Hydrogen-bonded networks from η5-semiquinone complexes of manganese tricarbonyl

Article abstract of DOI:10.1016/j.jorganchem.2003.08.012

The cationic manganese tricarbonyl complexes containing η⁶ -2-methylhydroquinone (2a), η⁶-2,3-dimethylhydroquinone (3a), η⁶-2-t-butylhydroquinone (4a), η ⁶-tetramethylhydroquinone (5a) and η⁶-4, 4′-bi

Full text of DOI:10.1016/j.jorganchem.2003.08.012

Journal of Organometallic Chemistry 687 (2003) 78ꢀ84
/
www.elsevier.com/locate/jorganchem
Hydrogen-bonded networks from h5-semiquinone complexes of
manganese tricarbonyl
Moonhyun Oh, Jeffrey A. Reingold, Gene B. Carpenter, Dwight A. Sweigart *
Department of Chemistry, Brown University, Box H, Providence, RI 02912, USA
Received 27 June 2003; accepted 7 August 2003
Abstract
The cationic manganese tricarbonyl complexes containing h6-2-methylhydroquinone (2a), h6-2,3-dimethylhydroquinone (3a), h6-
2-t-butylhydroquinone (4a), h6-tetramethylhydroquinone (5a) and h6-4,4?-biphenol (6a) are readily deprotonated to the
corresponding neutral (h5-semiquinone)Mn(CO)3 (2bꢀ
/
6b) and anionic (h4-quinone)Mn(CO)ꢁ3 (2cꢀ
6b feature strong intermolecular hydrogen bonding interactions that result in the formation of supramolecular
/
5c) complexes. The X-ray
structures of 2bꢀ
/
organometallic networks. Significantly, the substitution pattern at the semiquinone ring affects the stereochemistry of the hydrogen
bonding interactions. NMR spectra of 2b, 3b and 5b reveal dynamic hydrogen bonding in solution.
# 2003 Elsevier B.V. All rights reserved.
Keywords: Hydrogen-bonded networks; Organometallic networks; h5-Semiquinone complexes; Manganese
1. Introduction
deprotonations can be viewed as being coupled with
electron transfer from the quinonoid ring to the
attached manganese moiety, which serves as an internal
oxidant.
Substituted hydroquinones are fundamentally impor-
tant in mediating electron and proton transfer reactions
in biological systems [1]. The attachment of a metal unit
to the p-system may well facilitate proton and electron
transfer. There are, however, only few examples of
complexes containing a hydroquinone ligand p-bonded
to a transition metal [2,3]. This is due in part to a
propensity [4] for quinone-type ligands to s-bond to
metals through the oxygen atoms rather than p-bond
through the carbocyclic ring.
Previously, we reported that stable p-bonded hydro-
quinone, catechol and resorcinol complexes of manga-
nese tricarbonyl could be obtained by reacting the free
ligands with the manganese tricarbonyl transfer reagent
[(h6-acenaphthene)Mn(CO)3]BF4 [3]. The Mn(CO)ꢂ3
Herein we report the synthesis and deprotonation
chemistry of p-coordinated complexes 2aꢀ
the hydroquinone-type ligands indicated in Schemes 2
and 3. The crystal structures of 2bꢀ6b reveal that these
/6a containing
/
complexes exist as organometallic polymers due to
strong intermolecular hydrogen bonding interactions.
Significantly, it is demonstrated that the substitution
pattern on the semiquinone ring affects the stereochem-
istry with which the semiquinone Cꢁ
/
O oxygen lone pair
interacts with the ꢀOH group in the adjacent molecule.
/
2. Results and discussion
moiety in these complexes renders the ꢀ
/
OH protons
As with complex 1a, complexes 2aꢀ6a were easily
/
quite acidic and the complexes are easily deprotonated
with mild base to afford semiquinone and quinone
complexes, as shown in Scheme 1. Interestingly, these
made as the BFꢁ4 salt by reaction of the appropriate
hydroquinone ligand with the manganese tricarbonyl
transfer reagent [(h6-acenaphthene)Mn(CO)3]BF4 [5].
Complexes 2aꢀ
the solid state and were fully characterized by IR and
NMR spectroscopy. Complexes 2aꢀ6a undergo sponta-
neous proton dissociation in DMSO to give a mixture of
/6a are very stable in solution and in
* Corresponding author. Tel.:
8632594.
ꢂ/
1-401-8632767; fax:
ꢂ/1-401-
/
E-mail address: dwight_sweigart@brown.edu (D.A. Sweigart).
0022-328X/03/$ - see front matter # 2003 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2003.08.012

M. Oh et al. / Journal of Organometallic Chemistry 687 (2003) 78ꢀ
/
84
79
Scheme 1.
Fig. 1. IR spectra in DMSO showing reversible of deprotonation/
protonation of complex 2a according to Scheme 2. Spectrum (a),
complex 2a dissolved in DMSO showing dissociation into an
equilibrium mixture of 2a and 2b; (b), addition of NEt3 generates 2c;
(c), addition of HBF4×
addition of more HBF4×
/
Et2O to (b) protonates 2c to form 2b; (d),
/Et2O protonates 2b to form 2a.
A typical experiment is illustrated in Fig. 1 for
complex 2a. Spectrum (a) shows that 2a is ca. 50%
converted to 2b in pure DMSO. Spectrum (b) reveals
that several equivalents of NEt3 changes 2a to the
quinone complex 2c, which can be reprotonated to 2b
Scheme 2.
with an equivalent of HBF4×
(c). Additional HBF4×Et2O transforms 2b to 2a as
shown in spectrum (d). All five neutral h5-coordinated
semiquinone complexes 2bꢀ6b were found to be stable
in solution and in the solid state. The anionic quinone
/Et2O, as shown in spectrum
/
/
complexes 2cꢀ5c are stable in solution, although they
/
could not be isolated as the HNEtꢂ3 salts.
The neutral h5-semiquinone complex 2b was obtained
in good yield by adding an equivalent of NEt3 to a
solution of [2a]BF4 in acetone. The nCO bands of 2b are
ca. 18 wavenumbers higher than that normally found for
(h5-cyclohexadienyl)Mn(CO)3 complexes [6], a fact that
we ascribe to a significant contribution from the h6-
resonance form 2b? shown below.
Scheme 3.
2aꢀ
/
6a and the corresponding h5-semiquinone species
6b, as was previously demonstrated with the unsub-
2bꢀ
/
stituted complex 1a. This reversible proton loss is
illustrated in Scheme 2. It was found that both single
and double deprotonation of 2aꢀ5a could be conveni-
/
ently and reversibly effected by the addition of the weak
base NEt3. In contrast, the acidity of the OH group in 6b
is too weak to allow deprotonation by NEt3 (Scheme 3).
This is undoubtedly due to the inability of the Mn(CO)3ꢂ
moiety to sufficiently activate an arene ring adjacent to
the one coordinated to the metal.
The NMR spectra of 2b, 3b and 5b indicate dynamic,
strong hydrogen bonding in solution. There is, however,
no evidence of dynamic hydrogen bonding interactions

80
M. Oh et al. / Journal of Organometallic Chemistry 687 (2003) 78ꢀ84
/
in solution for 4b and 6b. The 1H-NMR spectrum of 2b
shows just one broad signal at 5.47 ppm for the three
aromatic protons, which suggests dynamic hydrogen
bonding that has the effect of ‘mixing’ the Cꢀ
/
OH and
the Cꢁ
/
O ends of the molecule (Scheme 4). The signals
for the methyl and hydroxy groups appear at 1.97 and
10.47 ppm, respectively.
1
The H-NMR spectrum of 3b also gives evidence for
dynamic hydrogen bonding interactions, with only one
signal at 5.23 ppm for the two aromatic protons and one
signal at 2.16 ppm for the two methyl groups present in
the 1H-NMR. Complex 5b has a singlet at 2.08 ppm for
four equivalents methyl groups in proton NMR, which
again indicates the presence of dynamic hydrogen
bonding in solution.
Fig. 2. Crystal structure of 2b with thermal ellipsoids at the 50%
probability level.
The 1H-NMR data of 4b, however, suggests that there
is no dynamic hydrogen bonding interaction in solution.
A singlet for H1 and doublet for H2 are present at 6.17
and 6.13 ppm, respectively, while an upfield doublet for
H3 is found at 4.54 ppm. While there is no evidence for
dynamic hydrogen interaction in solution, the X-ray
structure revealed that there are linear chains of strongly
hydrogen-bonded semiquinone molecules in the solid
state, just as with 2b and 3b (vide infra). This lack of
dynamic hydrogen bonding in solution for 4b is possibly
due to steric effects attributable to the t-butyl substi-
tuent.
Crystal structures were determined for all five h5-
semiquinone complexes 2bꢀ
shown in Figs. 2ꢀ
bond lengths and angles, are given in Tables 1ꢀ
/
6b. The structures are
6 and crystal data, along with selected
4. With
Fig. 3. Crystal structure of 3b with thermal ellipsoids at the 50%
probability level.
/
/
all five complexes, the most interesting feature is the
presence of intermolecular hydrogen bonding that leads
to 1D supramolecular chain structures. As shown in
Table 5, the hydrogen-bonded Oꢀ
/
O donorꢀacceptor
/
distances are remarkably short and can be compared to
˚
O distance of 2.74 A reported for the hydrogen-
the Oꢀ
/
bonded dimer consisting of hydroquinone and quinone
[7]. The hydrogen bonding has the effect of ‘mixing’ the
Cꢀ
consequence that both bend or ‘envelope’ out of the
plane defined by C(2)ꢀC(3)ꢀC(5)ꢀC(6) in complexes
2bꢀ5b. Thus, both planes defined by C(3)ꢀC(4)ꢀC(5)
and C(2)ꢀC(1)ꢀC(6) are bent up by ca. 5ꢀ108. The
interplanar angles between these planes and the C(2)ꢀ
C(6) plane is much less than that seen in
/
OH and the Cꢁ
/
O ends of the molecule with the
/
/
/
/
/
/
/
/
/
/
C(3)ꢀ
/
C(5)ꢀ
/
Fig. 4. Crystal structure of 4b with thermal ellipsoids at the 50%
probability level.
typical (cyclohexadienyl)Mn(CO)3 complexes [6] as well
as that found in (h5-pentamethylbenzyl)Mn(CO)3 [8]
and (h5-oxocyclohexadienyl)Mn(CO)3 [9]. In concert
with this, the Mnꢀ
short enough to indicate some bonding interaction at
the CꢁO link, although less than that which occurs at
the CꢀOH end of the ring (see Tables 1ꢀ4). Complex 6b
differs from the others in that the CꢀOH and the Cꢁ
/
C(1) [or Mnꢀ
/
C(4)] distances are
/
/
/
/
/O
Scheme 4.

M. Oh et al. / Journal of Organometallic Chemistry 687 (2003) 78ꢀ
/
84
81
Scheme 5.
considerably higher than those reported for other
anionic complexes, e.g.
(h4-diene)Mn(CO)ꢁ3
(h4-naphthalene)Mn(CO)3ꢁ and (h4-xylylene)Mn(CO)ꢁ3
[10]. In the case of 3c, for example, we interpret this to
mean that resonance forms 3c? and 3cƒ shown in Scheme
5 make a nontrivial contribution.
We previously demonstrated that 1c (QMTC) inter-
acts with a wide variety of metal ions by s-bonding
through the oxygen atoms to afford metalꢀ
tallic coordination networks (MOMNs) [11]. One can
anticipate that anionic complexes 2cꢀ5c could also act
/
organome-
Fig. 5. Crystal structure of 5b with thermal ellipsoids at the 50%
probability level.
/
as spacers to generate MOMNs. The substituent-in-
duced hydrogen bonding patterns observed in the
present work may be useful for predicting the architec-
ture of metalꢀorganometallic networks based on p-
/
bonded quinone spacers. Indeed, it has recently been
shown that the stereochemical switch from trans to cis
observed in the hydrogen bonding pattern upon going
from 1b to 3b is closely mimicked when the 1c and 3c
analogues are used as spacers to bind to divalent metal
ions [12].
3. Experimental
Fig. 6. Crystal structure of 6b with thermal ellipsoids at the 50%
probability level.
3.1. General
Standard materials were purchased from commercial
sources and used without further purification. Acetone
and dichloromethane solvents were HPLC grade and
opened under nitrogen. 1H- and 13C-NMR spectra were
recorded on Bruker 300 and 400 MHz instruments.
2,3,5,6-Tetramethylhydroquinone is synthesized from
duroquinone using the Allen synthesis [13].
ends of the molecule are not ‘similar’ as in the other
semiquinone complexes. The consequence of this that
˚
C(1) distance in 6b (2.45 A) is longer than the
the Mnꢀ
/
˚
corresponding distances in 2bꢀ
indicative of the expected diminished interaction.
Another interesting structural feature of 2bꢀ6b is the
/
5b (average 2.38 A),
/
stereochemistry of the polymer networks. The hydrogen
bonding is extended in a cis-fashion in 3b and 5b, as
shown in Figs. 3 and 5. With 2b, 4b, and 6b, however,
the hydrogen bonding pattern is trans (Figs. 2, 4 and 6).
Thus, the oxygen lone pairs function in a stereochemi-
cally active manner that seems to be largely dictated by
the steric influences of the ring substituents.
3.2. Synthesis of the cationic h6-coordinated complexes of
manganese tricarbonyl 2aꢀ6a
/
[(h6-2-Me-hydroquinone)Mn(CO)3]BF4 ([2a]BF4) was
synthesized by treating the manganese tricarbonyl
transfer reagent [(h6-acenaphthene)Mn(CO)3]BF4 with
2-methylhydroquinone according to a published proce-
dure [3]. 2-Methylhydroquinone (0.3 g) was added to a
solution of [(h6-acenaphthene)Mn(CO)3]BF4 (0.5 g) in
CH2Cl2 (ca. 15 ml) under N2. The mixture was sealed in
a pressure bottle and heated to 70 8C for 2 h. The
reaction mixture was then cooled to room temperature
(r.t.). Finally, the precipitated pale yellow powder was
Deprotonation of the semiquinone complexes 2bꢀ
was found to be facile in DMSO using NEt3 as the base
5c
/5b
(see Fig. 1). Isolation of the product quinone salts 2cꢀ
/
proved to be difficult with HNEtꢂ3 as the counterion,
but deprotonation with alkali metal acetates led to
stable metal salts. As in the case of the semiquinones, IR
spectra of 2cꢀ5c show nCO bands at wavenumbers
/

82
M. Oh et al. / Journal of Organometallic Chemistry 687 (2003) 78ꢀ84
/
Table 1
Crystallographic data for semiquinone complexes 2bꢀ
/6b
2b 3b
4b
5b
6b
Empirical Formula
Formula weight
Temperature (K)
C
10H7MnO5
C11H9MnO5
276.12
298
C13H13MnO5
304.17
298
C13H13MnO5
304.17
298
C15H9MnO5
324.16
298
262.10
298
0.71073
˚
Wavelength (A)
0.71073
Monoclinic
P21/c
0.71073
Monoclinic
P21/n
0.71073
Triclinic
¯
P1
0.71073
Triclinic
¯
P1
Crystal system
Space group
Triclinic
¯
P1
/
/
/
˚
a (A)
6.8520(5)
7.6545(5)
10.2065(7)
92.0890(10)
92.6330(10)
106.8000(10)
511.24(6)
2
8.9201(5)
9.1943(6)
13.8435(8)
90
6.8500(3)
12.8279(6)
15.3869(7)
90
14.2320(12)
18.7943(17)
20.2411(18)
81.564(2)
87.568(2)
86.787(2)
5343.9(8)
16
6.7260(7)
9.7440(10)
10.2105(10)
94.198(2)
100.262(2)
96.140(2)
651.78(11)
2
˚
b (A)
˚
c (A)
a (8)
b (8)
g (8)
95.8350(10)
90
101.7330(10)
90
3
˚
V (A )
Z
1129.48(12)
4
1.624
1323.8(10)
4
1.526
Dcalc (g cmꢁ3
)
1.703
1.292
264
1.512
1.000
2496
1.652
1.031
328
m (mmꢁ1
F(000)
)
1.174
560
1.009
624
Crystal dimension (mm)
u Range (8)
Reflections collected
Independent reflections
Data/restraints/parameters
0.23ꢄ
2.00ꢀ28.28
5509
2487 (Rint
2487/0/146
/
0.22ꢄ
/
0.20
0.38ꢄ
2.30ꢀ28.28
11 447
0.0169) 2787 (Rint
2787/0/156
/
0.32ꢄ
/
0.28
0.50ꢄ
2.70ꢀ28.30
13 994
0.0187) 3264 (Rint
3264/0/175
/
0.20ꢄ
/
0.19
0.34ꢄ
2.04ꢀ26.51
66 771 a
0.0196) 66 771 (Rint
66 771/0/1402
/
0.17ꢄ
/
0.07
0.28ꢄ
2.11ꢀ28.30
6963
3136 (Rint
3136/0/190
/
0.24ꢄ
/
0.11
/
/
/
/
/
ꢃ/
ꢃ/
ꢃ/
ꢃ
/
0.000) a
ꢃ/0.0250)
R1, wR2 [I ꢀ
R1, wR2 (all data)
Goodness-of-fit on F2
/
2s(I)]
0.0362, 0.0945
0.0391, 0.0964
1.091
0.0310, 0.0833
0.0362, 0.0876
1.030
0.0310, 0.0822
0.0348, 0.0850
1.068
0.0594, 0.1179
0.1596, 0.1395
0.782
0.0370, 0.1027
0.0411, 0.1055
1.086
a
The seemingly large number of reflections is a consequence of software used to account for crystal twinning.
Table 2
Selected bond distances (A) and angles (8) for complexes 2b and 3b
Table 3
Selected bond distances (A) and angles (8) for complexes 4b and 5b
˚
˚
2b
3b
4b
5b
Bond distances
Bond distances
Mn(1)ꢀ
Mn(1)ꢀ
Mn(1)ꢀ
Mn(1)ꢀ
Mn(1)ꢀ
Mn(1)ꢀ
/
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
2.2341(18)
2.2065(18)
2.1962(17)
2.3673(18)
2.193(2)
Mn(1)ꢀ
Mn(1)ꢀ
Mn(1)ꢀ
Mn(1)ꢀ
Mn(1)ꢀ
Mn(1)ꢀ
C(1)ꢀ
C(4)ꢀ
/
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
2.2310(15)
2.2086(15)
2.2235(15)
2.3777(16)
2.1880(17)
2.1651(15)
1.3360(18)
1.267(2)
Mn(1)ꢀ
Mn(1)ꢀ
Mn(1)ꢀ
Mn(1)ꢀ
Mn(1)ꢀ
Mn(1)ꢀ
/
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
2.3909(13)
2.2366(13)
2.1649(13)
2.2324(13)
2.1728(14)
2.1897(14)
1.2702(16)
1.3259(15)
Mn(1)ꢀ
Mn(1)ꢀ
Mn(1)ꢀ
Mn(1)ꢀ
Mn(1)ꢀ
Mn(1)ꢀ
C(1)ꢀ
C(4)ꢀ
/
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
2.203(4)
2.198(4)
2.196(4)
2.401(5)
2.216(4)
2.192(4)
1.364(4)
1.243(4)
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
2.165(2)
/
/
/
C(1)ꢀ
/
O(1)
1.327(2)
1.269(2)
/
O(1)
C(1)ꢀ
/
O(1)
/
O(1)
C(4)ꢀ
/
O(2)
/
O(2)
C(4)ꢀ
/
O(2)
/
O(2)
Bond angles
O(1)ꢀC(1)ꢀ
O(1)ꢀC(1)ꢀ
O(2)ꢀC(4)ꢀ
O(2)ꢀC(4)ꢀ
C(6)ꢀC(1)ꢀ
C(3)ꢀC(2)ꢀ
C(2)ꢀC(3)ꢀ
C(5)ꢀC(4)ꢀ
C(6)ꢀC(5)ꢀ
C(5)ꢀC(6)ꢀ
Bond angles
O(1)ꢀC(1)ꢀ
O(1)ꢀC(1)ꢀ
O(2)ꢀC(4)ꢀ
O(2)ꢀC(4)ꢀ
C(6)ꢀC(1)ꢀ
C(3)ꢀC(2)ꢀ
C(4)ꢀC(3)ꢀ
C(3)ꢀC(4)ꢀ
C(6)ꢀC(5)ꢀ
C(5)ꢀC(6)ꢀ
/
/
C(6)
C(2)
C(5)
C(3)
123.25(16)
118.74(16)
122.66(17)
122.57(15)
117.95(15)
119.45(16)
123.38(15)
114.47(15)
121.10(17)
121.89(16)
O(1)ꢀ
O(1)ꢀ
O(2)ꢀ
O(2)ꢀ
C(6)ꢀ
C(3)ꢀ
C(2)ꢀ
C(5)ꢀ
C(6)ꢀ
C(1)ꢀ
/
C(1)ꢀ
C(1)ꢀ
C(4)ꢀ
C(4)ꢀ
C(1)ꢀ
C(2)ꢀ
C(3)ꢀ
C(4)ꢀ
C(5)ꢀ
C(6)ꢀ
/
C(6)
C(2)
C(5)
C(3)
C(2)
C(1)
C(4)
C(3)
C(4)
C(5)
123.09(14)
117.68(15)
121.89(18)
122.45(17)
119.20(13)
119.12(15)
121.61(14)
115.44(14)
121.84(15)
120.76(15)
/
/
C(6)
C(2)
C(3)
C(5)
121.04(13)
122.91(13)
124.13(13)
118.64(13)
115.73(11)
118.06(12)
123.69(12)
117.16(11)
120.14(12)
122.98(12)
O(1)ꢀ
O(1)ꢀ
O(2)ꢀ
O(2)ꢀ
C(6)ꢀ
C(3)ꢀ
C(4)ꢀ
C(3)ꢀ
C(6)ꢀ
C(5)ꢀ
/
C(1)ꢀ
C(1)ꢀ
C(4)ꢀ
C(4)ꢀ
C(1)ꢀ
C(2)ꢀ
C(3)ꢀ
C(4)ꢀ
C(5)ꢀ
C(6)ꢀ
/
C(6)
C(2)
C(3)
C(5)
C(2)
C(1)
C(2)
C(5)
C(4)
C(1)
115.5(4)
122.9(4)
122.2(4)
123.1(4)
121.5(4)
117.8(4)
123.0(4)
114.4(4)
121.2(4)
119.7(4)
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
C(2)
C(1)
C(4)
C(3)
C(4)
C(1)
/
/
/
/
C(2)
C(1)
C(2)
C(5)
C(4)
C(1)
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
7.43, 2.25 Hz, H2, 1H), 2.32 (s, CH3, 3H). 1H-NMR (d6-
acetone): d 6.57 (d, Jꢃ7.46 Hz, H3, 1H), 6.48 (d, Jꢃ
2.81 Hz, H1, 1H), 6.18 (dd, Jꢃ7.46, 2.81 Hz, H2, 1H),
2.32 (s, CH3, 3H). 13C-NMR (CD3CN): d 218.2 (Mnꢀ
CO), 139.8, 135.1, 107.6, 89.0, 87.3, 82.9, 15.8 (CH3).
collected by filtration, washed with CH2Cl2 and dried in
vacuo. For [2a]BF4: yield 87%. IR (Me2SO): nCO 2055
/
/
(s), 1988 (s, br) cmꢁ1. IR (acetone): nCO 2064 (s), 2001
/
1
(s, br) cmꢁ1. H-NMR (CD3CN): d 6.19 (d, Jꢃ
/
7.43
/
Hz, H3, 1H), 6.05 (d, Jꢃ
/
2.25 Hz, H1, 1H), 5.81 (dd, Jꢃ
/

M. Oh et al. / Journal of Organometallic Chemistry 687 (2003) 78ꢀ
/
84
83
1
Table 4
cmꢁ1. H-NMR (d6-acetone): d 7.74 (d, Jꢃ
H3, 2H), 7.30 (d, Jꢃ
Hz, H4, 2H), 6.10 (d, Jꢃ
/
8.48 Hz,
˚
Selected bond distances (A) and angles (8) for complex 6b
/
7.30 Hz, H2, 2H), 7.00 (d, Jꢃ
/8.48
/
7.30 Hz, H1, 2H).
Bond distances
Mn(1)ꢀ
Mn(1)ꢀ
Mn(1)ꢀ
Mn(1)ꢀ
/
C(1)
C(2)
C(3)
C(4)
2.4468(18) Mn(1)ꢀ
2.2132(17) Mn(1)ꢀ
2.1502(17) C(1)ꢀ
2.1936(17) C(10)ꢀ
/
C(5)
2.1587(16)
2.2115(18)
1.251(2)
3.3. Synthesis of the neutral h5-coordinated complexes of
manganese tricarbonyl 2bꢀ6b
/
/C(6)
/
/
O(1)
/
/
/
O(2)
1.348(2)
Bond angles
O(1)ꢀC(1)ꢀ
O(1)ꢀC(1)ꢀ
O(2)ꢀ
O(2)ꢀ
C(2)ꢀ
Triethylamine (0.33 mmol) was added to a solution of
[2a]BF4 (100 mg, 0.29 mmol) in acetone (10 ml) under
nitrogen at r.t. After removing some acetone solvent by
bubbling N2, a pale yellow precipitate of 2b formed,
which was filtered and washed three times with acetone
and dried in vacuo. Yield 75%. IR (Me2SO): nCO 2028
/
/
C(2)
124.24(17) C(3)ꢀ
122.47(17) C(2)ꢀ
118.65(16) C(3)ꢀ
121.97(17) C(6)ꢀ
112.87(15) C(5)ꢀ
/
C(2)ꢀ
C(3)ꢀ
C(4)ꢀ
C(5)ꢀ
C(6)ꢀ
/
C(1)
C(4)
C(5)
C(4)
C(1)
122.23(15)
122.17(15)
115.66(15)
122.35(16)
122.11(16)
/
/C(6)
/
/
/
C(10)ꢀ
C(10)ꢀ
C(1)ꢀ
/C(9)
/
/
/
/C(11)
/
/
/
/C(6)
/
/
1
(s), 1950 (s, br) cmꢁ1. H-NMR (d6-Me2SO): d 10.47
(br, OH, 1H), 5.47 (br, aromatic protons, 3H), 1.97 (s,
Table 5
Hydrogen bond parameters for the semiquinone complexes 1bꢀ
3H). To synthesize complexes 3bꢀ6b, the same proce-
/
/
6b
dure used for the synthesis of 2b was followed, except
5b. For 5b, the acetone solvent was removed and the
product taken up in dichloromethane and precipitated
with diethyl ether. For 3b: yield 78%. IR (Me2SO): nCO
2025 (s), 1948 (s, br) cmꢁ1. IR (acetone): nCO 2028 (s),
1947 (s, br) cmꢁ1. IR (CH2Cl2): nCO 2038 (s), 1965 (s,
Complexes
D-HÁ Á ÁA
d(DÁ Á ÁA)
B
(DHA)
/
1b [3]
O(1)ꢀ
/
2.47
2.63
2.52
2.54
2.48
2.53
2.63
172.8
H(1)Á Á ÁO(2)
(h5-o-Semiqinone)Mn(CO)3 O(2)ꢀ
[3]
2b
/
153.7
176.1
173.6
174.7
141.3
171.8
1
br) cmꢁ1. H-NMR (d6-Acetone): d 5.23 (br, H1 and
H(2)Á Á ÁO(1)
O(1)ꢀ
H(1)Á Á ÁO(2)
O(1)ꢀ
H(1)Á Á ÁO(2)
O(2)ꢀ
H(2)Á Á ÁO(1)
O(1)ꢀ
H(1)Á Á ÁO(7)
O(2)ꢀ
H(2)Á Á ÁO(1)
H2, 2H), 2.16 (s, 2(CH3), 6H). For 4b: yield 88%. IR
(Me2SO): nCO 2025 (s), 1941 (s, br) cmꢁ1. 1H-NMR (d6-
Me2SO): d 10.33 (br, OH, 1H), 6.17 (s, H1, 1H), 6.13 (d,
/
3b
4b
5b
6b
/
Jꢃ
/
7.63 Hz, H2, 1H), 4.54 (d, Jꢃ7.63 Hz, H3, 1H), 1.26
/
/
(s, C(CH3)3, 9H). 13C-NMR (d6-Me2SO): d 221.9 (Mnꢀ
CO), 163.5, 125.5, 107.5, 91.8, 78.3, 34.3 (C(CH3)3),
/
/
28.9 (C(CH3)3). For 5b: yield 45%. IR (CH3CN): nCO
1
2026 (s), 1953 (s, br) cmꢁ1. H-NMR (CD3CN): d 2.08
/
(s, CH3, 12H). For 6b: yield 82%. IR (Me2SO): nCO 2036
(s), 1965 (s, br) cmꢁ1. 1H-NMR (d6-Me2SO): d 9.83 (br,
To synthesize complexes 3aꢀ/6a, the same procedure
OH, 1H), 7.57 (d, Jꢃ
Hz, H2, 2H), 6.83 (d, Jꢃ
7.83 Hz, H1, 2H). 1H-NMR (d6-acetone): d 7.63 (d, Jꢃ
8.46 Hz, H3, 2H), 6.93 (d, Jꢃ8.46 Hz, H4, 2H), 6.79 (d,
Jꢃ7.79 Hz, H2, 2H), 4.92 (d, Jꢃ
7.79 Hz, H1, 2H). 13C-
NMR (d6-Me2SO): d 220.1 (MnꢀCO), 166.0, 158.3,
127.7, 124.2, 115.8, 103.4, 95.9, 82.9.
/
8.23 Hz, H3, 2H), 6.86 (d, Jꢃ
/7.83
used for the synthesis of 2a was followed. For [3a]BF4:
yield 88%. IR (Me2SO): nCO 2053 (s), 1985 (s, br) cmꢁ1
/
8.23 Hz, H4, 2H), 4.89 (d, Jꢃ
/
.
/
IR (acetone): nCO 2061 (s), 1997 (s, br) cmꢁ1. 1H-NMR
(d6-acetone): d 7.37 (OH), 6.31 (s, H1, 2H), 2.53 (s, CH3,
/
/
/
1
6H). H-NMR (d6-Me2SO): d 5.85 (s, H1, 2H), 2.23 (s,
/
CH3, 6H). For [4a]BF4: yield 90%. IR (Me2SO): nCO
2054 (s), 1987 (s, br) cmꢁ1. IR (acetone): nCO 2062 (s),
1999 (s, br) cmꢁ1. IR (CH3CN): nCO 2065 (s), 2003 (s,
3.4. Synthesis of the anionic h4-coordinated complexes
2cꢀ5c
1
br) cmꢁ1. H-NMR (CD3CN): d 8.69 (br, OH, 1H),
/
6.34 (d, Jꢃ
Hz, H2, 1H), 5.90 (d, Jꢃ
/
2.11 Hz, H1, 1H), 6.27 (dd, Jꢃ
7.58 Hz, H3, 1H), 1.43 (s,
C(CH3)3, 9H). H-NMR (CD3OD): d 6.28 (d, Jꢃ2.18
Hz, H1, 1H), 6.24 (dd, Jꢃ7.63, 2.18 Hz, H2, 1H), 5.59
(d, Jꢃ
7.63 Hz, H3, 1H), 1.39 (s, C(CH3)3, 9H). 13C-
NMR (CD3CN): d 218.3 (MnꢀCO), 140.2, 134.3, 114.4,
89.7, 89.5, 85.2, 35.9 (C(CH3)3), 29.6 (C(CH3)3). 13C-
NMR (CD3OD): d 219.3 (MnꢀCO), 142.8, 135.3, 114.0,
/
7.58, 2.11
The HNEtꢂ3 salts of the anionic quinone complexes
2cꢀ5c, were synthesized by the addition of excess NEt3
(at least two equivalents) to h6-complexes 2aꢀ
5a or by
the addition of NEt3 to h5-complexes 2bꢀ
5b. The
/
1
/
/
/
/
/
/
/
products could not be isolated as solids because they
easily convert to semiquinone complexes. For
[2c]HNEt3, IR (Me2SO): nCO 1996 (s), 1915 (s, br)
/
1
cmꢁ1. H-NMR (d6-Me2SO): d 5.09 (br, 1H), 4.94 (br,
90.7, 89.5, 84.8, 36.0 (C(CH3)3), 29.8 (C(CH3)3). For
[5a]BF4: yield 94%. IR (CH3CN): nCO 2059 (s), 1995 (s,
1
1H), 4.76 (br, 1H), 1.86 (s, CH3, 3H), 2.69
(N(CH2CH3)3, 6H), 1.02 (N(CH2CH3)3, 9H). For
[3c]HNEt3, IR (Me2SO): nCO 1993 (s), 1911 (s, br)
cmꢁ1. For [4c]HNEt3, IR (Me2SO): nCO 1993 (s), 1915
br) cmꢁ1. H-NMR (CD3CN): d 2.07 (s, CH3, 12H).
For [6a]BF4: yield 82%. IR (CH3CN): nCO 2071 (s), 1912
(s, br) cmꢁ1. IR (acetone): nCO 2068 (s), 2010 (s, br)

84
M. Oh et al. / Journal of Organometallic Chemistry 687 (2003) 78ꢀ84
/
1
(s, br) cmꢁ1. H-NMR (d6-Me2SO): d 5.24 (br, 1H),
5.33 (br, 1H), 4.40 (br, 1H) 1.24 (s, C(CH3)3, 9H), 2.74
(N(CH2CH3)3, 6H), 1.04 (N(CH2CH3)3, 9H). For
(1990) 1677;
(c) G. Fairhurst, C. White, J. Chem. Soc. Dalton Trans. (1979)
1531;
(d) Y.-S. Huang, S. Sabo-Etienne, X.-D. He, B. Chaudret,
Organometallics 11 (1992) 3031;
[5c]HNEt3, IR (Me2SO): nCO 1983 (s), 1900 (s, br) cmꢁ1
.
(e) U. Koelle, C. Weisschadel, U. Englert, J. Organomet. Chem.
¨
3.5. Crystal structures
490 (1995) 101;
(f) S. Sun, G.B. Carpenter, D.A. Sweigart, J. Organomet. Chem.
512 (1996) 257;
X-ray data collection with MoꢀKa radiation was
/
(g) J. Le Bras, H. Amouri, J. Vaissermann, Organometallics 17
(1998) 1116.
carried out at 298 K using a Bruker Apex diffractometer
equipped with a CCD area detector. Structures were
determined by direct methods and refined on F2. All
hydrogen atoms were inserted in ideal positions, riding
on their carbon atoms.
[3] M. Oh, G.B. Carpenter, D.A. Sweigart, Organometallics 21
(2002) 1290.
[4] (a) C.G. Pierpont, C.W. Langi, Prog. Inorg. Chem. 41 (1994) 331;
(b) O.-S. Jung, D.H. Jo, Y.A. Lee, B.J. Conklin, C.G. Pierpont,
Inorg. Chem. 36 (1997) 19;
(c) D.M. Adams, D.N. Hendrickson, J. Am. Chem. Soc. 118
(1996) 11515;
4. Supplementary material
(d) F. Hartl, A. Vlcek, Inorg. Chem. 35 (1996) 1257.
[5] S. Sun, L.K. Yeung, D.A. Sweigart, T.-Y. Lee, S.S. Lee, Y.K.
Chung, S.R. Switzer, R.D. Pike, Organometallics 14 (1995) 2613.
[6] (a) M.R. Churchill, S. Scholer, Inorg. Chem. 8 (1969) 1950;
(b) S.D. Ittel, J.F. Whitney, Y.K. Chung, P.G. Williard, D.A.
Sweigart, Organometallics 7 (1988) 1323;
X-ray crystallographic data have been deposited with
the Cambridge Crystallographic Data Centre, CCDC
nos. 213260ꢀ
/
213264 for complexes 2bꢀ6b. Copies of
/
this information may be obtained free of charge from
The Director, CCDC, 12 Union Road, Cambridge CB2
(c) T.-Y. Lee, H.-K. Bae, Y.K. Chung, W.A. Hallows, D.A.
Sweigart, Inorg. Chim. Acta 224 (1994) 147.
[7] T. Sakurai, Acta Crystallogr. B24 (1968) 403.
[8] D.M. LaBrush, D.P. Eyman, N.C. Baenziger, L.M. Mallis,
Organometallics 10 (1991) 1026.
1EZ, UK (Fax: ꢂ44-1223-336033; e-mail: depos-
/
it@ccdc.cam.ac.uk or www: http://www.ccdc.cam.a-
c.uk).
[9] S.-G. Lee, J.-A. Kim, Y.K. Chung, T.-S. Yoon, N. Kim, W. Shin,
Organometallics 14 (1995) 1023.
[10] (a) R.L. Thompson, S. Lee, A.L. Rheingold, N.J. Cooper,
Organometallics 10 (1991) 1657;
Acknowledgements
(b) J.W. Hull, K.J. Roesselet, W.L. Gladfelter, Organometallics
11 (1992) 3630.
Acknowledgment is made to the donors of The
American Chemical Society Petroleum Research Fund
for support of this research.
[11] (a) M. Oh, G.B. Carpenter, D.A. Sweigart, Angew. Chem. Int.
Ed. 40 (2001) 3191;
(b) M. Oh, G.B. Carpenter, D.A. Sweigart, Angew. Chem. Int.
Ed. 41 (2002) 3650;
(c) M. Oh, G.B. Carpenter, D.A. Sweigart, Angew. Chem. Int.
Ed. 42 (2003) 2026;
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