Tunable N-substitution in zwitterionic benzoquinonemonoimine derivatives: Metal coordination, tandemlike synthesis of zwitterionic metal complexes, and supramolecular structures

Article abstract of DOI:10.1002/chem.200500704

Full details on a very efficient transamination reaction for the synthesis of zwitterionic N,N′-dialkyl-2-amino-5-alcoholate-1,4- benzoquinonemonoiminium derivatives [C₆H₂(=NHR) ₂(=O)₂] 5-16 are reported. The mo

Full text of DOI:10.1002/chem.200500704

FULL PAPER
DOI: 10.1002/chem.200500704
Tunable N-substitution in Zwitterionic Benzoquinonemonoimine
Derivatives: Metal Coordination, Tandemlike Synthesis of Zwitterionic Metal
Complexes, and Supramolecular Structures
Qing-Zheng Yang, Olivier Siri,* and Pierre Braunstein*[a]
Dedicated to Professor D. M. P. Mingos
Abstract: Full details on a very effi-
cient transamination reaction for the
synthesis of zwitterionic N,N’-dialkyl-2-
amino-5-alcoholate-1,4-benzoquinone-
and allowing fine-tuning of the supra-
molecular arrangements in the solid
state. As previously described for 15,
which reacted with Zn(acac)2 to afford
give the stable, crystallographically char-
acterized ZnII zwitterionic complexes
[ZnCl2{C6H2(=NCH2CH2NR1R2)O(=O)-
(NHCH2CH2NHR1R2)}] 22 (R1 =R2 =
Me) and 23 (R1 =Et, R2 =H) by means
of an unprecedented, tandemlike syn-
thesis in which 1) the two pendant
amino groups of the organic benzoqui-
nonemonoimine zwitterionic precursor
favor metal coordination and proton
transfer and 2) the saturated linker
prevents p-conjugation between the
charges. The nature of the structural ar-
rangements in the solid state for both
inorganic (20, 22, 23) and organic (5, 9,
13, and 15) molecules is determined by
subtle variations in the nature of the
N-substituent on the zwitterion precur-
sor.
monoiminium
derivatives
[C6H2-
the
octahedral
ZnII
complex
(PNHR)2(PO)2] 5–16 are reported. The
molecular structures of zwitterions 5
[Zn{C6H2(=NCH2CH2NMe2)O(=O)-
(NHCH2CH2NMe2)}2] (20), ligands 13
and 16 with coordinating “arms” af-
forded with Zn(acac)2 the 2:1 adducts
[Zn{C6H2(=NCH2CH2X)O(=O)(NH-
CH2CH2NX)}2] 19 (X=OMe) and 21
(X=NHEt), with N2O4 and N4O2
donor sets around the octahedral ZnII
center, respectively. Furthermore, zwit-
terions 15 and 16 reacted with ZnCl2 to
(R=CH3)
in
5·H2O,
13
(R=
CH2CH2OMe), 15 (R=CH2CH2NMe2),
and of the parent, unsubstituted system
[C6H2(PNH2)2(PO)2] 4 in 4·H2O have
been established by single-crystal X-
ray diffraction. This one-pot prepara-
tion can be carried out in water,
MeOH, or EtOH and allows access to
new zwitterions with N-substituents
ꢀ
bearing functionalities such as OMe
Keywords: coordination modes
·
1
2
(13), OH (9–12), NR R with R1 =
or ¼R2 (14–16) or an alkene (8), lead-
ing to a rich coordination chemistry
ꢀ
ꢀ
organic synthesis · quinones · supra-
molecular chemistry · zwitterions
Introduction
by carefully selecting building blocks made of organic li-
gands containing appropriate functional groups.[2] Consider-
ing the importance of noncovalent interactions in nature
and the large number of natural quinonoid compounds
available, it appears that studying the supramolecular prop-
erties of quinonoid molecules should provide an interesting
field of research.[3] Among the natural quinones that contain
an acidic proton, some play an important role as bioinhib-
itors,[4] because they can interact with the ATP binding site
through hydrogen bonding.[4j]
Noncovalent interactions play a key role in the fields of
chemistry, molecular biology, and material science.[1] Numer-
ous supramolecular chemical assemblies have been obtained
[a] Dr. Q.-Z. Yang, Dr. O. Siri, Dr. P. Braunstein
Laboratoire de Chimie de Coordination, UMR 7513CNRS
UniversitØ Louis Pasteur, 4, rue Blaise Pascal
67070 Strasbourg Cedex (France)
Fax : (+33)390-241-322
E-mail: siri@luminy.univ-mrs.fr
Recently, zwitterionic N-substituted benzoquinonemono-
imine derivatives (2) were shown to result from proton mi-
gration from the oxygen of a postulated hydroxyquinone in-
termediate 1 onto the more basic nitrogen site [Eq. (1)].[5]
The first member of this new class of quinones (R=tBu)[5]
has attracted considerable theoretical interest, as it is a rare
braunst@chimie.u-strasbg.fr
Supporting information for this article is available on the WWW
under http://www.chemeurj.org/ or from the author. Supporting infor-
mation for this article contains a description of the molecular packing
in 4·H2O and 5·H2O
Chem. Eur. J. 2005, 11, 7237 – 7246
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7237

of ZnII complexes in the presence of multifunctional ligands
are of increasing relevance in bioinorganic chemistry.[15]
The formation of metal complexes from zwitterionic li-
gands is often limited by the low reactivity of the lat-
ter,[6a,9,16] the poor stability of the complexes,[17] or by restric-
tions to certain pH ranges.[16,17] We are aware of only one
study reporting the preparation of a zwitterionic complex
from an organic zwitterion.[11f] Its formation was, however,
unexpected and not fully understood.
example of a potentially antiaromatic zwitterion being more
stable than its canonical forms.[6]
Such quinonoids display interesting supramolecular struc-
tural properties,[5,6a,7] and appear very attractive in organic
chemistry,[6a,7] color chemistry,[8] and coordination chemis-
try[6a,9] owing to their remarkable chemical and physical
properties: 1) as zwitterions they are strongly dipolar (elec-
trostatic interactions), 2) they possess two hydrogen-donor
sites and two hydrogen-acceptor sites (hydrogen-bonding in-
teractions), 3) they have a conjugated p system (p–p inter-
action), and 4) it is possible to vary the nature of the N-sub-
stituent (tuning of the steric properties and introduction of
heteroatoms and/or hydrogen-donor and -acceptor sites).
However, the preparation of a wide range of such
NCH2R-substituted zwitterions could not be achieved by the
initial synthetic procedure owing to the need to use highly
reactive acid chlorides,[5,6a] in which the choice of other func-
tional groups is limited. For further applications of this class
of molecules, in particular as colorants, a “greener” synthe-
sis (i.e. without organic solvent) was of great interest.
A new, efficient synthesis of various functional N-substi-
tuted, 6p+6p-electron zwitterionic benzoquinonemonoimine
derivatives involves the first transamination reactions in qui-
nonoid chemistry.[10] This one-pot preparation can often be
performed in water and provides an access to new zwitter-
ions not available by the previously reported methods.[5,6a] It
allows a fine-tuning of the solubility of these molecules,
which is a key point for their subsequent applications. Fur-
thermore, the introduction of various functionalities on the
zwitterionic skeleton opens new possibilities in supramolec-
ular chemistry and for the synthesis of novel coordination
complexes.
Herein, we wish to describe the synthesis of a range of
zwitterionic quinones, their metal coordination, and supra-
molecular organizations. The synthesis of new ammonium
metalate zwitterionic complexes from such quinonemono-
imine 6p+6p organic zwitterions involves a controlled met-
alation operating in a tandemlike manner, with each of the
initially identical pendant amino functions of the organic
precursor playing a different role with anchimeric assistance.
The nature of the structural arrangements in the solid state
for both inorganic and organic molecules is determined by
subtle variations in the nature of the N-substituent on the
zwitterion precursor.
Results and Discussion
Ligand synthesis: We have extended the family of zwitter-
ionic quinones 2 by applying our recent transamination pro-
cedure.[10a] Compound 3·2HCl reacted smoothly at room
temperature and in air with a large excess of primary
amines RNH2 in water, MeOH, or EtOH to afford the cor-
responding zwitterions [C6H2(PNHR)2(PO)2] 5–16 in high
yield (see Experimental Section; Scheme 1). The zwitterion
4 was shown to be an intermediate in this reaction.[10a] Func-
tionalities such as OH, OMe, NR1R2 (R1 = or ¼R2), or an
alkene could thus be introduced. In contrast to 6 and 7,
which are only soluble in organic solvents, 9–12 are almost
Among them, zwitterionic metal complexes have been
recognized as an important class of molecules endowed with
interesting structural, electronic, magnetic, nonlinear optical,
or catalytic properties.[11] It is usually the metal center that
carries the positive charge. The reverse situation in which an
integral negative charge would be formally localized on the
metal center is uncommon, although this is the case, for ex-
ample, in complexes derived from phosphonium ylids.[12]
When the negative charge is delocalized between the metal
center and the coordinated ligand through a conjugated p
system, different nonzwitterionic Lewis structures can be en-
visaged.[12] Therefore, true zwitterionic metalates with the
opposite charges separated by sp3 carbon atoms are particu-
larly interesting, but much less common.[11f,13] They are at-
tracting increasing interest owing to their potential in non-
linear optics, molecular electronics, and catalysis.[12,14] In ad-
dition, the nature and geometry of the coordination sphere
Scheme 1. One-pot synthesis of zwitterions 5–16.
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Chem. Eur. J. 2005, 11, 7237 – 7246

Coordination Chemistry
FULL PAPER
insoluble in most organic solvents, but are soluble in water
owing to the presence of hydrophilic groups (-OH). Zwitter-
ions 5 and 13–16 are soluble in both organic solvents and
water.
It is known that nucleophilic substitution reactions can
occur smoothly on quinonoid rings. For instance, an amino
group can substitute an hydroxyl group, a methoxy group,
and sometimes alkyl groups of quinones.[18] However, to the
best of our knowledge, substitution of an amino group by
another amine was unprecedented in quinonoid chemistry
(Scheme 1).[10] This transamination reaction under mild con-
ditions may be rationalized by the fact that in the parent
zwitterion 4, the positive charge is p-delocalized between
excess to afford 18. Intermediate D could also react with the
amine to regenerate the zwitterion 6 (Scheme 3), but the ir-
reversible transformation D!18 shifts the equilibrium be-
tween 6 and D to the right. In the absence of water, 6 is
quantitatively obtained by the reaction of D with an excess
of n-butylamine in MeOH, similarly to the reactions shown
in Scheme 2.
Crystal structures of the ligands: The molecular structures
of compounds 4·H2O, 5·H2O, 13, and 15 have been elucidat-
ed by X-ray crystallography (Figure 1). A symmetry axis
ꢀ
the nitrogen atoms, making the C N carbon atoms (i.e., C3
and C5) more electrophilic. Although monosubstituted B
would be a likely intermediate (Scheme 1), it could not be
isolated owing to the fast kinetics of the reaction.
Interestingly, hydroxybenzoquinone derivatives, related to
17,[7] react with amines to afford quinonemonoimine deriva-
tives; this represents an important step in enzyme-catalyzed
deamination reactions.[18c,d] We anticipated that reaction of
17 with n-butylamine could afford the unsymmetrical zwit-
terion C (Scheme 2). However, zwitterion 6 was isolated in-
Scheme 2. Reaction of hydroxybenzoquinone 17 with excess amine.
stead, showing that the amine reacted with both the carbon-
yl and the neopentylamino groups of 17, probably via inter-
mediate C. This constitutes the first direct synthesis of zwit-
terionic benzoquinonemonoimines from benzoquinones.
Influence of the reaction time: We noticed that when
3·2HCl was treated with excess nBuNH2 in water for a long
period of time (3days), 2,5-diaminoquinone 18 was formed
in high yield. This reaction may proceed according to
Scheme 3: first, the zwitterion 6 (obtained in 2 h from 3 ac-
Figure 1. ORTEP views of 4 in 4·H2O, 5 in 5·H2O, 13, and 15. Thermal el-
lipsoids are drawn at the 50% probability level. Only the NH protons
are shown.
passes through the carbon atoms C1 and C4 of 13 and 15.
Selected bond lengths and angles are listed in Tables 1 and
2, respectively.
Whereas more than one century ago, the air oxidation
product of diaminoresorcinol was erroneously described as
intermediate A in Scheme 1,[19] we recently concluded on
1
the basis of H NMR data that its true structure is 4.[10] This
has now been confirmed by an X-ray diffraction study on
single crystals of 4·H2O, obtained by slow aerobic reaction
in water of diaminoresorcinol dihydrochloride with glycin.
The structure of the parent member of the family of 6p+6p-
electron molecules 2 confirms its zwitterionic character, with
a fully delocalized p system within the O1-C2-C1-C6-O2
and N1-C3-C4-C5-N2 moieties (Figure 1). The correspond-
Scheme 3. Competing reactions involving D.
cording to Scheme 1) would be hydrolyzed under basic con-
ditions to afford an aminohydroxyquinone intermediate D
(see Experimental Section), as recently reported,[7] and then
the OH group of D would be substituted by the amine in
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7239

P. Braunstein, O. Siri, and Q.-Z. Yang
ence of additional coordinating “arms”.[10a] Reactions of
these ligands at room temperature with Zn(acac)2 in a 2:1
ligand/metal ratio readily afforded high yields of the octahe-
dral, neutral complexes [Zn{C6H2(=NCH2CH2NX)O(=O)-
(NHCH2CH2NX)}2] 19 (X=OMe), 20 (X=NMe2),[10] and 21
(X=NHEt) which contain a uninegative, N,N,O-tridentate
ligand as a result of monodeprotonation by the acac ligand
(Scheme 4). No zwitterionic complex was formed.[10a] In con-
trast, reaction of 2 (R=tBu) with M(acac)2 (M=Ni, Cu,
Zn) required higher temperatures and longer reaction
times.[6a]
Table 1. Selected bond lengths [Š] in 4·H2O, 5·H2O, 13, and 15.
4·H2O
5·H2O
13
15
ꢀ
O1 C2
ꢀ
C1 C2
1.261(3)
1.393(3)
1.400(3)
1.251(3)
1.317(3)
1.382(3)
1.395(3)
1.310(3)
1.520(3)
1.514(3)
1.251(2)
1.387(2)
1.388(2)
1.258(2)
1.310(2)
1.386(2)
1.383(2)
1.315(2)
1.523(2)
1.526(2)
1.250(1)
1.394(1)
1.252(1)
1.393(1)
ꢀ
C1 C6
ꢀ
C6 O2
ꢀ
N1 C3
1.316(1)
1.391(1)
1.317(1)
1.383(1)
ꢀ
C3 C4
ꢀ
C4 C5
ꢀ
C5 N2
ꢀ
C2 C3
1.526(1)
1.527(2)
ꢀ
C5 C6
Whereas no intramolecular acid–base reaction occurs in
the free ligands 15[10a] or 16, their reaction with ZnCl2 (1 equiv)
in MeOH at room temperature afforded the zwitterionic
mononuclear complexes [ZnCl2{C6H2(=NCH2CH2NR1R2)O-
(=O)(NHCH2CH2NHR1R2)}] 22 (R1 =R2 =Me) and 23
(R1 =Et, R2 =H), respectively (Scheme 4). The negative
charge of the metalate moiety, which is of course shared by
the electronegative ligands but formally shown on the metal
center in Scheme 4, is balanced by the ammonium cation re-
sulting from intramolecular proton shift (i.e., acid–base re-
action). This is consistent with the formation of intermediate
A in which the interaction of the PNHR function with the
metal center, assisted by chelation of the NR1R2 arm, results
in an increased acidity of this PNHR proton. Whereas in
earlier complexation studies[6a,9] involving 2 (R=tBu),[5]
prior deprotonation of the PNHR group by an external re-
agent was required, the amino function carried by the or-
ganic precursors 15 and 16 acts here as an intramolecular
base and removes the proton, made more acidic upon coor-
dination of the ligand to the metal. The description of com-
plexes 22 and 23 as zwitterions is consistent with the X-ray
data (Table 3and Figure 2). In their tautomeric forms, 15
and 16 act as tridentate ligands, and the coordination sphere
of the pentacoordinate metal center is completed by the two
chlorine ligands.
Table 2. Selected bond angles [8] in 4·H2O, 5·H2O, 13, and 15.
4·H2O
5·H2O
13
15
O1-C2-C1
O1-C2-C3115.9(2)
N1-C3-C4
N1-C3-C2
C2-C1-C6
126.2(2)
125.7(1)
(91)16.43 116.1(1)
125.2(1)
113.7(1)
122.5(1)
119.2(1)
125.8(1)
126.6(1)
116.2(2)
123.7(2)
115.1(2)
122.5(2)
119.4(2)
124.7(1)
113.87(8)
124.4(1)
113.8(1)
C3-C4-C5
C2-C1-C2’
C3-C4-C3’
122.7(1)
119.0(1)
123.0(1)
118.9(1)
ing pairs of CPO, CPN and CPC bond lengths are very simi-
ꢀ
ꢀ
lar (Table 1). The C2 C3and C6 C5 distances of 1.519(5)
and 1.517(5) Š, respectively, correspond to single bonds and
indicate a lack of conjugation between the two “6p halves”
of the compound.[5,6a] As a result, molecule 4 can be consid-
ered as a trimethine oxonol subunit chemically connected to
a trimethine cyanine subunit.[20] From this point of view, our
transmination reaction by means of nucleophilic substitution
bears similarities with reactions observed in the polymethine
series.[21]
Similarly, the bond lengths found for molecules 5·H2O, 13,
and 15 are consistent with their zwitterionic structure, with
two fully delocalized 6p subsystems that are chemically con-
nected by two single bonds but electronically independent.
In the solid state, compounds 4·H2O and 5·H2O develop in-
termolecular interactions with p–p stacking and strong hy-
drogen bonding with water molecules that generate compli-
cated architectures (see the Supporting Information).
In these ZnII complexes, examination of the respective
bond lengths within the O1-C2-C1-C6-O2 and N1-C3-C4-
C5-N2 moieties reveal an alternation of single and double
bonds, consistent with two conjugated but localized p sys-
tems (Table 3), whereas the free ligands 15 and 16 present a
perfectly delocalized form. As in all previously described re-
lated crystallographic structures,[6a,9] the C2 C3and C6 C5
distances around 1.52 Š correspond to single bonds and in-
dicate the lack of conjugation between the two p subsys-
tems. Interestingly, the ammonium metalates 22 and 23 are
ꢀ
ꢀ
Coordination chemistry: The new ligands 13 and 16, pre-
pared similarly to 15,[10a] show better coordination abilities
toward metal precursors than 2 (R=tBu) owing to the pres-
Scheme 4. Reactions of ligands 13, 15, and 16 with ZnII precursors.
7240
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Coordination Chemistry
FULL PAPER
Table 3. Selected bond lengths [Š] and angles [8] in complexes 22 and
23.
It is worth noting that no reaction was observed between
2 (R=tBu) and ZnCl2 when NEt3 was used as a base under
similar conditions. This result demonstrates the assistance of
the ligand pendant arm to metal coordination which induces
deprotonation of the iminium nitrogen (see intermediate A,
Scheme 4). Molecules 15 and 16 constitute rare examples of
ligands operating both as a chelate and base in an anchimer-
ic manner.
22
23
ꢀ
O1 C2
ꢀ
C1 C2
1.285(3)
1.372(3)
1.416(3)
1.239(3)
1.268(8)
1.379(9)
1.395(9)
1.240(8)
ꢀ
C1 C6
ꢀ
C6 O2
ꢀ
)
)
N1 C31.2961(3.287(8)
ꢀ
C2 C31.5121(.3521(8)
ꢀ
C3 C4
1.428(3)
1.368(3)
1.346(3)
1.519(3)
2.227(2)
2.042(2)
2.217(6)
2.2815(9)
2.302(1)
1.430(9)
1.344(9)
1.358(9)
1.523(10)
2.183(5)
2.061(5)
ꢀ
C4 C5
Supramolecular arrangements: A comparison of selected
noncovalent interaction distances in ligands 9,[10a] 13, and 15,
and complexes 20,[10a] 22, and 23 is provided in Table 4.
ꢀ
C5 N2
ꢀ
C5 C6
ꢀ
Zn O1
ꢀ
Zn N1
ꢀ
Table 4. Comparison of selected noncovalent distances [Š] in ligands
Zn N32.246(2)
9,[10a] 13, and 15, and complexes 20,[10a] 22, and 23.
ꢀ
Zn Cl1
2.279(2)
2.310(2)
ꢀ
Zn Cl2
Intramolecular
hydrogen-bonding
interaction
Intermolecular
hydrogen-bonding
interaction
p–p
interaction
Cl1-Zn-Cl2
O1-Zn-N1
O2-C6-C1
C6-C1-C2
C1-C2-O1
108.53(4)
75.35(8)
125.0(2)
122.3(2)
125.1(2)
126.2(2)
112.49(8)
75.1(2)
125.1(6)
122.5(6)
125.4(6)
125.8(7)
ꢀ
9
O1···H N1=2.177(3)
N1···O1=2.996(4)
O3···O1=2.723(4)
N2···O2=3.029(4)
O2···O4=2.710(4)
C6···O2’=3.241(4)
ꢀ
O2···H N2=2.192(3)
N2-C5-C4
C5-C4-C3119.8(2)
C4-C3-N1
119.7(6)
ꢀ
13
15
O1···H N1=2.190(3)
N1···O1=2.899(4)
no
125.6(2)
127.3(6)
ꢀ
O···H N1=2.180(3)
no
C1···C4=3.677(4)
ꢀ
N2···H N1=2.365(3)
ꢀ
20
O2···H N2=2.252(3)
N2···O2=2.962(4)
N4···O1=2.936(4)
C15···C18=3.550(4)
ꢀ
O4···H N4=2.204(3)
ꢀ
22
23
O2···H N2=2.191(3)
N4···O1=2.773(4)
C1···C4=3.528(4)
C1···C4=3.581(4)
ꢀ
O2···H N2=2.241(3)
N4···O1=2.718(4)
N4···O2=2.751(4)
All of them have intramolecular NH···O bonding distan-
ces in the range 2.177(3)–2.365(3) Š. Molecule 15 revealed
an additional hydrogen bond owing to the presence of the
ꢀ
ꢀ
basic functions NMe2 (N2···H N1 interaction).
We have previously shown that the supramolecular net-
work of zwitterion 2 (R=tBu) forms a wavelike arrange-
ment with head-to-tail hydrogen-bonding interactions owing
to the presence of two bulky N-neopentyl substituents
(Figure 3).[5]
Figure 2. ORTEP views of the structure of complexes 22 (a) and 23 (b)
(ellipsoids drawn at the 50% probability level).
not stabilized by intramolecular hydrogen-bonding interac-
tions. The influence of the metal center and of the substitu-
ents R1 and R2 on their supramolecular structures will be
discussed below.
Figure 3. View of the supramolecular array generated by 2 (R=tBu) in
the solid state. A) Top view, and B) side view. Color coding: nitrogen,
blue; oxygen, red.
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P. Braunstein, O. Siri, and Q.-Z. Yang
Zwitterions of type 2 with no bulky N-substituents could
be readily prepared by using our versatile synthetic ap-
proach. This is the case for 5, and in contrast to the solid-
state packing of 5·H2O (see Supporting Information), that of
the solvent-free molecules consists of a head-to-tail but now
almost coplanar arrangement (Figure 4), at variance to that
Figure 4. Views of the supramolecular array generated by 5 in the solid
state. A) Top view and B) side view. Color coding: nitrogen, blue;
oxygen, red.
of 2 with R=tBu. This was clearly observed although the
quality of the crystal did not allow a complete structural res-
olution (crystallization from CH2Cl2 with no solvent mole-
cule incorporated in the crystal).
Figure 5. View of the supramolecular array generated by 9 in the solid
state. A) Top view, B) side view, and C) local view of B). Color coding:
nitrogen, blue; oxygen, red.
Although the N-substituents in 9 are bulkier than those in
ꢀ
5 (i.e., two CH2CH2OH groups), this molecule shows in
the solid state a similar arrangement owing to hydrogen-
ꢀ
bonding interactions between hydrogen donors of N1 H
ꢀ
and O3 H and hydrogen acceptor O1 with N1···O1 and
O3···O1 bond lengths of 2.996(4) and 2.723(4) Š, respective-
ly, which force the system to become coplanar.[10] Therefore,
in contrast to 2 (R=tBu), molecules of 9 form a head-to-tail
and coplanar 1-D supramolecular network in the solid state
owing to the presence of the OH groups (i.e., two acidic
protons; Figure 5).
Interestingly, the replacement of the OH proton in 9 by a
methyl group (molecule 13) prevents hydrogen-bonding in-
teractions involving the “arms” of the ligand. As a result,
these are situated out of the molecular plane, preventing
formation of p–p staking (Figure 6), in contrast to 9, which
reveals a succession of layers in the solid state (see Table 4
and Figure 5B).
Figure 6. View of the supramolecular array generated by 13 in the solid
state. A) Top view and B) side view. Color coding: nitrogen, blue;
oxygen, red.
Although zwitterion 15 can be viewed as analogous of 2
(R=tBu), this molecule leads to a different arrangement in
the solid state. No intermolecular hydrogen bonding is ob-
served owing to the presence of the hydrogen-acceptor
groups (CH2)2NMe2 that interact only through intramolecu-
ꢀ
lar hydrogen bonding (N1 H···N2=2.365(3) Š; see Figure 1
and Table 4). Thus, intermolecular interactions occur only
by p–p stacking (C1···C4=3.677(4) Š) in a head-to-tail
manner (Figure 7) instead of the head-to-tail but wavelike
arrangement observed for 2 (R=tBu).
The diversity of supramolecular networks generated by
these ligands led us to examine the situation with the ZnII
complex 20, which has two hydrogen-donor sites and several
hydrogen-acceptor sites.[10a] Its crystal packing revealed in-
termolecular hydrogen bonding interactions in the solid
Figure 7. View of the stacking arrangement generated by 15 in the solid
state. Color coding: nitrogen, blue; oxygen, red.
7242
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Chem. Eur. J. 2005, 11, 7237 – 7246

Coordination Chemistry
FULL PAPER
state with (N2···O2=2.962(4) and N4···O1=2.936(4) Š)
leading to a one-dimensional wavelike chain (Figure 8). In
addition, p–p interactions with a C15···C18 distance of
3.550(4) Š between two quinone rings contribute to the sta-
bility of this chain.
tuning of the structural arrangements in the solid state. The
new ligand 13 and 16 show better coordination abilities
toward metal precursors than 2 (R=tBu) and react with Zn-
(acac)2, as previously shown for 15,[10a] to afford complexes
19 and 21 with N2O4 and N4O2 donor sets around the ZnII
center, respectively. Zwitter-
ions 15 and 16 were shown to
react with ZnCl2 to give zwit-
terionic complexes 22 and 23.
The nature of the arrange-
ments in the solid state of inor-
ganic (20, 22, 23) and organic
(5, 9, 13 and 15) molecules was
found to be determined by
subtle variations in the nature
of the N-substituent of the
zwitterion precursor.
Figure 8. View of the supramolecular array generated by the ZnII complex 20 in the solid state. Color coding:
nitrogen, blue; oxygen, red; zinc, green.
The zwitterionic ZnII complex 22 forms a pseudodimer in
ꢀ
the solid state that is stabilized by the N4 H···O1 interac-
tion (N4···O1=2.773(4) Š) and p–p stacking (see Table 3
and Figure 9).
Figure 9. View of the supramolecular array generated by the zwitterionic
ZnII complex 22 in the solid state. Color coding: nitrogen, blue; oxygen,
red; zinc, green.
Interestingly, the presence of an additional proton located
on N4 in 23, instead of the methyl group in 22, allows fur-
Figure 10. View of the supramolecular array generated by the zwitterion-
ic ZnII complex 23 in the solid state. Color coding: nitrogen, blue;
oxygen, red; zinc, green.
ther hydrogen-bonding interactions between these pseudo-
dimers (N4···O1=2.718(4) and N4···O2=2.751(4) Š) as
shown in Figure 10.
Experimental Section
1H (300 MHz) and 13C NMR (75 MHz) spectra were recorded on a
Bruker AC300 instrument. MALDI-TOF mass spectra were recorded on
a Biflex III Bruker mass spectrometer. Elemental analyses were per-
formed by the “Service de Microanalyse, UniversitØ Louis Pasteur (Stras-
bourg, France)”. Solvents were freshly distilled under nitrogen prior to
use. 4,6-Diaminoresorcinol dihydrochloride and the functional amines
are commercially available. Ligands 4–7, 9, and 15, and complex 20 were
prepared according to the literature.[10a]
Conclusion
We have reported here full details on a new and very effi-
cient transamination reaction for the synthesis of N-substi-
tuted zwitterionic benzoquinonemonoimine derivatives that
can be carried out in water. This new one-pot synthetic ap-
proach provides access to a series of quinonoid zwitterions
5–16 with different N-substitutents bearing functionalities
such as OMe, OH, NR1R2 (R1 = or ¼R2), or an alkene,
leading to a rich coordination chemistry and allowing fine-
General procedure: Typically, diaminoresorcinol dihydrochloride
(0.500 g, 2.35 mmol) was dissolved in water (ca. 10 mL) and then excess
of amine (ca. 7 equiv) was added to the solution. For the compounds that
Chem. Eur. J. 2005, 11, 7237 – 7246
ꢀ 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
7243

P. Braunstein, O. Siri, and Q.-Z. Yang
are not or only poorly soluble in water, purple crystals appeared rapidly.
30–120 minutes later, the crystals were isolated by filtration and washed
with cold water, and dried in air. In other cases, details are given below.
45.23(s, NHCH 2), 82.53(s, N PCPC), 99.89 (s, OPCPC), 156.17 (s, NPC),
175.23ppm
(s,
O PC); elemental analysis calcd
(%)
for
C10H16N4O2·1.5H2O: C 47.80, H 7.62, N 22.30; found: C 48.53, H 7.37, N
22.42. Despite several attempts, no better results (C) could be obtained
for this compound. MS (MALDI-TOFꢀ): m/z: 223.1 [M-1]ꢀ.
Ligand 8: The amine used was allylamine; yield: 82%; 1H NMR
3
(300 MHz, [D6]DMSO, 258C): d=4.05 (d, J=5.5 Hz, 4H; NHCH2), 4.99
(s, 1H; NPCPCH), 5.17 (m, 2H; CH=CH1H2), 5.22 (m, CH=CH1H2),
5.42 (s, 1H; OPCPCH), 5.84 (ddt, 3J=16.9, 10.7, 5.5 Hz, 2H; CH=CH2),
9.25 ppm (brs, 2H; NH); 13C{1H} NMR (75 MHz, [D6]DMSO, 258C): d=
45.25 (s, NHCH2), 82.85 (s, NPCPC) 98.09 (s, OPCPC), 117.89 (s, CH=
CH2), 132.60 (s, CH=CH2), 156.90 (s, NPC), 172.46 ppm (s, OPC); ele-
mental analysis calcd (%) for C12H14N2O2·0.5H2O: C 63.42, H 6.65, N
12.33; found: C 63.29, H 6.45, N 12.30; MS (MALDI-TOF+): m/z: 219.1
[M+1]+.
Ligand 16: An excess of N-ethylethylenediamine (6.171 g, 70 mmol) was
added to
a suspension of 3·2HCl (2.131 g, 10 mmol) in methanol
(30 mL). After the reaction mixture was stirred for 2 h, NaOH (2 equiv)
were added to the solution, which was then stirred for 0.5 h. After con-
centration, diethyl ether was added to the solution and the precipitate
was filtered. The product was dissolved in dichloromethane, and the solu-
tion filtered through Celite. The pale orange brown product was obtained
after evaporation of the solvent and precipitation from a mixture of di-
chloromethane and pentane. This compound was soluble in H2O, alcohol,
or CHCl3 and gave purple solutions. Yield: 63%; 1H NMR (300 MHz,
CDCl3, 258C): d=1.12 (t, 3J=7.1 Hz, 6H; CH2CH3), 2.69 (q, 3J=7.1 Hz,
4H; CH2CH3), 2.97 (t, 3J=6.0 Hz, 4H; CPNHCH2CH2), 3.43 (t, 3J=
6.0 Hz, 4H; CPNHCH2), 5.19 (s, 1H; NPCPCH), 5.45 ppm (s, 1H;
OPCPCH); 13C NMR (75 MHz, CDCl3, 258C): d=15.32 (s, CH3), 42.98
(s, CH2CH3), 43.84 (s, CPNHCH2CH2), 47.00 (s, CPNHCH2), 81.19 (s,
NPCPC), 98.96 (s, OPCPC), 156.90 (s, NPC), 172.36 ppm (s, OPC); ele-
mental analysis calcd (%) for C14H24N4O2·0.5H2O: C 58.11, H 8.71,
N19.36; found: C 58.82, H 8.51, N 19.87; MS (MALDI-TOFꢀ): m/z: 279.2
[Mꢀ1]ꢀ.
Ligand 10: A similar procedure was used with the amine 3-amino-1-prop-
1
anol; yield: 72%; H NMR (300 MHz, [D6]DMSO, 258C): d=1.77 (pent,
3J=6.4 Hz, 4H; CH2CH2OH), 3.47 (m, 8H; CH2OH, CH2NH), 4.70 (brs,
2H; OH), 4.97 (s, 1H; NPCPCH), 5.52 (s, 1H; OPCPCH), 8.99 ppm
(brs, 2H; NH); 13C{1H} NMR (75 MHz, [D6]DMSO, 258C): d=31.32 (s,
CH2CH2OH), 40.70 (s, NCH2), 58.85 (s, CH2OH), 81.66 (s, NPCPC),
98.02 (s, OPCPC), 156.59 (s, NPC), 172.56 ppm (s, OPC); elemental anal-
ysis calcd (%) for C12H18N2O4: C 56.68, H 7.13, N 11.02; found: C 56.35,
H 7.23, N 10.79; MS (MALDI-TOFꢀ): m/z: 253.1 [Mꢀ1]ꢀ.
Ligand 11: An excess of 3-amino-1,2-propanediol (1.594 g, 17.5 mmol)
was added to a suspension of 3·2HCl (0.533 g, 2.50 mmol) in ethanol
(12 mL) and the mixture was then stirred overnight at room temperature.
After filtration and washing with cold ethanol, a dark brown powder was
Intermediate D: Although this intermediate was not isolated in the reac-
tions of Scheme 3, it can be obtained by reaction of 6 with LiOH in a
THF/H2O mixture, as described for 17 in reference [7]. 1H NMR
1
obtained. Yield: 89%; H NMR (300 MHz, D2O, 25 8C): d=3.47–3.64 (m,
3
(300 MHz, CDCl3, 258C): d=0.96 (t, J=7.3Hz, 3H; CH 3), 1.42 (m, 2H;
8H; NHCH2 and CH2OH), 3.96 (m, 2H; CHOH), 5.26 (s, 1H;
NPCPCH), 5.54 ppm (s, 1H; OPCPCH); 13C{1H} NMR (75 MHz, D2O,
258C): d=45.55 (s, NHCH2), 63.13 (s, CH2OH), 69.60 (s, CHOH), 83.00
(s, NPCPC), 99.80 (s, OPCPC), 156.44 (s, NPC), 175.28 ppm (s, OPC); el-
emental analysis calcd (%) for C12H18N2O6: C 50.35, H 6.34, N 9.79;
found: C 50.17, H 6.27, N 9.84; MS (MALDI-TOFꢀ): m/z: 285.1 [Mꢀ1]ꢀ.
CH3CH2), 1.66 (m, 2H; CH3CH2CH2), 3.18 (q owing to overlapping dt,
3J=6.1 Hz, 2H; NHCH2), 5.43(s, 1H; NHC =CH), 5.90 (s, 1H; HOC=
CH), 6.42 (brs, 1H; NH), 8.22 ppm (brs, 1H; OH); 13C{1H} NMR
(75 MHz, CDCl3, 258C): d=13.64 (s, CH3), 20.15 (s, CH3CH2), 30.13 (s,
CH3CH2CH2), 42.58 (s, NHCH2), 92.17 (s, NHC=CH), 102.28 (s, HOC=
CH), 150.01 (s, CNH), 159.37 (s, HOC), 178.13, 182.54 ppm (s, CO); ele-
mental analysis calcd (%) for C10H13NO3: C 61.53, H 6.71, N 7.18; found:
C 61.16, H 6.78, N 7.03; MS (MALDI-TOF +): m/z: 196.1 [M+1]+.
Ligand 12: An excess of serinol (1.594 g, 17.5 mmol) was added to a sus-
pension of 3·2HCl (0.533 g, 2.50 mmol) in ethanol (12 mL). Then the
mixture was refluxed for 6 h. After filtration and washing with cold etha-
a
dark brown powder was obtained. Yield: 85%; 1H NMR
Ligand 18: Diaminoresorcinol dihydrochloride 3·2HCl (0.500 g,
2.35 mmol) was dissolved in water and excess of n-butylamine was added
to the solution. The reaction mixture was allowed to stand for 3days to
afford a red crystalline solid. Yield: 71%; 1H NMR (300 MHz, CDCl3,
258C): d=0.95 (t, 3J=7.4 Hz, 6H; CH3), 1.40 (sext, 3J=7.4 Hz, 4H;
CH3CH2), 1.64 (pent, 3J=7.4 Hz, 4H; CH3CH2CH2), 3.15 (q owing to
overlapping dt, 3J=6.6 Hz, 4H; NHCH2), 5.30 (s, 2H; CH), 6.60 ppm
(brs, 2H; NH); 13C{1H} NMR (75 MHz, CDCl3, 258C): d=13.66 (s, CH3),
20.17 (s, CH3CH2), 30.25 (s, CH3CH2CH2), 42.30 (s, NHCH2), 92.64 (s,
CH), 151.36 (s, CNH), 178.13 ppm (s, CO); elemental analysis calcd (%)
for C14H22N2O2·0.25H2O: C 65.98, H 8.90, N 10.99; found: C 66.08, H
8.78, N 10.96; MS (MALDI-TOF+): m/z: 251.2 [M+1]+.
nol,
(300 MHz, [D6]DMSO, 258C): d=3.61 (t, 3J=5.3Hz, 8H; C H2OH), 3.85
(pent, 3J=5.2 Hz, 2H; NHCH), 5.03(t, 3J=5.2 Hz, 5H; NPCPCH and
OH), 5.71 (s, 1H; OPCPCH), 8.45 ppm (brs, 2H; NH); 13C{1H} NMR
(75 MHz, [D6]DMSO, 258C): d=57.18 (s, CH2OH), 60.12 (s, CHNH),
82.94 (s, NPCPC), 97.54 (s, OPCPC), 156.84 (s, NPC), 172.29 ppm (s,
OPC); elemental analysis calcd (%) for C12H18N2O6: C 50.35, H 6.34, N
9.79; found: C 49.71, H 6.34, 10.31; MS (MALDI-TOFꢀ): m/z: 285.1
[Mꢀ1]ꢀ.
Ligand 13: An excess of 2-methoxyethylamine (5.258 g, 70 mmol) was
added to a solution of 3·2HCl (2.131 g, 10 mmol) in H2O (20 mL). After
2 h the reaction mixture was extracted by CH2Cl2, the organic layer was
collected and dried with MgSO4. After concentration, diethylether was
added to the solution and the precipitate was filtered. The purple crystal-
line solid was obtained after filtration and drying in air. This compound
was highly soluble in water and organic solvents and gave purple solu-
tions. Yield: 76%. 1H NMR (300 MHz, CDCl3, 258C): d=3.39 (s, 6H;
CH3), 3.53 (t, 3J=5.0 Hz, 4H; NHCH2), 3.64 (t, 3J=5.0 Hz, 4H; CH2O),
5.23(s, 1H; N PCPCH), 5.42 (s, 1H; OPCPCH), 8.42 ppm (brs, 2H;
NH); 13C{1H} NMR (75 MHz, CDCl3, 258C): d=43.22 (s, NCH2), 59.14
(s, CH3), 69.37 (s, OCH2), 81.27 (s, NPCPC), 98.77 (s, OPCPC), 157.21 (s,
NPC), 172.22 ppm (s, OPC); elemental analysis calcd (%) for
C12H18N2O4: C 56.68, H 7.13, N 11.02; found: C 56.09, H 7.17, N 11.37;
MS (MALDI-TOF+): m/z: 255.1 [M+1]+.
Complex 19: Ligand 13 (0.20 g, 0.787 mmol) was dissolved in anhydrous
dichloromethane (50 mL) and Zn(acac)2 (0.5 equiv) was added to the so-
lution. After the solution was stirred at room temperature for 3h, the
solvent was evaporated and the red, crystalline complex 19 was obtained
by precipitation from a mixture of dichloromethane and pentane. Yield:
87%; 1H NMR (300 MHz, CDCl3, 258C): d=3.16 (s, 6H; uncoordinated
OCH3), 3.35 (q, 3J=5.5 Hz, 4H; NHCH2), 3.38 (s, coordinated OCH3),
3.61 (m, 12H; NCH2 and OCH2), 5.13(s, 2H; N =CCH), 5.58 (s, 2H; O=
CCH), 6.93ppm (t, 3J=5.5 Hz, 2H; NH); 13C{1H} NMR (75 MHz,
CDCl3, 258C): d=42.43(s, uncoordinated OCH 3), 47.12 (s, coordinated
OCH3), 58.57 (s, CH2), 59.05 (s, CH2), 69.69 (s, CH2), 70.09 (s, CH2),
82.87 (s, NHC=CH), 101.22 (s, O=CCH), 149.67 (s, NHC), 161.78 (s,
COZn), 173.43 (s, C=NZn), 179.20 ppm (s, C=O); elemental analysis
calcd (%) for C24H34N4O8Zn: C 50.40, H 5.99, N 9.80; found: C 49.76, H
6.01, N 9.49; MS (MALDI-TOF+): m/z: 570.2 [M]+.
Ligand 14: An excess of ethylenediamine (1.052 g, 17.5 mmol) was added
to a suspension of 3·2HCl (0.533 g, 2.50 mmol) in ethanol (12 mL) and
the mixture was stirred for 2 h. After filtration and washing with cold
ethanol, a dark brown powder was obtained. This compound was highly
soluble in H2O, and resulted in a purple solution. Yield: 86%; 1H NMR
(300 MHz, D2O, 25 8C): d=2.86 (t, 3J=6.1 Hz, 4H; CH2NH2), 3.48 (t,
3J=6.1 Hz, 4H; NHCH2), 5.26 (s, 1H; NPCPCH), 5.48 ppm (s, 1H;
OPCPCH); 13C{1H} NMR (75 MHz, D2O, 25 8C): d=39.08 (s, CH2NH2),
Complex 21: The procedure used was similar to that described for 19, but
using ligand 16 instead of 13. Yield: 71%; 1H NMR (300 MHz, CDCl3,
258C): d=1.02 (t, 3J=7.1 Hz, 6H; uncoordinated NHCH2CH3), 1.11 (t,
3J=7.1 Hz, 6H; coordinated NHCH2CH3), 2.64 (m, 8H; CH2), 2.90 (brt,
8H; CH2), 3.29 (q, 3J=5.9 Hz, 4H; CH2), 3.46 (brt, 4H; CH2), 5.11 (s,
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Chem. Eur. J. 2005, 11, 7237 – 7246

Coordination Chemistry
FULL PAPER
2H; NHC=CH), 5.48 (s, 2H; O=CCH), 6.87 ppm (t, 3J=5.5 Hz, 2H;
NHC=CH); 13C{1H} NMR (75 MHz, CDCl3, 258C): d=14.55 (s, uncoor-
dinated NHCH2CH3), 15.33 (s, coordinated NHCH2CH3), 42.42 (s, unco-
ordinated NHCH2CH3), 43.99 (s, coordinated NHCH2CH3), 44.08 (s, un-
coordinated CH2NHCH2CH3), 45.63(s, coordinated CH2NHCH2CH3),
47.62 (s, uncoordinated CH2NHCH2CH2), 48.10 (s, coordinated C=
NCH2), 83.17 (s, NHC=CH), 100.47 (s, O=CCH), 149.87 (s, NHC),
159.80 (s, COZn), 173.93 (s, C=NZn), 178.76 ppm (s, C=O); elemental
analysis calcd (%) for C28H46N8O4Zn: C 53.98, H 7.43, N 17.95; found: C
53.60, H 7.50, N 17.96; MS (MALDI-TOF+): m/z: 623.3 [M+1]+.
Acknowledgements
This work was supported by the Centre National de la Recherche Scienti-
fique and we are grateful to the Minist›re de la Recherche et des Nou-
velles Technologies and Clariant for a postdoctoral grant to Q.-Z.Y. We
are grateful to Prof. R. Welter and Dr. A. DeCian for the determination
of the crystal structures and wish to thank a referee for the details of ref-
erences [20] and [21].
Complex 22: A solution of 15 (100 mg) in methanol (10 mL) was slowly
added to ZnCl2 (1 equiv) in methanol (5 mL). After stirring for 1 h, filtra-
tion, washing with methanol and drying in air, a red powder was ob-
tained. Single crystals suitable for X-ray analysis were obtained from a
slow reaction between ZnCl2 and the ligand in methanol (i.e. a solution
of ligand was slowly added to the solution of ZnCl2). Yield: 76%;
1H NMR (300 MHz, D2O, 25 8C): d=2.40 (br, 6H; Me2NZr), 2.78 (br,
2H; CH2), 2.86 (br, 6H; Me2NH), 3.36 (br, 2H; CH2), 3.60 (brwith sh,
4H; 2CH2), 5.34 ppm (br, 2H; CH); the signal for the CH protons splits
at 658C into two singlets at d=5.82 and 5.83ppm; elemental analysis
calcd (%) for C14H24Cl2N4O2Zn: C 40.36, H 5.81, N 13.45; found: C
40.19, H 6.00, N 13.28; MS (MALDI-TOFꢀ): m/z: 415.0 [Mꢀ1]ꢀ.
[1] a) A. Gavezzotti, Crystallogr. Rev. 1998, 7, 5; b) J.-M. Lehn, Supra-
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Complex 23: The procedure used for the preparation and crystallization
was similar to that described for 22, but with ligand 16 instead of 15.
[3] R. H. Thompson, Naturally Occurring Quinones IV, Recent Advan-
ces, 4th ed., Chapman and Hall, London, 1997.
Yield: 77%; 1H NMR (300 MHz, D2O, 25 8C): d=0.90 (br, 3H;
[4] a) T. Ling, E. Poupon, E. J. Rueden, S. H. Kim, E. A. Theodorakis,
J. Am. Chem. Soc. 2002, 124, 12261; b) G. Meazza, B. E. Scheffler,
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[5] O. Siri, P. Braunstein, Chem. Commun. 2002, 208.
3
CH3CH2NZn), 1.22 (t, J=7.2 Hz, CH3CH2NH), 2.53(br, 2H; CH ), 2.94
2
3
(br, 2H; CH2), 3.06 (q, J=7.2 Hz, CH3CH2NH), 3.26 (br, 2H; CH2), 3.59
(brwith sh, 4H; 2CH2), 5.34 (s, 1H; NPCPCH), 5.44 ppm (s, 1H;
OPCPCH); elemental analysis calcd (%) for C14H24Cl2N4O2Zn: C 40.36,
H 5.81, N 13.45; found: C 39.74, H 5.89, N 13.04; MS (MALDI-TOFꢀ):
m/z: 415.0 [Mꢀ1]ꢀ.
X-ray data: The selected single crystals were mounted on a Nonius
Kappa-CCD area-detector diffractometer. The complete conditions of
data collection (Denzo software) and structure refinements are given in
Table 5. The structures were solved by using direct methods (SIR97) and
refined against F2 by using the SHELXL97 software. The absorption was
not corrected. All non-hydrogen atoms were refined anisotropically. Hy-
drogen atoms were generated according to stereochemistry and refined
using a riding model in SHELXL97.[22] CCDC 273367–273370 (4·H2O,
5·H2O, 13, and 15, respectively) and CCDC 267838 and 267839 (22 and
23) contains the supplementary crystallographic data for this paper.
These data can be obtained free of charge from The Cambridge Crystal-
lographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif. The sup-
porting information for this article contains a description of the molecu-
lar packing in 4·H2O and 5·H2O and the cif file for the crystal structure
of 5, which could not be fully refined and was therefore not deposited
with CCDC.
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Table 5. Crystal data and details of the structure determination for compounds 4·H2O, 5·H2O, 13, 15, 22, and 23.
4·H2O
5·H2O
13
15
22
23
formula
Mr
C6H8N2O3
156.14
C8H12N2O3
184.20
C12H18N2O4
254.28
C14H24N4O2
280.37
C14H24N4O2Zn2Cl2
416.64
C14H24N4O2Zn2Cl2
416.64
crystal system
space group
a [Š]
b [Š]
c [Š]
monoclinic
P21/c
monoclinic
P21/n
orthorhombic
Pnma
8.5800(3)
14.7120(4)
10.6120(8)
90
1339.54(12)
4
1.261
monoclinic
C2/c
monoclinic
P21/n
monoclinic
P21/c
3.6540(3)
14.4280(12)
12.6590(9)
95.270(5)
664.56(9)
4
7.3470(10)
8.8780(10)
13.967(2)
96.27(5)
905.6(2)
4
29.9490(9)
7.3910(3)
6.9050(2)
98.430(2)
1511.93(9)
4
7.683(5)
9.938(5)
22.846(5)
92.91(5)
1742.1(15)
4
10.2640(4)
13.2900(5)
13.4400(6)
94.2350(14)
1828.33(13)
4
b [8]
V [Š3]
Z
1 [gcmꢀ3
T [K]
]
1.561
173(2)
1.351
293(2)
1.232
173(2)
1.589
173(2)
1.514
173(2)
173(2)
l [Š]
reflns collected
independent reflns
R1/wR2 [I>2s(I)]
R1, wR2 (all data)
0.71070
1915
1296
0.0933/0.1303
0.1584/0.1472
0.71070
26432212
1697
0.0598/0.1406
0.1017/0.1605
0.710730.71070
2196
1491
0.0453/0.1119
0.0768/0.1257
0.71069
5089
0.71073
5243
1456
3302
3638
0.1418/0.2006
0.1985/0.2191
0.0495/0.1392
0.0830/0.1613
0.0372/0.0905
0.0691/0.1008
Chem. Eur. J. 2005, 11, 7237 – 7246
ꢀ 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
7245

P. Braunstein, O. Siri, and Q.-Z. Yang
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Received: June 20, 2005
Published online: September 30, 2005
7246
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ꢀ 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2005, 11, 7237 – 7246