ 7.60 (d, 4H, Ar H), 7.37 (d, 4H, Ar H), 7.22 (t, 2H, Ar
H), 7.09 (d, 4H, Ar H), 3.11 (sept, J ) 6.80 Hz, 4H, CHMe2), 2.34
(s, 6H, PhMe), 1.44 (d, J ) 6.80 Hz, 12H, CHMe2), 0.92 (d, J )
6.80 Hz, 12H, CHMe2), 0.97 (m, 12H, CH2CH3), -0.20 (m, 4H,
CH2CH3), -0.32 (m, 4H, CH2CH3). 13C NMR (100.63 MHz,
DMSO): δ 148.2, 141.9, 139.5, 129.1, 128.8, 128.1, 126.8, 123.5
(Ar C), 27.7 (CHMe2), 24.0 (CHMe2), 20.8 (CMe), 9.7 (AlCH2CH3),
9.5 (AlCH2CH3), 9.4 (AlCH2CH3), 0.7 (AlCH2CH3). IR (cm-1):
3648 (m), 3260 (m), 3056 (m), 2926 (s), 2930 (s), 2865 (s), 1596
(m), 1494 (m), 1461 (m), 1441 (m), 1421 (m), 1382 (m), 1318
(m), 1282 (s), 1159 (s), 1108 (s), 1071(s), 1019 (m), 955 (s), 886
(m), 871 (m), 799 (s), 736 (m), 716 (m), 674 (s), 651 (m), 631
(m), 561 (s), 529 (m), 471 (m), 422 (m).
[ArN(SO2-p-Tol)]2AlEt (2). A mixture of 1 (0.42 g, 1.0 mmol)
and ArNH(SO2-p-Tol) (0.33 g, 1.0 mmol) in toluene (20 mL) was
stirred at room temperature for 24 h. The volatiles were removed
under vacuum to yield a white solid of 2 (0.72 g, 100%). Crystals
of 2 were obtained from toluene at room temperature. Mp: 267-
268 °C. Anal. Calcd for C40H53AlN2O4S2 (716.33): C, 67.01; H,
7.45; N, 3.91. Found: C, 66.91; H, 7.54; N, 3.55. 1H NMR (400.15
MHz, CDCl3): δ 7.40 (d, 4H, Ar H), 7.22 (d, 2H, Ar H), 7.13 (t,
2H, Ar H), 7.09 (d, 4H, Ar H), 6.88 (d, 2H, Ar H), 4.14 (sept, J )
6.80 Hz, 2H, CHMe2), 2.80 (sept, J ) 6.80 Hz, 2H, CHMe2), 2.25
(s, 6H, PhMe), 1.44 (d, J ) 6.80 Hz, 6H, CHMe2), 1.31 (d, J )
6.80 Hz, 6H, CHMe2), 1.22 (t, J ) 8.0 Hz, 3H, CH2CH3), 0.95 (d,
J ) 6.80 Hz, 6H, CHMe2), 0.46 (m, J ) 8.2 Hz, 2H, CH2CH3),
0.25 (d, J ) 6.80 Hz, 6H, CHMe2). 13C NMR (100.63 MHz,
CDCl3): δ 149.4, 147.3, 143.8, 135.2, 130.6, 129.4, 127.3, 124.9,
123.2 (Ar C), 29.1, 28.2, 26.7, 26.2, 25.3 (CHMe2), 21.4 (CMe),
10.7 (AlCH2CH3), 0.6 (AlCH2CH3). IR (cm-1): 3649 (m), 3258
(s), 3061 (m), 2969 (s), 2869 (s), 2805 (m), 2590 (m), 1917 (m),
1869 (m), 1801 (m), 1701 (m), 1652 (m), 1596 (m), 1494 (m),
1463 (s), 1442 (s), 1383 (m), 1363 (m), 1324 (s), 1290 (s), 1256
(m), 1205 (m), 1183 (m), 1157 (s), 1111 (s), 1093 (m), 1057 (s),
974 (s), 931 (m), 854 (s), 800 (s), 752 (m), 674 (s), 624 (m), 588
(s), 560 (m), 528 (m), 493 (m).
Figure 7. Ortep drawing of 9 (30% probability). Hydrogen atoms
have been omitted for clarity. Selected bond distances (Å) and
angles (deg): S1-O1 ) 1.463(2), S1-O2 ) 1.464(2), S1-N1 )
1.520(3), O2-Li1 ) 1.866(6), O3-Li1 ) 1.983(6), O4-Li1 )
1.969(6), Li1-O1* ) 1.881(6); O1-S1-O2 ) 110.67(16), O1-
S1-N1 ) 115.25(15), O2-S1-N1 ) 115.55(15), S1-O1-Li1*
) 148.7(2), S1-O2-Li1 ) 145.6(2), O2-Li1-O1* ) 124.8(3),
O2-Li1-O4 ) 105.3(3), O1*-Li1-O4 ) 111.0(3), O2-Li1-
O3 ) 105.3(3), O1*-Li1-O3 ) 105.0(3), O4-Li1-O3 )
103.3(3).
Table 3. Solution Polymerization of D,L-Lactide
time
(h)
T
conversn
(%)c
d
d
entry
cat.a
(°C)b
Mw
Mn
PDId
nd
1
2
3
L2AlOCHPh2
L2AlOCHPh2
L2AlH
10
10
10
70
130
130
40
91
85
nd
nd
9776 6232 1.56
7945 5426 1.46
a Conditions: 20 mL of toluene solvent, 1.44 g of D,L-lactide, [LA]/
[Al] ) 100. b Oil bath temperature. c Conversion determined via 1H NMR.
d The weight average molecular weights (Mw), the number average molecular
weights (Mn), and the polydispersity indices (PDI ) Mw/Mn) were
determined by GPC. nd ) not determined.
polymerization have been examined. Both compounds have low
catalytic activity at high temperatures (70-130 °C) to give low-
molecular-weight polylactides with relatively narrow molecular
weight distributions (Table 3). The experimental results show
that the alkoxide 8 is more efficient than the corresponding
1
hydride species. Both H and 13C NMR spectra of the PLAs
indicate the formation of atactic polymers.
Conclusion
Three bonding modes have been observed in the aluminum
and lithium sulfonamide complexes. The ligand displays a µ2
coordination mode in mono(sulfonamide) aluminum complexes
and an η2-coordination mode in bis(sulfonamide) complexes.
The sulfonamide ligand in these aluminum complexes shows
remarkable electron delocalization over the N-S-O backbone.
The lithium complex shows an unusual µ2 coordination with
the two oxygen atoms of the ligand attached to the lithium ions.
This study demonstrates that by employing steric demanding
substituents on the sulfonamide ligand backbone it is possible
to isolate mononuclear metal sulfonamide complexes and that
sulfonamides are potentially useful as spectator chelating
ligands.
[ArN(SO2-p-Tol)]2AlH (3). To a stirred solution of ArNH(SO2-
p-Tol) (13.24 g, 40.0 mmol) in toluene (100 mL) was added AlH3‚
NMe3 (2.0 M, 10 mL) in toluene over a period of 30 min. The
mixture was stirred at room temperature for an additional 4 h. The
resulting solution was concentrated (to ca. 15 mL) and stored at
-25 °C overnight to give colorless crystals of 3 (12.41 g, 90%).
Mp: 254-255 °C. Anal. Calcd for C38H49AlN2O4S2 (688.29): C,
1
66.25; H, 7.17; N, 4.07. Found: C, 66.24; H, 6.91; N, 3.86. H
NMR (400.15 MHz, CDCl3): δ 7.57 (d, 4H, Ar H), 7.14 (m, 8H,
Ar H), 6.86 (d, 2H, Ar H), 4.05 (sept, J ) 6.80 Hz, 2H, CHMe2),
2.81 (sept, J ) 6.80 Hz, 2H, CHMe2), 2.28 (s, 6H, PhMe), 1.41 (d,
J ) 6.80 Hz, 6H, CHMe2), 1.32 (d, J ) 6.80 Hz, 6H, CHMe2),
(17) Fox examples, see: (a) Hormnirun, P.; Marshall, E. L.; Gibson, V.
C.; White, A. J. P.; Williams, D. J. J. Am. Chem. Soc. 2004, 126, 2688. (b)
Nomura, N.; Ishii, R.; Akakura, M.; Aoi, K. J. Am. Chem. Soc. 2002, 124,
5938.

Aluminum Sulfonamide Alkyls and Hydride
Organometallics, Vol. 26, No. 8, 2007 1953
0.97 (d, J ) 6.80 Hz, 6H, CHMe2), 0.26 (d, J ) 6.80 Hz, 6H,
CHMe2). 13C NMR (100.63 MHz, CDCl3): δ 149.0, 147.1, 144.2,
134.8, 130.0, 129.9, 129.7, 127.7, 127.4, 124.6, 123.3 (Ar C), 28.9,
28.2, 26.0, 25.7, 24.5 (CHMe2), 21.5 (CMe). IR (cm-1): 3257 (s),
3026 (m), 2969 (s), 2927 (s), 2868 (s), 2802 (m), 2713 (m), 2593
(m), 1925 (m), 1865 (m), 1846 (m), 1800(m), 1699 (m), 1653 (m),
1595 (s), 1495 (m), 1463 (s), 1444 (s), 1398 (m), 1383 (m), 1362
(m), 1323 (s), 1297 (s), 1257 (m), 1210 (m), 1183 (m), 1154 (s),
1112 (s), 1091 (m), 1058 (s), 1020 (m), 976 (m), 917 (m), 863 (s),
800 (s), 705 (m), 673 (s), 633 (m), 587 (m), 561 (m).
J ) 6.80 Hz, 2H, CHMe2), 3.57 (s, 1H, NH), 3.11 (sept, J ) 6.80
Hz, 2H, CHMe2), 2.20 (s, 6H, PhMe), 1.45 (d, J ) 6.80 Hz, 6H,
CHMe2), 1.34 (d, J ) 6.80 Hz, 6H, CHMe2), 1.00 (d, J ) 6.80 Hz,
6H, CHMe2), 0.00 (d, J ) 6.8 Hz, 6H, CHMe2). 13C NMR (100.63
MHz, CDCl3): δ 151.5, 149.4, 147.7, 144.3, 134.1, 129.8, 129.6,
129.3, 128.7, 127.4, 124.8, 123.8, 117.8, 116.1 (Ar C), 29.1, 27.7,
26.6, 26.1, 25.2, 22.7 (CHMe2), 21.4 (CMe). IR (cm-1): 3832 (m),
3600 (m), 3511 (m), 3440 (m), 3250 (s), 2971 (s), 2867 (s), 1930
(m), 1596 (m), 1499 (m), 1467 (m), 1444(m), 1401 (m), 1324 (s),
1254 (m), 1185 (m), 1153 (s), 1089(m), 1049 (m), 916 (m), 794
(m), 750 (m), 666 (s), 612 (m), 559 (s), 477 (m).
[ArN(SO2-p-Tol)AlI2]2 (4). A rapidly stirred solution of LAlEt2
(4.15 g, 10.0 mmol) in toluene (80 mL) was combined with I2 (5.08
g, 20.0 mmol) at room temperature. The deep red solution was
stirred for 2 h to give a colorless solution. The solution was
concentrated (to ca. 10 mL) and stored at -25 °C overnight to
afford white crystals of 4 (5.86 g, 96%). Mp: 226-227 °C. Anal.
Calcd for C38H48Al2I4N2O4S2 (1221.98): C, 37.33; H, 3.96; N, 2.29.
Found: C, 37.74; H, 4.09; N, 2.31. 1H NMR (400.15 MHz,
DMSO): δ 7.60 (d, 4H, Ar H), 7.37 (d, 4H, Ar H), 7.22 (t, 2H, Ar
H), 7.09 (d, 4H, Ar H), 3.11 (sept, J ) 6.80 Hz, 4H, CHMe2), 2.34
(s, 6H, Me) 1.44 (d, J ) 6.80 Hz, 12H, CHMe2), 0.92 (d, J ) 6.80
Hz, 12H, CHMe2). 13C NMR (100.63 MHz, DMSO): δ 148.3,
142.3, 139.0, 129.9, 129.8, 129.3, 127.9, 126.3, 123.3, (Ar C), 27.8
(CHMe2), 23.6 (br, CHMe2), 20.8 (CMe). IR (cm-1): 3258 (vs),
2971 (s), 2868 (s), 1925 (m), 1807 (m), 1619 (m), 1597 (m), 1495
(m), 1463 (m), 1398 (m), 1382 (m), 1360 (m), 1323 (s), 1308 (m),
1259 (m), 1182 (m), 1154 (s), 1091 (m), 1052 (m), 917 (m), 796
(s), 670 (s), 611 (m), 560 (m).
[ArN(SO2-p-Tol)]2AlCCPh (7). To a stirred solution of 3 (3.44
g, 5.0 mmol) in toluene (80 mL) was added phenylacetylene (0.55
mL, 5.0 mmol). The solution was refluxed for 10 h and then cooled
to room temperature. The solution was concentrated (to ca. 20 mL)
and cooled to -25 °C to give colorless crystals of 7 (2.55 g, 65%).
Mp: 142 °C dec. Anal. Calcd for C46H53AlN2O4S2 (788.33): C,
1
70.02; H, 6.77; N, 3.55. Found: C, 70.43; H, 6.55; N, 3.49. H
NMR (400.15 MHz, CDCl3): δ 7.88 (d, 4H, Ar H), 7.47 (d, 2H,
Ar H), 7.33 (m, 3H, Ar H), 7.18 (t, 2H, Ar H), 7.12 (m, 6H, Ar
H), 6.88 (d, 2H, Ar H), 4.06 (sept, J ) 6.80 Hz, 2H, CHMe2), 3.19
(sept, J ) 6.80 Hz, 2H, CHMe2), 2.28 (s, 6H, PhMe), 1.43 (d, J )
6.80 Hz, 6H, CHMe2), 1.33 (d, J ) 6.80 Hz, 6H, CHMe2), 1.04 (d,
J ) 6.80 Hz, 6H, CHMe2), 0.26 (d, J ) 6.80 Hz, 6H, CHMe2). 13
C
NMR (100.63 MHz, CDCl3): δ 149.1, 147.8, 144.3, 134.5, 131.6,
129.7, 129.5, 128.6, 128.4, 127.8, 127.5, 125.1, 124.5, 123.5, 109.8
(AlC), 106.5 (CPh), 29.0, 28.2, 26.8, 25.8, 24.7, 21.8 (CHMe2),
21.5 (CMe). IR (cm-1): 3257 (s), 2972 (s), 2870 (m), 2798 (m),
2579 (m), 2353 (m), 2102(m), 2025(m), 1930 (m), 1661 (m), 1595
(m), 1456 (s), 1401 (s), 1320 (m), 1258 (m), 1213 (m), 1155 (s),
1093 (s), 1051 (s), 980 (m), 915 (m), 863 (m), 805 (m), 753 (m),
669 (s), 604 (m), 552 (m).
[ArN(SO2-p-Tol)]2AlI (5). Method A. A rapidly stirred solution
of [ArN(SO2-p-Tol)]2AlEt (3.59 g, 5.0 mmol) in toluene (40 mL)
was combined with I2 (1.27 g, 5.0 mmol) at room temperature.
The deep red solution was stirred for 3 days to give an orange-red
solution. The solution was concentrated (to ca. 10 mL) and stored
at -25 °C overnight to afford yellow crystals of 5 (4.07 g, 75%).
Mp: 307-308 °C. Anal. Calcd for C38H48AlIN2O4S2 (814.19): C,
[ArN(SO2-p-Tol)]2AlOCHPh2 (8). To a stirred solution of 3
(1.38 g, 2.0 mmol) in toluene (40 mL) was added benzophenone
(0.36 g, 2 mmol). The solution was refluxed for 6 h and then cooled
to room temperature. The solution was concentrated (to ca. 10 mL)
and stored at -25 °C overnight to yield colorless crystals of 8 (0.91
g, 52%). Mp: 112 °C dec. Anal. Calcd for C51H59AlN2O5S2
(870.37): C, 70.32; H, 6.83; N, 3.22. Found: C, 69.90; H, 6.60;
1
55.52; H, 5.94; N, 3.44. Found: C, 55.52; H, 6.15; N, 3.14. H
NMR (400.15 MHz, CDCl3): δ 7.79 (d, 4H, Ar H), 7.16 (m, 8H,
Ar H), 6.88 (d, 2H, Ar H), 4.03 (sept, J ) 6.80 Hz, 2H, CHMe2),
3.03 (sept, J ) 6.80 Hz, 2H, CHMe2), 2.29 (s, 6H, PhMe), 1.44 (d,
J ) 6.80 Hz, 6H, CHMe2), 1.32 (d, J ) 6.80 Hz, 6H, CHMe2),
0.95 (d, J ) 6.80 Hz, 6H, CHMe2), 0.19 (d, J ) 6.80 Hz, 6H,
CHMe2). 13C NMR (100.63 MHz, CDCl3): δ 149.5, 148.4, 145.2,
133.5, 129.9, 129.5, 129.0, 128.1, 124.9, 124.1 (Ar C), 29.5, 28.5,
28.4, 26.3, 25.3 (CHMe2), 21.8 (CMe). IR (cm-1): 3260 (s), 3059
(s), 2970 (s), 2868 (s), 2591 (m), 1916 (m), 1873 (m), 1800 (m),
1699 (m), 1650 (m), 1595 (s), 1558 (m), 1494 (m), 1463 (s), 1441
(s), 1384 (m), 1363 (m), 1325 (s), 1296 (s), 1255 (m), 1206 (s),
1183 (m), 1158 (s), 1108 (s), 1047 (s), 1032 (s), 972 (s), 932 (m),
861 (s), 802 (s), 753 (m), 720 (m), 704 (m), 676 (s), 597 (s), 561
(m), 515 (m), 443 (m), 411 (m).
1
N, 3.21. H NMR (400.15 MHz, CDCl3): δ 7.66 (d, 2H, Ar H),
7.45 (d, 2H, Ar H), 7.33 (m, 8H, Ar H), 7.08 (d, 6H, Ar H), 6.88
(d, 4H, Ar H), 6.59 (d, 2H, Ar H), 6.32 (s, 1H, CHPh2), 4.09 (sept,
J ) 6.80 Hz, 2H, CHMe2), 3.15 (sept, J ) 6.80 Hz, 2H, CHMe2),
2.13 (s, 6H, PhMe), 1.44 (d, J ) 6.80 Hz, 6H, CHMe2), 1.28 (t, J
) 7.60 Hz, 12H, CHMe2), 0.04 (d, J ) 6.80 Hz, 6H, CHMe2). 13
C
NMR (100.63 MHz, CDCl3): δ 149.5, 148.0, 147.5, 143.7, 137.9,
133.8, 130.0, 129.5, 129.4, 129.0, 128.7, 128.4, 128.2, 127.4, 127.0,
126.5, 125.8, 125.3, 124.9, 123.7, 109.7 (CHPh2), 29.2, 27.7, 27.2,
26.4, 25.2, 22.1 (CHMe2), 21.4 (CMe). IR (cm-1): 3260 (s), 3063
(m), 3027 (m), 2975 (s), 2867 (m), 1804 (m), 1656 (m), 1595 (m),
1495 (m), 1453 (s), 1397 (m), 1324 (s), 1288 (s), 1252 (m), 1203
(m), 1152 (s), 1054 (s), 974 (m), 917 (m), 862 (s), 796 (s), 739
(m), 668 (s), 696 (m), 559 (m).
Method B. A solution of LAlI2 (0.61 g, 1.0 mmol) in diethyl
ether (40 mL) was added to a suspension of KC8, which was freshly
prepared from graphite and potassium (0.08, 2.0 mmol) in diethyl
ether (10 mL). The mixture was stirred at room temperature for 24
h. It was filtered, and the yellow filtrate was concentrated (to ca.
5 mL) and stored at -25 °C overnight to yield yellow crystals of
5 (0.31 g, 46%).
[ArN(SO2-p-Tol)Li(THF)2]2 (9). To a stirred solution of ArNH-
(SO2-p-Tol) (1.66 g, 5.0 mmol) in toluene (40 mL) was added
n-BuLi (2.5 M, 2 mL) in n-hexane. The mixture was stirred at room
temperature for 24 h, during which time a white solid was formed.
The solid was isolated by filtration and crystallized from THF at
-25 °C to give colorless crystals of 9 (1.23 g, 52%). Mp: 330-
332 °C. Anal. Calcd for C54H80Li2N2O8S2 (962.57): C, 67.33; H,
8.37; N, 2.91. Found: C, 67.09; H, 8.37; N, 3.03. 1H NMR (400.15
MHz, DMSO): δ 7.41 (d, 4H, Ar H), 7.05 (d, 4H, Ar H), 6.76 (d,
4H, Ar H), 6.64 (t, 2H, Ar H), 3.60 (J ) 6.40 Hz, 8H, OCH2CH2),
3.51 (sept., J ) 6.80 Hz, 4H, CHMe2), 2.27 (s, 6H, PhMe) 1.76(m,
8H, OCH2CH2), 0.84 (d, J ) 6.80 Hz, 24H, CHMe2). 13C NMR
(100.63 MHz, DMSO): δ 147.9, 144.7, 144.0, 136.6, 127.6, 125.3,
121.6, 119.7 (Ar C), 66.97 (OCH2CH2), 27.0 (CHMe2), 25.1
[ArN(SO2-p-Tol)]2AlNHPh (6). To a stirred solution of L2AlH
(3.44 g, 5.0 mmol) in toluene (50 mL) was added PhNH2 (0.46
mL, 5.0 mmol). The solution was refluxed for 2 h and then cooled
to room temperature and concentrated (ca. 10 mL). The solution
was stored at -25 °C overnight to afford colorless crystals of 6
(3.28 g, 84%). Mp: 164 °C dec. Anal. Calcd for C44H54AlN3O4S2
(779.34): C, 67.75; H, 6.98; N, 5.39. Found: C, 67.67; H, 6.82;
1
N, 5.39. H NMR (400.15 MHz, CDCl3): δ 7.51 (d, 4H, Ar H),
7.20 (d, 2H, Ar H), 7.15 (m, 4H, Ar H), 6.96 (d, 4H, Ar H), 6.85
(d, 2H, Ar H), 6.78 (d, 2H, Ar H), 6.63 (t, 1H, Ar H), 4.11 (sept,

1954 Organometallics, Vol. 26, No. 8, 2007
Zhao et al.
(CHMe2), 24.0 (OCH2CH2), 20.8 (CMe). IR (cm-1): 2864 (s), 1495
(m), 1465 (m), 1436 (s), 1380 (m), 1321 (s), 1257(m), 1209(m),
1116 (s), 1084 (s), 990 (s), 819 (m), 784 (m), 568 (m).
matrix least squares on F2. Hydrogen atoms were considered in
calculated positions. All non-hydrogen atoms were refined aniso-
tropically. Crystal data and data collection details are collected in
Tables 1 and 2. Crystals of 1-4, 7 and 8 suitable for X-ray analysis
were obtained from toluene at room temperature, and those of 9
were obtained from THF at room temperature.
Polymerization Procedure. Lactide polymerizations were car-
ried out by charging a Schlenk flask with rac-lactide (1.44 g) and
toluene (20 mL) with the appropriate amount of catalysts. The flask
was immediately immersed in an oil bath at 125 °C. After an
appropriate time, the oil bath was removed, and all volatiles were
removed. The remaining solid was dissolved in a small amount of
THF, and then water was added to incipient precipitation. The
precipitated polymers were collected, washed with water twice, and
Acknowledgment. This work was supported by the Program
for New Century Excellent Talents in Universities (the NCET)
and Tianjin Natural Science Foundation.
1
dried under vacuum for 24 h. The H and 13C NMR spectra of
Supporting Information Available: CIF files for compounds
1-4, and 7-9. This material is available free of charge via the
Internet at http://pubs.acs.org.
PLA samples were recorded in CDCl3.
X-ray Structural Determination. All intensity data were
collected with a Bruker SMART CCD diffractometer, using
graphite-monochromated Mo KR radiation (λ ) 0.710 73 Å). The
structures were resolved by direct methods and refined by full-
OM0611296