2,6-Di(4-t-butylphenyl)phenyl-group 13 organometallic compounds

Article abstract of DOI:10.1016/j.jorganchem.2006.05.024

Reaction of MX₃ (M = Al, Ga, In; X = Br, Cl) with RLi (R = 2,6-(4-t-BuC₆H₄)₂C₆H₃) affords RGaCl₂ · OEt₂, 1, RAlBr₂ · OEt₂, 2, R₂GaCl, 3, and R₃In, 4. These sterically demanding compounds have been characterized by elemental analyses, ¹H NMR spectroscopy, and single crystal X-ray diffraction. The geometry about the metal centers in 1 and 2 is best described as distorted tetrahedral while the coordination about the gallium atom in 3 is distorted trigonal planar. Compound 4, with the indium atom in a trigonal planar environment, is noteworthy as the first example of a tris(m-terphenyl)group 13 metal compound. The propeller arrangement of the three ligands in compound 4 serves to virtually encapsulate the metallic center.

Full text of DOI:10.1016/j.jorganchem.2006.05.024

Journal of Organometallic Chemistry 691 (2006) 3765–3770
www.elsevier.com/locate/jorganchem
2,6-Di(4-t-butylphenyl)phenyl-group 13 organometallic compounds
*
Brandon Quillian, Yuzhong Wang, Pingrong Wei, Adele Handy, Gregory H. Robinson
Department of Chemistry, The University of Georgia, Athens, GA 30602-2556, USA
Received 19 April 2006; received in revised form 12 May 2006; accepted 12 May 2006
Available online 20 May 2006
Abstract
Reaction of MX3 (M = Al, Ga, In; X = Br, Cl) with RLi (R = 2,6-(4-t-BuC6H4)2C6H3) affords RGaCl2 Æ OEt2, 1, RAlBr2 Æ OEt2, 2,
R2GaCl, 3, and R3In, 4. These sterically demanding compounds have been characterized by elemental analyses, 1H NMR spectroscopy,
and single crystal X-ray diffraction. The geometry about the metal centers in 1 and 2 is best described as distorted tetrahedral while the
coordination about the gallium atom in 3 is distorted trigonal planar. Compound 4, with the indium atom in a trigonal planar environ-
ment, is noteworthy as the first example of a tris(m-terphenyl)group 13 metal compound. The propeller arrangement of the three ligands
in compound 4 serves to virtually encapsulate the metallic center.
Ó 2006 Elsevier B.V. All rights reserved.
Keywords: Aluminum; Gallium; Group 13; Indium; Terphenyl ligand
1. Introduction
limited. Herein, we report the syntheses and molecular
structures of RGaCl2 Æ OEt2, 1, RAlBr2 Æ OEt2, 2, R2GaCl,
3, and R3In, 4 (R = 2,6-di(4-t-butylphenyl)phenyl, 2,6-
(4-t-BuC6H4)2C6H3). The geometry about the metal centers
in 1 and 2 is best described as distorted tetrahedral while
the coordination about the gallium atom in 3 approaches
distorted trigonal planar. Compound 4, with the indium
atom in a trigonal planar environment, is noteworthy as
a rare example of a tris-m-terphenyl-group 13 metal com-
pound. The propeller arrangement of the three ligands in
4 serves to effectively shield the indium center.
Sterically demanding ligands have played a prominent
role in the development of group 13 organometallic chem-
istry. In particular, m-terphenyl ligands have been exten-
sively utilized to stabilize low-valent, low-coordinate,
organometallic group 13 compounds [1–3]. That the struc-
ture and bonding of a given compound may be dramati-
cally tuned as a function of ligand steric loading has been
a practical method to afford interesting organometallic
compounds with intriguing properties. This concept is ele-
gantly illustrated by cyclogallenes, M2[GaR]3 (M = Na [4],
K [5]; R = 2,6-Mes2C6H3; Mes = 2,4,6-Me3C6H2), metal-
loaromatic gallium ring systems [1,6]. Another notable
example of this concept is the digallyne, Na2[RGa„GaR]
(R = 2,6-(2,4,6-i-Pr3C6H2)2C6H3) [7]. The digallyne and
cyclogallenes are typically prepared by alkali metal reduc-
tion of the respective RGaCl2 (R = m-terphenyl) species.
Surprisingly, efforts to evaluate the organometallic group
13 chemistry of less bulky m-terphenyl ligands have been
2. Results and discussion
Investigation of the 2,6-di(4-t-butylphenyl)phenyl ligand
was undertaken in an effort to gain further insight into the
significance of substitution at the ortho position of the
outer phenyl rings, or the lack thereof, when employing ste-
rically encumbered m-terphenyl-based ligands [8]. It has
been shown that this ligand has the tendency for facile
intramolecular C–H bond activation of the ortho position
of the outer phenyl ring, which may serve as a mechanism
to form an in situ generated bidentate ligand that provides
robust steric protection for the metal center [9]. The
*
Corresponding author. Tel.: +1 706 542 1853; fax: +1 706 542 9454/
1972.
E-mail address: robinson@chem.uga.edu (G.H. Robinson).
0022-328X/$ - see front matter Ó 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2006.05.024

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B. Quillian et al. / Journal of Organometallic Chemistry 691 (2006) 3765–3770
gallium halides are illustrated as neutral monomers without
diethyl ether coordination, RGaCl2 [13], dimeric com-
plexes, [RGaCl2]2 [13–15], and anionic complexes,
[RGaCl3]À (R = m-terphenyl ligand) [16]. Although the
synthesis of RGaCl2 Æ OEt2 (R = 2,6-(2,4,6-i-Pr3C6H2)2-
C6H3) was previously reported [13], structural data was
MX3
.
1: M = Al; X = Br
2: M = Ga; X = Cl
RMX2 OEt2
GaCl3
InCl3
RLi
R2GaCl, 3
˚
R3In, 4
not presented. The Ga(1)–O(1) distance in 1, 2.041(4) A,
is only slightly longer than that of (2,4,6-i-Pr3C6H2)Ga-
Cl2 Æ THF (2.011(4) A) [12]. The Ga(1)–O(1) bond distance
Scheme 1.
˚
in 1 is longer than the Ga–O bonds of 2,6-Mes2C6H3-
˚
based/gallium compounds, R2GaOH (1.7833(17) A),
literature reveals a paucity of reports of 2,6-di(4-t-butyl-
phenyl)phenyl based group 13 compounds [10,11]. The
reactivity of RLi (R = 2,6-(4-t-BuC6H4)2C6H3) with group
13 metals was of interest, as to ascertain the stability and
structural properties of the ligand–metal complexes. Com-
pounds 1–4 were prepared by reaction of the appropriate
group 13 halide with RLi (Scheme 1). Although these com-
pounds are all air- and moisture-sensitive, they are stable
for months under an inert atmosphere.
Single crystal X-ray analysis reveals that 1 is a mono-
meric 2,6-di(4-t-butylphenyl)phenylgallium chloride ether-
ate with two independent molecules in one asymmetric
unit (Fig. 1). Compound 1 is the first single crystal X-ray
structurally characterized m-terphenylgallium halide ether-
ate, RGaX2 Æ OEt2. In general, halide-bridged dimers,
[RGaCl2]2 [12], are usually observed for (m-terphenyl)gal-
lium dihalides. Thus, the formation of 1 is notable.
Previous structural reports of mono-ligated m-terphenyl-
˚
[RGa(Cl)(l-OH)]2 (1.938(2)–1.942(2) A), and [RGa(Me)-
(l-OH)]2 (1.9110(9)–1.942(2) A) [17], and exemplifies the
˚
weak diethyl ether coordination interaction with the metal
in 1. The C(1)–Ga(1)–O(1) bond angle, 105.89(15)°, is the
largest bond angle of those involving the ether donor mol-
ecule in 1 and most closely fits with tetrahedral geometry.
Notably, the O(1)–Ga(1)–Cl(2) bond angle, 95.05(11)°, is
quite small, and although the O(1)–Ga(1)–Cl(1) bond
angle, 101.47(11)°, is larger, it still deviates from the
expected value. Inspection of the remaining bond angles
in 1 reveals that the C(1)–Ga(1)–Cl(1) and C(1)–Ga(1)–
Cl(2) bond angles, 123.49(12)° and 118.72(13)°, respec-
tively, are much larger than the Cl(1)–Ga(1)–Cl(2) bond
angle, 106.70(6)°, which may be a consequence of steric
repulsion between the ligand and chlorides. In fact, acute
Cl–Ga–Cl bond angles are common among four coordi-
nate m-terphenylgallium chloride complexes. The dimeric
complex, [RGaCl2]2 (R = 2,6-Mes2C6H3), was shown to
have Cl–Ga–Cl bond angles as small as 86.8(2)° [14,15].
˚
The Ga–C bond distance in 1 of 1.985(5) A compares well
with other m-terphenylgallium chloride compounds, which
˚
range from 1.930(8) to 1.985(1) A [13–15,18], and similarly
to those in (Me5C6)3Ga, (mean bond distance of
˚
1.981(5) A) [19]. The Ga–Cl bond distances in 1 are unre-
˚
markable with a mean bond distance of 2.205 A.
The structure of 2 (Fig. 2) reveals a four-coordinate alu-
minum atom in a distorted tetrahedral environment. The
Fig. 1. Molecular structure of (2,6-(4-t-BuC6H4)2C6H3)GaCl2 Æ OEt2, 1
Fig. 2. Molecular structure of (2,6-(4-t-BuC6H4)2C6H3)AlBr2 Æ OEt2, 2
(thermal ellipsoids are shown at 35% probability levels). Selected bond
distances (A) and angles (°): Ga(1)–C(1), 1.985(5); Ga(1)–Cl(1),
(thermal ellipsoids are shown at 35% probability levels). Selected bond
˚
˚
distances (A) and angles (°): Al(1)–C(1), 1.979(5); Al(1)–Br(1), 2.3175(17);
2.1872(13); Ga(1)–Cl(2), 2.2238(14); Ga(1)–O(1), 2.041(4); C(1)–Ga(1)–
Cl(1), 123.49(12); C(1)–Ga(1)–Cl(2), 118.72(13); C(1)–Ga(1)–O(1),
105.89(15); O(1)–Ga(1)–Cl(1), 101.47(11); O(1)–Ga(1)–Cl(2), 95.05(11);
Cl(1)–Ga(1)–Cl(2), 106.70(6).
Al(1)–Br(2), 2.3010(16); Al(1)–O(1), 1.876(4); C(1)–Al(1)–Br(1),
117.46(15); C(1)–Al(1)–Br(2), 120.10(15); C(1)–Al(1)–O(1), 106.67(19);
O(1)–Al(1)–Br(1), 97.94(14); O(1)–Al(1)–Br(2), 104.23(14); Br(1)–Al(1)–
Br(2), 107.23(6).

B. Quillian et al. / Journal of Organometallic Chemistry 691 (2006) 3765–3770
3767
C(1)–Al(1)–Br(1) and C(1)–Al(1)–Br(2) bond angles,
117.46(15)° and 120.10(15)°, respectively, are significantly
distorted from classical tetrahedral geometry and are closer
to predicted trigonal planar angles. Conversely, the Br(1)–
Al(1)–O(1) bond angle, 97.94(14)°, is much smaller than
the anticipated 109.5°. An interesting feature of 2 can be
seen along the Al–C(1) vector, which is bent away from
the phenyl ring plane by 15.54°(avg.). This distortion
may be due to packing forces in the crystal lattice, a factor
that allows flexibility in the ionic Al–C bond [20]. Compar-
ison of 2 with (2,6-(4-t-BuC6H4)2C6H3)AlH2(NMe3), 5, is
warranted, as it is the only 2,6-di(4-t-butylphenyl)phenyl-
aluminum compound [10]. The Al(1)–C(1) bond distance
˚
˚
in 2, 1.979(5) A, is shorter than that in 5 (2.018(2) A), but
compares well with the only other reported m-terphenyl
stabilized aluminum bromide etherate, RAlBr2 Æ OEt2,
˚
(R = 2,4,6-Ph3C6H2) (1.983(9) A) [20], and the organoalu-
minum bromide dimer, [RAlBr3Li]2 (R = 2,6-Mes2C6H3),
˚
1.96(2) A [21]. The structure of 2 shows that the Br(2) atom
is almost orthogonal with respect of the central phenyl
ring, and the two outer phenyl rings are tilted to it. The
˚
Al(1)–Br(1) bond distance in 2, 2.3175(17) A, is slightly
longer than the Al(1)–Br(2) bond, 2.3010(16) A, but both
Fig. 3. Molecular structure of (2,6-(4-t-BuC6H4)2C6H3)2GaCl, 3 (thermal
˚
ellipsoids are shown at 35% probability levels). Selected bond distances
are similar to those in RAlBr2 Æ OEt2 (R = 2,4,6-Ph3C6H2),
˚
(A) and angles (°): Ga(1)–C(1), 1.981(3); Ga(1)–C(27), 1.997(3); Ga(1)–
˚
(2.297(3) and 2.302(3) A), but slightly shorter than those in
Cl(1), 2.2537(10); C(1)–Ga(1)–C(27), 137.37(12); C(1)–Ga(1)–Cl(1),
106.69(9); C(27)–Ga(1)–Cl(1), 115.76(9).
˚
[RAlBr3Li]2, (R = 2,6-Mes2C6H3), (mean 2.347 A) [21].
Compound 3 joins a small group of R2GaX compounds,
(R = m-terphenyl, X = halide) [14,16,22], although a series
of analogous hydrides, alkyls, and a hydroxyl have been
reported [17]. The gallium atom in 3 is three-coordinate
in a distorted trigonal planar environment (Fig. 3). Corre-
spondingly, other R2GaX compounds (R = 2,6-Ph2C6H3;
X = I [16], and R = 2,6-Mes2C6H3; X = Cl [22], Br [14]),
all have distorted trigonal planar environments around
the gallium metal center. The C–Ga–Br bond angles in
(2,6-Mes2C6H3)2GaBr, are identical (101.8(2)°). Similarly,
the chloride analogue has C–Ga–Cl bond angles of
103.2(4)° and 103.4(4)°. However, the corresponding
C(1)–Ga(1)–Cl(1) and C(27)–Ga(1)–Cl(1) bond angles in
3, 106.69(9)° and 115.76(9)°, respectively, are asymmetric.
The C(1)–Ga(1)–C(27) bond angle of 3, 137.37(12)°, is lar-
ger than the C(1)–Ga(1)–C(1a) bond angle (134.3(3)°) in
(2,6-Ph2C6H3)2GaI, but expectedly smaller than that of
the ‘‘T shaped’’ (2,6-Mes2C6H3)2GaX (X = Cl, Br) com-
pounds (153.5°). The Ga(1)–C(1) and Ga(1)–C(27) bond
formation of 4 from reaction of RLi and InCl3 in a 1:1
ratio is interesting. The poor solubility of InCl3 may have
been a factor in the preparation of 4. The sharp melting
point and accurate elemental analysis is indicative of 4
being the sole product. Consideration of the X-ray
structure of 4 provides an interesting contrast from the
organo/group 13 halides discussed above (Fig. 4). Com-
pound 4 crystallizes as a monomer with one molecule of
diethyl ether per asymmetric unit. The indium atom in 4
is in a distorted trigonal planar coordination environment
with C–In–C angles of C(1)–In(1)–C(27), 114.77(13)°;
C(1)–In(1)–C(53),
120.34(12)°;
C(27)–In(1)–C(53),
124.83(13)° and are similar to those in trimesitylindium,
Mes3In [29], and triphenylindium, Ph3In [30,31]. However,
a twofold axis was observed for Ph3In that is not evident in
4. The three ligands in 4 are arranged about the indium
atom in a propeller like fashion and are not crystallograph-
ically equivalent due to differing dihedral angles with
respect to the InC3-core plane. The dihedral planes were
found to be 39.84°, 31.95°, and 65.37° for the C(1), C(27)
and C(53) central phenyl ring planes, respectively. The
˚
lengths in 3, 1.981(3) and 1.997(3) A, respectively, compare
well with other reported diarylgallium halides, while the
˚
Ga(1)–Cl(1) bond length in 3, 2.2537(10) A, is somewhat
˚
longer than that in (2,6-Mes2C6H3)2GaCl, 2.177(5) A.
˚
In–C bonds in 4 (In(1)–C(1), 2.200(3) A; In(1)–C(27),
With the growing utility of triorganoindium compounds
for fundamental organic transformations such as conjugate
addition [23], cross-coupling [24–26], and allylic substitu-
tion reactions [27,28], and the ubiquitous use of m-terphe-
nyl ligands in organometallic-group 13 chemistry, it is
noteworthy that there are no reports of tris(m-terphe-
nyl)indium compounds. Compound 4, the first tris
(m-terphenyl)group 13 compound, is noteworthy. The
˚
˚
2.199(3) A; In(1)–C(53), 2.193(3) A) are comparable to
˚
˚
˚
those in Mes3In (2.170(5) A; 2.170(5) A; 2.163(5) A), Ph3In
(2.111(14) A; 2.155(14) A), and (2,6-Mes2C6H3)2InBr
(2.171(25) A; 2.166(26) A) [32]. These values for 4 are com-
parable to those in [(2,6-Mes2C6H3)InCl2]2 (2.138(8) A)
˚
˚
˚
˚
˚
˚
[33] and [(2,6-(2,4,6-i-Pr3C6H2)2C6H3)InCl2]2 (2.129(5) A)
[15].

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B. Quillian et al. / Journal of Organometallic Chemistry 691 (2006) 3765–3770
4.2. Synthesis of (2,6-(4-t-BuC6H4)2C6H3)GaCl2 Æ OEt2
(1)
GaCl3 (1.76 g, 10 mmol) in diethyl ether (25 mL) was
rapidly transferred to a yellow slurry of (2,6-(4-t-BuC6H4)2-
C6H3)Li (3.47 g, 10 mmol) in diethyl ether (40 mL) at ca.
À78 °C and allowed to slowly warm to r.t. After stirring
for 48 h, a clear pale yellow solution was filtered from a
white precipitate. All solvent was removed in vacuo and then
the residue was extracted in hexane/diethyl ether (1:1,
20 mL) and placed at r.t. for 2 days, which resulted colorless,
cubic crystals (2.13 g, 38% m.p. 212–214 °C), Elemental
Anal. Calc. (found) for C30H39Cl2GaO (556.26): C, 64.78
1
(64.67); H, 7.07 (6.94); H NMR (THF-D8, 400 MHz) d
1.116 (q, 6H, –OCH2CH3); 1.360 (s, 18H, C(CH3)3); 3.385
(t, 4H, –OCH2CH3); 7.377–7.493 (m, 11H, Ar–H).
4.3. Synthesis of (2,6-(4-t-BuC6H4)2C6H3)AlBr2 Æ OEt2
(2)
Fig. 4. Molecular structure of (2,6-(4-t-BuC6H4)2C6H3)3In, 4 (thermal
ellipsoids are shown at 35% probability levels). Selected bond distances
(A) and angles (°): In(1)–C(1), 2.200(3); In(1)–C(27), 2.199(3); In(1)–C(53),
2.193(3); C(1)–In(1)–C(27), 114.77(13); C(1)–In(1)–C(53), 120.34(12);
AlBr3 (1.29 g, 4.8 mmol) in diethyl ether (30 mL) was
rapidly transferred by cannula to a yellow slurry of (2,6-
(4-t-BuC6H4)2C6H3)Li (1.69 g, 4.8 mmol) in diethyl ether
(40 mL) at ca. À78 °C and allowed to warm slowly to r.t.
After stirring for 72 h, a colorless solution with white preci-
pitant was observed. The solution was filtered from precipi-
tant and solvent reduced by a third and then placed in
freezer at À20 °C. After 3 days a yellow viscous, oily residue
formed. The colorless solution was filtered from the oil and
then reduced by a third and placed at r.t. for 3 days which
gave colorless, rectangular crystals (2.25 g, 78%; m.p. 196–
198 °C), Elemental Anal. Calc. (found) for C30H39AlBr2O
˚
C(27)–In(1)–C(53), 124.83(13).
3. Conclusion
In summary, 2,6-di(4-t-butylphenyl)phenyl-based group
13 organometallic compounds, 1–4, have been synthesized
1
and characterized by elemental analyses, H NMR spec-
troscopy, and single crystal X-ray diffraction. Compound
1 represents the first single crystal X-ray structurally
characterized m-terphenylgallium dihalide etherate, while
4 represents the first reported tris(m-terphenyl)group 13
compound.
1
(604.42): C, 59.81 (59.64); H, 6.53 (6.50); H NMR (D6-
benzene, 400 MHz) d 0.451 (t, 6H, –OCH2CH3), 1.236 (s,
18H, C(CH3)3), 3.219 (q, 4H, –OCH2CH3), 7.347–7.410
(m, 7H, Ar–H), 7.866–7.887 (m, 4H, Ar–H).
4. Experimental
4.4. Synthesis of (2,6-(4-t-BuC6H4)2C6H3)2GaCl (3)
4.1. General comments
GaCl3 (1.22 g, 6.95 mmol) in diethyl ether (25 mL) was
rapidly transferred to a yellow slurry of (2,6-(4-t-BuC6H4)2-
C6H3)Li (4.85 g, 13.9 mmol) in diethyl ether (40 mL) at ca.
À78 °C and allowed to slowly warm to r.t. After stirring for
12 h, a clear yellow solution with white precipitant was
observed. The solution was filtered from the precipitant
and solvent reduced by half. After 3 days at r.t. colorless,
cubic crystals formed (2.35 g, 43%; m.p. 202–204 °C),
Elemental Anal. Calc. (found) for C52H58GaCl (788.19):
C, 79.24 (79.06); H, 7.42 (7.61); 1H NMR (THF-D8,
400 MHz) d 1.31 (s, 18H, C(CH3)3); 6.987–7.267 (m,
11H, Ar–H).
Standard Schlenk techniques were employed in
conjunction with an inert-atmosphere drybox (MBraun
Labmaster 130). Solvents were distilled under an argon
atmosphere with sodium benzophenone. Argon was
passed through copper-based purification and molecular
sieve drying columns prior to use. Aluminum(III)
bromide, gallium(III) chloride, indium(III) chloride,
4-tert-butylphenyl bromide, n-butyllithium, and 1,3-
dichlorobenzene were purchased from Aldrich Chemical
Co. (Milwaukee, WI) and used without further purifica-
tion. 2,6-Di(4-tert-butylphenyl)iodobenzene, 2,6-(4-t-Bu-
C6H4)2C6H3I [34], and (2,6-(4-t-BuC6H4)2C6H3)Li [35],
were prepared according to the literature methods. Ele-
mental analyses were performed by Complete Analysis
Laboratories Inc. (Parsippany, NJ). 1H NMR spectra
were recorded on a Varian Mercury plus 400 MHz
spectrometer.
4.5. Synthesis of (2,6-(4-t-BuC6H4)2C6H3)3In (4)
A yellow slurry of (2,6-(4-t-BuC6H4)2C6H3)Li (1.69 g,
4.8 mmol) in diethyl ether (40 mL) was transferred by can-
nula to a slurry of InCl3 (1.07 g, 4.8 mmol) in diethyl ether

B. Quillian et al. / Journal of Organometallic Chemistry 691 (2006) 3765–3770
3769
Table 1
Crystal data and structural refinement for compounds 1–4
Compound
1
2
3
4
Empirical formula
Formula weight
Color, habit
C30H39GaCl2O
556.23
Colorless, cubic
Orthorhombic
Pna21
24.640(7)
11.365(3)
21.545(6)
C60H78Al2Br4O2
1204.82
Colorless, cubic
Monoclinic
P21/n
24.1758(17)
11.5810(8)
24.6206(16)
C52H58GaCl
788.15
Colorless, cubic
Monoclinic
P21/n
17.587(4)
13.911(3)
19.968(4)
C82H97InO
1213.42
Colorless, cubic
Triclinic
Crystal system
ꢀ
Space group
P1
˚
a (A)
11.6636(13)
15.0818(16)
21.278(2)
103.912(2)
96.812(2)
90.555(2)
2
˚
b (A)
˚
c (A)
a (°)
b (°)
c (°)
Z
118.4790(10)
110.010(4)
8
4
4
3
˚
V (A )
6033(3)
50
6059.1(7)
50
4590.4(16)
50
3604.6(7)
50
Maximum 2h
Unique reflections
Observed reflections [I > 2r(I)]
R1 [I > 2r(I)], wR2
Goodness-of-fit
10,454
8626
0.0463, 0.1124
1.042
0.416 and À0.213
10,646
6450
0.0550, 0.1512
1.008
0.605 and À0.755
8018
5961
0.0472, 0.1284
1.019
0.789 and À0.188
12,638
10,872
0.0531, 0.1444
1.068
0.883 and À0.536
3
˚
Largest difference in peak and hole (e/A )
(30 mL) at ca. À78 °C. The reaction was allowed slowly
warm to r.t. After 3 days of stirring, a clear, colorless solu-
tion with an appreciable amount of white precipitant was
observed. The solution was filtered from precipitant and
solvent reduced and placed in freezer at À20 °C. After 10
days, colorless, flat, rectangular crystals formed (0.21 g,
11.5%; m.p. 288–290 °C), Elemental Anal. Calc. (found)
for C78H87In (1139.34): C, 82.23 (82.51); H, 7.70 (7.76);
1H NMR (D6-benzene, 400 MHz) d1.218 (s, 18H,
C(CH3)3), 6.972–7.227 (m, 11H, Ar–H).
tropically except for one carbon atom (C60) on the coor-
dinated ether molecule. For compound 2, the non-
hydrogen atoms were refined anisotropically except for
t
carbon atoms on three disordered Bu groups and two
disordered ether molecules which coordinate with Al
t
atoms. The three Bu groups on the phenyl of the ligand
are found disordered in adjacent positions with half occu-
pancies of each, while four ethyl groups on the two
diethyl ether groups are found disordered in adjacent
positions in four sets which are divided using the PART
command. For compound 4 non-hydrogen atoms were
refined anisotropically except for four disordered tBu
groups on the phenyl rings. The four tBu groups on
the phenyl of ligands are found disordered in adjacent
positions with half occupancies of each. Except for the
4.6. X-ray crystallographic study
Colorless crystals of 1–4 were mounted in glass capil-
laries under an atmosphere of argon in the drybox. The
X-ray intensity data were collected at room temperature
on a Bruker SMART TM CCD-based X-ray diffractom-
eter system with graphite-monochromated Mo Ka radia-
t
carbon atoms of disordered Bu groups, hydrogen atom
positions were calculated. Crystallographic data for 1–4
are summarized in Table 1.
˚
tion (k = 0.710–73 A), using the x-scan technique. The
structures were solved by direct methods using the SHEL-
XTL 6.1 bundled software package [36]. The data were
corrected for Lorentz and polarization effects and
integrated with the manufacturer’s SAINT software.
Absorption corrections were applied with the SADABS.
Non-hydrogen atomic scattering factors were taken from
the literature tabulations [37]. The heavy atom positions
were determined using direct methods employing the
SHELXTL routine methods. The remaining non-hydrogen
atoms were located from successive difference Fourier
map calculations. In the final cycles of each refinement
hydrogen atom positions were calculated and allowed
to ride on the carbon to which they are bonded assuming
Acknowledgement
We are grateful to the National Science Foundation and
to the donors of the Petroleum Research Fund, adminis-
tered by the American Chemical Society, for support of
this work.
Appendix A. Supplementary material
Crystallographic data (excluding structure factors) for
the structures 1–4 have been deposited with the Cambridge
crystallographic Data Centre 1: CCDC No. 601863; 2:
CCDC No. 601866; 3 CCDC No. 601864; 4 CCDC No.
601865. These can be obtained free of charge via
www.ccdc.cam.ac.uk/data_request/cif, or by emailing
data_request@ccdc.cam.ac.uk, or by contacting The Cam-
bridge Crystallographic Data Centre, 12, Union Road,
˚
a C–H bond length of 0.95 A. Hydrogen atom tempera-
ture factors were fixed at 1.10 times the isotropic temper-
ature factor of the C-atom to which they are bonded. For
compound 1, the non-hydrogen atoms were refined aniso-

3770
B. Quillian et al. / Journal of Organometallic Chemistry 691 (2006) 3765–3770
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