Five-coordinate organoaluminum acetylides and crystal structure of the hydrosylate, [Salophen(tBu)Al]2O

Article abstract of DOI:10.1016/j.jorganchem.2003.12.011

The first examples of five coordinate aluminum acetylide compounds chelated by a single ligand are reported in this paper. The combination of L(^tBu)AlCl (where L=Salen (1), Salpen (2), Salophen (3), Salomphen (4)) with LiC≡CPh in THF at-78 °C leads to the formation of the four acetylides (5-8), LC≡CPh. These are extremely moisture sensitive and readily hydrolyze to form aluminum hydroxides and with condensation form compounds of formula [L(^tBu)Al]₂O. The hydrosylate [Salophen(^tBu)Al]₂O (9) has been structurally characterized.

Full text of DOI:10.1016/j.jorganchem.2003.12.011

Journal of Organometallic Chemistry 689 (2004) 759–765
www.elsevier.com/locate/jorganchem
Five-coordinate organoaluminum acetylides and crystal structure
of the hydrosylate, [Salophen(tBu)Al]2O
*
Yuzhong Wang, Sonali Bhandari, Sean Parkin, David A. Atwood
Department of Chemistry, University of Kentucky Chemistry-Physics Building Lexington, KT 40506-0055, USA
Received 10 October 2003; accepted 1 December 2003
Abstract
The first examples of five coordinate aluminum acetylide compounds chelated by a single ligand are reported in this paper. The
combination of L(tBu)AlCl (where L ¼ Salen (1), Salpen (2), Salophen (3), Salomphen (4)) with LiCBCPh in THF at )78 °C leads
to the formation of the four acetylides (5–8), LCBCPh. These are extremely moisture sensitive and readily hydrolyze to form
aluminum hydroxides and with condensation form compounds of formula [L(tBu)Al]2O. The hydrosylate [Salophen(tBu)Al]2O (9)
has been structurally characterized.
Ó 2003 Elsevier B.V. All rights reserved.
Keywords: Aluminum; Acetylides; Five-coordinate; Salen
1. Introduction
dium [13] have been reported. Some of these can act as
precursors to six-coordinate cations [14]. Beyond their
fundamental interest and novelty, these high coordinate
Salen-main group compounds are finding applications
in catalysis [15–17]. For example, the asymmetric addi-
tion of diorgano-H-phosphonates to carbonyls (the
phospho-aldol reaction) has been found to be catalyzed
by chiral complexes of aluminum containing the salycen
ligand framework, [(R,R)-Salcyen]AlX (X ¼ Me, OSi-
Since the first aluminum acetylide was reported in
1960 [1], aluminum acetylides have been used as versatile
tools in organic synthesis [2–4]. For instance, al-
kynyldiethyl alanes have been used to alkynylate acyclic
epoxides [2] and diethylalkylnylalane reagents have been
employed to add acetylene units to simple a,b-unsatu-
rated ketones [3]. Chemo-, regio, and diastereoselective
alkylation via Lewis acid promoted substitution of
sulfones have been achieved with vinylalanaes [4]. Al-
though aluminum acetylides are generally dimeric with
bridging acetylide ligands between two four-coordinate
aluminum atoms, monomeric terminal aluminum acet-
ylides have been reported recently [5]. The only example
of a six-coordinate aluminum acetylide was observed in
a new kind of carbaalane [6]. However, there have been
no reports of five-coordinate aluminum acetylides. The
Salen ligands can be used to achieve this coordination
number for soluble, stable, and higher-coordinate main
group compounds [7]. For example, some five-coordi-
nate compounds of aluminum [8–11], gallium [12], in-
t
Me2 Bu) [17]. In this paper, we have reported the use of
the Salen ligands to prepare five-coordinate aluminum
compounds with a single terminal acetylide ligand. They
are of formula L(tBu)AlCBCPh (where L ¼ Salen (5),
Salpen (6), Salophen (7), and Salomphen (8)). Their
syntheses and spectroscopic properties will be discussed
along with the crystal structure of the hydrolyzed by-
product of 7, [Salophen(tBu)Al]2O (9).
2. Results and discussion
2.1. Synthesis and characterization of 5–8
As the reactants to synthesize compounds 5–8, the
Salen aluminum chlorides of formula L(tBu)AlCl (where
L ¼ Salen (1), Salpen (2), Salophen (3), Salomphen (4))
* Corresponding author. Tel.: +1-859-718-2405; fax: +1-859-323-
1069.
E-mail address: datwood@uky.edu (D.A. Atwood).
0022-328X/$ - see front matter Ó 2003 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2003.12.011

760
Y. Wang et al. / Journal of Organometallic Chemistry 689 (2004) 759–765
were prepared by combining the ligand with dimethyl
aluminum chloride in a 1:1 ratio in toluene (Scheme 1)
[9]. The NMR, IR and mass spectrometry data for
compounds 1–9 are summarized in Table 1. The 27Al
NMR shifts in the range 43–57 ppm unambiguously
confirm the existence of five-coordinate aluminum atoms
in these compounds. Depending on the nature of the
connection between the two nitrogen atoms of the ligand
(the ‘‘backbone’’ of the ligand) [18], the compounds are
either square pyramidal (with aryl backbones) or trigo-
nal bipyramidal (with alkylene backbones). The acety-
lides 5–8 can be prepared in high yields by combining 1–4
with LiCBCPh in THF at )78 °C (Scheme 1). The
compounds can be isolated in good yields by filtration in
CH2Cl2.
1
The H NMR data for 5–8 contain two singlets for
t
the Bu groups and one singlet for the azomethine hy-
drogen, which are closely comparable to those in the
chloride derivatives 1–4. The acetylide phenyl reso-
nances were observed as multiplets in the range d 7.12–
7.17 ppm. The integrated areas of protons of the phenyl
and protons of the azomethine carbons are in the ex-
pected ratio of 5:2. 13C NMR data for 5–8 display one
relatively broad singlet at d 105.5 ppm for the a-C of the
R
R
Toluene
[AlMe2Cl]
+
N
N
N
N
-2CH4
Al
Cl
OH
tBu
HO
tBu
O
O
tBu
tBu
tBu
tBu
tBu
tBu
R = Et (1), Pr (2), Ph(3), 4,5-Me2Ph (4)
Li
-78˚C
Ph
R
R = -(CH2)2-; Salen(tBu)ClCCPh (5)
Pr; Salpen(tBu)AlCCPh
(6)
N
N
O
Al
O
Ph; Salophen(tBu)AlCCPh (7)
4,5-Me2Ph; Salomphen(tBu)AlCCPh (8)
tBu
tBu
tBu
tBu
Ph
Scheme 1. Syntheses of five-coordinate aluminum acetylides.
Table 1
Selected spectroscopic Data for compounds 5–9
1H NMR (ppm)
Compound
27Al NMR
13C NMR
dCBC (ppm) [Mþ]
MS
IR
tBu
Backbone N–CHR
CCPh-H
(ppm) (W1=2
)
mCBC (cmꢀ1
2119
)
Salen(tBu)AlCBCPh (5)
Salpen(tBu)AlCBCPh (6)
1.33 (s)
1.59 (s)
3.73 (m)
4.18 (m)
8.35 (s)
7.17 (m)
39 (1042 Hz)
106.0 (br)
122.0 (s)
618, 100%
1.32 (s)
1.54 (s)
2.20 (m)
3.63 (m)
4.07 (m)
8.24 (s)
7.17 (m)
41 (1302 Hz)
105.5 (br)
122.0 (s)
632, 100%
2121
Salophen(tBu)AlCBCPh (7)
1.40 (s)
7.68 (d)
1.69 (s)
8.91 (s)
7.77 (m)
7.15 (m)
7.12 (m)
40 (834 Hz)
40 (625 Hz)
48 (3751 Hz)
105.1 (br)
666, 100%
122.1 (s)
2121
2121
Salomphen(tBu)AlCBCPh (8) 1.38 (s)
1.66 (s)
2.38 (s)
7.22 (d)
8.87 (s)
105.1 (br)
122.0 (s)
694, 100%
[Salophen(tBu)Al]2O (9)
1.30 (s)
1.46 (s)
7.35 (m)
7.49 (d)
7.90 (s)
1147, 12%

Y. Wang et al. / Journal of Organometallic Chemistry 689 (2004) 759–765
761
acetylides and another singlet at 122.0 ppm for the b-
carbon. The 27Al NMR for 5–8 display sharp resonances
(W1=2 ranging between 625 and 1302 Hz) compared to
those for 1–4 (W1=2 ranging between 5000 and 6500 Hz).
The chemical shifts of 5–8 in 27Al NMR, d 39–41 ppm,
are in the normal range for five-coordinate complexes
[19]. The spectroscopic data show that 5–8 have mo-
nomeric structures and the acetylide group is terminally
bound to the aluminum center.
Mass spectral data (EI) afford further support for the
presence of monomeric compounds, whose molecular
ion peaks were observed as m=z 618, 632, 666, and 694,
respectively. It should be noted that these molecular
ion peaks are base peaks. This reflects the stability of
Al–CBCPh unit in the absence of protic reagents such
as H2O.
trace amounts of water, acetylides 5–8 hydrolyze to
form aluminum hydroxides (e.g., Salophen(tBu)AlOH
(Scheme 2)). The hydroxides then undergo intermolecu-
lar condensation to form dimeric molecules of formula
[L(tBu)Al]2O, (L ¼ Salen, Salpen, Salophen, Salomphen)
(Scheme 1).
The hydrolysate [Salophen(tBu)Al]2O (9) was isolated
and fully characterized. In the 1H NMR the azomethine
hydrogen (d 7.90 ppm) shifts upfield compared to those
for 1–8 (d 8.24–8.97 ppm). A relatively broad resonance
was observed at d 48 ppm (W1=2 ¼ 3751 Hz) in the 27Al
NMR, which confirms the presence of five-coordinate
aluminum atoms. The molecular ion peak (m=z 1147)
with an intensity of 12% in the mass spectrum could be
attributed to a dimer.
The CBC stretching bands for 5–8 are observed in the
range, 2119–2121 cmꢀ1. When compared to LiCBCPh
(2036 cmꢀ1), they clearly confirm the presence of alu-
minum acetylides. Other terminal aluminum acetylides
[5] such as [(tBu2Pz)Al(CBCPh)2]2 (2129, 2143 cmꢀ1),
(tBu2Pz)Al(CBCPh)2(HCCSiMe3) (2075 cmꢀ1) as well
as aluminum compounds with bridging acetylide ligands
between two aluminum atoms such as [(CH3)2AlCB
CCH3]2 (2101 cmꢀ1) [20] have CBC stretching fre-
quencies comparable with those in 5–8. However, the
CBC stretching band in carbaalane (AlMe)8(CCH2Ph)5
(CBCPh) [6] (1957 cmꢀ1), where the acetylide ligand is
bridging between four aluminum atoms, is lower than
those in 5–8. It is not possible to assign the bonding
mode of acetylides in 5–8 from infrared spectroscopy.
The variation of the Salen ligand seems to have no effect
on the CBC stretch.
2.3. Structural description of [Salophen(tBu)Al]2O (9)
The structure is unambiguously confirmed in the
single crystal analysis (Fig. 1). Table 2 summarizes the
crystal data and Table 3 the bond angles and lengths of
9. In one molecule, two Salophen(tBu)Al units are
connected together through a bridging oxygen atom.
This is similar to the reported dimeric structure of [Sa-
len(tBu)Al]2O [9]. The largest Al–O–Al bond angle
(173.1(1)°) was reported for 9 (Table 2) in comparison
with other Al analogues (e.g., 159.5(5)° in [Sa-
len(tBu)Al]2O, 152.0(3)° in (SalenAl)2O [21]) and
(139.1–144.6°) in (SalenFe)2O [22]). The large Al–O–Al
bond angle and staggered conformation of the salo-
phen(tBu) ligands result from steric contact between the
ꢀ
ligands. The Al–(l-O) bond distance (1.6840(4) A) in 9 is
shorter than that observed in [Salen(tBu)Al]2O
ꢀ
(1.696(3)A). According to the reported method, the va-
2.2. Synthesis and characterization of 9
lue s (Tau), which measures how closely a distorted five-
coordinate compound approximates either a trigonal
bipyramidal or square pyramidal geometry, was calcu-
lated [23]. The s value (0.23) of 9 suggests that the
Like Salen aluminum amides [9] and azides [18],
5–8 are very moisture sensitive. In the presence of
N
N
N
N
Al
H2O
Al
O
O
O
O
OH
-
H
Ph
tBu
tBu
tBu
tBu
tBu
tBu
tBu
tBu
Ph
Salophen(tBu)AlOH
-H2O
[Salophen(tBu)Al]2O (9)
Scheme 2. Hydrolysis mechanism of five-coordinate aluminum acetylides.

762
Y. Wang et al. / Journal of Organometallic Chemistry 689 (2004) 759–765
Fig. 1. Structure of [Salophen(tBu)Al]2O (9).
Table 3
Table 2
Crystal data for compound [Salophen(tBu)Al]2O (9)
t
ꢀ
Selected bond lengths (A) and angles (°) for [Salophen( Bu)Al]2O (9)
Al–O(1)
Al–O(2)
Al–O(3)
Al–N(1)
Al–N(2)
O(1)-C(1)
1.8168(10) O(2)–C(24)
1.8074(10) O(3)–Al(A)
1.3125(16)
1.6842(4)
Formula weight
Color
Crystal size (mm3)
Crystal system
Space group
665.86
Yellow
0.38 ꢁ 0.32 ꢁ 0.30
monoclinic
C2=c
24.489(2)
17.0210(10)
18.9950(10)
89.89
1.6840(4)
N(1)–C(15)
1.2957(18)
1.4218(17)
1.4211(17)
1.3008(18)
2.0479(12) N(1)–C(16)
2.0341(12) N(2)–C(21)
1.3188(17) N(2)–C(22)
ꢀ
a (A)
ꢀ
b (A)
O(1)–Al–O(2)
O(1)–Al–O(3)
O(2)–Al–O(3)
O(1)–Al–N(1)
O(2)–Al–N(1)
O(3)–Al–N(1)
O(1)–Al–N(2)
O(2)–Al–N(2)
O(3)–Al–N(2)
Al–O(1)–C(1)
89.69(4)
110.63(4)
107.23(6)
86.44(5)
C(15)–N(1)–C(16) 121.03(12)
ꢀ
c (A)
Al–N(2)–C(21)
Al–N(2)–C(22)
C(21)–N(2)–C(22) 119.66(12)
115.83(9)
124.07(10)
a (°)
b (°)
c (°)
106.263(10)
89.97
152.67(5)
99.43(5)
O(1)–C(1)–C(2)
O(1)–C(1)–C(14)
120.82(12)
121.22(12)
ꢀ3
V (A )
7600.8(9)
8
2872
Z
139.00(5)
87.87(5)
N(1)–C(15)–C(14) 124.79(13)
N(1)–C(16)–C(17) 126.13(13)
N(1)–C(16)–C(21) 113.73(12)
N(2)–C(22)–C(23) 126.49(13)
N(2)–C(21)–C(16) 114.40(12)
N(2)–C(21)–C(20) 126.35(13)
O(2)–C(24)–C(23) 120.57(12)
O(2)–C(24)–C(25) 121.41(12)
F ð000Þ
D(calcd) (g cmꢀ3
)
1.164
0.092
109.15(4)
129.20(9)
l (mmꢀ1
Unique data measured
)
8684
1.05
Al–O(2)–C(24) 132.79(9)
Al–O(3)–Al(A) 173.1(1)
Al–N(1)–C(15) 123.04(10)
Al–N(1)–C(16) 115.30(9)
S (goodness of fit)
structure is best described as distorted square pyramidal.
This value is comparable with Salophen(tBu)AlOSiPh3
(s 0.17) [18]. For the analogue [Salen(tBu)Al]2O, how-
ever, the s value is 0.46. A value of 0.50 is intermediary
between trigonal bipyramidal and square pyramidal.
use. NMR data were obtained on JEOL-GSX-400 and
)270 instruments at 270.17 (1H), 62.5 (13C), and 104.5
(27Al) MHz. Chemical shifts are reported relative to
SiMe4 and are in ppm. Elemental analyses were ob-
tained on a Perkin–Elmer 2400 analyzer and were found
to be within acceptable limits for 5–9. Infrared data
were recorded as KBr pellets on a Matheson Instru-
ments 2020 Galaxy Series spectrometer and are re-
ported in cmꢀ1. LiCBCPh was purchased from Aldrich
and used without further purification. L(tBu)AlCl
(where L ¼ Salen (1), Salpen (2), Salophen (3), Salom-
phen (4)) were prepared by the literature method [9].
3. Experimental
3.1. General
All manipulations were conducted using Schlenck
techniques in conjunction with an inert atmosphere
Glove box. All solvents were rigorously dried prior to

Y. Wang et al. / Journal of Organometallic Chemistry 689 (2004) 759–765
763
The common names of the Salen-ligands are created by
inserting the backbone abbreviation between ‘‘Sal-’’ and
‘‘en’’.
(CBCPh), 171.1 (NCH). d 27Al NMR (52.1 MHz,
CDCl3) 41 (W1=2 ¼ 1302 Hz). MS(EI, positive): m=z: 632
([Mþ], 100%). IR (KBr, m, cmꢀ1): 2957(vs), 2905(m),
2868(m), 1640(s), 1619(vs), 1604(s), 1556(m), 1542(m),
1485(m), 1475(s), 1461(s), 1440(m), 1417(m), 1391(m),
1361(m), 1343(m), 1315(m), 1278(m), 1258(m), 1238(m),
1202(m), 1177(s), 860(m), 844(m), 757(m), 633(m). Anal.
Calc. for C41H53N2O2Al: C, 77.81; H, 8.44. Found: C,
77.97; H, 8.39%.
3.2. Syntheses
3.2.1. Salen(tBu)AlCBCPh (5)
Salen(tBu)AlCl (0.500 g, 0.904 mmol) was dissolved
in 40 mL of THF and cooled to )78 °C, and then a
cooled solution ()78 °C) of lithium phenylacetylide
(0.098 g, 0.905 mmol) in 40 mL of THF was added. The
solution was gradually warmed to ambient temperature
and stirred for an additional 4 h, and then the solvent
was removed under reduced pressure to give a pale
yellow solid, which was extracted using 80 mL of di-
chloromethane and then filtered. Compound 5 was iso-
lated by removing the solvent from the filtrate. Yield:
0.47 g (84%). Melting point 244–246 °C.
3.2.3. Salomphen(tBu)AlCBCPh (7)
Salomphen(tBu)AlCl (0.500 g, 0.795 mmol) was dis-
solved in 40 mL of THF and cooled to )78 °C, and then
a cooled solution ()78 °C) of lithium phenylacetylide
(0.086 g, 0.796 mmol) in 40 mL of THF was added. The
solution was gradually warmed to ambient temperature
and stirred for an additional 4 h, and then the solvent
was removed under reduced pressure to give a deep red
solid. This was then extracted using 50 mL of dichlo-
romethane, filtered and the compound isolated by re-
moving the solvent from the filtrate. Yield: 0.51 g (92%).
Melting point 270–273 °C.
1
Spectroscopic data: d H NMR (200 MHz, CDCl3)
1.33 (s, 18H, CCH3), 1.59 (s, 18H, CCH3), 3.73 (m, 2H,
NCH2), 4.18 (m, 2H, NCH2), 7.04 (d, 2H, Ph-H), 7.17
(m, 5H, CBCPh-H), 7.56 (d, 2H, Ph-H), 8.35 (s, 2H,
NCH). d 13C NMR (50 MHz, CDCl3) 29.7 (CCH3), 31.3
(CCH3), 33.9 (CCH3), 35.5 (CCH3), 54.9 (NCH2), 106.0
(br, AlCB), 122.0 (CBCPh), 118.3, 127.1, 131.7, 138.0,
141.2, 163.3 (Ph-ligand), 126.0, 126.4, 127.6, 130.7
(CBCPh), 169.8 (NCH). d 27Al NMR (52.1 MHz,
CDCl3) 39 (W1=2 ¼ 1042 Hz). MS(EI, positive): m=z: 618
([Mþ], 100%). IR (KBr, m, cmꢀ1): 2956(s), 2905(m),
2868(m), 1648(s), 1625(vs), 1556(m), 1541(m), 1486(m),
1474(m), 1444(m), 1418(m), 1390(m), 1361(m), 1336(m),
1311(m), 1276(m), 1256(m), 1236(m), 1203(m), 1177(m),
865(m), 754(m). Anal. Calc. for C40H51N2O2Al: C,
77.64; H, 8.31. Found: C, 77.48; H, 8.29%.
1
Spectroscopic data: d H NMR (200 MHz, CDCl3)
1.38 (s, 18H, CCH3), 1.66 (s, 18H, CCH3), 2.38 (s, 6H,
Ph-CH3), 7.12 (m, 5H, CBCPh-H), 7.22 (d, 2H, Ph-H),
7.53 (s, 2H, Ph-H), 7.64 (d, 2H, Ph-H), 8.87 (s, 2H,
NCH). d 13C NMR (50 MHz, CDCl3) 20.0 (Ph-C H3),
29.9 (CCH3), 31.3 (CCH3), 34.0 (CCH3), 35.4 (CCH3),
105.1 (br, AlCB), 122.0 (CBCPh), 116.4, 118.8, 127.6,
131.9, 136.3, 137.3, 138.7, 141.5, 161.4 (Ph-ligand),
126.0, 126.3, 128.0, 131.7 (CBCPh), 164.4 (NCH). d 27Al
NMR (52.1 MHz, CDCl3) 40 (W1=2 ¼ 625 Hz). MS(EI,
positive): m=z: 694 ([Mþ], 100%). IR (KBr, m, cmꢀ1):
2955(vs), 2905(m), 2868(m), 1619(vs), 1590(s), 1552(s),
1537(vs), 1501(m), 1486(m), 1470(s), 1441(m), 1418(m),
1386(m), 1360(m), 1278(m), 1255(m), 1234(m), 1202(m),
1193(m), 1178(s), 1045(m), 846(m), 788(m), 755(m),
639(m). Anal. Calc. for C46H55N2O2Al: C, 79.50; H,
7.98. Found: C, 79.11; H, 8.25%.
3.2.2. Salpen(tBu)AlCBCPh (6)
Salpen(tBu)AlCl (1.000 g, 1.763 mmol) was dissolved
in 40 mL of THF and cooled to )78 °C, and then a
cooled solution ()78 °C) of lithium phenylacetylide
(0.191 g, 1.767 mmol) in 40 mL of THF was added. The
solution was gradually warmed to ambient temperature
and stirred for an additional 4 h, and then the solvent
was removed under reduced pressure to give a pale
yellow solid, which was extracted using 80 mL of di-
chloromethane and then filtered. Compound 6 was iso-
lated by removing the solvent from the filtrate. Yield:
0.98 g (88%). Melting point 217–219 °C.
3.2.4. Salophen(tBu)AlCBCPh (8)
Salophen(tBu)AlCl (1.000 g, 1.663 mmol) was dis-
solved in 40 mL of THF and cooled to )78 °C, and then
a cooled solution ()78 °C) of lithium phenylacetylide
(0.180 g, 1.664 mmol) in 40 mL of THF was added. The
solution was gradually warmed to ambient temperature
and stirred for an additional 4h, and then the solvent
was removed under reduced pressure to give a deep red
solid, which was then extracted using 50 mL of dichlo-
romethane, filtered and compound (8) was isolated by
removing the solvent from the filtrate. Yield: 0.98 g
(88%). Melting point 98–103 °C.
1
Spectroscopic data: d H NMR (200 MHz, CDCl3)
1.32 (s, 18H, CCH3), 1.54 (s, 18H, CCH3), 2.20 (m, 2H,
CH2CH2), 3.63 (m, 2H, NCH2), 4.07 (m, 2H, NCH2),
7.03 (d, 2H, Ph-H ), 7.17 (m, 5H, CCPh-H), 7.52 (d, 2H,
Ph-H), 8.24 (s, 2H, NCH). d 13C NMR (50 MHz,
CDCl3) 27.5 (CH2CH2), 29.7 (CCH3), 31.4 (CCH3),
34.0 (CCH3), 35.4 (CCH3), 54.9 (NCH2), 105.5 (br,
AlCB), 122.0 (CBCPh), 118.1, 127.0, 131.7, 137.9,
141.0, 163.0 (Ph-ligand), 126.1, 126.4, 127.7, 130.6
1
Spectroscopic data: d H NMR (200 MHz, CDCl3)
1.40 (s, 18H, CCH3), 1.69 (s, 18H, CCH3), 7.15 (m, 5H,
CBCPh-H), 7.24 (d, 2H, Ph-H), 7.41 (m, 2H, Ph-H),
7.68 (d, 2H, Ph-H), 7.77 (m, 2H, Ph-H), 8.91 (s, 2H,

764
Y. Wang et al. / Journal of Organometallic Chemistry 689 (2004) 759–765
NCH). d 13C NMR (50 MHz, CDCl3) 29.8 (CCH3), 31.3
(CCH3), 34.0 (CCH3), 35.6 (CCH3), 105.1 (br, AlCB),
122.1 (CBCPh), 115.6, 118.6, 127.5, 131.5, 132.3, 138.4,
138.7, 141.4, 162.3 (Ph-ligand), 125.8, 126.3, 128.0, 131.6
(CBCPh), 164.7 (NCH). d 27Al NMR (52.1 MHz,
CDCl3) 40 (W1=2 ¼ 834 Hz). MS (EI, positive): m=z: 666
([Mþ], 100 %). IR (KBr, m, cmꢀ1): 2956(vs), 2904(m),
2868(m), 1617(vs), 1583(s), 1552(s), 1538(vs), 1487(m),
1470(m), 1441(m), 1414(m), 1388(m), 1360(m), 1275(m),
1261(m), 1200(m), 1180(m), 1047(m), 845(m), 788(m),
755(m), 639(m), 598(m). Anal. Found: C, 79.40; H, 7.75.
Calc. for C44H51N2O2Al: C, 79.25; H, 7.71.
4. Supplementary Material
Crystallographic data for the structure described in
this paper have been deposited with the Cambridge
Crystallographic Data Center, CCDC number 223833.
Copies of the data can be obtained free of charge on
application to The Director, CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK (Fax: +44-1223-336033;
e-mail deposit@ccdc.cam.ac.uk or http://www.ccdc.cam.
ac.uk).
Acknowledgements
3.2.5. [Salophen(tBu)Al]2O (9)
(a) Salophen(tBu)AlCBCPh (0.01 g, 0.015 mmol) was
dissolved in 5 mL of toluene in an NMR tube. Yel-
low crystals of compound 9 were observed in the
tube after being left close-capped in air for one
week. The byproduct HCBCPh was observed by
1H NMR.
NMR instruments used in this study were obtained
with funds from the CRIF program of the NSF (CHE
997841).
(b) Salophen(tBu)AlCl (1.000 g, 1.663 mmol) was dis-
solved in 40 mL of THF and cooled to )78 °C,
and then a cooled solution ()78 °C) of lithium
phenylacetylide (0.180 g, 1.664 mmol) in 40 mL of
THF was added. The solution was gradually
warmed to ambient temperature and stirred for an
additional 4h, and then the solvent was removed
under reduced pressure to give a deep red solid.
The red solid was added into 20 mL of toluene
and heated at reflux for 30 min. Overnight a large
number of yellow crystals of [Salophen(tBu)Al]2O
were observed. Yield: 0.830 g (87%). Melting point
400 °C.
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Spectroscopic data: d H NMR (200 MHz, CDCl3)
1.30(s, 36H, CCH3), 1.46(s, 36H, CCH3), 6.80(d, 4H, Ph-
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