Coordination chemistry of the tetrakis(2-hydroxyphenyl)ethene support mimic - Polymetallic magnesium, aluminum, and titanium derivatives

Article abstract of DOI:10.1139/v05-108

The crystal structures of magnesium, aluminum, and titanium coordination complexes of the structurally preorganized tetrakis(2-hydroxyphenyl)ethene are reported. As a result of the absence of steric shielding and the conformational flexibility of the ligand, pseudo-dimeric complexes are formed instead of crown- or raft-like compounds. The unsubstituted tetrakis(2-hydroxyphenyl)ethene ligand thus emulates the complexation characteristics of the sterically open calix[4]arene system.

Full text of DOI:10.1139/v05-108

9
22
Coordination chemistry of the tetrakis(2-
hydroxyphenyl)ethene support mimic —
Polymetallic magnesium, aluminum, and titanium
1
derivatives
Udo H. Verkerk, Robert McDonald, and Jeffrey M. Stryker
Abstract: The crystal structures of magnesium, aluminum, and titanium coordination complexes of the structurally
preorganized tetrakis(2-hydroxyphenyl)ethene are reported. As a result of the absence of steric shielding and the
conformational flexibility of the ligand, pseudo-dimeric complexes are formed instead of crown- or raft-like com-
pounds. The unsubstituted tetrakis(2-hydroxyphenyl)ethene ligand thus emulates the complexation characteristics of the
sterically open calix[4]arene system.
Key words: coordination chemistry, polymetallic, titanium complexes, magnesium complexes, aluminum complexes,
tetrakis(2-hydroxyphenyl)ethene ligands, crystal structures.
Résumé : On a déterminé les structures cristallines de complexes de coordination de tétrakis(2-hydroxyphényl)éthène
structuralement préorganisés avec du magnésium, de l’aluminium et du titane. En raison de l’absence de protection sté-
rique et de flexibilité conformationnelle du ligand, il y a formation de complexes pseudodimères au lieu de composés
en forme de couronnes ou de bateau. Le ligand non substitué tétrakis(2-hydroxyphényl)éthène émule donc les caracté-
ristiques de complexation du système calix[4]arène stériquement ouvert.
Mots clés : chimie de coordination, polymétallique, complexes du titane, complexes du magnésium, complexes de
l’aluminium, ligands tétrakis(2-hydroxyphényl)éthène, structures cristallines.
[
Traduit par la Rédaction] Verkerk et al. 928
Introduction
complexes formed by coordination to tetrakis(2-
hydroxyphenyl)ethene.
The recently introduced tetrakis(2-hydroxyphenyl)ethene
ligand I (1), a topologically unique analogue of calix[4]-
arene II (2), should by virtue of the constrained arrangement
of four phenol groups be useful for modeling the coordina-
tion chemistry of an oxo surface. As reported for various
calix[4]arenes (2b, 3), such an arrangement imposes unique
reactivity on complexed metals (3) and could act as an addi-
tive (4) or model (3c) for heterogeneous supports as used in
industrial polymerization catalysis (5). Here we report the
crystal structures of magnesium, aluminum, and titanium
O
O O O
O
O
O
O
R
R
R R
I
II
Results and discussion
Whereas the reaction of tetrakis(2-hydroxyphenyl)ethene
(
1) with Et Al in pentane yields the hydrocarbon soluble,
3
Received 3 December 2004. Published on the NRC Research
Press Web site at http://canjchem.nrc.ca on 28 July 2005.
crown-like compound 2, the reaction of the tetraarylethene
with Et AlCl generates a pentane insoluble precipitate, pre-
2
Dedicated to Professor Howard Alper for his many and
unique contributions to transition-metal catalysis and his
extraordinary service to the field of chemistry in Canada.
sumably the result of predominant intermolecular association
(
Scheme 1). The addition of THF as a stronger coordinating
solvent discourages intermolecular coordination and improves
the solubility, allowing isolation of tetrametallic aluminum
complex 3 after crystallization from THF–toluene. Com-
pound 3 shows, in the centrosymmetric crystal structure
(Fig. 1), two pentacoordinate aluminum centers as part of a
Al O four-membered ring and two pentacoordinate
2
U.H. Verkerk and J.M. Stryker. Department of Chemistry,
University of Alberta, 11227 Saskatchewan Drive NW,
Edmonton, AB T6G 2G2, Canada.
R. McDonald. X-Ray Crystallography Laboratory,
Department of Chemistry, University of Alberta, 11227
Saskatchewan Drive NW, Edmonton, AB T6G 2G2, Canada.
2
2
ethylaluminum chloride fragments sandwiched in between
two highly distorted tetraphenylethene ligands. The observed
Al2—O4 bond length in the peripheral pentacoordinate frag-
ment Al2 (Table 1) is within the range observed for alumi-
1This article is part of a Special Issue dedicated to Professor
Howard Alper.
2
Corresponding author (e-mail: jeff.stryker@ualberta.ca).
Can. J. Chem. 83: 922–928 (2005)
doi: 10.1139/V05-108
© 2005 NRC Canada

Verkerk et al.
923
Scheme 1.
Table 1. Key bond lengths (Å), angles (°), and dihed-
ral angles (°) for aluminum complex 3.
Et
Al
Et
Al
Et
Al
Et
Et
O
O
Bond lengths (Å)
Et
O
Al
Et
Et Al (xs)
3
O
Al1—O1
Al1—O3
Al1—O4
Al2—O4
Al2—Cl
Al1—O2′
Al1—O3′
Al2—O2′
Al2—O5
Al2—C3
1.741(4)
1.860(3)
1.923(3)
1.844(4)
2.166(2)
1.802(4)
1.895(3)
2.080(4)
2.010(4)
1.959(6)
Et
pentane, RT
(ref. 1a)
HO
OH
OH
2
OH
1
Et
i. Et AlCl (xs)
2
O O
Al
O
Cl
O
O
pentane, RT
Al
Al
Al
ii. Toluene,
THF, RT
Cl
O
O
O
O
Et
O
Bond angles (°)
O1-Al1-O4
O3-Al1-O4
O2′-Al1-O4
O4-Al1-O3′
O5-Al2-O2
93.47(16)
93.70(15)
78.19(15)
169.21(16)
160.64(16)
3
Fig. 1. Perspective view (ORTEP) of compound 3 showing the
atom labeling scheme. Hydrogen atoms have been omitted for
clarity. Primed atoms are related to the unprimed ones via the
crystallographic inversion center (0,0,0).
Tetrakis(2-phenoxy)ethene ligand dihedral angles (°)
C2-C1-C11-C16
C11-C1-C2-C41
C21-C1-C2-C31
135.9(5)
–14.4(8)
–24.4(7)
The tetrakis(2-phenoxy)ethene ligand itself is highly dis-
torted in the crystal structure (Fig. 2), with three phenoxy
groups coordinating to Al1 and the other phenoxy group co-
ordinating to Al1′. One of the phenoxy groups (O1) coordi-
nated to Al1 is angled in towards the plane of the ethene
bond (dihedral angle C2-C1-C11-C16: 135.9°) to bring that
group into an equatorial binding position. This position re-
sembles one of the transition states for the rotational
isomerization of the tetraarylethene aryl ring (8). Simulta-
neously, the geminal phenoxy O2 is rotated outward into a
position that allows the bridging of Al1′ and Al2′. As a re-
sult, the double bond is twisted between 14° and 24° to ac-
commodate the metal binding (Table 1).
It is of interest to compare the observed bonding with that
of the previously reported aluminum-fused bis-p-tert-
butylcalix[4]arene (7). This structure was obtained by the re-
action of the corresponding calix[4]arene with the tertiary
amine adduct of aluminum hydride, and shows a sandwich
ligand arrangement around a Al O core similar to the crys-
tal structure reported here. The calix[4]arene ligands, how-
ever, are only slightly distorted, presumably a function of the
markedly different topology inherent to the [4]cyclophane
structure. In contrast to the tetrakis(2-hydroxyphenyl)ethene
derived complex, one calix[4]arene ligand binds all four
phenoxy groups to a single, distorted, pentacoordinate alu-
minum atom.
num phenoxides (lit. (6, 7) value 1.79–1.895 Å), as are the
Al2—Cl (lit. (6) value 2.104–2.199 Å) and Al2—C3 (lit. (6)
value 1.946–1.994 Å) bond lengths. The axial Al2—O
bonds are considerably longer (avg. 2.045 Å). The varying
2
2
3
bond angles O -Al2-O (see Supplementary information),
eq
eq
and the O5-Al2-O2′ bond angle of 160.64(16)° (Table 1) in-
dicate a distorted trigonal bipyramidal geometry. These fea-
tures are repeated in the pentacoordinate fragment around
Al1, with longer Oaxial—Al (avg. 1.909 Å) compared to the
Oequatorial—Al (avg. 1.801 Å) bond lengths (see Table 1).
The observed range of O4-Al1-O1, O2′, and O3 angles
(
(
78.19–93.70°, Table 1), and the O4-Al1-O3′ angle
The reaction of tetrakis(2-hydroxyphenyl)ethene with
methylmagnesium chloride is of interest because it may be
possible to isolate discrete, raft-like, magnesium complexes
169.21(16)°) again indicate a significantly distorted trigonal
bipyramidal geometry.
3
Supplementary data for this article are available on the Web site or may be purchased from the Depository of Unpublished Data, Document
Delivery, CISTI, National Research Council Canada, Ottawa, ON K1A 0S2, Canada. DUD 4001. For more information on obtaining mate-
rial refer to http://cisti-icist.nrc-cnrc.gc.ca/irm/unpub_e.shtml. CCDC 263379–263381 contain the crystallographic data for this manuscript.
These data can be obtained, free of charge, via www.ccdc.cam.ac.uk/conts/retrieving.html (Or from the Cambridge Crystallographic Data
Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax +44 1223 336033; or deposit@ccdc.cam.ac.uk).
©
2005 NRC Canada

9
24
Can. J. Chem. Vol. 83, 2005
Fig. 2. Alternate view of compound 3 from “above” the
tetrakis(2-phenoxy)ethane ligand showing the variation in twist-
ing of the phenyl rings.
Fig. 3. Perspective view (ORTEP) of compound 4 showing the
atom labeling scheme. Hydrogen atoms have been omitted for
clarity. A weak interaction between Mg1 and the C1=C2 double
bond is indicated by the thin Mg1-C1 and Mg1-C2 lines.
that could be used to introduce transition metals on the mag-
nesium oxide like layer and study the catalytic behavior of
such bimetallic heterogeneous catalyst models. However,
even in the strongly coordinating solvent THF, the reaction
between the Grignard reagent and tetrakis(2-hydroxy-
phenyl)ethene yields only sparingly soluble material, from
which the unusual polymagnesiated complex 4 could be iso-
lated by crystallization from hot THF – toluene (eq. [1]).
The crystal structure of compound 4 shows a sandwich of
five magnesium atoms, with coordination numbers ranging
from four to six, arrayed between two tetrakis(phen-
oxy)ethene molecules (Fig. 3). Such an arrangement mini-
mizes intermolecular interactions and accommodates
saturating the coordination demands of the magnesium cat-
ions; as a result, the cluster shows significant solubility. Un-
fortunately, the crystallographic analysis is hindered by the
weak data set obtained and by the limited number of previ-
ously reported aryloxymagnesium solid-state structures (9).
In the crystal structure, Mg4 and Mg5 (Fig. 4) are four co-
ordinate with a distorted tetrahedral geometry according to
the wide range of O-Mg-Cl and O-Mg-O angles (see Supple-
length of 2.031(4) Å, also follows observations in the litera-
ture (9e). Pentacoordinate Mg2 has a distorted trigonal
bipyramidal coordination with O -Mg-O angles ranging
eq
ax
from 80.1° to 102.5°, and an O -Mg-O range of 90.6°–
eq
eq
3
143.1° (see Supplementary information). The Mg—O bond
lengths are irregular, but more or less follow the behavior of
metal alkoxides (9e): as the degree of bridging by an oxygen
increases, so does the Mg—O bond length (Mg2—O1,
Mg2—O8 > Mg2—O5, Mg2—O6; Table 2). Within the ob-
served range, the Mg2—O8 bond length (2.241(12) Å) is
much larger than the Mg2—O1 bond length (2.020(12) Å).
This may be a ligand imposed effect or, possibly, a conse-
quence of crystal packing forces. The observed Mg—OTHF
bond length falls within the reported range of Mg–ether
bonds (2.033–2.232 Å) (9d).
In the crystal structure, two hexacoordinate magnesium at-
oms are also present, Mg1 and Mg3 (Fig. 5), with a wide
range of bond lengths (Mg—O: 1.973(12)–2.317(11) Å, lit.
(9) value 2.0379–2.244 Å) and bond angles (O-Mg-O, cis:
77.6(4)°–106.7(5)°, lit. (9) value 78.4°–85.5°; see Supple-
3
mentary information). The observed Mg—O (avg. 1.97 Å),
and Mg—Cl (avg. 2.27 Å) bond lengths are comparable to
published bond lengths for Mg—µ-O (1.93–1.98 Å) and
Mg—Cl (2.27 Å) in tetracoordinate magnesium structures
3
mentary information). No π complexes of an olefin with
Mg are known, but the data presented here do not support a
definitive Mg–ethene interaction. First, the shortest Mg1—C
(
9). The Mg–THF coordination, Mg4—O12, with a bond
HO
OH
OH
i. MeMgCl
4 equiv.)
OH
O
Mg
O
O
O
O
Cl
(
O
[1]
Mg
Mg
O
O
O
Mg
THF, RT
ii. THF,
toluene, ∆
Cl
Mg
O
O
O
1
4
©
2005 NRC Canada

Verkerk et al.
925
Fig. 5. Alternate view of compound 4, omitting thermal ellip-
soids for the carbon atoms, emphasizing the coordination envi-
ronment for Mg1 and Mg3. A weak interaction between Mg1
and the C1, C2 double bond is indicated by dashed lines. The
distance between Mg1 and the center of the C1, C2 double bond
is 2.432 Å.
Fig. 4. Alternate view of compound 4, omitting thermal ellip-
soids for the carbon atoms, emphasizing the coordination envi-
ronment for Mg2, Mg4, and Mg5.
Table 2. Key bond lengths (Å), angles (°), and dihedral angles
(
°) for magnesium complex 4.
Mg1, Mg3 (hexacoordinated) bond lengths (Å)
The tetraarylethene framework involved in bonding to
Mg1 shows minimal distortion of the C1—C2 ethene bond,
with phenyl ring – ethene bond dihedral angles ranging from
C1—Mg1
C2—Mg1
2.530(17)
2.514(17)
Mg2 (pentacoordinated) bond lengths (Å)
9
4° to 107° (Table 2) and Mg1—O bond lengths ranging
Mg2—O1
Mg2—O6
Mg2—O11
Mg2—O5
Mg2—O8
2.020(12)
1.994(11)
2.069(13)
1.994(11)
2.241(12)
from 1.973(12) to 2.120(11) Å (see Supplementary informa-
tion). The second tetraarylethene moiety centered around
3
C3—C4 shows a distorted double bond and an irregular
phenyl ring twist motif (Table 2). As observed for the alumi-
num compound, the metal coordination preferences appear
to dictate the ligand geometry and binding.
Mg4, Mg5 (tetracoordinated) bond lengths (Å)
The direct approach to forming Mg–Ti bimetallic
procatalysts was attempted by using nonheterogeneous con-
ditions for in situ generation of the magnesium salt of the
Mg4—O12
2.031(13)
Tetrakis(2-phenoxy)ethene ligands dihedral angles (°)
C51-C3-C4-C71
C51-C3-C4-C81
C1-C2-C31-C36
C1-C2-C41-C42
C3-C4-C71-C76
C3-C4-C81-C82
C11-C1-C2-C41
C61-C3-C4-C71
C61-C3-C4-C81
C2-C1-C21-C22
C2-C1-C11-C16
C4-C3-C51-C56
C4-C3-C61-C62
–154(16)
21(3)
97(2)
94(2)
61(2)
74(2)
–1(3)
18(3)
–166.6(16)
107(2)
103.3(19)
82(2)
more
soluble
ligand
tetrakis(2-hydroxy-5-tert-butyl-
phenyl)ethene (5) (1a). Thus, the magnesium salt was gener-
ated in THF, followed by the addition of TiCl (eq. [2]). Un-
4
fortunately, crystallization did not result in isolation of a
bimetallic Ti–Mg compound, producing instead a homobi-
metallic titanitum complex. The crystal structure of
dititanium complex 6 is quite similar to the aluminum and
magnesium sandwich complexes 3 and 4 (Fig. 6). Trapped
tBu
tBu
tBu
tBu
58(2)
HO
OH
OH
OH
i. EtMgCl
4 equiv.)
O O
O
Ti
(
O
[
2]
Ti
O
O
distance (2.514(17) Å) is well beyond the Mg—C bond dis-
tances observed for an alkyne complex (10d), although
within the range of Mg—(π-C) bonds observed for magne-
sium-cyclopentadienyl interactions (10a–10c). Secondly, the
position of the Mg relative to a plane defined by O1-O2-O3-
O4 is 0.1 Å further away from the ethene bond.
THF, RT
ii. TiCl4
(1 equiv.)
O
tBu
O
tBu
tBu
5
tBu
tBu
tBu
tBu
6
©
2005 NRC Canada

9
26
Can. J. Chem. Vol. 83, 2005
Fig. 6. Perspective view (ORTEP) of compound 6 showing the
atom labeling scheme. Hydrogen atoms are not shown. Primed
atoms are related to unprimed ones via the crystallographic in-
version center (0, 0, 0) at the center of the molecule.
Table 3. Key bond lengths (Å), angles (°), and dihedral angles
(°) for titanium complex 6.
Bond lengths (Å)
Ti—O1
Ti—O2
Ti—O4′
Ti—O3
1.812(4)
1.806(4)
1.813(4)
1.934(4)
2.122(4)
Ti—O3′
Bond angles (°)
O1-Ti-O3
O1-Ti-O4′
O1-Ti-O3′
O2-Ti-O3
O2-Ti-O4′
O3-Ti-O4′
93.93(19)
102.43(19)
166.14(19)
128.11(18)
112.12(19)
112.53(18)
Tetrakis(2-phenoxy)ethene ligands dihedral angles (°)
C11-C1-C2-C41
C11-C1-C2-C31
C1-C2-C41-C46
C1-C2-C31-C32
C21-C1-C2-C31
C21-C1-C2-C41
C2-C1-C21-C22
C2-C1-C11-C16
–172.5(5)
7.6(8)
36.8(8)
88.1(7)
–169.3(6)
10.6(10)
76.2(8)
95.1(7)
nificantly tilted towards the ethene bond plane with a dihed-
ral angle of 37° (Table 3). A similar combination of a single
phenyl ring and double bond torque is also observed in alu-
minum complex 3.
between two tetraarylethene units are two titanium atoms in
a centrosymmetric arrangement. No coordinating solvent
molecules or magnesium chloride fragments are present. The
observed Ti—O bond lengths are within the expected range
Conclusion
(
lit. (11, 12) value 1.809–1.937 Å, Table 3), except for the
In all cases reported here, ligand dimers surrounding a set
of metal atoms rather than raft-like surface analogues are
isolated. In this way, intermolecular interactions are mini-
mized to produce the solubility required for crystallization.
The tetrakis(2-aryloxy)ethene ligands incorporated in these
structures show a surprising flexibility in both ethene bond
torsion and aryl ring twist. Taken together, the limited solu-
bility of the initially obtained metal–ligand complexes, the
preferential formation of pseudo-dimeric products, and the
pronounced deformation of the ligand geometry all suggest
that modification of the ligand system (1b) is required to
prevent indiscriminate ligand–metal interactions. The results
of such ligand modifications on the ligand–metal coordina-
tion will be reported in forthcoming publications.
Ti—O3′ bond length (2.122(4) Å), which is significantly
longer. If four coordination is assumed, the Ti—O1, O2,
O4′, and O3 bond lengths should be approximately the same,
which is the case. However, the observed bond angles of
O1-Ti-O3 (93.93°) and O2-Ti-O3 (128.11°) show significant
deviations from true tetrahedral geometry. The deviation
could be due to ligand-imposed restrictions on the O2-Ti-O3
angle, given that the O2 and O3 are positioned across the
ethene bond, but this argument does not appear to apply to
the O1-Ti-O3 angle. If instead a pentacoordinate titanium is
assumed, the variation in the Ti—Oaxial and Ti—Oequatorial
bond lengths become apparent, as well as the irregularity of
O -Ti-O and O -Ti-O bond angles (see Table 3). On
eq
eq
eq
ax
this basis, the metals in complex 6 may best be considered
five-coordinate, albeit distorted. The dilemma with regard to
coordination of the titanium atoms is similar to that reported
for a p-tert-butylcalix[4]arene titanium complex (12). This
structure, obtained from the reaction of Ti(NMe ) with p-
tert-butylcalix[4]arene, shows two tetracoordinated titanium
atoms between two calix[4]arene ligands. The authors opted
for tetracoordination on the basis of a weak Ti—O bridging
interaction (2.473 Å), a significantly longer bond than that
observed for Ti—O3′ in complex 6 (2.122(4) Å) (Table 3).
The tetraarylethene framework also shows distortion in
the planarity of the ethene bond, with a dihedral angle range
of 7.6°–10.6°. Three of the phenyl ring – ethene bond dihed-
ral angles fall in the range of 76°–88°, the fourth ring is sig-
Experimental
Reagents and solvents
All solvents were distilled from appropriate drying agents
under nitrogen. The tetrakis(2-hydroxyaryl)ethene ligands
were prepared by published procedures (1).
2
4
General methods
All manipulations were carried out in oven-dried glass-
ware, under a dry and oxygen-free nitrogen atmosphere
using a Vacuum Atmospheres drybox. Spectroscopic and el-
emental analyses to establish the identity and purity of bulk
samples were severely constrained by a combination of very
©
2005 NRC Canada

Verkerk et al.
927
Table 4. Crystallographic experimental details.
Crystal
Complex 3
Complex 4
Complex 6
Empirical formula
C H Al Cl O
C H Cl Mg O
C H O Ti
2
7
8
74
4
2
10
77 76
2
5
12.5
98 112
8
Formula mass
Crystal habit
Crystal dimensions (mm )
Crystal system
1350.19
1 393.83
1513.68
Colorless, block
0.27 × 0.23 × 0.21
Triclinic
Colorless, block
0.19 × 0.10 × 0.09
Orthorhombic
Plates, red-brown
0.20 × 0.08 × 0.06
Monoclinic
3
Space group
P1 (No. 2)
Pna2 (No. 33)
P2 /c (No. 14)
1
1
Z
1
4
2
Unit cell parameters
a (Å)
b (Å)
c (Å)
α (°)
β (°)
γ (°)
12.184 0 (13)
12.890 7 (18)
13.556 8 (13)
66.485 (9)
87.343 (8)
62.822 (9)
24.781 2 (16)
20.720 9 (16)
14.849 5 (11)
12.325 6 (16)
23.396 (3)
15.248 4 (17)
107.982 (3)
Collection ranges
–14 ≤ h ≤ 0,
–27 ≤ h ≤ 31,
–25 ≤ k ≤ 25,
–15 ≤ h ≤ 15,
–29 ≤ k ≤ 29,
–
13 ≤ k ≤ 12,
–
213
16 ≤ l ≤ 16
–17 ≤ l ≤ 18
193
–15 ≤ l ≤ 19
193
Temperature (K)
3
Volume (Å )
1712.6 (3)
1.309
7 625.1 (10)
1.214
4182.4 (9)
1.202
–
3
Dcalcd. (g cm )
Diffractometer
Siemens P4/RA
Bruker P4/RA/SMART 1000 CCD Bruker P4/RA/SMART 1000
CCD
Radiation (λ, Å)
Graphite-monochromated
Mo Kα (0.710 73)
Graphite-monochromated
Mo Kα (0.710 73)
Graphite-monochromated
Mo Kα (0.710 73)
φ Rotations (0.3°) / ω scans
(0.3°) (30 s exposures)
0.248
Scan type
φ Rotations (0.3°) / ω scans
(
0.3°) (30 s exposures)
–
1
Absorption coeff. (µ, mm ) 0.207
Absorption correction
Data collection 2θ limit (°)
Observed reflections (NO)
0.185
Semi-empirical (ψ scans)
Multi-scan (SADABS)
52.80
Multi-scan (SADABS)
52.88
50.00
3333 (Fo2 ≥ 2σ(F ))
2
4 463 (Fo ≥ 2σ(F ))
2
2
2426 (Fo ≥ 2σ(F ))
2
2
o
o
o
Independent reflections
Data/restraints/parameters
Goodness-of-fit (S)
Final R indices
5519 (Rint = 0.040 7)
15 313 (Rint = 0.256 3)
8559 (Rint = 0.241 6)
5519 (F 2 ≥ –3σ(F )) / 6 / 386
2
15 313 (Fo2 ≥ –3σ(F )) / 10 / 784 8559 (Fo2 ≥ –3σ(F )) / 6 / 436
2
2
o
o
o
o
1.013 (F 2 ≥ –3σ(F ))
2
0.887 (Fo2 ≥ –3σ(F ))
2
0.812 (Fo2 ≥ –3σ (F ))
2
o
o
o
o
R1 [Fo2 ≥ 2σ(F )] = 0.074 7,
wR [Fo2 ≥ –3σ(F )] = 0.182 0
2
R1 [Fo2 ≥ 2σ(F )] = 0.086 4,
2
R1 [Fo2 ≥ 2σ(F )] = 0.072 5,
2
o
o
o
2
2
2
2
2
wR [F
≥
–3 (F )] = 0.282 8
σ
wR [F ≥ –3σ(F )] = 0.180 5
2 o o
2
o
2
o
o
Largest difference peak and 0.749 and –0.569
hole (e Å )
0.811 and –0.382
0.498 and –0.586
–
3
low solubility (complexes 3 and 4) and systematic inconsis-
tencies in the analytical data obtained from combustion ele-
mental analyses. The latter may arise either from bulk
heterogeneity or from incomplete combustion (presumably a
consequence of metal oxide formation), difficulties common
to the coordination complexes of highly electrophilic metals.
To some extent, such problems mirror those identified in the
coordination chemistry of the calix[4]arenes.
from toluene at –30 °C in a glovebox freezer, yielded crys-
tals of insufficient quality and size. This material was
redissolved in toluene with the addition of a small amount of
THF, from which crystals of sufficient quality for X-ray dif-
fraction were obtained at –30 °C.
Polymagnesium complex 4
A
solution of 0.12 g (0.3 mmol) of tetrakis(2-
hydroxyphenyl)ethene in 12 mL THF was added to 0.5 mL
(1.2 mmol) of a rapidly stirred solution of 3 mol/L
Tetraaluminum complex 3
To a stirred suspension of 37 mg (0.1 mmol) tetrakis(2-
hydroxyphenyl)ethene in 10 mL pentane was added 245 mg
methylmagnesium chloride solution in Et O. After 12 h at
2
room temperature, the solvents were removed under vacuum
and the resulting solid resuspended in a small amount of
THF. After removal of soluble by-products by decanting, the
remaining solid was dissolved in a minimum of boiling THF.
After addition of toluene, crystals of sufficient quality for an
X-ray diffraction study were obtained by leaving the solu-
tion undisturbed at room temperature for several days.
(
0.5 mmol) Et AlCl as a 25 wt% solution in toluene diluted
2
in 5 mL pentane. A bright yellow suspension formed. No
ethane formation was observed. After stirring overnight, the
solvent was removed under vacuum and the remaining resi-
due resuspended in pentane. After removal of the pentane by
decanting, a solid was obtained that, after crystallization
©
2005 NRC Canada

9
28
Can. J. Chem. Vol. 83, 2005
Dititanium complex 6
Fujita, G. Qi, U.H. Verkerk, T.L. Dzwiniel, R. McDonald, and
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Wieser, C.B. Dieleman, and D. Matt. Coord. Chem. Rev. 165,
A solution of 0.12 g (0.2 mmol) of tetrakis(2-hydroxy-5-
tert-butyl-phenyl)ethene in 10 mL of THF was slowly added
to a stirred THF solution (10 mL) of EtMgCl (70 mg,
2
3
0
.8 mmol). After stirring for 1 h at room temperature, a so-
lution of 65 mg (0.2 mmol) TiCl ·2THF dissolved in 3 mL
4
THF was added. After stirring for 12 h at room temperature,
the solution was reduced in vacuo to 5 mL and 20 mL
pentane was added. The precipitate obtained was isolated
from the supernatant by decanting and washed with and ad-
ditional 20 mL of pentane. The solid was extracted with
9
3 (1997); (c) C. Floriani and R. Floriani-Moro. Adv.
Organomet. Chem. 47, 167 (2001); (d) F.T. Ladipo, V.
Sarveswaran, J.V. Kingston, R.A. Huyck, S.Y. Bylikin, S.D.
Carr, R. Watts, and S. Parkin. J. Organomet. Chem. 689, 502
(2004).
4
0 mL of toluene and the resulting deep red solution reduced
in vacuo to 5 mL. Crystals of sufficient quality for an X-ray
diffraction study were obtained after repeated recrystalliza-
tions from toluene at –30 °C.
4. R.A. Kemp, D.S. Brown, M. Lattman, and J. Li. J. Mol. Catal.
A: Chem. 149, 125 (1999).
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H.A. Jasim, M.F. Lappert, and H.D. Williams. Polyhedron, 9,
X-ray crystallographic analysis
Crystals obtained as described were mounted on a glass
fiber from a pool of Paratone-N and immediately placed un-
6
der
a
cold nitrogen stream and mounted on the
diffractometer. Diffraction data were collected on Siemens
P4/RA (compound 3) or Bruker P4/RA/SMART 1000 CCD
2
39 (1990); (c) R. Kumar, M.L. Sierra, V.S. de Mel, and J.P.
(
compounds 4 and 6) using Mo Kα radiation (Table 4); de-
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Rappoport and S.E. Biali. Acc. Chem. Res. 30, 307 (1997).
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3
tails are reported as Supplementary information. For com-
pound 3, unit cell parameters were obtained from least-
squares refinement of 44 reflections with 22.0° < 2θ < 24.8°.
Unit cell parameters for compounds 4 and 6 were obtained
from least-squares refinement of 5270 and 3028 centered re-
flections, respectively. The data for compound 3 were semi-
empirically corrected for absorption. The data for com-
pounds 4 and 6 were absorption corrected using the
SADABS procedure (15). The structures of compounds 3
and 6 were solved using the SHELXS-86 program (13), the
7
2
refinement method was a full-matrix least-squares on F
using the program SHELXL-93 (14). For compound 3,
distances involving the methyl carbons of the inversion-
disordered solvent toluene molecules were given fixed ideal-
ized values. For compound 6, the methyl carbon positions of
the disordered solvent toluene molecule were refined in
idealized positions by fixing d(Cmethyl—Cipso) = 1.54 Å and
d(Cmethyl···Cortho) = 2.54 Å. The toluene ring carbons were
refined as idealized hexagons with d(C—C) = 1.39 Å. For
compound 4, the structure solution program used was a
DIRDIF-96 (16) and the refinement program SHELXL-93
3
9, 235 (2000); (d) G. Guillemot, E. Solari, C. Rizzoli, and C.
Floriani. Chem. Eur. J. 8, 2072 (2002); (e) K.W. Henderson,
G.W. Honeyman, A.R. Kennedy, R.E. Mulvey, J.A. Parkinson,
and D.C. Sherrington. J. Chem. Soc. Dalton Trans. 1365 (2003).
0. (a) J.L. Atwood and K.D. Smith. J. Am. Chem. Soc. 96, 994
1
1
(
(
1974); (b) P. Jutzi. Adv. Organomet. Chem. 26, 217 (1975);
c) C. Johnson, J. Toney, and G.D. Stucky. J. Organomet.
Chem. 40, C11 (1975); (d) S.I. Troyanov, V. Varga, and K.
Mach. Organometallics, 12, 2820 (1993).
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Chem. Commun. 610 (1986); (b) A.G. Orpen, L. Brammer,
F.H. Allen, O. Kennard, D.G. Watson, and R. Taylor. J. Chem
Soc. Dalton Trans. S1 (1989); (c) W. Clegg, M.R.J. Elsegood,
S.J. Teat, C. Redshaw, and V.C. Gibson. J. Chem. Soc. Dalton
Trans. 3037 (1998).
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Am. Chem. Soc. 107, 8087 (1985).
3. G.M. Sheldrick. Acta Crystallogr. Sect. A, A46, 467 (1990).
4. G.M. Sheldrick. SHELXL-93 [computer program]. University
of Göttingen, Göttingen, Germany. 1993.
5. G.M. Sheldrick. SADABS [computer program]. University of
Göttingen, Göttingen, Germany. 1996.
6. P.T. Beurskens, G. Beurskens, W.P. Bosman, R. de Gelder, S.
Garcia Granda, R.O. Gould, R. Israel, and J.M.M. Smits. The
DIRDIF-96 program system. Crystallography Laboratory, Uni-
versity of Nijmegen, Nijmegen, The Netherlands. 1996.
(
14). An idealized geometry was imposed upon the solvent
THF. Full details of the crystal structure determinations are
included as Supplementary information.3
Acknowledgement
1
Financial support from NOVA Chemicals Corporation and
the Natural Sciences and Engineering Research Council of
Canada (NSERC, CRD and CRO grant programs) is grate-
fully acknowledged.
1
1
1
1
References
1
. (a) U.H. Verkerk, M. Fujita, T.L. Dzwiniel, R. McDonald, and
J.M. Stryker. J. Am. Chem. Soc. 124, 9988 (2002); (b) M.
©
2005 NRC Canada