Racemic and chiral expanded salen-type complexes derived from biphenol and binaphthol: Salbip and salbin

Article abstract of DOI:10.1016/j.jorganchem.2005.03.034

The reaction of 2-fluoronitrobenzene with 2,2′-biphenol or (R)-binaphthol, followed by reduction and subsequent reaction of the resulting diamine with two equivalents of a salicylaldehyde, affords expanded salen-type ligands having backbones based on biphenol or binaphthol: salbipH₂, (R)-salbinH₂ and (R)-salbin(t-Bu)₄H₂. Deprotonation of these ligands with sodium methoxide or potassium hydride, followed by metallation with M(OAc)₂ (M = Mn, Co, Ni, or Cu), affords the corresponding metal complexes in good yield (61-85%). The species containing Mn, Co, and Ni all have distorted octahedral geometry, as determined by X-ray crystallography. The ethereal oxygen atoms occupy two coordination sites with metal-oxygen distances ranging from 2.19 to 2.36 ?. The imine nitrogen atoms are trans to each other in the solid state, an impossible geometry in traditional salen-type complexes. The species containing Cu are distorted square planar and show much longer metal-ethereal oxygen distances ranging from 2.79 to 3.22 ?. The manganese complexes are competent catalysts for the epoxidation of olefins.

Full text of DOI:10.1016/j.jorganchem.2005.03.034

Journal of Organometallic Chemistry 690 (2005) 3009–3017
www.elsevier.com/locate/jorganchem
Racemic and chiral expanded salen-type complexes derived from
biphenol and binaphthol: Salbip and salbin
*
Joseph M. Grill, Joseph H. Reibenspies, Stephen A. Miller
Department of Chemistry, Texas A&M University, College Station, Texas 77843-3255, United States
Received 3 March 2005; revised 18 March 2005; accepted 18 March 2005
Available online 12 May 2005
Abstract
The reaction of 2-fluoronitrobenzene with 2,20-biphenol or (R)-binaphthol, followed by reduction and subsequent reaction of the
resulting diamine with two equivalents of a salicylaldehyde, affords expanded salen-type ligands having backbones based on biphe-
nol or binaphthol: salbipH2, (R)-salbinH2 and (R)-salbin(t-Bu)4H2. Deprotonation of these ligands with sodium methoxide or potas-
sium hydride, followed by metallation with M(OAc)2 (M = Mn, Co, Ni, or Cu), affords the corresponding metal complexes in good
yield (61–85%). The species containing Mn, Co, and Ni all have distorted octahedral geometry, as determined by X-ray crystallog-
˚
raphy. The ethereal oxygen atoms occupy two coordination sites with metal–oxygen distances ranging from 2.19 to 2.36 A. The
imine nitrogen atoms are trans to each other in the solid state, an impossible geometry in traditional salen-type complexes. The spe-
˚
cies containing Cu are distorted square planar and show much longer metal–ethereal oxygen distances ranging from 2.79 to 3.22 A.
The manganese complexes are competent catalysts for the epoxidation of olefins.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Salen; Catalytic epoxidation; R-binaphthol; 2,20-Biphenol; Chiral
1. Introduction
Jacobsen and coworkers [17,20,21] reported the syn-
thesis of a very successful chiral variant of the salen
ligand (Scheme 1). The corresponding manganese (III)-
based catalyst is useful for the epoxidation of cis-disub-
stituted olefins in the presence of commercial bleach [2].
Overall the asymmetric epoxidation of cis-olefins with
Jacobsenꢀs catalyst is effective but the optimized condi-
tions rely on a large catalyst loading (6 mol%) and the
use of 4-phenylpyridine-N-oxide as an additive in order
to obtain high enantiomeric excesses (eeꢀs). Gilheany
and coworkers [22–25] reported the synthesis of a series
of chiral chromium–salen complexes capable of epoxi-
dizing trans-disubstituted olefins with poor to good
eeꢀs, but the system suffers from limited substrate toler-
ance and requires high catalyst loading (10 mol%). Fur-
thermore, it requires an expensive additive and an
expensive oxidant (PhIO). The eeꢀs obtained by Gilhe-
any range from 10% to 92% depending on the catalyst,
the conditions, and the substrate, and the isolated yields
The salen ligand is a versatile, widely used ligand for
homogeneous transition metal mediated catalysis [1–11].
The simple salen ligand is synthesized by the condensa-
tion of two equivalents of salicylaldehyde with one
equivalent of ethylene diamine (Scheme 1) [12]. Transi-
tion metal complexes of salen have been known since
at least 1931 [12–15], but the most intense investigations
have occurred since chiral variants were first applied to
asymmetric catalysis in the early 1990s [16,17]. Modified
salen complexes have served as catalysts in varied reac-
tions such as asymmetric epoxidation [2], copolymeriza-
tion of carbon dioxide with epoxides [5,6], and
hydrolytic kinetic resolution of racemic epoxides
[18,19], depending on the metal employed.
*
Corresponding author. Tel.: +979 8452543; fax: +979 8459452.
E-mail address: samiller@mail.chem.tamu.edu (S.A. Miller).
0022-328X/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.03.034

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J.M. Grill et al. / Journal of Organometallic Chemistry 690 (2005) 3009–3017
Scheme 1. Synthesis of the original salen ligand and Jacobsenꢀs ligand.
in most cases are 40% or less. The need for new catalysts
that are more efficient, less expensive, and more selective
is evident.
We have general goals of designing and synthesizing
new chiral ligands in an efficient and economical manner
on large scale. In this work, we exploit an underutilized
nucleophilic aromatic substitution reaction for the syn-
thesis of a novel class of racemic and chiral expanded
salen-type ligands derived from 2,20-biphenol and R-
binaphthol. These new ligands are readily coordinated
to manganese, cobalt, nickel, and copper. The X-ray
crystal structures of six of these complexes are reported
and interpreted. The catalytic abilities of these species
are briefly investigated and compared to those of exist-
ing systems.
Scheme 2. Synthesis of an expanded salen-type ligand (3, salbipH2)
and its coordination to metals.
2. Results and discussion
to transition metal acetates affords salbipM coordina-
tion complexes (Scheme 2).
2.1. Complex synthesis and X-ray crystallography
The X-ray structures of 4-Mn, 4-Co, 4-Ni and 4-Cu
were obtained (Fig. 1). Crystallographic data are given
in Table 1 and selected bond lengths and angles are gi-
ven in Table 2. The complexes containing Mn, Co,
and Ni have distorted octahedral geometries with trans
nitrogen atoms. The observation of trans nitrogen chela-
tion is quite unusual because in conventional salen com-
plexes, trans coordination of the nitrogen atoms is
geometrically impossible. The N–M–N angle increases
with increasing atomic number (Mn, 159.9ꢁ; Co,
167.2ꢁ; Ni, 167.6ꢁ) as a consequence of the decreasing io-
nic radius of the metal. In 4-Mn, 4-Co, and 4-Ni, the
ethereal oxygen atoms are coordinated to the metal in
the solid state. The increase in the N–M–N angle is
accompanied by a decrease in average metal–ethereal
2-fluoronitrobenzene reacts readily with a variety of
mildly nucleophilic species, such as alcohols or amines,
to generate a new carbon-nucleophile bond and hydro-
fluoric acid [26]. In order to synthesize new salen-type li-
gands, we took advantage of this facile nucleophilic
aromatic substitution reaction (Scheme 2). 2,20-biphenol
reacts readily with 2-fluoronitrobenzene in refluxing
THF to give the doubly arylated product 1. Reduction
of 1 with hydrogen using a palladium on carbon catalyst
gives the previously unknown diamine 2 in excellent
overall yield (97%).
Reaction of 2 with two equivalents of salicylaldehyde
gives the corresponding dialdimine, 3 (Scheme 2). This
ligand is an ‘‘expanded salen ligand’’ because it has
the usual chelating atoms of salen (two imines, two aryl-
oxides) plus two additional neutral donor atoms
(ethers). However, since it is derived from salicylalde-
hyde and biphenol, the moniker salbipH2 is applied.
Facile deprotonation of 3 (salbipH2) is accomplished
with sodium methoxide in ethanol; subsequent exposure
˚
oxygen distances, which are 2.36, 2.23 and 2.19 A,
respectively. The copper complex 4-Cu has distorted
square planar geometry and its ethereal oxygen atoms
are apparently less strongly bound to the metal com-
pared to the Mn, Co, and Ni species. The average me-
˚
tal–ethereal oxygen distance is quite large (2.79 A) and
a N–M–N angle of only 164.6ꢁ is observed.

J.M. Grill et al. / Journal of Organometallic Chemistry 690 (2005) 3009–3017
3011
Fig. 1. X-ray structures of 4-Mn, 4-Co, 4-Ni, and 4-Cu with thermal ellipsoids drawn at 50% probability and hydrogen atoms omitted for clarity.
O(3) and O(4) are the ethereal oxygen atoms.
Given the facility of the salbipH2 ligand synthesis, we
sought to synthesize a chiral version of our expanded
salen ligand using (R)-binaphthol. Unfortunately (R)-
binaphthol reacts very slowly with 2-fluoronitrobenzene
in refluxing THF, taking up to two weeks for complete
reaction. However, the reaction proceeds quite rapidly
in DMF, affording the expected product 5 in high yield
after several hours (Scheme 3). Reduction of 5 in THF
with hydrogen using a palladium on carbon catalyst
gives the previously unknown chiral diamine 6 in excel-
lent overall yield (90.1%). Reaction of 6 with two equiv-
alents of salicylaldehyde or a substituted salicylaldehyde
affords the expected chiral expanded salen ligand 7a or
7b (Scheme 3). These are termed salbinH2 and salbin
(t-Bu)4H2 because they are derived from salicylaldehyde
and binaphthol.
4-Co. Also, the ethereal oxygen atoms in 8-Co are
˚
2.31 and 2.25 A from the cobalt atom. This compares
˚
well to distances of 2.23 and 2.24 A in 4-Co. Fig. 3
shows the similarities in the core structures of 4-Co
and 8-Co. Additionally, X-ray quality crystals of
8-Cu were obtained (Fig. 2). Its structure is similar
to that of 4-Cu (Fig. 1) with minor differences. The
N–Cu–N angle in 8-Cu is 160.5ꢁ, whereas the
N–Cu–N angle in 4-Cu is 164.6ꢁ. Also, the ethereal
˚
oxygen atoms in 8-Cu are 3.22 and 2.76 A from the
copper atom. This contrasts with the nearly identical
˚
copper-ethereal oxygen distances of 2.80 and 2.79 A
in 4-Cu. Fig. 4 shows the similarities in the core struc-
tures of 4-Cu and 8-Cu.
2.2. Catalytic epoxidation of olefins
Ligands 7a and 7b are readily deprotonated in
THF with potassium hydride and coordinated to tran-
sition metals (Scheme 3). The complexes are very dif-
ficult to crystallize and in many cases crystals suitable
for X-ray diffraction could not be grown. Nonetheless,
we were able to obtain crystals of 8-Co (Fig. 2). Its
structure is similar to that of 4-Co (Fig. 1) with minor
differences. For example, the N–Co–N angle is 164.8ꢁ
in 8-Co, compared to the N–Co–N angle of 167.2ꢁ in
Using commercially available Mn(III) Jacobsenꢀs
catalyst, it is possible to obtain high eeꢀs for the epox-
idation of many cis olefins. However, a pyridine-
N-oxide derivative (or other additive) is required, usually
with a 25 mol% loading relative to the olefin substrate.
Jacobsen asserts that this additive acts as an axial li-
gand to the manganese center [1,2]. Our initial hope
that the ethereal oxygens of 4 or 8 may supplant this

Table 1
Crystallographic data
Compound
4-Mn
4-Co
4-Ni
4-Cu
8-Co
8-Cu
Empirical formula
C
38H26MnN2O4
C38H26CoN2O4 Æ
2(CH2Cl2)
803.39
C38H26NiN2O4 Æ
2(CH2Cl2)
803.17
C38H26CuN2O4 Æ
(CH2Cl2)
723.07
C46H30CoN2O4 Æ
0.67(C4H8O2)
792.39
C46H30CuN2O4 Æ
(C4H8O2)
826.36
Formula weight
Temperature (K)
˚
Wavelength (A)
629.55
110(2)
110(2)
1.54178
110(2)
0.71069
110(2)
1.54178
110(2)
110(2)
1.54184
Triclinic
1.54184
Tetragonal
P41212
1.54178
Monoclinic
P1
Crystal system
Space group
Triclinic
ꢀ
Triclinic
ꢀ
Triclinic
ꢀ
ꢀ
P1
P1
P1
P1
˚
a (A)
10.040(2)
10.464(2)
15.633(3)
84.865(11)
79.931(11)
66.126(11)
1478.4(5)
2
12.151(5)
12.226(5)
12.890(5)
77.837(5)
88.325(5)
73.528(5)
1794.1(13)
2
12.062(5)
12.119(5)
12.858(5)
78.888(5)
88.475(5)
74.846(5)
1779.6(12)
2
10.1638(14)
10.7654(15)
14.831(2)
86.426(8) 53 + (8)
79.784(8)
80.540(8)
1574.4(4)
2
15.439(2)
15.439(2)
56.434(12)
90
9.6049(2)
20.1868(4)
10.4445(2)
90
˚
b (A)
˚
c (A)
a(ꢁ)
b(ꢁ)
c(ꢁ)
90
90
95.9610(10)
90
3
˚
Volume (A )
13452(4)
12
1.174
2014.16(7)
2
1.363
Z
Density (calc., gcmꢀ3
)
1.414
4.004
1.487
6.860
1.499
0.891
1.525
2.926
l (mmꢀ1
)
3.369
1.207
Crystal size (mm3)
Reflections
0.10 · 0.10 · 0.10
13845
4035
0.30 · 0.10 · 0.05
10841
4868
0.30 · 0.30 · 0.10
19921
7993
0.10 · 0.10 · 0.30
8824
4175
0.20 · 0.10 · 0.10
107481
9364
0.10 · 0.10 · 0.05
00807
4955
Independent reflections
Data/restraints/parameters
GOF (F2)
4035/0/404
1.068
0.0475
4868/0/461
1.059
0.0427
7993/4/476
1.079
0.0452
4175/0/433
1.006
0.0521
9364/604/766
1.003
0.1038
4955/1/534
1.009
0.315
R1[I > 2r(I)]
wR2[I > 2r(I)]
R1 (all data)
0.0646
0.1017
0.0991
0.0556
0.1179
0.0574
0.1068
0.1074
0.2095
0.1783
0.0798
0.0347
wR2 (all data)
Largest difference in peak, hole (e A
0.0725
0.339, 0.428
0.1047
0.811, ꢀ0.586
0.1323
1.114, ꢀ0.530
0.1240
0.527, ꢀ0.449
0.2477
0.455, ꢀ0.365
0.0816
0.335, ꢀ0.297
ꢀ3
˚
)

J.M. Grill et al. / Journal of Organometallic Chemistry 690 (2005) 3009–3017
3013
Table 2
Selected bond lengths (A) and angles (ꢁ)
˚
4-Mn
4-Co
4-Ni
4-Cu
1.91
8-Co
1.96
8-Cu
1.90
M–O(1)
M–O(2)
M–O(3)
M–O(4)
M–N(1)
M–N(2)
2.02
2.02
2.37
2.35
2.22
2.22
1.97
1.96
1.97
2.23
2.24
2.08
2.07
1.96
2.18
2.20
2.01
2.01
1.91
2.80
2.79
1.97
1.98
1.95
2.31
2.25
2.07
2.10
1.89
3.22
2.76
1.98
1.99
N(1)–M–N(2) 159.9
O(1)–M–O(2) 109.5
O(1)–M–O(3) 152.1
167.2
167.6
164.6
164.8
160.5
110.5
159.2
88.8
103.5
165.2
89.2
149.3
127.4
82.3
106.1
161.5
87.4
87.0
81.7
64.3
156.9
125.6
84.5
O(1)–M–O(4)
O(2)–M–O(3)
90.9
94.7
88.1
158.0
75.0
89.5
165.2
79.0
81.9
126.6
57.4
74.4
117.6
61.6
O(2)–M–O(4) 149.2
O(3)–M–O(4) 74.2
additive was not realized; an additive is indeed required
to obtain reasonable catalytic activity. The ether oxy-
gen atom, along with its persistence by chelation, does
not mimic the net electronic effects of the pyridine-
N-oxide additive.
The octahedral manganese complex 4-Mn catalyzes
the epoxidation of various olefins under the standard
conditions used by Jacobsen [2] with 5 mol% catalyst
loading (Scheme 4). The results are listed in Table 3.
Overall, the performance of the achiral catalyst 4-Mn
is comparable to other salen–manganese complexes with
regard to turnover numbers and rates [1,2,22].
Encouraged by the results with racemic 4-Mn, we
sought to employ our chiral manganese complexes to
obtain enantiomerically enriched epoxides (also under
the standard conditions outlined in Scheme 4). (R)-
binaphthol-based complex 8-Mn is capable of epoxidiz-
ing olefins with an activity comparable to that of 4-Mn.
Unfortunately, the ee for the epoxidation of styrene is
quite low at 11%. Thus, we turned to the tert-butylated
complex 9-Mn in the pursuit of higher eeꢀs. Complex 9-
Mn is capable of epoxidizing olefins; however, the activ-
ity is lower. In order to obtain complete conversion of
styrene to styrene oxide, 10 mol% catalyst loading was
Scheme 3. Synthesis of an expanded chiral salen-type ligand (7a,
salbinH2; 7b, salbin(t-Bu)4H2) and its coordination to metals.
required. Furthermore, the addition of tert-butyl groups
to the catalyst only increased the ee in the case of styrene
oxide to 22%. In the epoxidation of trans-stilbene, the
reaction does not reach completion even with 10% cata-
lyst loading. The GC yield of epoxide is only 15% and
the ee is only 18%.
Finally, the initial testing of 4-Co, 8-Co, and 9-Co for
the hydrolytic kinetic resolution of racemic epoxides [18]
was unfruitful. This is not wholly unexpected because
Fig. 2. X-ray structures of 8-Co and 8-Cu with thermal ellipsoids drawn at 50% probability and hydrogen atoms omitted for clarity. O(3) and O(4)
are the ethereal oxygen atoms.

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J.M. Grill et al. / Journal of Organometallic Chemistry 690 (2005) 3009–3017
Table 3
Substrates, epoxidation products, and isolated yields for catalyst 4-Mn
Fig. 3. Coordination sphere of 4-Co and 8-Co with thermal ellipsoids
drawn at 50% probability.
Fig. 4. Coordination sphere of 4-Cu and 8-Cu with thermal ellipsoids
drawn at 50% probability.
4. Experimental
4.1. General remarks
All air sensitive procedures were conducted under a
purified atmosphere of nitrogen in a glove box or using
standard Schlenk line techniques. Solvents were distilled
under nitrogen using standard techniques. Manganese
(II) acetate tetrahydrate (Acros, 99+%), cobalt (II) ace-
tate tetrahydrate (Acros, 99+%), nickel (II) acetate tet-
rahydrate (Acros, 99+%), and copper (II) acetate
tetrahydrate (Acros, 99+%), were each dehydrated by
heating under dynamic vacuum at 150 ꢁC for 3 h. The
anhydrous materials were stored in a dry box under
nitrogen. (R)-binaphthol was obtained from ABCR
Chemical and 3,5-di-tert-butyl salicylaldehyde was ob-
tained from Advanced Asymmetrics. All other reagents
were used as received. All NMR chemical shifts are gi-
ven in ppm and were recorded on a Mercury-300BB
spectrometer (1H, 299.91 MHz; 13C {1H} 75.41 MHz)
using the solvent as an internal standard (CDCl3 (or
Scheme 4. Catalytic epoxidation of olefins with [Mn] = 4-Mn, 8-Mn,
or 9-Mn.
the ethereal oxygen atoms (Figs. 1, 2, O(3) and O(4))
seemingly prevent the creation of an open coordination
site, a prerequisite for coordination and activation of the
epoxide substrate.
3. Conclusions
1
residual CHCl3): H 7.27 ppm; 13C 77.0 ppm). Chiral
Novel racemic and chiral expanded salen ligands
were synthesized and readily coordinated to Mn, Co,
Ni, and Cu to yield complexes with unique structural
motifs. Catalytically, the manganese-based complexes
generally behaved comparably to their salen analogues
for the epoxidation of olefins. While asymmetric induc-
tion was minimal with 8-Mn and 9-Mn, a variety of
other asymmetric catalytic reactions will be explored
using these readily synthesized and inexpensive transi-
tion metal complexes derived from chiral binaphthol.
phase gas chromatography was performed on an Agilent
6850 gas chromatograph with a 30-m 3-o-trichloracetyl-
2,6-di-o-pentyl b-cyclodextrin column. X-ray crystallo-
graphic data were obtained using a Bruker SMART
1000 three-circle diffractometer operating at 50 kV and
˚
40 mA, Mo Ka (k = 0.71073 A) with a graphite mono-
chromator and a CCD-PXL-KAF2 detector or a Bruker
GADPS instrument operating at 40 kV and 40 mA, Cu
˚
Ka (k = 1.54578 A) with a graphite monochromator and
a CCD-PXL-KAF2 detector.

J.M. Grill et al. / Journal of Organometallic Chemistry 690 (2005) 3009–3017
3015
4.2. Synthesis of 2,20-bis-(2-nitrophenoxy)-biphenyl (1)
118.9, 119.5, 120.2, 121.4, 123.5, 124.0, 127.7, 129.1,
129.2, 132.5, 132.6, 133.2, 139.8, 149.8, 154.4, 161.5,
164.1. TOF MS/ESI: m/z 577 (M + H)+.
2,20-biphenol (10.00 g, 53.7 mmol) and potassium
carbonate (16.33 g, 118.2 mmol) were added to a 500
mL round bottom flask with THF (200 mL). The reac-
tion was refluxed for 72 h. Removal of the insoluble
potassium salts by filtration, followed by removal of
the THF by rotary evaporation and high vacuum gave
the product as a white solid: 22.36 g (97.2%). Note:
THF removal is not necessary as it is a suitable solvent
for the next reaction. 1H NMR (CDCl3): d 6.85 (d,
J = 8.4 Hz, 2H, ArH), 6.97 (d, J = 9.3 Hz, 2H, ArH),
7.05 (t, J = 6.3 Hz, 2H, ArH), 7.19 (t, J = 6.9 Hz, 2H,
ArH), 7.26–7.39 (m, 4H, ArH), 7.45 (d, J = 6.8 Hz,
2H, ArH), 7.80 (d, J = 4.1 Hz, 2H, ArH). 13C {1H}
NMR (CDCl3) d 119.8, 122.7, 125.0, 125.8, 129.3,
129.8, 132.7, 135.4, 137.5, 140.7, 151.8, 152.7. TOF
MS/ESI: m/z 429 (M + H)+.
4.5. Typical procedure for the metallation of ligand 3
(4-Mn, 4-Co, 4-Ni, 4-Cu)
A quantity of 3 (1.00 g, 1.7 mmol) and sodium meth-
oxide (0.18 g, 3.3 mmol) were placed into a swivel frit.
The vessel was evacuated and dry, degassed ethanol
(ꢁ40 mL) was vacuum transferred into the frit. The
solution was warmed to 50 ꢁC for 4 h. All solvent was
removed by vacuum. The frit was brought into the glove
box and anhydrous M(OAc)2 (1.8 mmol) was added.
Ethanol (ꢁ30 mL) was vacuum transferred into the frit.
The reaction was heated to 50 ꢁC for 4 h during which
time a precipitate formed. This precipitate was filtered,
washed with ethanol and dried under vacuum.
4.3. Synthesis of 2,20-bis-(2-aminophenoxy)-biphenyl (2)
4.5.1. Synthesis of salbipMn (4-Mn)
M = Mn: red-orange micro crystals, 0.87 g (79.9%).
Crystals (needles) for X-ray diffraction were grown by
cooling a saturated dichloromethane solution to ꢀ35 ꢁC.
A solution of 1 (10.00 g, 23.3 mmol) in THF (200
mL) was placed into a hydrogenation vessel with 10%
Pd/C (0.25 g) and one drop of concentrated sulfuric
acid. The vessel was purged for several minutes with
hydrogen and then pressurized to 40 psi. The slurry
was stirred for 8 h at room temperature. The pressure
was released and the solution was then filtered to re-
move the palladium catalyst. Removal of the solvent
by rotary evaporation and high vacuum gave the prod-
uct as an off-white solid which was sufficiently pure for
characterization and further use: 8.55 g (99.6%) 1H
NMR (CDCl3): d 3.749 (broad, 4H, NH), 6.66 (t,
J = 7.2 Hz, 2H, ArH), 6.75 (m, 4H, ArH), 6.87 (d,
J = 7.8 Hz, 2H, ArH), 6.95 (t, J = 7.8 Hz, 2H, ArH),
7.12 (t, J = 7.5 Hz, 2H, ArH), 7.25 (t, J = 7.5 Hz, 2H,
ArH), 7.40 (d, J = 7.2 Hz, ArH). 13C {1H} NMR
(CDCl3) d 115.5, 116.6, 118.8, 121.4, 122.6, 125.4,
128.6, 129.2, 132.0, 139.3, 142.7, 155.3. TOF MS/ESI:
m/z 369 (M + H)+.
4.5.2. Synthesis of salbipCo (4-Co)
M = Co: red micro crystals, 0.94 g (85.8%). Crystals
(needles) for X-ray diffraction were grown by cooling a
saturated dichloromethane solution to ꢀ35 ꢁC.
4.5.3. Synthesis of salbipNi (4-Ni)
M = Ni: yellow powder, 0.62 g (56.6%). Crystals (nee-
dles) for X-ray diffraction were grown by cooling a sat-
urated dichloromethane solution to ꢀ35 ꢁC.
4.5.4. Synthesis of salbipCu (4-Cu)
M = Cu: green-brown micro crystals, 0.79 g (71.8%).
Crystals (needles) for X-ray diffraction were grown by
cooling a saturated dichloromethane solution to ꢀ35 ꢁC.
4.6. Synthesis of (R)-2,20-bis-(2-nitrophenoxy)-
[1,10]binaphthalenyl (5)
4.4. Synthesis of salbipH2 (3)
R-binaphthol (10.00 g, 34.9 mmol) and potassium
carbonate (10.14 g, 73.3 mmol) were dissolved in
DMF (120 mL). 2-fluoronitrobenzene (9.85 g, 69.8
mmol) was added to the solution. The obtained solution
was stirred at 80 ꢁC for 6 h and then poured over ice
water (250 mL). A white precipitate formed immedi-
ately. The white precipitate was collected by filtration,
washed with hot water (3 · 50 mL) and dried under vac-
A quantity of 2 (10.00 g, 25.9 mmol) was added to a
round bottom flask with methanol (250 mL). Salicylal-
dehyde (6.32 g, 51.8 mmol) was added to the flask. A
yellow precipitate formed almost instantly. The slurry
was stirred for 3 h to ensure reaction completion. The
slurry was then cooled in an ice bath. The solid was col-
lected by filtration and washed with cold methanol
(3 · 100 mL). The yellow power was dried by vacuum:
14.1 g (91.6%). 1H NMR (CDCl3): d ꢀ1.95 (s, 2H,
OH), 6.78 (d, J = 9.6 Hz, 2H, ArH), 6.85–6.94 (m, 6H,
ArH), 7.00–7.13 (m, 8H, ArH), 7.20–7.35 (m, 6H,
ArH), 7.45 (d, J = 7.8 Hz, 2H, ArH), 8.47 (s, 2H, Ar–
N@CH–Ar). 13C {1H} NMR (CDCl3) d 117.5, 118.0,
1
uum: 18.0 g (97.8%) H NMR (CDCl3): d 7.00–7.04 (m,
4H, ArH), 7.23 (d, J = 9.0 Hz, 2H, ArH), 7.21–7.37 (m,
6H, ArH), 7.44 (t, J = 6.2 Hz, 2H, ArH), 7.72 (d, J = 8.4
Hz, 2H, ArH), 7.89 (d, J = 8.1 Hz, 2H, ArH), 7.941 (d,
J = 9.0 Hz, 2H, ArH). 13C {1H} NMR (CDCl3) d 119.1,
120.7, 122.4, 122.9, 125.5, 125.8, 126.1, 127.3, 128.3,

3016
J.M. Grill et al. / Journal of Organometallic Chemistry 690 (2005) 3009–3017
130.8, 131.1, 134.1, 134.3, 141.0, 150.8, 151.2. TOF MS/
ESI: m/z 529 (M + H)+.
fluxed for 3 h during which time approximately 0.75
mL of water were collected. The toluene was then re-
moved by rotary evaporation followed by high vacuum
to give a yellow glass: 27.32 g (93.5%). This glass was
sufficiently pure for characterization and further use.
A powder could be obtained by adding 100 mL of meth-
anol to the glass and stirring the slurry for 2 h. 1H NMR
(CDCl3): d–1.99 (s, 2H, OH), 1.26 (s, 18H, Ar–
C(CH3)3), 1.32 (s, 18H, Ar–C(CH3)3), 6.74 (t, J = 6.9
Hz, 2H, ArH), 6.82 (d, J = 8.1 Hz, 2H, ArH), 6.89–
6.99 (m, 6H, ArH), 7.17–7.28 (m, 6H, ArH), 7.39 (d,
J = 2.7 Hz, 2H, ArH), 7.80 (d, J = 8.1 Hz, 2H, ArH),
7.88 (d, J = 9.0 Hz, 2H, ArH), 8.25 (s, 2H, Ar–
N@CH–Ar). 13C {1H} NMR (CDCl3) d 29.5, 31.8,
34.4, 35.2, 118.6, 120.3, 121.6, 122.0, 123.9, 124.6,
126.1, 126.6, 127.0, 127.2, 127.9, 128.0, 128.5, 129.9,
130.6, 134.4, 137.1, 140.3, 140.5, 149.6, 152.5, 158.3,
165.5. TOF MS/ESI: m/z 901 (M + H)+.
4.7. Synthesis of (R)-2,20-bis-(2-aminophenoxy)-
[1,10]binaphthalenyl (6)
A quantity of 5 (10.00 g, 18.9 mmol) was dissolved in
THF (200 mL) and the solution was added to a hydro-
genation vessel containing 10% Pd/C (0.25 g). One drop
of concentrated sulfuric acid was added. The vessel was
flushed for several minutes with hydrogen and then pres-
surized to 40 psi. The slurry was stirred for 8 h at room
temperature. The pressure was released and the solution
was then filtered to remove the palladium catalyst. Re-
moval of the solvent by rotary evaporation and high
vacuum gave the product was an off-white solid, which
was sufficiently pure for characterization and further
1
use (14.83 g, 90.6%): H NMR (CDCl3): d 3.55 (broad,
4H, NH), 6.61 (t, J = 8.7 Hz, 2H, ArH), 6.66 (d, J = 6.6
Hz, 2H, ArH), 6.82 (d, J = 7.8 Hz, 2H, ArH), 6.90 (t,
J = 7.5 Hz, 2H, ArH), 7.20 (d, J = 9.0 Hz, 2H, ArH),
7.31–7.43 (m, 6H, ArH), 7.87–7.91 (m, 4H, ArH). 13C
{1H} NMR (CDCl3) d 116.4, 117.5, 118.7, 120.6,
120.7, 124.7, 124.9, 125.6, 127.0, 128.5, 130.0, 130.5,
134.4, 138.9, 143.5, 153.0. TOF MS/ESI: m/z 469
(M + H)+.
4.10. Typical procedure for the metallation of ligand
(7a) or (7b)
The ligand 7a or 7b (2.2 mmol) was placed into a swi-
vel frit with potassium hydride (0.18 g, 4.4 mmol) under
an atmosphere of nitrogen. THF (ꢁ40 mL) was trans-
ferred into the swivel frit. The reaction was stirred for
2 h at room temperature open to a bubbler during which
time the color changed from yellow to red-orange. The
THF was removed under high vacuum. The frit was
brought into the glove box and anhydrous M(OAc)2
(2.3 mmol) was added. THF (ꢁ40 mL) was transferred
into the swivel frit. The reaction was stirred at 50 ꢁC
for 6 h. The THF was removed by vacuum and toluene
(ꢁ40 mL) was transferred into the frit. The solution was
filtered to remove the potassium acetate salt. The salt
cake was washed several times with toluene to extract
the product. The volume of toluene was reduced to 10
mL and the solution was allowed to stand until precip-
itate formed. The precipitate was collected by filtration
and dried under high vacuum.
4.8. Synthesis of salbinH2 (7a)
A quantity of 6 (10.00 g, 21.3 mmol) was dissolved in
toluene (200 mL) in a round bottom flask with a few
crystals of p-toluenesulfonic acid (0.05 g). Salicylalde-
hyde (5.21 g, 42.7 mmol) was added and a Dean–Stark
trap was attached. The solution was refluxed for 3 h dur-
ing which time approximately 0.75 mL of water were
collected. The toluene was then removed by rotary evap-
oration followed by high vacuum to give a yellow glass:
13.69 g (98.4%). This glass was sufficiently pure for char-
acterization and further use. A powder could be ob-
tained by adding 100 mL of methanol to the glass and
1
stirring the slurry for 2 h. H NMR (CDCl3): d ꢀ2.24
(s, 2H, OH), 6.706–6.821 (m, 6H, ArH), 6.890–7.11
(m, 10H, ArH), 7.19–7.35 (m, 8H, ArH), 7.85–7.95 (m,
4H, ArH), 8.17 (s, 2H, Ar–N@CH–Ar). 13C {1H}
NMR (CDCl3) d 117.2, 118.3, 118.8, 119.4, 120.3,
123.0, 124.1, 124.9, 125.8, 125.9, 127.1, 127.3, 128.2,
130.1, 130.5, 132.7, 133.1, 134.4, 140.0, 149.2, 152.1,
161.2, 165.4. TOF MS/ESI: m/z 677 (M + H)+.
4.10.1. Synthesis of salbinMn (8-Mn)
M = Mn: red-orange powder, 1.78 g (82.5%).
4.10.2. Synthesis of salbinCo (8-Co)
M = Co: red powder, 1.24 g (77.1%). Crystals (nee-
dles) for X-ray diffraction were grown by cooling a sat-
urated ethyl acetate solution to ꢀ35 ꢁC.
4.9. Synthesis of salbin(t-Bu)4H2 (7b)
4.10.3. Synthesis of salbinNi (8-Ni)
M = Ni: yellow powder, 1.41 g (87.2%).
A quantity of 6 (10.00 g, 21.3 mmol) was dissolved in
toluene (200 mL) in a round bottom flask with a few
crystals of p-toluenesulfonic acid (0.05 g). 3,5-di-tert-bu-
tyl salicylaldehyde (10.00 g, 42.7 mmol) was added and a
Dean–Stark trap was attached. The solution was re-
4.10.4. Synthesis of salbinCu (8-Cu)
M = Cu: green-brown micro crystals, 1.90 g (87.1%).
Crystals (needles) for X-ray diffraction were grown by
cooling a saturated dichloromethane solution to ꢀ35 ꢁC.

J.M. Grill et al. / Journal of Organometallic Chemistry 690 (2005) 3009–3017
3017
4.10.5. Synthesis of salbin(t-Bu)4Mn (9-Mn)
M = Mn: red-orange powder, 1.83 g (84.0%).
Data Centre, 12, Union Road, Cambridge CB2 1EZ,
UK; fax: +44 1223 336033.
4.10.6. Synthesis of salbin(t-Bu)4Co (9-Co)
M = Co: red powder, 1.33 g (62.1%).
Acknowledgements
4.10.7. Synthesis of salbin(t-Bu)4Ni (9-Ni)
M = Ni: yellow powder, 1.98 g (90.9%).
We thank The Robert A. Welch Foundation (Grant
No. A-1537) for funding this project. We also thank
Professor Gyula Vigh and his research group for provid-
ing us with several chiral phase GC columns.
4.10.8. Synthesis of salbin(t-Bu)4Cu (9-Cu)
M = Cu: green-brown micro crystals, 1.49 g (68.4%).
Crystals (needles) for X-ray diffraction were grown by
cooling a saturated dichloromethane solution to ꢀ35 ꢁC.
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