Synthesis of the bulky m-terphenyl phenol Ar*OH (Ar* = C 6H3-2,6-Mes2, Mes = 2,4,6-trimethylphenyl) and the preparation and structural characterization of several of its metal complexes

Article abstract of DOI:10.1139/V07-131

The bulky m-terpheny1 phenol Ar*OH 1 (Ar* = C₆H ₃-2,6-Mes₂, Mes = 2,4,6-trimethylpheny1) was synthesized via the treatment of Ar*Li with nitrobenzene. The phenol 1 is prepared in modest to good yield using this method. Attempts were also made to prepare 1 through oxidation of the bulky boronic acid Ar*B(OH)₂ with Oxone, but this reaction was not suitable for preparative-scale reactions. Side products of the reaction between Ar*Li and nitrobenzene were identified as Ar*[N(O)Ph] and [C₆H₅N(O)]₂ and were characterized by X-ray crystallography and EPR spectroscopy. A variety of main-group and transition-metal complexes of Ar*OH were prepared, namely Sn(OAr*)₂, Ge(OAr*)₂, [N(SiMe ₃)₂]Ge(OAr*), [Me₂Al(OAr*)] ₂, and Ti(NMe₂)(OAr*)₂. All compounds were characterized spectroscopically and most were studied by single-crystal X-ray diffraction as well.

Full text of DOI:10.1139/V07-131

20
Synthesis of the bulky m-terphenyl phenol Ar*OH
(Ar* = C6H3-2,6-Mes2, Mes = 2,4,6-trimethylphenyl)
and the preparation and structural
characterization of several of its metal complexes
Diane A. Dickie, Ian S. MacIntosh, Daisuke D. Ino, Qi He, Ojisamola A. Labeodan,
Michael C. Jennings, Gabriele Schatte, Charles J. Walsby, and
Jason A.C. Clyburne
Abstract: The bulky m-terphenyl phenol Ar*OH 1 (Ar* = C6H3-2,6-Mes2, Mes = 2,4,6-trimethylphenyl) was synthe-
sized via the treatment of Ar*Li with nitrobenzene. The phenol 1 is prepared in modest to good yield using this
method. Attempts were also made to prepare 1 through oxidation of the bulky boronic acid Ar*B(OH)2 with Oxone®,
but this reaction was not suitable for preparative-scale reactions. Side products of the reaction between Ar*Li and
nitrobenzene were identified as Ar*[N(O)Ph] and [C6H5N(O)]2 and were characterized by X-ray crystallography and
EPR spectroscopy. A variety of main-group and transition-metal complexes of Ar*OH were prepared, namely
Sn(OAr*)2, Ge(OAr*)2, [N(SiMe3)2]Ge(OAr*), [Me2Al(OAr*)]2, and Ti(NMe2)(OAr*)2. All compounds were character-
ized spectroscopically and most were studied by single-crystal X-ray diffraction as well.
Key words: m-terphenyl, main-group compounds, X-ray crystallography, multinuclear NMR spectroscopy, EPR
spectroscopy.
Résumé : On a réalisé la synthèse du m-terphénylphénol encombré, Ar*OH, 1, (Ar* = C6H3-2,3-Mes2; Mes = 2,4,6-
triméthylphényle) en faisant réagir du Ar*Li avec du nitrobenzène. Avec cette méthode, on obtient le phénol 1 avec des
rendements allant de modestes à bon. On a aussi tenté de préparer le phénol 1 en procédant à l’oxydation de l’acide
boronique encombré Ar*B(OH)2 avec de l’Oxone®, mais cette réaction n’est pas appropriée pour des réactions à
l’échelle préparative. On a identifié des sous-produits de la réaction entre le Ar*Li et le nitrobenzène, dont le
Ar*[N(O)Ph] et le [C6H5N(O)] et on a procédé à leur identification par diffraction des rayons X et par spectroscopie
RPE. On a préparé une variété de complexes du Ar*OH avec des métaux de transition et du groupe principal, dont
Sn(OAr*)2, Ge(OAr*)2, [N(SiMe3)2]Ge(OAr*), [Me2Al(OAr*)]2 et Ti(NMe2)(OAr*)2. On a caractérisé tous les
composés par spectroscopie et la plupart de ces composés ont été étudiés par diffraction des rayons X de cristaux
uniques.
Mots-clés : m-terphényle, composés du groupe principal, diffraction des rayons X, spectroscopie RMN multinucléaire,
spectroscopie RPE.
[Traduit par la Rédaction] Dickie et al. 31
Introduction
(1), molecules with two aryl substituents arranged meta to
one another on a central phenyl ring. As shown in Fig. 1, the
aryl groups twist out of the plane of the central ring to form
a bowl-shaped pocket with a diameter of approximately
12 Å. This pocket acts as a steric shield for reactive species
found within it. The steric protection provided by the
m-terphenyl can be tuned by varying the nature of the aryl
The ability to control the coordination environment
around a metal is perhaps the most important factor in con-
trolling its reactivity. This is often achieved with the use of
sterically demanding ligands. Perhaps the most common
class of bulky substituents currently in use are m-terphenyls
Received 5 July 2007. Accepted 19 October 2007. Published on the NRC Research Press Web site at canjchem.nrc.ca on
7 December 2008.
D.A. Dickie, D.D. Ino, Q. He, O.A. Labeodan, and C.J. Walsby. Department of Chemistry, Simon Fraser University, Burnaby,
BC V5A 1S6, Canada.
I.S. MacIntosh, and J.A.C. Clyburne.1 Department of Chemistry, Saint Mary’s University, Halifax, NS B3H 3C3, Canada.
M.C. Jennings. Department of Chemistry, The University of Western Ontario, London, ON N6A 5B7, Canada.
G. Schatte. Saskatchewan Structural Sciences Centre, University of Saskatchewan, Saskatoon, SK S7N 5C9, Canada.
1Corresponding author: (email: jason.clyburne@smu.ca).
Can. J. Chem. 86: 20–31 (2008)
doi:10.1139/V07-131
© 2007 NRC Canada

Dickie et al.
21
Fig. 1. The pocket formed by the m-terphenyl 2,6-bis(2,4,6-
Scheme 1. Synthesis of boronic acids 4 and 5.
trimethylphenyl)benzene is shown in the space-filling diagram.
HO
OH
X
Li
B
R
Ar
Ar
Ar
Ar
1) B(OMe)3
2) H2O
Ar
Ar
Et2O
+ nBuLi
R
R
X = Br, Ar = Ph, R = Ph
X = I, Ar = Mes, R = Ph
4
5
Fig. 2. Selected m-terphenyl phenols, from least to most bulky.
oxygen (12), or through the palladium-catalyzed cross
coupling of phenol with 2,4,6-trimethylbromobenzene (13).
Neither of these routes involved the m-terphenyl precursors
that were readily available, namely Ar*I or a convenient
metallated derivative, so two alternative routes were devel-
oped.
OH
OH
OH
1
2 (11)
3 (11)
One proposed route involved the oxidation of m-terphenyl
boronic acids with Oxone® (14). Lithiation of either 2,4,6-
triphenylbromobenzene or 2,6-bis(2,4,6-trimethylphenyl)io-
dobenzene (Ar*I) in diethyl ether, followed by addition of
trimethylborate and aqueous work-up gave the m-terphenyl
boronic acids 4 and 5, respectively (Scheme 1). NMR spec-
troscopy was used to characterize the boronic acids 4 and 5.
The most definitive signal was the two-proton singlet at 4.11
or 4.06 ppm in the spectra of 4 and 5, respectively, assigned
to the –B(OH)2 protons. The upfield shift of these protons
relative to phenylboronic acid (4.61 ppm) (15) may be due
to shielding by the aryl substituents. The 11B NMR spectra
of 4 and 5 each showed a single sharp peak, at 31.4 ppm for
4 and 29.3 ppm for 5. These values are comparable to other
phenylboronic acids (16).
Although these compounds were initially prepared as
starting materials for the m-terphenyl phenol synthesis,
somewhat surprising differences in the O–H absorption re-
gion in the IR spectra of 4 and 5 prompted us to more
closely examine their intrinsic properties before proceeding
further. In the triphenyl-substituted derivative 4, there was a
very strong O–H stretch at 3586 cm–1 and a broad absorp-
tion at 3280 cm–1, while 5 showed instead four weak absorp-
tions between 3668 and 3417 cm–1. Since this region
is primarily affected by hydrogen bonding interactions, at-
tempts were made to grow crystals of both new m-terphenyl
boronic acids to see if they exhibited different intermole-
cular interactions. Unfortunately, only 5 yielded crystals
suitable for single crystal X-ray diffraction (Fig. 3).
substituents. Common groups include phenyl, 2,4,6-
trimethylphenyl (mesityl, Mes), 2,6-diisopropylphenyl
(Dipp), and 2,4,6-triisopropylphenyl (Trip).
During the past several years, we have been interested in
the coordination chemistry of “substituted” m-terphenyl lig-
ands. These studies have resulted in the isolation of unusual
coordination geometries for amidinates (2) and carboxylates
(3), and here we continue with an examination of phenoxide
chemistry. Alkoxides and aryloxides are among the most
versatile ligands known and have been placed on virtually
every element of the periodic table (4). It is not surprising,
therefore, that one of the very first substituted m-terphenyls
to be used as a ligand was 2,6-diphenylphenol, in a tungsten
complex that was subsequently used as an olefin metathesis
catalyst (5). Rothwell (6) and others (7) have since explored
the structure and reactivity, including catalytic behavior, of
many other early transition-metal complexes of this ligand.
The search for new and improved catalysts has also moti-
vated much of the research into main-group m-terphenyl
phenol complexes (8), based largely on the pioneering work
by Yamamoto and co-workers on aluminium tris(2,6-
diphenylphenoxide) (9). This molecule and related com-
plexes have served as useful catalysts for stereoselective
Claisen rearrangements as well as conjugate addition to α,β-
unsaturated carbonyl compounds, and exo-selective Diels–
Alder additions (opposite to the typical endo preference)
(10).
Key to the successful use of these bulky complexes is a
simple preparation of the ligands. Whereas some bulky phe-
nols, such as 2,6-diphenylphenol, are commercially avail-
able, most others are not. Since steric bulk often dominates
or governs the chemistry observed for the complexes, a con-
venient route into these molecules is desirable. We note here
that recent reports by the research group of Power and co-
workers described the preparation of bulky phenols 2 and 3
(11) (Fig. 2). Our work aims to complement these studies.
The X-ray crystallographic analysis revealed that, as ex-
pected, there is intermolecular [O–H···O] hydrogen bonding
in 5, with O(2) as the donor and O(1) as the acceptor, form-
ing a zigzag chain (Fig. 4). In the absence of other hydrogen
bond donor/acceptor groups, all other structurally character-
ized (17) phenylboronic acid derivatives form homodimers
with eight-membered B2O4H2 rings rather than infinite
chains like 5. Similar head-to-head homo-dimerization was
also observed in two related m-terphenyl substituted
carboxylic acids (18). Since the carboxylic acids both
feature smaller aryl substituents than 5 (phenyl vs. 2,4,6-
trimethylphenyl), 4, which also has the smaller phenyl sub-
stituents, may also form a homo-dimer, and that would
explain the differences in the IR spectra of 4 and 5.
Results and discussion
Ligand synthesis
The targeted m-terphenyl phenol for this study was 2,6-
bis(2,4,6-trimethylphenyl)phenol, Ar*OH 1, which had pre-
viously only been synthesized as a by-product in the reac-
tion of the corresponding m-terphenyl copper complex with
Once the boronic acids 4 and 5 were in hand, reactions to
oxidize them to the respective m-terphenyl phenols were
performed using Oxone® in basic solution (14). This reac-
© 2007 NRC Canada

22
Can. J. Chem. Vol. 86, 2008
Fig. 3. Molecular structure of 2,6-bis(2,4,6-trimethyl-
phenyl)phenylboronic acid 5. Thermal ellipsoids are shown at
50% probability, and hydrogen atoms, except OH protons, have
been removed for clarity. Selected bond lengths (Å) and angles
(°): B(1)—O(1A) 1.603(18); B(1)— O(2A) 1.212(12); B(1)—
C(1) 1.552(8); O(1A)–B(1)–O(2A) 112.9(9).
Fig. 4. [O–H···O] hydrogen bonds in 5, viewed along the crystal-
lographic a axis.
Scheme 2. Synthesis of m-terphenyl phenol 1 and
nitrosobenzene complex 6.
Fig. 5. Molecular structure of 2,6-bis(2,4,6-trimethylphenyl)phe-
nol 1. Thermal ellipsoids are shown at 50% probability, and all
hydrogens, except phenolic protons, have been removed for clar-
ity. Selected bond lengths (Å) and angles (°): O(1)—C(2)
1.356(3); O(31)—C(32) 1.375(3); O(1)–C(2)–C(7) 116.7(2);
O(1)–C(2)–C(3) 121.7(2); O(31)–C(32)–C(37) 116.3(2); O(31)–
C(32)–C(33) 121.0(2). Hydrogen-bond lengths (Å) and angles
(°): O(1)···O(31) 2.823(3); O(1)–H(1A)···O(31) 152.9.
nBuLi
1) Nitrobenzene
2) MeOH/HCl
O
I
Li
OH
N
+
Et2O
1
6
tion produces very low yield (trace) of the desired bulky
phenols, and hence work in this area was stopped and a new
route was sought.
Generation of bulky phenols from Ar*Li and
nitrobenzene
During the course of our boronic acid experiments, Power
and co-workers (11) developed a synthesis of bulkier m-
terphenyl phenols, namely 2 and 3, directly from the
lithiated intermediate Ar*Li, so this more direct and higher
yielding route was pursued. Lithiation of Ar*I with n-
butyllithium in ethereal solution followed by addition of
excess nitrobenzene at –78 °C results in the immediate for-
mation of a dark red solution that is quenched with methanol
to give 1 (Scheme 2).
1
In the H NMR spectrum of the m-terphenyl phenol 1, the
OH appears as a singlet at 4.53 ppm. The methyl groups are
found at 2.33 (para) and 2.06 (ortho) ppm. Additional evi-
dence for the presence of the OH was provided by strong IR
absorptions at 3486 and 3451 cm–1. These stretches are com-
parable to those reported by Lüning and co-workers (19) for
2,6-bis(2,6-dimethylphenyl)phenol, at 3482 and 3431 cm–1.
Four other previously published m-terphenyl phenols,
namely 2,6-diphenylphenol (20), 2,6-bis(3,5-dimethyl-
phenyl)phenol (19), 2,6-bis(2,6-diisopropylphenyl)phenol 2
(11), and 2,6-bis(2,4,6-triisopropylphenyl)phenol 3 (11),
each reported only a single OH stretch between 3520–
3533 cm–1 in the IR spectrum. Since three of these five com-
pounds had been crystallographically characterized, single-
crystal X-ray diffraction studies were performed on 1 to see
if there was a difference in hydrogen bonding that could ex-
plain the differences in the IR spectra.
The crystallographic studies revealed that in the solid
state, 1 exists as two crystallographically distinct molecules
(Fig. 5). These molecules are connected by a weak [O–
H···O] hydrogen bond to form a dimer. This is in contrast to
the unsubstituted phenol (C6H5OH), which forms infinite hy-
drogen-bonded chains (21) with an average [O···O] distance
of 2.67 Å, compared with 2.823(3) Å in 1. It is also in
contrast to all three previously structurally characterized m-
terphenyl phenols, none of which exhibits [O–H···O] hydro-
gen bonds. Based on the IR evidence, it would appear that
Lüning’s 2,6-bis(2,6-dimethylphenyl)phenol follows the
© 2007 NRC Canada

Dickie et al.
23
Fig. 6. Molecular structure of nitrosobenzene complex 6 that was
isolated as a co-crystal with [C6H5N(O)]2, the dimer of
nitrosobenzene. Thermal ellipsoids are shown at 50% probability,
and hydrogen atoms have been removed for clarity. Selected
bond lengths (Å) and angles (°):N(1)—O(1) 1.290(2); N(1)—
C(1) 1.443(3); N(1)—C(31) 1.406(3); N(2)—N(2)* 1.128(6);
N(2)—O(2) 1.301(5); N(2)—C(41) 1.564(5); O(1)–N(1)–C(1)
116.86(18); O(1)–N(1)–C(31) 119.32(17); C(1)–N(1)–C(31)
123.82(18).
Fig. 7. Main panel: Experimental (top) and simulated (bottom)
EPR spectra of nitrosobenzene complex 6 dissolved in CH2Cl2.
Experimental parameters: ν = 9.86 GHz, microwave attenuation =
20 dB, scan time = 21 s, time constant = 10.24 ms, modulation
amplitude = 0.0125 mT, receiver gain = 2.5 × 103, average of 17
scans. Simulation parameters: a(14N) = 1.024 mT; a(1H × 3) =
0.247 mT; a(1H × 2) = 0.088 mT, a(1H × 3) = 0.054 mT,
linewidth = 0.047 mT. Inset: EPR spectrum of single co-crystal
of nitrosobenzene complex 6 with [C6H5N(O)]2. Experimental
parameters: ν = 9.86 GHz, microwave attenuation = 25 dB, scan
time = 21 s, time constant = 10.24 ms, modulation amplitude =
0.01 mT, receiver gain = 6.3 × 103, 1 scan.
Solution EPR Spectrum
Crystal
Experimental
B (mT)
346 347 348 349 350 351
Simulation
346.5
347.0
347.5
348.0
348.5
B (mT)
349.0
349.5
350.0
same pattern as 1, while his 3,5-derivative is more similar to
the others (11, 20).
presence of both aromatic C–H and alkyl C–H fragments, as
well as peaks that were tentatively assigned to N–O bonds.
Another feature that was found in each of the crystallo-
graphically characterized m-terphenyl phenols, including 1,
is an intramolecular [O–H···π] interaction. In the case of the
extremely bulky 2,6-bis(2,4,6-triisopropylphenyl)phenol and
2,6-bis(2,6-diisopropylphenyl)phenol, steric hindrance ham-
pers intermolecular [O–H···O] interactions, but does not pre-
vent intramolecular [O–H···π] interactions with a flanking
aryl. This interaction occurs primarily through the ipso car-
bon atoms (H···Cipso = 2.64 and 2.39 Å, respectively) (11).
In fact, the restricted rotation caused by the presence of such
bulky groups may even enhance the interaction by locking
the aryls into place.
Restricted rotation is clearly not necessary though, since
the crystal structure of the least hindered m-terphenyl, 2,6-
diphenylphenol, also showed an [O–H···π] interaction of
2.43 Å (20). The corresponding H···Cipso distances in 1 are
2.41 and 2.47 Å [H(1A)···C(11) and H(31A)···C(41), respec-
tively]. It is not immediately clear why 2,6-diphenylphenol
does not also engage in [O–H···O] hydrogen bonds like 1,
but it may be that [C–H···π] interactions through the para
hydrogen of the central phenyl provide more favorable
packing interactions. Taken together, these examples illus-
trate how subtle changes in steric demands can have a large
effect on intermolecular interactions.
To unambiguously assign the structure, a crystallographic
study was performed on the block-shaped crystals (Fig. 6).
The results of these studies indicate that the m-terphenyl
nitrosobenzene addition complex 6 was formed and co-
crystallized with homodimerized nitrosobenzene, the other
by-product of the phenol synthesis. The formation of the m-
terphenyl by-product 6 was proposed by Power and co-
workers during the preparation of the bulkier m-terphenyl
phenols 2 and 3, but was not observed because of the higher
steric demands of his m-terphenyl backbone (11).
The structure of the nitrosobenzene compound 6 is inter-
esting for two reasons. First of all, it confirms that the bulky
Ar*Li can react with nitrobenzene either via oxygen atom
abstraction or it can react via addition to nitrogen. Further-
more, the co-crystallized PhNO dimer was isolated in a rare
trans configuration. Typically, PhNO does not dimerize, and
when it does, it crystallizes in the cis form (22). Other struc-
tural parameters for both components of the red co-crystal
are unremarkable, and no other unusual contacts were ob-
served in the packing diagrams.
EPR of nitrobenzene complex 6
During the work-up and recrystallization of 1, a small
amount of a highly colored red by-product was also isolated.
We performed spectroscopic studies on the red material, and
found that NMR studies were not informative because of ex-
tensive line broadening, and the IR studies indicated the
The EPR spectrum of a single co-crystal of complex 6
with homodimerized nitrosobenzene shows
a
single
Lorentzian line with relatively large peak-to-peak
a
linewidth of 0.42 mT (Fig. 7, inset). This result is consistent
with the presence of the paramagnetic nitroxide species,
© 2007 NRC Canada

24
Can. J. Chem. Vol. 86, 2008
Scheme 3. Synthesis of [Me2Al(µ-OC6H3Mes2)]2 7.
Fig. 8. Structure of [Me2Al(µ-OC6H3Mes2)]2 7. Thermal ellip-
soids are shown at 50% probability, and hydrogen atoms and
CH2Cl2 solvent have been removed for clarity. Selected bond
lengths (Å): Al(1)—O(21) 1.8871(16); Al(1)—O(11) 1.8979(17);
Al(2)—O(11) 1.8943(16); Al(2)—O(21) 1.9027(17); Al(1)—
C(41) 1.942(3); Al(1)—C(42) 1.939(3); Al(2)—C(81) 1.942(3);
Al(2)—C(82) 1.949(3); O(11)—C(11) 1.401(3); O(21)—C(51)
1.410(3). Selected bond angles (°): O(11)–Al(1)–O(21) 80.35(7);
O(11)–Al(2)–O(21) 80.04(7); Al(1)–O(11)–Al(2) 99.54(7); Al(1)–
O(21)–Al(2) 99.62(7).
OH
Al
Al
CH2Cl2
O
O
2
+ 2 AlMe3
-2 CH4
1
7
complex 6; the broad, unresolved line is due to cross-
relaxation between the spins of the radical species.
The crystal was dissolved in CH2Cl2 and a complex spec-
trum resulted, which was simulated accurately (Fig. 7, main
panel). The magnitude and multiplicity of the hyperfine cou-
plings are consistent with the structure of complex 6. The
large 14N coupling (I = 1, a(14N) = 1.024 mT) indicates that
the majority of the spin density lies on the nitroxide moiety;
1
couplings from a total of eight H nuclei (I = ½, a(1H × 3) =
0.247 mT; a(1H × 2) = 0.088 mT, a(1H × 3) = 0.054 mT)
demonstrate interactions with the eight protons of the phenyl
groups directly attached to the nitroxide and indicate
delocalization of spin density across both rings. The 14N and
1H hyperfine coupling constants measured for compound 6
are comparable to those observed for the symmetrical
nitrosyl radical C6H5N(O)C6H5 (23).
Metal complexes derived from Ar*OH
The reaction of the m-terphenyl phenol 1 with an
equimolar amount of AlMe3 in dichloromethane gives the
dialkylaluminium monophenoxide 7 (Scheme 3). Evidence
1
for this product is found in the H NMR spectrum, which
Fig. 9. Changes in the steric demands of the m-terphenyl back-
bone alter the coordination in the ligand binding pocket.
showed peaks at –1.26, 2.15, and 2.19 ppm with relative in-
tensities of 6:12:6, due to the aluminium methyls and m-
terphenyl ortho and para methyl groups, respectively.
X-ray crystallographic studies (Fig. 8) confirmed the for-
O
1
Al
mula suggested by the H NMR data, and showed that de-
Al
Al
Al
Al
O
O
O
O
spite the bulk of the m-terphenyl ligand, 7 exists in the solid
state as an oxygen-bridged dimer with a planar Al2O4 core.
An identical motif was described by Rothwell for his less
hindered 2,6-diphenylphenol aluminium complex (24). In
contrast, Power’s bulkier 2,6-bis(2,4,6-triisopropylphenyl)phenol
aluminium complex was isolated as a base-stabilized
monomeric ether solvate (25). As was the case in the free
ligands, the effects of subtle steric differences around the m-
terphenyl pocket have a remarkable effect on coordination
within that pocket (Fig. 9).
O
Ref. 24
7
Ref. 25
Scheme 4. Synthesis of [Sn(OC6H3Mes2)2] 8.
To see if it was possible to establish a trend in the coordi-
nation behavior of the m-terphenyl phenols, group 14 deriva-
tives were also prepared. Despite the fact that the first Sn(II)
and Ge(II) compounds found to exist as dicoordinate mono-
mers in the solid state were based upon bulky phenol ligands
(26), structural data on divalent group 14 alkoxy or aryloxy
compounds remains relatively rare. This makes the prepara-
tion of such compounds interesting simply from a funda-
mental perspective, but the fact that they are also being
studied as catalysts (27) and as molecular precursors to su-
perconductors and (or) ceramic materials for applications,
OH
C6H6
Si
Sn Si
N
N
O
O
+
2
-2 HN(SiMe3)2
Sn
Si Si
1
8
© 2007 NRC Canada

Dickie et al.
25
Fig. 10. Structure of [Sn(OC6H3Mes2)2] 8, showing Sn–π interac-
tions. Thermal ellipsoids are shown at 50% probability, and hy-
drogen atoms have been removed for clarity. Selected bond
lengths (Å) and angles (°): Sn(1)—O(1) 2.039(3); Sn(1)—O(2)
2.043(3); O(1)—C(101) 1.343(5); O(2)—C(201) 1.342(5); O(1)–
Sn(1)–O(2) 87.32(11); Sn(1)–O(1)–C(101) 127.7(2); Sn(1)–O(2)–
C(201) 125.7(2).
Scheme 5. Synthesis of [(Me3Si)2NGe(OC6H3Mes2)] 9 and
Ge(OC6H3Mes2)2 10.
Si
l 2
C
2
N Si
O
H
C
)
2
Ge
e 3
M
i
S
(
N
OH
H
-
Si
Ge Si
N
N
C
+
6 H
9
1
4
Si Si
-
2
H
N
(
S
i
M
e
)
3
2
1
O
O
Ge
10
ring) and 3.262 (C7 ring)]. The observed upfield 119Sn NMR
shift for compound 8 may be due to the stronger Sn–arene
interaction, but overall the interaction appears to be weak as
shown by the appearance of only one set of signals for the o-
1
Me protons in the H NMR spectra of 8.
The reaction in dichloromethane of Ge[N(SiMe3)2]2 with
the m-terphenyl phenol 1 gave a mixture of compounds, one
of which was the mixed aryloxy-amido germanium complex
1
9 (Scheme 5). This complex could be identified in the H
NMR spectrum of the crude reaction mixture as a singlet of
18 hydrogens at 0.00 ppm [–Si(CH3)3], and singlets at 2.18
and 2.42 ppm for the ortho and para methyls of the m-
terphenyl ligand. Since Sn[N(SiMe3)2]2 is known to react
with dichloromethane solvent (3c, 30), it seemed possible
that this could also be happening during the synthesis of 9,
so an attempt was made to repeat the synthesis in hexanes.
Unfortunately, only traces of the mixed complex 9 were ob-
including flat panel displays, gas sensors, solar cells, and
lithium battery anodes (28), makes structural data all the
more important.
1
The protonolysis reaction (Scheme 4) of Sn[N(SiMe3)2]2
with 1 in benzene gives the tin(II) complex 8 in good yield.
No signal from the CH3 groups of the trimethylsilylamide
served in the H NMR spectrum. The major product was the
germanium bis(aryloxide) 10. As with the tin bis(aryloxide)
8, the 1H NMR spectrum of 10 showed a pronounced upfield
shift of the ortho methyl protons to 1.79 ppm (1.82 ppm in
8). Similarities were also seen in the elevated melting point
of 10 at 318 °C, compared with 321 °C in 8. Elemental anal-
ysis was consistent with the proposed composition of 10.
Several attempts were made to grow crystals of 9 and 10,
but only 9 yielded single crystals suitable for X-ray diffrac-
tion studies (Fig. 11). Compound 9 is, to the best of our
knowledge, the first structurally characterized monomeric,
dicoordinate mixed aryloxy-amido germanium(II) complex
(31). The Ge—O bond length of 1.8414(16) Å is longer than
those found in other dicoordinate non-calixarene Ge(II)
compounds [1.814(2) to 1.8296(14) Å] (25, 32). The oppo-
site is true of the Ge—N bond, which, at 1.851(2) Å is
shorter than in comparable compounds [1.855(2) to 1.939(6)
Å] (33). The germanium atom does not engage in any signif-
icant inter- or intra-molecular interactions.
Given the interesting coordination patterns observed in the
main-group complexes of 1, we also wanted to probe its
transition-metal coordination. For the related ligand 2,6-
diphenylphenol, titanium complexes are by far the most
common. Virtually, all of these complexes feature two m-
terphenyl phenol ligands on the titanium centre, and a few
even accommodate three (34). Only one complex is known
with a single 2,6-diphenylphenol ligand, and it uses cyclo-
1
ligand was observed H NMR spectrum of 8, indicating that
both amido groups had been lost to give the tin(II)
bis(phenoxide) complex. The disappearance of the OH sig-
1
nal in both the H NMR and IR spectra also indicated the
formation of 8, as did the peak at –344 ppm in the 119Sn
NMR spectrum. This value is upfield of the signal at
–289 ppm for the most closely related Sn(OAr)2 compound
in the literature, namely Power’s recently reported tin(II)
bis(phenoxide) based on the m-terphenyl 2,6-bis(2,6-
diisopropylphenyl)phenol 2 (25).
Final confirmation of the structure of 8 was provided by
single-crystal X-ray diffraction. The crystallographic studies
revealed that it does indeed exist as a monomer in the solid
state (Fig. 10). The geometry at tin is v-shaped, due to the
stereochemically active lone pair. As in the few other known
monomeric Sn(II) bis(aryloxides) (25, 29), the O–Sn–O an-
gle is quite acute, measuring only 87.32(11)°. The tin atom
in 8 is not truly dicoordinate, however, as it has extensive
Sn–π interactions resulting from being sandwiched between
two flanking aryls of the m-terphenyl ligand. The Sn···cen-
troid distances measure 2.942 and 2.980 Å for the C(111)
and C(221) rings, respectively. Such interactions are also
present in Sn(OAr)2, where Ar = 2,6-bis(2,6-diisopropyl-
phenyl) although they are somewhat longer [3.064 (C49
© 2007 NRC Canada

26
Can. J. Chem. Vol. 86, 2008
Scheme 6. Synthesis of [(Me2N)2Ti(OC6H3Mes2)2] 11.
Fig. 11. Structure of [(Me3Si)2NGe(OC6H3Mes2)] 9. Thermal el-
lipsoids are shown at 50% probability, and hydrogen atoms have
been removed for clarity. Selected bond lengths (Å): Ge(1)—
N(1) 1.851(2); Ge(1)—O(1) 1.8414(16); Si(1)—N(1) 1.753(2);
Si(2)—N(1) 1.750(2); C(1)—O(1) 1.366(3). Selected bond angles
(°): O(1)–Ge(1)–N(1) 97.59(8); Ge(1)–N(1)–Si(1) 122.83(11);
Ge(1)–N(1)–Si(2) 114.71(11); Si(1)–N(1)–Si(2) 122.42(12).
N
OH
N
Ti
N
CH2Cl2
O
Ti
N
O
+
2
N
N
-2 HNMe2
1
11
Fig. 12. Structure of [(Me2N)2Ti(OC6H3Mes2)2] 11. Thermal el-
lipsoids are shown at 50% probability, and hydrogen atoms have
been removed for clarity. Selected bond lengths (Å): Ti(1)—
N(31) 1.8822(13); Ti(1)—N(41) 1.8763(13); Ti(1)—O(11)
1.8460(10); Ti(1)—O(21) 1.8495(10). Selected bond angles (°):
O(11)–Ti(1)–O(21) 119.25(5); O(11)–Ti(1)–N(41) 106.63(5);
O(21)–Ti(1)–N(31) 107.72(5); O(21)–Ti(1)–N(41) 109.98(5);
O(11)–Ti(1)–N(31) 109.17(5); N(31)–Ti(1)–N(41) 102.88(6).
pentadienyl as an ancillary ligand (35). Would the increased
bulk of 1 make it possible to isolate a titanium monophen-
oxide complex?
Addition of tetrakis(dimethylamino)titanium to a solution
of 1 in dichloromethane resulted in the formation of an or-
1
ange solid 11 (Scheme 6). The H NMR spectrum showed a
1:1 ratio between the NMe2 ligand at 2.30 ppm and the m-
terphenyl at 2.24 (para) and 2.11 (ortho) ppm. Given that ti-
tanium is tetravalent, these data suggested the formation of a
bis(phenoxide) complex with a formula of (Me2N)2Ti-
(OC6H3Mes2)2. This product was formed even when sub-
stoichiometric amounts of the m-terphenyl phenol ligand
were added.
X-ray crystallographic studies of 11 confirmed the
proposed structure (Fig. 12). The geometry at titanium is
tetrahedral, with the greatest deviation in the O(11)–Ti(1)–
O(21) angle [119.25.(5)°] and N(31)–Ti(1)–N(41) angle
[102.88(6)°]. The Ti—O bonds are the same within experi-
mental error, and are within the range of similar titanium
complexes [1.786(2)–1.862(5) Å] (36). The same is true for
the two Ti—N bond lengths, for which literature values of
similar compounds range from 1.854(7) to 1.897(5) Å (36).
The nature of the oxygen ligand appears to be the most-
important factor governing the coordination at titanium. All
but one of the structurally characterized examples of tetra-
coordinate titanium complexes with two oxygen donors and
two nitrogen donors of any type, i.e., [(R2N)2Ti(OR)2], were
based on 2,6-disubstituted phenol ligands. The one excep-
tion featured a 2,6-disubstituted aniline instead (37). It is not
immediately clear if this is merely a coincidence or if the
steric shielding of the meta substituents is chemically re-
quired.
Summary and conclusions
The X-ray crystal structures of a m-terphenyl phenol and a
m-terphenyl boronic acid were described. The hydrogen
bonding pattern observed in phenol 1, intermolecular
[O–H···O] dimerization, is very different from that observed
in related m-terphenyl phenols. The steric demands of 1 are
intermediate between those of previously characterized de-
rivatives. This balance appears to be the key to the supramo-
© 2007 NRC Canada

Dickie et al.
27
lecular interactions, as the same 2,4,6-trimethylphenyl
substituent was used in the boronic acid 5 that also exhibited
unprecedented [O–H···O] hydrogen bonds.
allowed to stir for 5 min, and then 20 mL of methanol was
added slowly. After warming to RT, 30 mL of H2O was
added, and the organic layer was separated. The aq. layer
was acidified with 1 mL concd. HCl and then extracted with
Et2O. The combined organic fractions were washed with wa-
ter and saturated NaCl(aq) and then dried over MgSO4. The
solution was concentrated to ~10 mL and then passed
through a plug of silica. After addition of ~10 mL pentane,
the solution was left to evaporate slowly at room tempera-
ture overnight. The resultant pale brown solid was
recrystallized to give colorless to pale blue crystals. Yield =
Given the differences in the structures of the free ligands,
it seemed possible that the main-group and transition-metal
complexes of 1 would also have features not found in more
and (or) less bulky analogues. This was not the case for the
titanium complex 11 and aluminium complex 7. Both
molecules were essentially isostructural to known 2,6-
diphenylphenol derivatives. The tin complex 8, on the other
hand, did exhibit a spectroscopic difference. The secondary
metal–π interaction between the tin atom and flanking aryls
of the m-terphenyl ligand in 8 result in an up-field shift of
the 119Sn NMR resonance relative to that observed for
Sn(OAr)2, where Ar = 2,6-bis(2,6-diisopropylphenyl).
0.39
g (40%); mp =
145 °C. 1H NMR (CDCl3,
499.767 MHz,) δ: 7.03 (m, 3H), 6.98 (s, 4H), 4.53 (s, 1H),
2.33 (s, 6H), 2.06 (s, 12H). 13C{1H} NMR (CDCl3,
100.624 MHz) δ: 137.5, 137.2, 135.9, 133.4, 129.6, 128.5,
128.1, 120.7, 21.2, 20.4. IR (nujol mull) ν: 3486 (s), 3451
(s), 1611 (w), 1584 (w), 1573 (w), 1490 (m), 1320 (s), 1260
(m), 1221 (vs), 1170 (s), 1089 (m), 1071 (m), 1030 (w),
1008 (w), 848 (vs), 829 (s), 797 (s), 780 (w), 752 (vs), 740
(w), 715 (w). Anal. calcd. for C24H26O: C, 87.23; H, 7.93.
Found: C, 87.50; H, 8.04. HR-MS (m/z): [M+] calculated for
C24H26O, 330.198. Found: 330.198. During recrystallization
small red single crystals of 6 can be isolated, a material that
was identified as a co-crystal of [C6H5N(O)]2 with
C6H5N(O)C6H3Mes2. The crystals can be isolated
reproducibly in low yield (mg) per reaction. Mp = 120–
123 °C. HR-MS C30H30NO calcd.: 420.2327; found, 420.2315.
IR (KBr pellet) ν: 2914 (s), 2857 (m), 1607 (m), 1573 (m),
1446 (vs), 1360 (m), 1307 (m), 1265 (m), 1221 (m), 1074
(m), 1024 (m), 846 (s), 753 (vs), 683 (s), 563 (m).
Experimental
General experimental
A nitrogen-atmosphere MBraun UL-99-245 dry box and
standard Schlenk techniques on a double manifold vacuum
line were used in the manipulation of air and moisture sensi-
tive compounds. Solution-state NMR spectra were recorded
in five millimetre tubes at Simon Fraser University on a
Bruker AMX 400 or 600 MHz spectrometers or Varian AS
400 or 500 MHz spectrometers. Chemical shifts are reported
in parts per million (ppm) downfield from SiMe4 (1H and
1
13C), BF3·Et2O (11B), or SnMe4 (119Sn). H and 13C spectra
are calibrated to the residual signal of the solvent. 11B and
119Sn spectra are calibrated to the external BF3·Et2O or
SnMe4 standard. Infrared spectra were obtained using a
Bomem MB spectrometer with the % transmittance values
reported in cm–1. EPR spectra were collected on a Bruker
ECS-106 EPR spectrometer. The CH2Cl2 solution was
deoxygenated by bubbling with nitrogen gas, to increase
spectral resolution. Spectral simulation used the Bruker
WinEPR SimFonia software. Melting points were measured
using a Mel-Temp apparatus and are uncorrected. Elemental
analyses were obtained at Simon Fraser University by
Mr. M.K. Yang on a Carlo Erba Model 1106 CHN analyzer.
Anhydrous solvents were obtained from an MBraun Sol-
vent Purification system, or were purchased from Aldrich
and used without further purification. All other reagents and
solvents were purchased from commercial sources, including
Aldrich, Strem, and Gelest, and used without further purifi-
cation, except deuterated solvents for NMR experiments on
air- and (or) moisture-sensitive compounds, which were dried
over P2O5 and distilled prior to use. The halogenated
m-terphenyl precursors 2,4,6-triphenylbromobenzene (38)
and 2,6-dimesityliodobenzene (39) were prepared according
to literature procedures.
2,4,6-Triphenylphenylboronic acid (4)
Under an inert atmosphere, n-BuLi (9.7 mL, 1.6 mol/L in
hexanes) was added to
a
suspension of 2,4,6-
triphenylbromobenzene (5.00 g, 12.98 mmol) in 50 mL
anhyd. Et2O. After 2 h, the solution was cooled to –30 °C in
a methanol/ice bath, and B(OMe)3 (1.62 g, 15.57 mmol) was
added dropwise. The reaction was warmed to RT and stirred
overnight. The reaction was quenched with H2O and allowed
to stir 4 h before being extracted with Et2O. The combined
organic fractions were dried over MgSO4, and then the sol-
vent was removed under vacuum to give a pale yellow solid.
1
Yield = 1.29 g (27%); mp = 356–357 °C. H NMR (CDCl3,
400.137 MHz) δ: 7.67 (d, 2H, J = 7.1 Hz), 7.63 (s, 2H), 7.53
(d, J = 6.8 Hz, 4H), 7.45 (t, J = 6.8 Hz, 6H), 7.40 (t, J =
7.1 Hz, 3H), 4.11 (s, 2H, B(OH)2). 13C{1H} (CDCl3,
125.679 MHz) δ: 146.8, 143.2, 142.1, 129.1, 128.8, 127.8,
127.5, 127.1, 126.9. 11B (CDCl3, 128.370 MHz) δ: 31.37. IR
(nujol mull) ν: 3586 (vs), 3280 (br), 3056 (w), 3057 (w),
1595 (s), 1575 (w), 1538 (w), 1492 (s), 1445 (s), 1396 (s),
1335 (vs), 1208 (w), 1193 (w), 1083 (m), 1041 (m), 1030
(m), 983 (w), 917 (w), 888 (s), 821 (m), 782 (m), 761 (s),
751 (s), 699 (vs). Anal. calcd. for C24H19BO2: C, 82.31; H,
5.47. Found: C, 82.62; H, 5.40.
Synthesis of ligands and precursors
2,6-bis(2,4,6-Trimethylphenyl)phenol (1)
2,6-bis(2,4,6-Trimethylphenyl)phenyl boronic acid (5)
Prepared according to the same procedure as 4, beginning
with 2,6-bis(2,4,6-trimethylphenyl)iodobenzene (5.0 g,
14.1 mmol). Yield = 3.67 g (73%); mp = 268–270 °C. H
NMR (CDCl3, 400.137 MHz) δ: 7.53 (t, J = 7.5 Hz, 1H),
7.06 (d, J = 7.5 Hz, 2H), 6.99 (s, 4H), 4.06 (s, 2H), 2.33 (s,
Under an inert atmosphere, n-BuLi (2.8 mL, 4.5 mmol,
1.6 mol/L in hexanes) was added dropwise to a suspension
of 2,6-bis(2,4,6-trimethylphenyl)iodobenzene (1.32 g,
3.0 mmol) in 20 mL anhyd. Et2O. After 2 h, the solution was
cooled to –78 °C, and freshly distilled nitrobenzene (1.5 mL,
15 mmol) was added dropwise. The bright red solution was
1
© 2007 NRC Canada

28
Can. J. Chem. Vol. 86, 2008
6H), 2.02 (s, 12H). 13C (CDCl3, 125.679 MHz) δ: 146.9,
139.4, 137.8, 135.9, 130.9 (d), 129.1 (d), 128.6 (d), 21.4 (q),
20.8 (q). 11B (CDCl3, 128.370 MHz) δ: 29.30. IR (nujol
mull) ν: 3668 (w), 3652 (w), 3646 (w), 3539 (br), 3417 (w),
1729 (w), 1613 (m), 1584 (m), 1561 (m), 1360 (s), 1309
(vs), 1261 (m), 1150 (w), 1112 (m), 1094 (m), 1087 (m),
1048 (m), 1038 (m), 848 (s), 811 (m), 759 (s), 742 (m), 666
(w), 656 (w). Anal. calcd. for C24H27BO2: C, 80.46; H, 7.60.
Found: C, 80.37; H, 7.49.
(C6D6, 499.768 MHz) δ: 7.62 (t, J = 7.5 Hz, 1H), 7.22 (d,
J = 7.5 Hz, 2H), 7.03 (s, 4H), 2.42 (s, 6H), 2.18 (s, 12H),
0.00 (s, 18H). (This molecule was not isolated as an analyti-
cally pure compound).
[Ge(OC6H3Mes2)2] (10)
Under an inert atmosphere, a solution of Ge[N(SiMe3)2]2
(0.24 g, 0.61 mmol) in 2 mL hexanes was added dropwise to
a suspension of 2,6-bis(2,4,6-trimethylphenyl)phenol 1
(0.20 g, 0.61 mmol) in 5 mL anhyd. hexanes. After 45 min,
the solvent was decanted from a white precipitate. Yield =
0.16 g (72%); mp = 318–319 °C. 1H NMR (CD2Cl2,
499.767 MHz) δ: 6.81–6.88 (m, 3H), 6.75 (s, 4H), 2.29 (s,
6H), 1.79 (s, 12H). 13C NMR (CD2Cl2, 125.678 MHz) δ:
138.1, 136.2, 129.5, 129.2, 128.8, 128.5, 119.2, 21.0, 20.1.
IR (nujol mull) ν: 1610 (w), 1585 (w), 1484 (m), 1414 (s),
1260 (s), 1230 (vs), 1091 (m), 1071 (s), 1016 (m), 948 (w),
845 (vs), 799 (m), 754 (s), 739 (w), 728 (w), 670 (m), 659
(s), 609 (m). Anal. calcd. for C48H50GeO2: C, 78.81; H,
6.89. Found: C, 79.14; H, 7.08.
Synthesis of metal complexes
[Me2Al(µ-OC6H3Mes2)]2 (7)
Under an inert atmosphere, AlMe3 (1.01 mL, 2.0 mol/L in
hexanes) was added dropwise to a solution of 2,6-bis(2,4,6-
trimethylphenyl)phenol 1 (0.56 g, 1.69 mmol) in 10 mL
anhyd. CH2Cl2. After stirring for 5 min at RT, the solution
was concentrated under vacuum and then cooled to –30 °C.
The next day, the solution was decanted from colorless crys-
1
tals. Yield = 0.25 g (38%); mp = 238–240 °C. H NMR
(C6D6, 499.767 MHz) δ: 6.85 (s, 4H), 6.69 (t, J = 7 Hz, 1H),
6.59 (d, J = 7 Hz, 2H), 2.19 (s, 6H), 2.15 (s, 12H), –1.26 (s,
6H). 13C NMR (C6D6, 125.680 MHz) δ: 138.3, 137.9, 135.9,
133.1, 129.5, 129.3, 128.3, 21.9, 21.7. IR (nujol mull) ν:
1610 (w), 1405 (m), 1261 (w), 1190 (m), 1182 (m), 1091
(m), 1032 (w), 848 (m), 825 (m), 803 (w), 774 (w), 758 (w),
701 (s), 635 (m). Anal. calcd. forC52H62Al2O2, C, 80.80; H,
8.08. Found: C, 81.14; H, 8.18.
[(Me2N)2Ti(OC6H3Mes2)2] (11)
Under an inert atmosphere, a solution of Ti(NMe2)4
(0.26 g, 1.15 mmol) in 5 mL anhyd. CH2Cl2 was added
dropwise to a solution of 2,6-bis(2,4,6-trimethylphenyl)phe-
nol 1 (0.76 g, 2.30 mmol) in 10 mL anhyd. CH2Cl2. The so-
lution was allowed to stir for 10 min at RT and then cooled
to –30 °C. After 3 h, the solution was decanted from orange
1
crystals. Yield = 0.59 g (64%); mp 180 °C (dec.). H NMR
[Sn(OC6H3Mes2)2] (8)
(C6D6, 400.137 MHz) δ: 6.82–6.87 (m, 7H), 2.30 (s, 6H),
2.24 (s, 6H), 2.11 (s, 12H). 13C NMR (C6D6, 100.624 MHz)
δ: 160.2, 137.3, 136.7, 135.6, 131.1, 130.5, 128.3, 120.2,
43.8, 21.0, 20.9. IR (nujol mull) ν: 3279 (m), 1611 (m),
1580 (m), 1484 (m), 1413 (vs), 1345 (m), 1251 (vs), 1229
(vs), 1146 (m), 1083 (s), 1054 (m), 1029 (m), 1008 (m), 950
(s), 904 (m), 876 (vs), 849 (vs), 799 (m), 778 (m), 757 (vs),
741 (w), 691 (vs), 679 (s), 597 (s). Anal. calcd. for
C52H62N2O2Ti: C, 78.57; H, 7.86; N, 3.52. Found: C, 78.20;
H, 7.83; N, 3.37.
Under an inert atmosphere, a solution of Sn[N(SiMe3)2]2
(0.33 g, 0.76 mmol) in 2 mL anhyd. benzene was added
dropwise to a solution of 2,6-bis(2,4,6-trimethylphenyl)phe-
nol 1 (0.50 g, 1.51 mmol) in 10 mL anhyd. benzene. The
mixture was allowed to stir for 3 h at RT and then filtered.
Slow evaporation of the solvent gave a yellow solid that was
recrystallized from warm hexanes to give colorless crystals:
1
Yield = 0.48 g (81%); mp = 321–322 °C. H NMR (CD2Cl2,
499.767 MHz) δ: 6.84 (d, J = 6.9 Hz, 2H), 6.79 (s, 4H), 6.73
(t, J = 6.9 Hz, 1H), 2.29 (s, 6H), 1.82 (s, 12H). 13C NMR
(100.624 MHz, C6D6) δ: 157.8, 138.5, 137.8, 137.4, 129.7,
129.5, 129.2, 117.9, 21.1, 20.5. 119Sn{1H} (CD2Cl2,
223.867 MHz) δ: -344.23. IR (nujol mull) ν: 1610 (m), 1584
(m), 1412 (s), 1262 (m), 1246 (s), 1088 (w), 1072 (m), 1031
(br), 844 (vs), 798 (w), 787 (w), 752 (m), 739 (w), 649 (m).
Anal. calcd. for C48H50O2Sn: C, 74.14; H, 6.48. Found: C,
74.03; H, 6.39.
Crystallographic studies2
The crystal was mounted on a glass fibre (1, 10) or on the
top of the nylon fibre of a CryoLoop™ (diameter of the ny-
lon fibre: 10 microns (1 micron = 1 µm); loop diameter =
0.2–0.3 mm; Hampton Research, USA) (5–8, 11). Data were
collected at the temperature indicated in Table 1 on a Nonius
Kappa-CCD diffractometer using monochromated Mo Kα
radiation (λ = 0.71073 Å) with COLLECT (40). The unit-
cell parameters were calculated and refined from the full
data set. Crystal cell refinement and data reduction were car-
ried out using DENZO (41). The data were scaled using
SCALEPACK (41). The structures were solved by direct
methods using SHELXTL-NT V6.1 suite of programs (42)
(1, 6, 8, 10) or SIR-97 (43) (5, 7, 11). All of the non-
[(Me3Si)2NGe(OC6H3Mes2)] (9)
Under an inert atmosphere, a solution of Ge[N(SiMe3)2]2
(0.57 g, 1.45 mmol) in 2 mL CH2Cl2 was added dropwise to
a solution of 2,6-bis(2,4,6-trimethylphenyl)phenol 1 (0.48 g,
1.45 mmol) in 5 mL anhyd. CH2Cl2. After 5 min, the solvent
was removed under vacuum, and the crude product was
recrystallized from benzene. Mp = 84–86 °C. 1H NMR
2 Supplementary data for this article are available on the journal Web site (canjchem.nrc.ca) or may be purchased from the Depository of Un-
published Data, Document Delivery, CISTI, National Research Council Canada, Ottawa, ON K1A 0R6, Canada. DUD 5242. For more in-
formation on obtaining material, refer to cisti-icist.nrc-cnrc.gc.ca/irm/unpub_e.shtml. CCDC 618683, 618675, 652069, 618680, 618685,
618681, and 618686 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).
© 2007 NRC Canada

Dickie et al.
29
© 2007 NRC Canada

30
Can. J. Chem. Vol. 86, 2008
Lentz, J.S. Vilardo, M.A. Lockwood, P.E. Fanwick, and I.P.
Rothwell. Organometallics, 23, 329 (2004).
hydrogen atoms were refined with anisotropic thermal pa-
rameters. The hydrogen-atom positions were calculated geo-
metrically and were included as riding on their respective
heavy atoms. All figures were generated using X-SEED
(44).
Due to the poor quality of the crystals for compound 5,
the quality of the data is rather low (parameter-to-reflection
ratio is 1:6), and the bond distances and angles for the disor-
dered BO2 part and for the hydrogen bonding are not precise
(rotational disorder of the oxygen atoms around the C–B
bond). However, we believe that the molecular structure of 5
is correct. The Friedel pairs were averaged during the refine-
ment, since this structure does not contain elements heavier
than Si.
The crystal structure of compound 7 contains a severely
disordered CH2Cl2 solvent molecule per asymmetric unit.
Attempts to refine, applying a split-atom model, were unsuc-
cessful. The data were corrected for the disordered electron
density using the SQUEEZE (45) procedure as implemented
in PLATON (46). A total solvent-accessible void volume
of 539.5 Å3 (11% of the unit-cell volume). Its contribution
to the structure factors was ascertained using
PLATON/SQUEEZE (35 e/unit cell). Derived values (for-
mula weight, density, absorption coefficient) do not contain
the contribution of the disordered solvent molecule
7. (a) J.R. Dilworth, J. Hanich, M. Krestel, J. Beck, and J.
Strähle. Organomet. Chem. 315, C9, (1986); (b) F. Quignard,
M. Leconte, J.-M. Basset, L.-Y. Hsu, J.J. Alexander, and S.G.
Shore. Inorg. Chem. 26, 4272 (1987); (c) D.J. Darensbourg,
B.L. Mueller, C.K. Bischoff, S.S. Chojnacki, and J.H.
Reibenspies. Inorg. Chem. 30, 2418 (1991); (d) R.K. Minhas,
J.J.H. Edema, S. Gambarotta, and A. Meetsma. J. Am. Chem.
Soc. 115, 6710 (1993); (e) M.B. O’Donoghue, R.R. Schrock,
A.M. LaPointe, and W.M. Davis. Organometallics, 15 1334
(1996); (f) T. Hascall, M.-H. Baik, B.M. Bridgewater, J.H.
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Acknowledgement
The authors thank Dr. Andrew Lewis (SFU) for collection
of 11B and 119Sn NMR data, and Dr. Hilary Jenkins (SMU)
for collection of X-ray crystallographic data. Funding was
provided by the Canada Research Chairs Program, the Cana-
dian Foundation for Innovation (CFI), the Natural Sciences
and Engineering Research Council of Canada (NSERC), Si-
mon Fraser University, and Saint Mary’s University.
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