Synthesis and properties of dimetallic complexes based on a new oxalamidine-derived ligand system with pendant pyridine functionality

Article abstract of DOI:10.1002/1099-0682(200103)2001:3<805::AID-EJIC805>3.0.CO;2-2

Reaction of sterically hindered bis(imidoyl)chlorides of oxalic acid with picolylamine afforded conformationally locked oxalic acid-derived amidines with pendant pyridine functionalities. Based on this new multivalent ligand system, dimetallic complexes were efficiently prepared.

Full text of DOI:10.1002/1099-0682(200103)2001:3<805::AID-EJIC805>3.0.CO;2-2

FULL PAPER
Synthesis and Properties of Dimetallic Complexes Based on a New
Oxalamidine-Derived Ligand System with Pendant Pyridine Functionality
Jörg Wuckelt,[a] Manfred Döring,*[a] Helmar Görls,[a] and Peter Langer*[b]
Keywords: Molybdenum / Cobalt / Hydrogen bonds / Chelates / N ligands
Reaction of sterically hindered bis(imidoyl)chlorides of oxalic
acid with picolylamine afforded conformationally locked ox-
alic acid-derived amidines with pendant pyridine functional-
ities. Based on this new multivalent ligand system, dimetallic
complexes were efficiently prepared.
Introduction
system allowed the efficient synthesis of a variety of hetero-
dimetallic diazadiene complexes.
The synthesis of dimetallic complexes, particularly those
containing two different transition metals ‘‘communicat-
ing’’ with each other, is of considerable current interest for
both theoretical and practical reasons.[1] Important proper-
ties have been postulated for these compounds, such as
cooperative effects in catalysis, intramolecular electron-
transfer reactions, molecular-based ferromagnetic and anti-
ferromagnetic interactions and self-organization processes.
However, the synthesis of heterodimetallic complexes is as-
sociated with severe problems, since two metals exhibiting
different demands in terms of their coordination sphere
have to be brought close together. Very recently, the pre-
paration of heterodimetallic complexes has been realized
using aminopyridines as bridging ligands.[2] Herein, we re-
port an efficient synthesis of heterodimetallic complexes
which relies on the use of a new multivalent ligating system.
The ability of amidinates to act as four-electron-donat-
ing, bidentate ligands for main group elements, transition
metals, and the lanthanides is well established.[3] We and
others have studied the coordination chemistry of oxalic
acid-derived amidines which can act as four-electron-donor
ligands (to give five-membered rings) or as bridging li-
gands.[4] Very recently, the coordination chemistry of ancil-
lary amidinate ligands with a pendant pyridine func-
tionality has been described by Arnold and co-workers. The
metal complexes (Mg, Al, Zr, La) prepared were shown to
be monomeric, with the pendant pyridine coordinated in-
tramolecularly.[5] In most cases, the tridentate ligands co-
ordinated meridionally to the metal centre. This work
prompted us to disclose our results related to the coordina-
tion chemistry of oxalic acid-derived amidines containing
pendant pyridine functionalities. The use of this new ligand
Results and Discussion
Unfortunately, our initial attempts to prepare the desired
ligands 3 by condensation of 2-aminomethylpyridine with
the oxalic acid bis(imidoyl)chlorides 1a؊c (R ϭ Tol, Ph,
MeOC6H4)[4e] in the presence of triethylamine were unsuc-
cessful, since cyclization products were exclusively obtai-
ned.[4f] The use of oxalic acid bis(imidoyl)esters, prepared
by reaction of the corresponding bis(imidoyl)chlorides with
ethanol, was equally disappointing and resulted in forma-
tion of complex reaction mixtures. Fortunately, the problem
could be eventually solved by the use of the sterically
hindered bis(imidoyl)chlorides 1d؊f [R ϭ 2,4,6-Me3C6H2,
2,6-Me2C6H3, 2,6-(iPr)2C6H3] which allowed the prepara-
tion of the desired oxalamidines 3a؊c, respectively, in good
yields (Scheme 1). During the synthesis of 3c, the cycliza-
tion product 2 was obtained as a side-product in 15% yield.
The use of sterically undemanding bis(imidoyl)chlorides
was possible in the reaction of 2-aminoethylpyridine with
[a]
Institut für Anorganische und Analytische Chemie der
Universität Jena,
August-Bebel-Straße 2, 07743 Jena, Germany
[b]
Institut für Organische Chemie der Georg-August-Universität
Göttingen,
Tammannstraße 2, 37077 Göttingen, Germany
Fax: (internat.) ϩ49-(0)551/399-475
E-mail: planger@uni-goettingen.de
Scheme 1. Preparation of oxalamidines with pendant pyridine func-
tionality
Eur. J. Inorg. Chem. 2001, 805Ϫ811
WILEY-VCH Verlag GmbH, 69451 Weinheim, 2001
1434Ϫ1948/01/0303Ϫ0805 $ 17.50ϩ.50/0
805

J. Wuckelt, M. Döring, H. Görls, P. Langer
FULL PAPER
bis(imidoyl)chlorides to give the amidines 4 (4a: R ϭ Tol,
4b: R ϭ Ph) in good yields.
Amidines represent flexible molecules which usually un-
dergo E/Z isomerization by a tautomeric rotation mechan-
ism.[6a] In the case of oxalamidines, two imino-groups are
present and rotation of the central CϪC bond can give rise
to s-trans or s-cis conformations.[6b] Therefore, very com-
1
plex or coalescent H NMR spectra are normally observed
at room temperature due to the highly flexible structure.
Interestingly, sharp signals and a low-field NH resonance
were observed for compounds 3 which suggested that the
latter are conformationally restricted by the presence of in-
tramolecular hydrogen bonds and by the high steric de-
mand of the substituents. Moderately broad signals were
observed only for the CH2 and the NH groups. The location
of the NH group was proven by low-temperature 1H NMR
measurements: upon cooling to 0 °C, formation of a doub-
3
let is observed for the CH2 groups due to a J coupling of
Figure 1. ORTEP plot of 3a with the atom numbering scheme; the
the latter with the adjacent NH group.
thermal ellipsoids of 50% probability are shown for the non-hydro-
The structure of amidine 3a was independently con-
firmed by X-ray crystallography (Figure 1). The amidine
moiety is planar and shows an s-trans-(Z/Z) configuration.
The bulky mesityl groups are twisted out-of-plane by
104.9°. It is noteworthy that the oxalamidines 3 represent
rare examples of systems containing intramolecular three-
centre (‘‘bifurcated’’) hydrogen bonds.[7] Two hydrogen
bonds (to the amidine nitrogen N1A and to the pyridine
nitrogen N3) are observed for the hydrogen atom located at
˚
gen atoms; selected bond lengths [A] and angles [°]: N1ϪC1
1.276(3), N2ϪC1 1.340(3), C1ϪC1A 1.526(4); N1ϪC1ϪC1A
116.5(2), N2ϪC1ϪC1A 113.1(2), C1ϪN2ϪC2 128.2(2),
N2ϪC2ϪC3ϪN3 40.3, C1ϪN1ϪC8ϪC9 104.9
˚
˚
nitrogen N2 (N1AϪH 2.18 A, N3ϪH 2.41 A). Bifurcated
hydrogen bonds are of great current interest since they play
an important role in DNA conformation[8] and in protein
hydration.[9] Two types of three-centre interaction can be
distinguished, one involving two donors and one acceptor
(‘‘HXH’’), and the other involving one donor and two ac-
ceptors (‘‘XHY’’). Very recently, computational studies of
a depsipeptide model have shown that addition of a second
acceptor (Y) to a hydrogen bond XH has no enthalpic be-
nefit, while addition of a second donor (H) to XH is mod-
estly favourable enthalpically.[10]
Two conformations are, in principle, possible for oxalami-
dine ligands coordinated to the metal. The ligand can
posses an s-trans- or an s-cis conformation. We have found
Scheme 2. Synthesis of hetero-dimetallic complexes 5؊8
that oxalamidinate complexes of molybdenum posses the s- observed in the 1H NMR spectrum. In the 13C NMR spec-
cis conformation.[4cϪ4d,12] These compounds are thus 1,4- trum of 5, separate signals are detected for all carbon atoms
diazadiene complexes.[11] The reaction of dibenzyldiphenyl- which could be assigned to the proposed structure. All spec-
oxalamidine with Mo(CO)4(nor) resulted in rotation of the troscopic data indicate that complex 5 adopts an unsym-
central CϪC bond and coordination of the aromatic (rather metrical structure containing an s-trans-configured oxalam-
than the aliphatic) imino groups to the metal to give an s- idine unit rather than a symmetrical structure containing a
cis-configured DAD complex (Scheme 2).[12] The chemose- cis-configured oxalamidine unit. The s-trans selectivity can
lectivity can be explained by the fact that protonation of be explained by the assumption that the hydrogen bond in-
the nitrogen atom would result in interruption of the con- volving the pyridine nitrogen is more stable than the hydro-
jugation of the phenyl and the imino group. Interestingly, gen bond located within the oxalamidine substructure. The
formation of the s-trans-configured complex 5 was observed 2-aminomethylpyridine subunit is planar due to intramolec-
in the reaction of ligand 3a with Mo(CO)4(nor) (Scheme 2). ular hydrogen bonding. Therefore, coordination of two aro-
The structure of complex 5 was determined by spectros- matic imino groups to the metal would result in severe steric
copic means: whereas only two carbonyl absorptions (IR) interactions. Coordination of two aliphatic imino groups to
are observed for Mo(CO)4(nor), four absorptions are ob- the metal would result in cleavage of two relatively stable
served for complex 5. In addition, two sets of signals are pyridine hydrogen bonds. In contrast, formation of complex
806
Eur. J. Inorg. Chem. 2001, 805Ϫ811

Dimetallic Complexes Based on a New Oxalamidine-Derived Ligand System
FULL PAPER
5 involves a prototropic shift, cleavage of a weak hydrogen amples are known where hydrogen bonding influences the
bond and formation of a strong one. selectivity or the rate of organic transformations, such ef-
To support our hypothesis, compound 3a was depro- fects are rare in complexation reactions. However, such pro-
tonated with NaN(SiMe3)2: reaction of the sodium salt of cesses should play an important role in the binding of trans-
3a with Mo(CO)4(nor) gave the s-cis-configured heterodi- ition metals to biomolecules.
metallic complex 6 (Scheme 2). The structure of complex 6
The synthesis and properties of homodimetallic com-
was independently confirmed by an X-ray structure analysis plexes were next studied. Reaction of Cu(OAc)2 with the
(Figure 2). The pyridine moieties are located above and be- pyridyloxalamidines 3 and 4 resulted in formation of the
low the plane of the chelate system. The mesityl substitu- deeply green to black coloured (Cu/Cu) complexes 9 and
ents of the ligand are located orthogonal to each other due 10 (Scheme 3). Reaction of ligands 3 with PdCl2(CH3CN)2
to steric interactions. The sodium atom is coordinated by resulted in formation of the orange coloured (Pd/Pd) com-
two pyridine nitrogens, by an amidinate-derived nitrogen plexes 11.
atom and by an oxygen atom of a neighbouring molecule.
These atoms define the equatorial square plane of a dis-
torted octahedron. The oxygen atoms of two THF molec-
ules are located at the axial positions. The MoϪC33 bond
is shorter than the other MoϪC distances due to the trans
effect of the nitrogen N1 and the polarizing influence of the
˚
sodium ion. The C35ϪO3 bond is elongated (1.189 A) and
lies in the same range as normal CϪO double bonds.[13]
Deprotonation of the NH group of complex 6 and sub-
sequent reaction with one equivalent of CoBr2 or PdCl2
resulted in formation of the heterodimetallic complexes 7
(Mo/Co) and 8 (Mo/Pd). The spectroscopic properties of
these products are very similar to those of complex 6, which
suggests that the same type of structure is adopted. For
compound 8 only two signals (1H NMR) are observed for
the CH3 groups and only one signal is observed for the CH2
Scheme 3. Synthesis of homo-dimetallic complexes 9؊11
groups. The chemical shifts are almost identical to those
observed for complex 6. Due to the anionic character of
the ligands, bathochromic shifts (IR) are observed for the
equatorial carbonyl ligands of complexes 6؊8. Whereas ex-
The structure of the Cu complex 10a was independently
confirmed by an X-ray structure analysis (Figure 3). Deeply
green coloured single crystals of 10a were obtained from a
Figure 2. ORTEP plot of 6 with the atom numbering scheme; the
thermal ellipsoids of 50% probability are shown for the non-hydro-
˚
gen atoms; selected bond lengths [A] and angles [°]: MoϪN1
2.244(3), MoϪC35 1.916(5), N3ϪC1 1.310(5), N5ϪNa 2.426(5),
O2ϪC34 117.2(6), MoϪN2 2.271(3), N1ϪC1 1.348(5), N3ϪNa
Figure 3. ORTEP plot of 10a with the atom numbering scheme;
2.652(4), N6ϪNa 2.518(4), O3ϪC35 1.184(5), MoϪC33 2.031(5), the thermal ellipsoids of 50% probability are shown for the non-
˚
N2ϪC2 1.289(5), N4ϪC2 1.360(5), O3AϪNa 2.378(4), C1ϪC2 hydrogen atoms; selected bond lengths [A] and angles [°]: N1ϪC1
1.524(6); N1ϪMoϪN2 71.52(12), N1ϪC1ϪC2 112.5(3), 1.314(6), CuϪN1 1.940(3), CuϪN3 2.008(3), N2ϪC1 1.316(4),
N4ϪC2ϪC1 112.4(4), MoϪN1ϪC1 119.6(3), N2ϪC2ϪC1 CuϪN2A 1.973(3), CuϪO1 1.953(3), C1ϪC1A 1.537(3);
117.4(4), C1ϪN3ϪNa 112.4(3), N3ϪNaϪN6 109.9(13),
MoϪN2ϪC2 118.3(3), N3ϪC1ϪC2 113.4(4), N3ϪNaϪN5
66.94(13)
N1ϪC1ϪC1A 113.4(4), N2AϪCuϪO1 94.16(11), C1ϪN1ϪCu
115.6(2), N2ϪC1ϪC1A 113.9(4), C1ϪN2ϪCuA 114.2(2),
N1ϪCuϪN3 94.22(12), N1ϪCuϪN2A 82.92(12)
Eur. J. Inorg. Chem. 2001, 805Ϫ811
807

J. Wuckelt, M. Döring, H. Görls, P. Langer
FULL PAPER
12 H, 2- and 6-CH3), 2.29 (s, 6 H, 4-CH3), 4.00 (s, 4 H, CH2), 6.82
(s, 4 H, CH), 7.02 (br. d, 2 H, Pyr-CH), 7.14 (t, 2 H, Pyr-CH), 7.59
(t, 2 H, Pyr-CH), 8.20 (br, 2 H, NH), 8.48 (d, 2 H, Pyr-CH). Ϫ 13C
NMR (50 MHz, CD2Cl2): δ ϭ 18.6 (2,6-CH3), 20.9 (4-CH3), 47.6,
121.6, 122.4, 128.3, 128.6, 131.6, 136.7, 144.5, 146.0 (br), 149.5,
158.1. IR (Nujol): ν˜ ϭ 3309 (m, νNH), 1648 (s, νCN), 1607 (m), 1592
(m), 1569 (m) cmϪ1. Ϫ MS [CI (H2O)]: m/z (%) ϭ 505 (100) [Mϩ
ϩ 1], 412 (24), 252 (18) [Mϩ/2], 93 (19). Ϫ C32H36N6 (504.7): calcd.
C 76.16, H 7.19, N 16.65; found C 76.21, H 7.11, N 16.33.
1:1 solution of MeOH and water. The ligand shows an s-
trans-(E/E) configuration. The square-planar coordination
spheres of the CuII atoms are distorted. The amidine moiety
is planar. In contrast, the tolyl groups are twisted out of
plane by ca. 90°. The bond lengths C1ϪN1 and C1ϪN2
are almost identical, due to delocalization of the π-electrons
(N1ϪC1ϪN2). Whereas intense (CϭN) absorptions (IR)
were observed for the free ligands, no respective absorptions
were present for the metal complexes 9؊11, again due to
delocalization of the π-electrons. In the electron paramag-
netic resonance (EPR) spectrum of complex 10b a signal
was detected at g ϭ 2.082. Although the hyperfine structure
could not be resolved, the value and the anisotropy of the
resonance line were typical for the gЌ signal of CuII. An
antiferromagnetic interaction between the Cu atoms can be
anticipated.[14] Quantitative EPR measurements showed
that only ca. 15% of CuII with s ϭ 0.5 was present. The
magnetic moment of complex 10b (µeff ϭ 1.55 BM, T ϭ
296 K) was lower than the spin-only value of the CuII ion
(µeff ϭ 1.73 BM).
1,2-Bis(2,6-dimethylphenylimino)-N,NЈ-bis(2-pyridylmethyl)ethane-
1,2-diamine (3b): Yield: 1.1 g of colourless crystals (58%), m.p.
136Ϫ138 °C. 1H NMR (200 MHz, CD2Cl2): δ ϭ 2.14 (s, 12 H,
CH3), 4.00 (d, J ϭ 4.4 Hz, 4 H, CH2), 6.87 (t, J ϭ 6.3 Hz, 2 H,
Pyr-CH), 7.00 (d, J ϭ 6.7 Hz, 6 H, Ar), 7.13 (t, J ϭ 5.0 Hz, 2 H,
Pyr), 7.58 (t, J ϭ 7.7 Hz, 2 H, Pyr), 8.19 (br, 2 H, NH), 8.48 (d,
J ϭ 4.8 Hz, 2 H, Pyr). Ϫ 13C NMR (50 MHz, CD2Cl2): δ ϭ 18.6
(CH3), 47.5 (CH2), 121.6, 122.4, 127.6, 128.9, 136.7, 145.6, 147.2,
149.5, 157.9. Ϫ IR (Nujol): ν˜ ϭ 3301 (s, νNH), 1662 (s, νCN), 1588
(s), 1569 (m), 1492 (s) cmϪ1. Ϫ MS [CI (H2O)]: m/z (%) ϭ 477
(100) [Mϩ ϩ 1], 384 (19), 238 (10) [Mϩ/2], 147 (4), 126 (7), 110 (5),
93 (12). Ϫ C30H32N6 (476.6): calcd. C 75.60, H 6.77, N 17.63; found
C 75.74, H 7.17, N 17.32.
In conclusion, we have reported the synthesis of con-
formationally locked oxalic acid-derived amidines with pen-
dant pyridine functionalities. Based on this multivalent li-
gand system, new hetero- and homodimetallic complexes
were efficiently prepared.
1,2-Bis(2,6-diisopropylphenylimino)-N,NЈ-bis(2-pyridylmethyl)-
ethane-1,2-diamine (3c): Yield: 0.85 g of colourless crystals (72%),
m.p. 144Ϫ146 °C. Ϫ 1H NMR (200 MHz, CD2Cl2): δ ϭ 1.19, 1.23
(2 ϫ d, J ϭ 1.9 Hz, 2 ϫ 12 H, iPr-CH3), 3.14 (m, 4 H, iPr-CH),
4.11 (s, 4 H, CH2), 7.01Ϫ7.28 (m, 10 H, Ar, Hetar), 7.58 (t, 2 H,
J ϭ 7.7 Hz, Hetar), 8.21 (br, 2 H, NH), 8.46 (d, J ϭ 4.8 Hz, 2 H,
Hetar). 13C NMR (50 MHz, CD2Cl2): δ ϭ 22.5, 22.6 (iPr-CH3),
29.3 (iPr-C), 47.7, 121.4, 122.4, 122.8, 123.0, 136.8, 138.9, 145.2,
149.6, 157.9. Ϫ IR (Nujol): ν˜ ϭ 3289 (s, νNH), 1658 (s, νCN), 1592
(s), 1582 (m), 1569 (m) cmϪ1. Ϫ MS [CI (H2O)]: m/z (%) ϭ 589
(100) [Mϩ ϩ 1], 294 (8) [Mϩ/2]. Ϫ C38H48N6 (588.8): calcd. C
77.51, H 8.22, N 14.27; found C 76.88, H 8.29, N 14.08.
Experimental Section
General: All solvents were dried by standard methods and all reac-
tions were carried out under an inert atmosphere. Petroleum ether
(PE, b.p. 40Ϫ70 °C), diethyl ether (E), tert-butyl methyl ether
(MTBE), toluene and acetone were distilled prior to use. The solv-
ents that were used for the reactions (THF and ether), were distilled
from sodium/benzophenone immediately prior to use. The oxalic
acid bis(imidoyl)chlorides were prepared according to literature
3-(2,6-Diisopropylphenylamino)-4-(diisopropylphenylimino)-4H-
pyrido[1,2-a]pyrazine (2): During the synthesis of 3c, 2 was isolated
as an orange coloured solid (250 mg, 15%); m.p. 147Ϫ148 °C. Ϫ
1H NMR (200 MHz, CD2Cl2): δ ϭ 1.12Ϫ1.27 (m, J ϭ 6.9 Hz, 12
H, iPr-CH3), 3.04 (hex, J ϭ 6.9 Hz, 4 H, iPr-CH), 6.14 (t, J ϭ
6.7 Hz, 1 H, Py), 6.43 (t, J ϭ 7.6 Hz, 1 H, Py), 6.92Ϫ7,33 (m, 8 H,
Ar), 7.42 (s, 1 H, NH), 7.97 (d, J ϭ 7.7 Hz, 1 H, Py). Ϫ 13C NMR
(50 MHz, CD2Cl2): δ ϭ 22.7, 2.8 (iPr-CH3), 29.1, 29.5 (iPr-CH),
113.3, 117.4, 120.6, 122.8, 123.1, 123.8, 125.8, 126.1, 127.1, 127.8,
129.8, 134.3, 137.9, 145.1, 146.2, 147.3. Ϫ IR (Nujol): ν˜ ϭ 3376 (s,
νNH); 1624 (s, νCϭN); 1586 (m); 1556 (s) u. 1496 (s) cmϪ1. Ϫ MS
[CI (H2O)]: m/z (%) ϭ 481 (100) [Mϩ ϩ 1], 437 (8), 293 (10), 187
(7), 146 (6). Ϫ C32H40N4 (480.70): calcd. C 79.96, H 8.39, N 11.66;
found C 79.20, H 8.42, N 12.17.
1
procedures.[4e] NMR: 200 MHz and 50 MHz (for H and 13C, re-
spectively), if not quoted otherwise, on an AC 200 F (Bruker) ap-
paratus. The solvents CDCl3, CD2Cl2 and [D8]THF were used as
received. The multiplicity of the carbon atoms was determined by
the DEPT 135 technique and quoted as: CH3, CH2, CH and C for
primary, secondary, tertiary and quaternary carbon atoms. MS: EI,
70 eV; CI, H2O: chemical ionization with water. Preparative scale
chromatography: J. T. Baker silica gel (60Ϫ200 mesh). For the EPR
measurements, an ESP 300 E apparatus (Bruker, ν ϭ 9.4 GHz, in-
ternal standard: diphenylpicrylhydrazyl). Melting points, uncorrec-
ted, were measured using a Büchi apparatus. Elemental analyses:
Microanalytical laboratory of the Universities of Hannover and
Jena.
General Procedure for the Preparation of Ligands 4: To a THF solu-
tion (100 mL) of 2-(2-aminoethyl)pyridine (20 mmol) and NEt3
(2.8 mL, 20 mmol) was slowly added a THF solution (50 mL) of 1
(10 mmol) at 0 °C. The mixture was slowly warmed to ambient
temperature and was then stirred at 50 °C for 1 h. After cooling,
the precipitated HNEt3Cl was filtered and the solvent of the filtrate
was removed in vacuo. The residue was isolated by addition of
ether to the crude product and purified by recrystallization from
MeOH/H2O.
General Procedure for the Preparation of Oxalic Acid Amidines (3):
A THF solution of 1 (2.0 mmol), 2-picolylamine (0.44 mL) and
NEt3 (0.63 mL, 4.5 mmol) was refluxed for 48 h. After cooling, the
precipitated HNEt3Cl was filtered and the solvent of the filtrate
was removed in vacuo. The residue was purified by chromatography
(toluene Ǟ toluene/acetone ϭ 1:1).
N,NЈ-Bis[(2-aminoethyl)-2-pyridyl]-1,2-bis(4-tolylimino)ethane-1,2-
diamine (4a): Yield: 0.51 g of a brown-yellow solid (53%), m.p.
N,NЈ-Bis(2-pyridylmethyl)-1,2-bis(2,4,6-trimethylphenylimino)-
ethane-1,2-diamine (3a): Yield: 0.73 g of colourless crystals (72%),
1
125Ϫ126 °C. Ϫ H NMR (200 MHz, [D8]THF): δ ϭ 2.22 (s, 6 H,
m.p. 148Ϫ150 °C. Ϫ 1H NMR (200 MHz, CD2Cl2): δ ϭ 2.10 (s, Tol-CH3), 2.98 (br, 4 H, CH2 to Pyr), 3.60 (br, 4 H, CH2 to NH),
808
Eur. J. Inorg. Chem. 2001, 805Ϫ811

Dimetallic Complexes Based on a New Oxalamidine-Derived Ligand System
FULL PAPER
6.43 (br, 4 H, Ar), 6.80 (d, J ϭ 7.1 Hz, Pyr, 2 H), 7.12 (m, 6 H, Ar, Cobalt(II) Bis(tetrahydrofuran)[N,NЈ-bis(2-pyridylmethyl)-1,2-
Pyr), 7.58 (t, J ϭ 7.2 Hz, 4 H, Pyr), 8.45 (d, J ϭ 6.5 Hz, 2 H, NH). bis(2,4,6-trimethylphenylimino)ethane-1,2-diaminato]molybdate
Ϫ
13C NMR (50 MHz, [D8]THF): δ ϭ 20.8 (CH3), 37.4 (CH2 to
(7a): Yield: 0.52 g (68%). Ϫ IR (Nujol): ν˜ ϭ 1983, 1929, 1854,
Pyr), 41.2 (CH2 to NH), 121.7, 122.6, 123.8, 129.0, 130.9, 136.6, 1838, 1805 (s, νCϵO), 1610 (s, νCϭN), 1579 (s), 1558 (s) cmϪ1. Ϫ
148.2, 149.8, 151.9, 161.3. Ϫ IR (Nujol): ν˜ ϭ 3261 (s, νNH), 1639
C44H50CoMoN6O6 (913.78): calcd. C 57.83, H 5.52, N 9.20, Co
(s, νCϭN), 1622 (s), 1605 (s), 1588 (m), 1536 (s), 1507 (s) cmϪ1. Ϫ 6.45; found C 57.19, H 5.93, N 9.42, Co 6.55.
MS [EI]: m/z (%) ϭ 476 (8) [Mϩ], 383 (7), 370 (5), 278 (16) [Mϩ/
Palladium(II) Bis(tetrahydrofuran)[N,NЈ-bis(2-pyridylmethyl)-1,2-
2], 145 (6), 134 (9), 118 (12), 106 (100), 94 (17), 91 (13), 78 (14), 65
(5). Ϫ C30H32N6 (476.6): calcd. C 75.60, H 6.77, N 17.63; found C
75.63, H 6.77, N 17.63.
bis(2,4,6-trimethylphenylimino)ethane-1,2-diaminato]molybdate
(7b): Yield: 0.71 g (74%). Ϫ 1H NMR (200 MHz, [D6]DMSO): δ ϭ
2.04, 2.14 (2 ϫ s, 18 H, CH3), 4.16 (br, 4 H, CH2), 6.64, 8.54 (m,
12 H, Ar, Pyr). Ϫ IR (Nujol): ν˜ ϭ 1995, 1914, 1883, 1822, 1745 (s,
νCϵO), 1611 (s, νCϭN), 1586 (s), 1562 (s) cmϪ1. Ϫ C44H50MoN6-
O6Pd (961.3): calcd. C 54.98, H 5.24, N 8.74; found C 54.43, H
5.13, N 9.00.
N,NЈ-Bis[(2-aminoethyl)-2-pyridyl]-1,2-bis(4-methoxyphenylimino)-
ethane-1,2-diamine (4b): Yield: 3.9 g of a brown-yellow solid (76%),
m.p. 85Ϫ87 °C. Ϫ 1H NMR (200 MHz, [D6]DMSO): δ ϭ 2.96,
3.49 (br, 2 ϫ 4 H, CH2), 3.65 (s, 6 H, OCH3), 3.60, 6.57 (2 ϫ d,
J ϭ 8.5 Hz, 2 ϫ 4 H, Ar), 7.24 (m, 6 H, Pyr), 7.73 (m, 2 H, Pyr),
8.48 (d, J ϭ 4.5 Hz, 2 H, NH). Ϫ 13C NMR (50 MHz, [D6]DMSO):
δ ϭ 36.3, 40.8 (CH2), 55.0 (OCH3), 112.9, 121.3, 122.5, 123.0,
136.3, 143.0, 148.9, 151.2, 154.2, 159.6. Ϫ IR (Nujol): ν˜ ϭ 3248 (s,
νNH), 1638 (s), 1618 (s), 1566 (s), 1531 (s), 1504(s) cmϪ1. Ϫ MS [CI
(H2O)]: m/z (%) ϭ 509 (100) [Mϩ ϩ 1], 415 (8), 301 (41), 254 (6)
[Mϩ/2], 149 (10), 124 (37), 106 (61), 93 (7). Ϫ C30H32N6O2 (508.6):
calcd. C 70.84, H 6.34, N 16.52; found C 70.49, H 6.58, N 16.07.
Synthesis of the Dimetallic Cu Complexes (9a؊c) and (10a؊b): A
MeOH solution (25 mL) of Cu(OAc)2(H2O) (0.36 g, 2.0 mmol) and
of the ligand 3 or 4 (1 mmol) was stirred for 2 h at 50 °C. The
deep green solution was filtered and the solvent of the filtrate was
removed in vacuo. To the residue was added ether and the precipit-
ate was filtered and dried in vacuo. The crude product was recrys-
tallized from MeOH or H2O/MeOH (1:1).
Bis(acetato)[N,NЈ-bis(2-pyridylmethyl)-1,2-bis(2,4,6-trimethyl-
phenylimino)ethane-1,2-diaminato]dicuprate(II) (9a): Yield: 0.25 g of
deep green to black crystals (34%). Ϫ IR (Nujol): ν˜ ϭ 1613 (s),
1595 (s), 1566 (s) cmϪ1. Ϫ C36H40Cu2N6O4 (747.8): calcd. C 57.82,
H 5.39, N 11.24, Cu 16.99; found C 57.80, H 5.38, N 11.19, Cu
16.41.
Synthesis of Tetracarbonyl[N,NЈ-bis(2-pyridylmethyl)-1,2-bis(2,4,6-
trimethylphenylimino)ethane-1,2-diamine]molybdenum (5): An ether
solution of Mo(CO)4(nor) (0.30 g, 1.0 mmol) and 3a (1.0 mmol)
was stirred for 24 h. The product was filtered, washed with a small
amount of cold ether and dried in vacuo to give 0.39 g of red crys-
tals (55%). 1H NMR (200 MHz, CD2Cl2): δ ϭ 2.22Ϫ2.38 (m, 18
H, CH3), 5.00, 5.26 (2 ϫ s, 2 ϫ 2 H, CH2), 6.55Ϫ8.86 (m, 12 H,
Ar), 10.42 (s, 2 H, NH). Ϫ 13C NMR (50 MHz, CD2Cl2): δ ϭ 18.8,
19.3, 21.0 (CH3), 121.1, 121.6, 121.8, 122.4, 123.1, 123.2, 128.3,
128.8, 128.9, 129.3, 129.5, 130.3, 132.3, 132.8, 132.9, 136.7, 137.1,
138.0, 138.8, 148.9, 149.6, 152.9, 156.1, 160.1, 161.1, 205.4, 206.9,
221.9; IR (Nujol): ν˜ ϭ 3400 (w, νNH), 2006, 1907, 1893, 1862, 1815,
1803, 1781 (s, νCϵO), 1592 (s), 1572 (s), 1561 (s), 1484 (s) cmϪ1. Ϫ
C36H36MoN6O4 (712.7): calcd. C 60.67, H 5.09, N 11.79; found C
60.11, H 5.03, N 11.72.
Bis(methanol)bis(acetato)[1,2-bis(2,6-dimethylphenylimino)-
N,NЈ-bis(2-pyridylmethyl)ethane-1,2-diaminato]dicuprate(II) (9b):
Yield: 0.40 g of deep green to black crystals (50%). Ϫ IR (Nujol):
ν˜ ϭ 3370 (br, νOH(MeOH)), 1611 (s), 1582 (s), 1567 (s) cmϪ1. Ϫ
C36H42Cu2N6O6 (781.9): calcd. C 55.30, H 5.41, N 10.75, Cu 16.26;
found C 55.06, H 5.38, N 10.87, Cu 15.95.
Bis(acetato)[1,2-bis(2,6-diisopropylphenylimino)-N,NЈ-bis(2-pyridyl-
methyl)ethane-1,2-diaminato]dicuprate(II) (9c): Yield: 0.57 g of deep
green to black crystals (69%). Ϫ IR (Nujol): ν˜ ϭ 1625 (s), 1599 (s),
1582 (s), 1567 (s) cmϪ1. Ϫ C42H52Cu2N6O4 (832.0): calcd. C 60.63,
H 6.30, N 10.10, Cu 15.28; found C 60.71, H 6.42, N 10.11, Cu
14.87.
Synthesis of Bis(tetrahydrofuran)sodium Tetracarbonyl[N,NЈ-bis(2-
pyridylmethyl)-1,2-bis(2,4,6-trimethylphenylimino)ethane-1,2-
diaminato]molybdate (6): To a THF solution (25 mL) of 3a (0.51 g,
1.0 mmol) was slowly added a THF solution of NaN(SiMe3)2
(1 mL, 1 ). After stirring for 30 min the solution was warmed
to 20 °C and a THF solution (30 mL) of Mo(CO)4(nor) (0.30 g,
1.0 mmol) was added. After stirring for 2 h, the precipitated yellow
solid was filtered, washed three times with THF (10 mL) and dried
in vacuo to give 0.45 g of yellow crystals (52%). 1H NMR
(200 MHz, [D6]DMSO): δ ϭ 2.00, 2.13 (2 ϫ s, 2 ϫ 9 H, CH3),
5.32, 4.12 (2 ϫ s, 2 ϫ 2 H, CH2), 6.55Ϫ8.27 (m, 12 H, Ar). Ϫ IR
(Nujol): ν˜ ϭ 1991, 1877, 1863, 1812, 1769, 1754 (s, νCϵO), 1593
(m), 1566 (m), 1537 (s) cmϪ1. Ϫ C44H51N6MoNaO6 (878.9): calcd.
C 60.13, H 5.85, N 9.56; found C 59.59, H 5.65, N 9.26.
Bis(methanol)bis(acetato){N,NЈ-bis[(2-aminoethyl)-2-pyridyl]-1,2-
bis(4-tolylimino)ethane-1,2-diaminato}dicuprate(II) (10a): Yield:
0.49 g of deeply green to black coloured crystals (62%). Ϫ IR (Nu-
jol): ν˜ ϭ 3265 (br, νOH(MeOH)), 1607 (s), 1571 (s), 1505 (s), 1485 (s)
cmϪ1. Ϫ C36H42Cu2N6O6 (781.9): calcd. C 55.30, H 5.41, N 10.75,
Cu 16.26; found C 55.37, H 5.58, N 10.67, Cu 15.74.
Bis(methanol)bis(acetato){N,NЈ-bis[(2-aminoethyl)-2-pyridyl]-1,2-
bis(4-methoxyphenylimino)ethane-1,2-diaminato}dicuprate(II)
(10b): Yield: 0.53 g of deep green to black crystals (68%). Ϫ IR
(Nujol): ν˜ ϭ 3390 (br, νOH, MeOH), 1606 (s), 1586 (s), 1502 (s),
1486 (s) cmϪ1. Ϫ µeff ϭ 1.5 BM. Ϫ EPR (296 K, solid): gЌ
ϭ
2.0036. Ϫ C35H40Cu2N6O7 (783.8): calcd. C 53.70, H 5.15, N 10.74,
Cu 16.09; found C 53.36, H 5.01, N 10.88, Cu 15.87.
Synthesis of Metal Complexes (7a؊b): To a THF solution (25 mL)
of 6 (0.51 g, 1.0 mmol) was added a THF solution of NaN(SiMe3)2
(2 mL, 1 ⁾. After stirring for 30 min a THF solution (30 mL) of
Mo(CO)4(nor) (0.30 g, 1.0 mmol) was added. The solution was
stirred for 30 min and subsequently a THF solution (25 mL) of
CoBr2(THF)2 or PdCl2(CH3CN)2 (1 mmol) was added. After stir-
ring for 4 h the solution was filtered (celite) and the filtrate was
concentrated in vacuo. An ether layer was added on the top of
the THF solution which resulted in precipitation of the product as
greenish crystals.
Synthesis of the Dimetallic Pd Complexes (11a؊c): A THF solution
(30 mL) of PdCl2(CH3CN)2 (0.52 g, 2.0 mmol) and of the ligand 3
or 4 (1.0 mmol) was stirred for 24 h at 20 °C. The product, which
precipitated as an orange solid, was filtered, washed with THF and
dried in vacuo.
Dichloro[N,NЈ-bis(2-pyridylmethyl)-1,2-bis(2,4,6-trimethylphenyl-
imino)ethane-1,2-diaminato]dipalladate(II) (11a): Yield: 0.36 g of an
Eur. J. Inorg. Chem. 2001, 805Ϫ811
809

J. Wuckelt, M. Döring, H. Görls, P. Langer
FULL PAPER
orange solid (41%). Ϫ IR (Nujol): ν˜ ϭ 1633 (s), 1610 (m), 1593 (s),
1577 (s), 1568 (s), 1515 cmϪ1. Ϫ C38H46Cl2N6Pd2 (870.6): calcd. C
52.43, H 5.33, N 9.65, Cl 8.14; found C 51.88, H 5.35, N 10.45,
Cl 8.12.
Acknowledgments
P. L. thanks Professor Dr. A. de Meijere for his support. Financial
support from the Fonds der Chemischen Industrie (Liebig scholar-
ship and funds for P. L.) and from the Deutsche Forschungs-
gemeinschaft is gratefully acknowledged.
Dichloro[1,2-bis(2,6-diisopropylphenylimino)-N,NЈ-bis(2-pyridyl-
methyl)ethane-1,2-diaminato]dipalladate(II) (11b): Yield: 0.50 g of
an orange solid (58%). Ϫ IR (Nujol): ν˜ ϭ 1610 (m), 1593 (s), 1577
(s), 1564 (s) cmϪ1. Ϫ C38H46Cl2N6Pd2 (870.6): calcd. C 52.43, H
5.33, N 9.65, Cl 8.14; found C 51.88, H 5.35, N 10.04, Cl 8.45.
[1] [1a]
[1b]
D. W. Stephan, Coord. Chem. Rev. 1989, 95, 41. Ϫ
W.
A. Herrmann, B. Cornils, Angew. Chem. 1997, 109, 1074; An-
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A. Spannenberg, M. Oberthür, H. Noss, A. Tillack, P. Arndt,
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Ed. 1998, 37, 2079.
Dichloro{N,NЈ-bis[(2-aminoethyl)-2-pyridyl]-1,2-bis(4-tolylimino)-
ethane-1,2-diaminato}dipalladate(II) (11c): Yield: 0.39 g of an or-
ange solid (52%). Ϫ 1H NMR (200 MHz, [D6]DMSO): δ ϭ 2.18
(s, 6 H, CH3), 2.97, 3.31 (2 ϫ br, 2 ϫ 4 H, CH2), 6.93 (m, 4 H,
Ar), 6.85 (t, J ϭ 7.6 Hz, 1 h, Pyr), 6.93 (d, J ϭ 6.9 Hz, 1 H, Pyr),
7.41 (t, J ϭ 8.4 Hz, 1 H, Pyr), 8.40 (d, J ϭ 5.4 Hz, 1 H, Pyr). Ϫ
IR (Nujol): ν˜ ϭ 1673 (s), 1605 (m), 1579 (s), 1504 (m) cmϪ1. Ϫ
C30H30N6Cl2Pd2 (758.4): calcd. C 47.51, H 3.99, N 11.08, Cl 9.35;
found C 47.39, H 4.38, N 11.53, Cl 9.51.
[3] [3a]
[3b]
F. T. Edelmann, Coord. Chem. Rev. 1994, 137, 403. Ϫ
[3c]
J. Barker, M. Kilner, Chem. Rev. 1994, 133, 219. Ϫ
Hagadorn, J. Arnold, Angew. Chem. 1998, 110, 1813; Angew.
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[3d]
Chem. Int. Ed. 1998, 37, 1729. Ϫ
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[4a]
For the coordination to boron, see:
Chem. Soc. 1969, 91, 2139. Ϫ For titanium, see:
quali, C. Floriani, A. Chiesi-Villa, C. Guastini, J. Am. Chem.
S. Trofimenko, J. Am.
[4b]
M. Pas-
[4c]
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M. Döring, H. Görls, R. Beckert,
[4d]
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405. Ϫ For the synthesis of oxalic acid-bis(imidoyl)chlorides,
Crystal Structure Determinations: The intensity data for the com-
pound were collected on a Nonius Kappa CCD diffractometer, us-
ing graphite-monochromated Mo-Kα radiation. Data were cor-
rected for Lorentz and polarization effects, but not for absorp-
tion.[15,16]
see: [4e] D.Lindauer, R. Beckert, T. Billert, M. Döring, H. Görls,
[4f]
J. Prakt. Chem. 1995, 337, 143. Ϫ
J. Brandenburg, R.
Beckert, P. Fehling, M. Döring, H. Görls, J. Prakt. Chem. 1996,
338, 430.
[5]
K. Kincaid, C. P. Gerlach, G. R. Giesbrecht, J. R. Hagadorn,
G. D. Whitener, A. Shafir, J. Arnold, Organometallics 1999,
18, 5360.
The structures were solved by direct methods (SHELXS [17]) and
refined by full-matrix least-squares techniques against F2o
(SHELXL-97[18]). The hydrogen atoms of the structures were in-
cluded at calculated positions with fixed thermal parameters. All
non-hydrogen atoms were refined anisotropically.[18] XP (SIE-
MENS Analytical X-ray Instruments, Inc.) was used for structure
representations.
[6] [6a]
L. M. Jackman, T. Jen, J. Am. Chem. Soc. 1975, 97, 2811.
[6b]
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G. Scherer, H.-H. Limbach, J. Am. Chem. Soc. 1994,
116, 1230.
[7] [7a]
A. K. Aggarwal, D. W. Rodgers, M. Drottar, M. Ptashne,
[7b]
S. C. Harrison, Science 1988, 242, 899. Ϫ
M. Sundaral-
[7c]
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[7d]
M. M. Conn, J. Rebek, Chem. Rev. 1997, 97, 1647.
[8] [8a]
Crystal Data for 3a:[19] C32H36N6, Mr ϭ 504.67 g molϪ1, colourless
prism, size 0.40 ϫ 0.38 ϫ 0.32 mm3, monoclinic, space group P21/
H. C. M. Nelson, J. T. Finch, B. F. Luisi, A. Klug, Nature
1987, 330, 221. Ϫ [8b] V. Fritsch, E. Westhof, J. Am. Chem. Soc.
1991, 113, 8271.
˚
n, a ϭ 6.4164(5), b ϭ 21.157(2), c ϭ 10.3108(6) A, β ϭ 94.085(2)°,
[9] [9a]
H. J. Savage, C. J. Elliot, C. M. Freeman, J. L. Finney, J.
Chem. Soc., Faraday Trans. 1993, 89, 2609. Ϫ [9b] I. K. McDon-
ald, J. M. Thornton, J. Mol. Biol. 1994, 238, 777.
3
V ϭ 1396.2(2) A , T ϭ 183 K, Z ϭ 2, ρcalcd. ϭ 1.200 gcmϪ3, µ
˚
(Mo-Kα) ϭ 0.73 cmϪ1, F(000) ϭ 540, 3067 reflections, Θmax
ϭ
[10]
[11]
J. Yang, S. H. Gellman, J. Am. Chem. Soc. 1998, 120, 9090.
Diazadiene transition metal complexes represent efficient cata-
26.27°, 2815 independent reflections, 1724 reflections with Fo
Ͼ
4σ(Fo), 208 parameters, R ϭ 0.0568, Rw ϭ 0.1645, largest difference
lysts for olefin polymerization: [11a] L. K. Johnson, S. Mecking,
Ϫ3
˚
peak and hole: 0.369 e A
.
[11b]
M. Brookhart, J. Am. Chem. Soc. 1996, 118, 267. Ϫ
A. S.
Abu-Surrah, B. Rieger, Angew. Chem. 1996, 108, 2627; Angew.
[11c]
Crystal Data for 6:[19] C44H51MoN6NaO6, Mr ϭ 878.84 g molϪ1
,
Chem. Int. Ed. Engl. 1996, 35, 2475. Ϫ
C. M. Killian, L.
colourless prism, size 0.30 ϫ 0.25 ϫ 0.15 mm3, monoclinic, space
K. Johnson, M. Brookhart, Organometallics 1997, 16, 2005. Ϫ
[11d]
A. S. Abu-Surrah, B. Rieger, Angew. Chem. 1996, 108,
˚
group P21/n, a ϭ 12.3530(6), b ϭ 20.6111(5), c ϭ 17.2796(8) A,
2627; Angew. Chem. Int. Ed. Engl. 1996, 35, 2475. See also: Ϫ
3
˚
[11e]
β ϭ 94.755(1)°, V ϭ 4384.4(3) A , Tϭ Ϫ90 °C, Z ϭ 4, ρcalcd.
ϭ
G. van Koten, K. Vrieze, Adv. Organomet. Chem. 1982,
1.331 gcmϪ3, µ(Mo-Kα) ϭ 3.62 cmϪ1, F(000) ϭ 1832, 11681
reflections in h(Ϫ13/0), k(Ϫ22/21), l(Ϫ19/19), measured in the
range 3.95° Յ Θ Յ 23.31°, completeness Θmax ϭ 98.6%, 6126 inde-
pendent reflections, Rint ϭ 0.036, 5706 reflections with Fo Ͼ 4σ(Fo),
527 parameters, 0 restraints, R1obs ϭ 0.047, wR2obs ϭ 0.121, R1all ϭ
0.066, wR2all ϭ 1.134, GOOF ϭ 1.084, largest difference peak and
21, 151.
[12]
[13]
[14]
M. Döring, P. Fehling, H. Görls, W. Imhof, R. Beckert, D.
Lindauer, J. Prakt. Chem. 1999, 341, 748.
F. H. Allen, O. Kennard, D. G. Watson, L. Brammer, A. G.
Orpen, R. Taylor, J. Chem. Soc., Perkin Trans. 2 1987, 1.
For molecular-based ferromagnetic interactions in heterodime-
tallic complexes, see: K. Nakatani, J. Y. Carriat, Y. Journaux,
Y., O. Kahn, F. Lloret, J. P. Renard, Y. Pei, J. Sletten, M. Verda-
guer, J. Am. Chem. Soc. 1989, 111, 5739.
COLLECT, Data Collection Software; Nonius B.V.,
Netherlands, 1998.
Z. Otwinowski, W. Minor, ‘‘Processing of X-ray Diffraction
Data Collected in Oscillation Mode‘‘, in Methods in Enzymo-
logy, Vol.- 276, Macromolecular Crystallography, Part A, ed-
ited by C.W. Carter, R.M. Sweet, pp. 307Ϫ326, Academic
Press 1997.
Ϫ3
˚
hole: 0.485/Ϫ0.555 e A
.
[15]
[16]
Crystal Data for 10a:[19] C36H44N6O6Cu2, Mr ϭ 783.85 g molϪ1
,
brown prism, size 0.40 ϫ 0.38 ϫ 0.36 mm3, orthorhombic, space
˚
group Pbca, a ϭ 9.173(1), b ϭ 14.853(1), c ϭ 26.275(1) A, α ϭ
3
˚
β ϭ γ ϭ 90°, V ϭ 3579.9(5) A , T ϭ 183 K, Z ϭ 4, ρcalcd. ϭ 1.454
gcmϪ3, µ(Mo-Kα) ϭ 0.73 cmϪ1, F(000) ϭ 1632, 3634 reflections,
Θmax ϭ 26.31°, 3634 independent reflections, 2228 reflections with
Fo Ͼ 4σ(Fo), 278 parameters, R ϭ 0.0431, Rw ϭ 0.0979, largest
[17]
[18]
G.M. Sheldrick, Acta Crystallogr. Sect. A 1990, 46, 467.
G.M. Sheldrick, SHELXL-97 (Release 97.2), University of
Göttingen, Germany, 1997.
Ϫ3
˚
difference peak and hole: 0.413 e A
.
810
Eur. J. Inorg. Chem. 2001, 805Ϫ811

Dimetallic Complexes Based on a New Oxalamidine-Derived Ligand System
FULL PAPER
[19]
Crystallographic data (excluding structure factors) for the
of charge on application to CCDC, 12 Union Road, Cam-
bridge CB2 1EZ, UK [Fax: (internat.) ϩ 44-1223/336-033;
E-mail: deposit@ccdc.cam.ac.uk].
structure(s) included in this paper have been deposited with
the Cambridge Crystallographic Data Centre as supplementary
publication nos. CCDC-145494 (3a), CCDC-140090 (6), and
CCDC-145493 (10a). Copies of the data can be obtained free
Received June 14, 2000
[I00234]
Eur. J. Inorg. Chem. 2001, 805Ϫ811
811