Reduction of a 1-aza-1,3-diene to a 1-azabut-2-ene-1,4-diyl dianion: An unusual reaction course

Article abstract of DOI:10.1002/anie.200250116

A suprising intermediate during the reduction of the 1-aza-1,3-diene 1 with lithium is the dilithium hexa-1,5-dien-1,6-diamide 2, which probably forms by dimerization of the initially generated radical anion of 1. However, the new C-C bond of 2 is not very resistant to the alkali metal and is reductively cleaved, which leads to the formation of the dark red (1-azabut-2-en-1,4-diyl)dilithium compound 3.

Full text of DOI:10.1002/anie.200250116

Angewandte
Chemie
Monoazadiene Complexes
Reduction of a 1-Aza-1,3-diene to a 1-Azabut-2-
ene-1,4-diyl Dianion: An Unusual Reaction
Course**
Volker Lorenz, Helmar Görls, and Joachim Scholz*
We have been searching for a rather simple method for the
synthesis of 1-aza-1,3-diene complexes of early transition
metals for quite some time. This search is motivated by some
remarkable applications of these compounds:For example,
(1-aza-1,3-diene)zirconocene complexes react diastereoselec-
tively with carbonyl compounds to form seven-membered
[
1a]
zirconacycles,
from which highly substituted five-mem-
bered oxygen heterocycles, which are applied in the synthesis
of natural products and active agents, can be separated.[
Titanium 1-aza-1,3-diene complexes in turn offer a simple
approach to novel metallacyclic alkylidene complexes. For
example, in attempts to methylate (1-aza-1,3-diene)titanium
1b]
!
complexes even under mild conditions, an a-agostic Ti HÀC
interaction on the terminal methine group of the 1-aza-1,3-
diene ligand triggers an a-methane elimination that results in
[
*] Prof. Dr. J. Scholz, Dr. V. Lorenz
Institut für Chemie der Universität Koblenz-Landau
Universitätsstrasse 1, 56070 Koblenz (Germany)
Fax: (+49)261-287-2251
E-mail: scholz@uni-koblenz.de
Dr. H. Görls
Institut für Anorganische und Analytische Chemie
der Friedrich-Schiller-Universität Jena (Germany)
[
**] Monoazadiene Complexes of Early Transition Metals: Part 4. This
work was supported by the Deutsche Forschungsgemeinschaft. We
are grateful to Prof. D. Steinborn, Universität Halle-Wittenberg, for
providing laboratory facilities. Part 3: Ref. [2].
Angew. Chem. Int. Ed. 2003, 42, 2253 – 2257
DOI: 10.1002/anie.200250116
ꢀ 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
2253

Communications
[
2]
the formation of the Ti¼C double bond. Furthermore, we
found that different (1-aza-1,3-diene)titanium and -zirconium
complexes catalyze the polymerization of olefins with high
shows the typical configuration of the planar N¼CÀC¼C
framework (N-C1-C2-C3 175.6(1)8) that was found in other 1-
aza-1,3-dienes as well (Figure 1).
[
8,9]
[
3]
activity.
Despite these interesting applications 1-aza-1,3-diene
complexes of the early-transition metals, in contrast to the
“
related” buta-1,3-diene or 1,4-diaza-1,3-diene complexes,
are still rare, and corresponding complexes of lanthanides
have not yet been described at all.[
4]
The reason for this is quite clear:While with the (but-2-
ene-1,4-diyl)magnesium complex (“magnesium butadiene”)
[
5]
1
2
and the (1,4-diazabut-2-ene-1,4-diyl)dilithium complexes
(Scheme 1) there are readily available dianion equivalents
[
6]
Scheme 1. Readily available dianion equivalents 1 and (1,4-diazabut-2-
ene-1,4-diyl)dilithium compounds 2 for the synthesis of the buta-1,3-
diene and 1,4-diaza-1,3-diene complexes.
Figure 1. Molecular structure of 3. Selected bond lengths [Š] and
angles [8]: N-C1 1.269(2), N-C10 1.466(2), C1-C2 1.470(2), C2-C3
1.341(2), C3-C4 1.475(2); N-C1-C2 122.5(1), C1-C2-C3 117.6(1), C2-C3-
C4 128.0(1); N-C1-C2-C3 175.6(1).
for the synthesis of buta-1,3-diene and 1,4-diaza-1,3-diene
complexes, corresponding (1-azabut-2-ene-1,4-diyl)magne-
sium or -dilithium complexes are still unknown. To fill the
gap we studied the behavior of 1-aza-1,3-dienes towards alkali
metals. Herein we report on the reduction of a 1-aza-1,3-diene
with lithium, which initially takes an unexpected reaction
course but finally leads to the desired (1-azabut-2-ene-1,4-
diyl)dilithium compound (Scheme 2).
If a solution of 3 in diethyl ether is mixed with an excess of
lithium then immediately an exothermic reaction is initiated.
After the reaction has subsided and subsequent separation of
unreacted lithium, pale yellow crystals precipitate out of the
orange solution. Surprisingly, the crystal structure analysis
reveals the precipitate to be the N,N’-dilithium-hexa-1,5-
[
8]
diene-1,6-diamide 4 (Figure 2). Hence, we conclude that
under the influence of lithium in the first step of the reaction
the 1-aza-1,3-diene 3 is reduced to a radical anion, which
stabilizes by dimerization. The formation of the CÀC bond
occurs between the terminal carbon atoms (C3ÀC4
1
.532(4) Š). As both isolated C¼C double bonds of the new
hexa-1,5-diene structure C1¼C2 (1.357(4) Š) and C5¼C6
(
1.367(4) Š) are cis-configured, the terminal amide groups
approach close enough to be bridged by the two lithium
atoms. Overall, the result is the boat-shaped ring structure of
[
10]
4.
The formation of CÀC bonds as a result of an electron
transfer step are not unusual and belong to the standard
repertoire of organic synthetic chemistry. Thus, there are
numerous examples for the reductive coupling of imines, and
some are of preparative use for the synthesis of vicinal
[
11]
diamines.
Nevertheless, the formation of 4 is unprece-
dented, because the reductive C–C coupling of the 1-aza-1,3-
dienes 3 does not occur as expected via the imine but instead
via the terminal b-carbon atoms. Evidently, in agreement with
[
12]
the principle of vinylogy, during the reduction of 3 on the
phenyl-substituted terminal carbon atom C3 a sufficiently
stable benzyl radical is formed, whose longevity allows a
recombination to 4.
Scheme 2. Reaction of the 1-aza-1,3-diene 3 with lithium. Treatment
with ultrasound is necessary for the formation of 5.
If 3 is reduced with lithium in THF and if additionally the
reaction mixture is treated with ultrasound for a few hours, its
color changes to dark red and the extremely air- and
moisture-sensitive lithium compound 5 is formed. Evidently,
the extent of the reduction of 3 strongly depends on the
For our investigations we chose the 1-aza-1,3-diene 3,
which was synthesized by a condensation reaction of a-methyl
cinnamaldehyde with 2-propylamine.[ Compound 3 is a
yellowish oil that congeals at 58C. Its solid-state structure
7]
2
254
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Angewandte
Chemie
Table 1: NMR spectroscopic data of 3–6.[a]
1
3
: H NMR (CDCl ): d=7.99 (s, 1H; CH¼N), 7.42–7.32 (m, 4H; o/m-
3
Ph), 7.29–7.22 (m, 1H; p-Ph), 6.75 (s, 1H; CH¼CMe), 3.47 (sept,
3
J(H,H)=6.3 Hz, 1H; NCHMe ), 2.17 (s, 3H, CH¼CMe), 1.24 ppm (d,
2
3
13
J(H,H)=6.3 Hz, 6H; NCHMe ); C NMR (CDCl ): d=162.97 (CH¼N),
2
3
1
1
1
38.20 (CH¼CMe), 136.99 (i-Ph), 136.62 (CH¼CMe), 129.16 (o/m-Ph),
28.13 (o/m-Ph), 127.37 (p-Ph), 61.14 (NCHMe ), 24.12 (NCHMe ),
2
2
3.30 ppm (CH¼CMe).
1
4
: H NMR ([D ]THF): d=7.49 (br d, 4H; o-Ph), 6.92 (br t, 4H; m-Ph),
8
6
.79 (br t, 2H; p-Ph), 6.10 (s, 2H; CH¼CMe), 4.07 (br s, 2H; CHPh), 3.35
3
3
(q, J(H,H)=7.0 Hz, 8H; OCH CH ), 2.99 (sept, J(H,H)=6.3 Hz, 2H;
2 3
3
NCHMe ), 1.54 (s, 6H; CH¼CMe), 1.12 (d, J(H,H)=6.3 Hz, 6H;
2
3
NCHMe ), 1.09 (t, J(H,H)=7.0 Hz, 12H; OCH CH ), 1.05 ppm (d,
2
2
3
3
13
J(H,H)=6.3 Hz, 6H; NCHMe ); C NMR ([D ]THF): d=148.26 (i-Ph),
2
8
1
9
2
47.62 (CH¼CMe), 128.59 (o,m-Ph), 127.06 (o,m-Ph), 124.79 (p-Ph),
7.01 (CH¼CMe), 66.07 (OCH CH ), 57.71 (NCHMe ), 52.50 (CHPh),
2
2
2
7.90 (CH¼CMe), 27.32 (br, NCHMe ), 21.80 (br, NCHMe ), 15.54 ppm
2
2
(
OCH CH ).
2 3
1
5
6
6
3
1
: H NMR ([D ]THF): d=7.50 (br d, 4H; o-Ph), 6.93 (br t, 4H; m-Ph),
8
.80 (br t, 2H; p-Ph), 6.45 (br m, 3H; o,m-Ph), 6.10 (s, 2H; CH¼CMe),
Figure 2. Molecular structure of one of the two crystallographically
independent molecules of 4 (molecule A). Hydrogen atoms are omit-
ted for clarity. Selected bond lengths [Š] and angles [8]: Li1A-N1A
.04 (s, 1H; CH¼CMe), 5.28 (br t, 2H; p-Ph), 5.08 (br m, 1H; o,m-Ph),
3
3
.38 (q, J(H,H)=7.0 Hz, 16H; OCH CH ), 3.06 (sept, J(H,H)=6.3 Hz,
2
3
3
H; NCHMe ), 3.00 (sept, J(H,H)=6.3 Hz, 2H; NCHMe ), 2.93 (br s,
2
2
1
.989(5), Li1A-N2A 1.982(5), Li2A-N1A 2.101(5), Li2A-N2A 2.058(5),
Li2A-C1A 2.260(5), Li2A-C6A 2.320(5), Li1A-O1A 1.967(5), Li2A-O2A
.024(5), N1A-C1A 1.378(4), N2A-C6A 1.376(3), C1A-C2A 1.357(4),
C2A-C3A 1.536(4), C3A-C4A 1.532(4), C4A-C5A 1.517(4), C5A-C6A
.367(4); N1A-C1A-C2A 128.4(2), C1A-C2A-C3A 122.9(2), N2A-C6A-
1
H; CHPh), 1.63 (s, 3H; CH¼CMe), 1.54 (s, 6H; CH¼CMe), 1.12 (q,
3
3
J(H,H)=7.0 Hz, 16H; OCH CH ), 1.15 (d, J(H,H)=6.3 Hz, 6H;
2
3
2
3
NCHMe ), 1.05 (d, J(H,H)=6.3 Hz, 6H; NCHMe ), 0.99 ppm (d,
2
2
3
13
J(H,H)=6.3 Hz, 6H; NCHMe ); C NMR ([D ]THF): d=148.39 (i-Ph),
2
8
1
1
1
1
5
47.84 (i-Ph), 141.18 (CH¼CMe), 130.4 (br, o,m-Ph), 128.72 (o,m-Ph),
C5A 130.9(2), C4A-C5A-C6A 127.9(2); C2A-C3A-C4A-C5A 53.8(2), N1A-
C1A-C2A-C3A 12.8(2), N2A-C6A-C5A-C4A À14.2(2), Li1A-N1A-Li2A-
N2A 5.2(2).
28.5 (br, o,m-Ph), 127.13 (o,m-Ph), 124.84 (p-Ph), 118.7 (br, o,m-Ph),
06.1 (br, o,m-Ph), 103.32 (p-Ph), 97.04 (CH¼CMe), 60.88 (NCHMe ),
2
7.82 (NCHMe ), 55.06 (CHPh), 52.62 (CHPh), 28.30 (NCHMe ), 27.92
2
2
(
CH¼CMe), 27.4 (br, NCHMe ), 22.85 (CH¼CMe), 21.8 ppm (br,
2
NCHMe ).
2
reaction conditions. Many NMR signals of 5 are largely
consistent with those of the coupling product 4 (Table 1).
However, several new signals indicate that there is another 1-
aza-1,3-diene unit in this compound, but there is no strong
hint upon its structure. A marked high-field shift of the
significantly broadened phenyl proton signals (d = 6.45, 5.28,
and 5.08 ppm) indicates that the phenyl substituent of this 1-
aza-1,3-diene unit is also involved in the coupling process.
These findings are also confirmed by the results of the X-
ray structure analysis of 5 (Figure 3).[ Suitable single crystals
of 5 were obtained by recrystallization from a solution in
diethyl ether. The molecular structure of 5 is exceptionally
complex and can be described as an aggregate of 4 and a novel
1
6
: H NMR ([D ]THF): d=6.60–5.90 (br m, 3H; m,o-Ph), 6.06 (s, 1H;
8
CH¼CMe), 5.29 (br t, 1H; p-Ph), 5.05 (br m, 1H, o-Ph), 3.62 (m, 12H;
3
THF), 3.05 (sept, J(H,H)=6.3 Hz, 1H; NCHMe ), 2.95 (s, 1H; CHPh),
2
1
.77 (m, 12H; THF), 1.61 (s, 3H; CH¼CMe), 1.03 ppm (d,
3
13
J(H,H)=6.3 Hz, 6H; NCHMe ); C NMR ([D ]THF): d=147.01 (s; i-
2
8
1
Ph), 140.78 (d, J(C,H)=146.0 Hz; CH¼CMe), 131.6 (br d; o,m-Ph),
128.3 (br d; o,m-Ph), 118.4 (br d; o,m-Ph) 105.9 (br d; o,m-Ph) 102.66 (d,
1
J(C,H)=157.2 Hz; p-Ph), 97.01 (s; CH¼CMe), 68.42 (t,
1
1
J(C,H)=144.6 Hz; OCH CH , THF), 62.66 (d, J(C,H)=141.5 Hz;
2
2
1
NCHMe ), 55.08 (d, J(C,H)=127.1 Hz; CHPh), 28.36 (q,
J(C,H)=125.3 Hz; NCHMe ), 26.26 (t, J(C,H)=131.7 Hz; OCH CH ,
THF), 23.27 ppm (q, J(C,H)=124.3 Hz; CH¼CMe).
a] The NMR spectra were recorded at 258C in [D ]THF at 300.075 ( H)
and 75.462 MHz ( C) with a Varian Gemini 300 BB. Correct elemental
analysis was obtained for all compounds.
8]
2
1
1
2
2
2
1
1
[
8
1
3
(
1-azabut-2-ene-1,4-diyl)dilithium compound. Thus, did we
really succeed in reducing the 1-aza-1,3-diene 3 into the
dianion? The answer lies in the major structure parameters of
the (1-azabut-2-ene-1,4-diyl)dilithium unit. The NÀC¼CÀC
organometallic compounds of alkali metals,[13] the lithium
atom Li4 is placed directly above the point of highest charge
density of the 1-azabut-2-ene-1,4-diyl dianion. In contrast, the
backbone is cis-configured and planar (N3-C27-C28-C29
À9.7(2)8). The comparison of the sequence of NÀC and CÀ lithium atom Li3 lies in the plane of the 1-azabut-2-ene-1,4-
C bond lengths (“long–short–long”) in the 1-azabut-2-ene-
,4-diyl units with that of 3 (“short–long–short”) leaves no
diyl backbone and thus compensates its charge deficit by an
additional interaction with the p-electron system of the
phenyl group (Li3ÀC34 2.406(5), Li3ÀC35 2.478(5) Š). In
1
doubt that a two-electron reduction has occurred. The two
lithium atoms Li3 and Li4 bridge the terminal atoms N3 and
C29 of the 1-azabut-2-ene-1,4-diyl unit (Li3ÀC29 2.574(5),
Li3ÀN3 1.962(5), Li4ÀC29 2.419(5), Li4ÀN3 2.057(5) Š). The
spite of this special bonding situation of Li3 the structure of
the (1-azabut-2-ene-1,4-diyl)dilithium unit is very reminiscent
of the molecular structures of related compounds (see
[
6]
distance between the lithium atom Li4 and the two inner
carbon atoms C27 and C28 is even shorter (Li4ÀC27 2.213(5),
Li4ÀC28 2.318(5) Š). According to the structure principles of
reference [14] and 2, Scheme 1).
Indeed, the route by which the (1-azabut-2-ene-1,4-
diyl)dilithium unit in 5 is formed still requires clarification.
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Communications
Figure 3. Molecular structure of 5. Hydrogen atoms are omitted for
clarity. Selected bond lengths [Š] and angles [8]: Li1-N1 1.987(4), Li4-
N1 2.027(5), Li2-N2 1.983(5), Li3-N2 2.012(5), Li3-N3 1.962(5), Li4-N3
Figure 4. Molecular structure of 6. Hydrogen atoms are omitted for
clarity. Selected bond lengths [Š] and angles [8]: Li1-N1 2.027(4), Li2-
N1 1.963(4), Li1-O1 2.009(4), Li1-O2 1.904(4), Li2-O1 2.424(6), Li2-O3
1.945(4), Li1-C1 2.183(4), Li1-C2 2.273(5), Li1-C3 2.386(5), Li2-C3
2.722(5), Li2-C5 2.395(5), Li2-C10 2.363(6), N1-C1 1.375(3), C1-C2
1.355(3), C2-C3 1.470(3), C3-C5 1.408(3); N1-C1-C2 125.0(2), C1-C2-
C3 123.2(2), N1-Li1-C3 83.8(2), N1-Li2-C3 76.4(1); N1-C1-C2-C3
À10.4(2).
2
2
2
2
1
1
.057(5), Li1-O1 1.932(5), Li1-O2 1.927(5), Li2-O3 1.957(5), Li2-C37
.555(6), Li2-C38 2.428(5), Li2-C39 2.711(5), Li3-C29 2.574(5), Li3-C34
.406(5), Li3-C35 2.478(5), Li4-C27 2.213(5), Li4-C28 2.318(5), Li4-C29
.419(5), N1-C1 1.382(3), N2-C6 1.379(3), C1-C2 1.347(3), C2-C3
.521(3), C3-C4 1.553(3),C4-C5 1.519(3), C5-C6 1.352(3), N3-C27
.381(3),C27-C28 1.363(3), C28-C29 1.481(3), C29-C34 1.405(3); N3-
Li3-C29 79.1(2), N3-Li4-C29 81.3(2), N3-C27-C28 124.6(2), C27-C28-
C29 121.3(2); N1-C1-C2-C3 176.8(2), C2-C3-C4-C5 À49.1(2), N2-C6-C5-
C4 177.5(2), N3-C27-C28-C29 À9.7(2).
one hand the isolated intermediate products allow an insight
into important fundamental steps of this unexpected reaction
course and hence contribute to the general understanding of
the redox reaction of alkali metals with unsaturated hydro-
carbons. On the other hand the successful synthesis of the (1-
azabut-2-ene-1,4-diyl)dilithium compound 6 now provides an
opportunity to demonstrate the much wider synthetic poten-
tial of the 1-aza-1,3-diene complexes and to include even the
lanthanides. This is all the more valid as recently we even
found that 3 can be converted quickly and directly into the
dianion equivalent 6 if lithium powder is used for the
reduction reaction.
We assume that 4 reacts further with the excessive lithium,
which results in the reductive cleavage of its C3ÀC4 bond.
Initially, the lithium atoms of the new (1-azabut-2-ene-1,4-
diyl)dilithium units are coordinated by the amide groups of
the remaining 4 because their donor strength certainly
exceeds that of the solvent THF. Furthermore, the two C¼C
double bonds of the hexa-1,5-diene-1,6-diamide unit of 5 are
now, in contrast to those of the coupling product 4, trans-
configured. Hence, the two amide groups reach a sufficient
distance to enable them to function as “molecular brackets”
and thereby stabilize the lithium atoms Li3 and Li4 and thus
the central dilithium 1-azabut-2-ene-1,4-diyl unit.
Longer reaction times in THF and a large excess of
lithium are sufficient to completely convert the intermediate 5 Experimental Section
into the (1-azabut-2-ene-1,4-diyl)dilithium compound 6 by
reductive cleavage of the CÀC bond of the hexa-1,5-diene-1,6-
All work was carried out under argon and in carefully dried and
degassed solvents.
:According to reference [7] 2-propylamine (40.0 g, 676.7 mmol)
were added to a solution of a-methyl cinnamaldehyde (50.0 g,
42.0 mmol) in diethyl ether (100 mL) at room temperature. During
the reaction molecular sieves (ca. 40 g with color indicator) were
added in portions to adsorb the resulting water. After 12 h the
reaction was complete and the solvent and the excess 2-propylamine
were evaporated in vacuo. Compound 3 is a pale yellow oil that
crystallized at + 58C and was kept under argon. Yield:60.0 g (94%).
3
diamide unit. After several hours red cubic crystals of 6
precipitate directly from the reaction mixture.
3
The result of the crystal structure analysis[ (Figure 4)
shows that the geometry of 6 is nearly unchanged compared
with that of the 1-azabut-2-ene-1,4-diyl unit of the intermedi-
ate 5. In place of the amide groups of the hexa-1,5-diene-1,6-
diamide brackets of 5 two THF molecules are coordinated to
8]
4
:Small pieces of lithium (1.0 g, 142.8 mmol) was added at room
temperature to a solution of 3 (20.0 g, 106.8 mmol) in diethyl ether
100 mL). The reaction mixture was stirred for 24 h. Afterwards, the
the lithium atoms with a third molecule of THF additionally
bridging the two alkali metals.[
6,15]
Notably, the characteristic
(
interaction between the lithium atom Li2 and the p-electron
system of the phenyl group remains the same as in 5 (Li2ÀC5
excess lithium was filtered off and the filtrate was reduced to one-half
of its volume. At a temperature of À58C, pale yellow crystals of 4
precipitate (23.0 g, 42.7 mmol; 80%).
2
.395(5), Li2ÀC10 2.363(6) Š). Considering the line-broad-
1 13
5:Application of ultrasound for 3 h to the reaction of 3 (20.0 g,
ening and the striking high-field shift of the H and C NMR
signals of the phenyl group in the NMR spectra of 6 (Table 1)
it becomes evident that this contact is not broken even by the
donor solvent THF.
106.8 mmol) with lithium (2.0 g, 285.6 mmol) in THF (100 mL) at
room temperature led to a color change to red. After a reaction time
of 48 h the excess lithium was filtered off, the solvent THF was
removed under vacuum, and the residue was taken up in diethyl ether.
Red crystals of compound 5 (21.0 g, 77%) separated when the
solution was left to stand at À58C.
The presented findings on the reaction of the 1-aza-1,3-
diene 3 with lithium are of interest for two reasons:On the
2
256
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Chemie
6
:When the reaction mixture was kept in the ultrasound bath for
Vꢀ 25.328, V = 99.6%, 9760 symmetry-independent reflec-
max
three more hours its color deepened to dark red. After the reaction
was complete, the unreacted lithium was filtered off, and the dark red
THF solution was cooled down to À208C. After a longer period of
time red cubic crystals of 6 (30.3 g, 68%) precipitated. If highly active
lithium powder (Firma UD-FC/MO, Merseburg) was used instead of
the compact lithium pieces for the reduction of 3, then within five
hours the dark red compound 6 was formed.
tions, R = 0.041, 5154 observed reflections with F > 4s(F ), 562
int
o
o
2
refined parameters, 0 restraints, R1 = 0.058, wR = 0.156,
obs
obs
2
R1all = 0.116, wR = 0.181, GOOF = 0.963, max. residual elec-
all
À3
tron density:0.388/ À0.288 eŠ
. 6: C H Li NO , M =
25 41 2 3 r
À1
3
417.47 gmol , orange cubes, crystal size 0.10 ” 0.08 ” 0.06 mm ,
monoclinic, space group P2 /c, a = 18.2920(4), b = 9.4405(2), c =
1
3
15.2487(3) Š, b = 103.976(1)8, V= 2555.28(9) Š , T= À908C,
À3
À1
Z = 4, 1
= 1.085 gcm , m(Mo ) = 0.68 cm , F(000) = 912,
Ka
calcd.
Received:September 6, 2002 [Z50116]
Publication delayed at authors's request
15928 reflections collected, h(À23/23), k(À10/12), l(À9/19),
range 2.678 ꢀ Vꢀ 27.458, V = 98.9%, 5777 symmetry-inde-
max
pendent reflections, R = 0.027, 4193 observed reflections with
int
F > 4s(F ), 280 refined parameters, 0 restraints, R1 = 0.067,
o
o
obs
Keywords: amides · heterodienes · lithium · reduction
2
2
.
wR = 0.189, R1all = 0.092, wR = 0.215, GOOF = 1.001, max.
o
b
s
a
l
l
À3
residual electron density:0.516/ À0.286 eŠ . CCDC-191595 (3),
CCDC-191596 (4), CCDC-191597 (5) and CCDC-191598 (6)
contain the supplementary crystallographic data for this paper.
These data can be obtained free of charge via www.ccdc.can.a-
c.uk/conts/retrieving.html (or from the Cambridge Crystallo-
graphic Centre, 12 Union Road, Cambridge CB21EZ, UK; Fax:
[
1] a) J. Scholz, M. Nolte, C. Krüger, Chem. Ber. 1993, 126, 803 –
809; b) D. Enders, M. Kroll, G. Raabe, J. Runsink, Angew. Chem.
1998, 110, 1770 – 1773; Angew. Chem. Int. Ed. 1998, 37, 1673 –
1675.
[
[
[
2] St. Kahlert, H. Görls, J. Scholz, Angew. Chem. 1998, 110, 1958 –
(
+ 44)1223-336033; or deposit@ccdc.cam.ac.uk).
9] a) R. F. Childs, G. S. Shaw, C. J. L. Lock, J. Am. Chem. Soc. 1989,
11, 5424 – 5429; b) J. Wunderle, J. Scholz, E. Hovestreydt, Z.
1962; Angew. Chem. Int. Ed. 1998, 37, 1857 – 1861.
[
3] S. Becke, H. Windisch, J. Scholz, St. Kahlert (Bayer AG), US
Pat. 5 965 678, 1999 [Chem. Abstr. 1999, 130, P125529p].
4] a) J. M. Davis, R. J. Whitby, A. Jaxa-Chamiec, J. Chem. Soc.
Chem. Commun. 1991, 1743 – 1745; b) J. Scholz, St. Kahlert, H.
Görls, Organometallics 1998, 17, 2876 – 2884; c) K. Mashima, Y.
Matsuo, S. Nakahara, K. Tani, J. Organomet. Chem. 2000, 593–
1
Kristallogr. 1993, 208, 274 – 276; c) W. Imhof, A. Göbel, D.
Braga, P. DeLeonardis, E. Tedesco, Organometallics 1999, 18,
736 – 747.
[
10] Running the reductive C–C coupling of 1-aza-1,3-dienes with
sterically demanding N-substituents (i.e. 2,6-(iPr) C H ) leads to
2
6
3
594, 69 – 76; d) Y. Matsuo, K. Mashima, K. Tani, Organometallics
the formation of two diastereomeric N,N’-dilithium-hexa-1,5-
diene-1,6-diamides (according to NMR spectroscopy). In con-
trast to 4 their molecular structures have a linear hexa-1,5-diene
skeletal structure. J. Scholz, V. Lorenz, H. Görls, unpublished
results.
2002, 21, 138 – 143.
[
5] a) K. Fujita, Y. Ohnuma, H. Yasuda, H. Tani, J. Organomet.
Chem. 1976, 113, 201 – 213; b) S. S. Wreford, J. F. Whitney, Inorg.
Chem. 1981, 20, 3918 – 3924; c) Y. Kai, N. Kanehisa, K. Miki, N.
Kasai, K. Mashima, H. Yasuda, A. Nakamura, Chem. Lett. 1982,
[
[
[
[
11] D. Lucet, T. Le Gall, C. Mioskowski, Angew. Chem. 1998, 110,
1
277 – 1280.
6] a) J. Scholz, B. Richter, R. Goddard, C. Krüger, Chem. Ber. 1993,
26, 57 – 61; b) M. Haaf, A. Schmiedl, T. A. Schmedake, D. R.
Powell, A. J. Millevolte, M. Denk, R. West, J. Am. Chem. Soc.
998, 120, 12714 – 12719.
7] O. Doebner, W. Miller, Ber. Dtsch. Chem. Ges. 1883, 16, 1664 –
668. See also Experimental Section.
8] Crystal structure analyses: 3: C H N, M = 187.28 gmol
2
725 – 2772; Angew. Chem. Int. Ed. 1998, 37, 2580 – 2627.
12] K. Schwetlik, Organikum, 21st ed., Wiley-VCH, Weinheim,
001, p. 592.
13] W. N. Setzer, P. von Raguꢀ Schleyer, Adv. Organomet. Chem.
985, 24, 353 – 451.
[
1
2
1
1
[
[
14] a) D. Wilhelm, T. Clark, P. von Raguꢀ Schleyer, H. Dietrich, W.
Mahdi, J. Organomet. Chem. 1985, 280, C6-C10; b) L. D. Field,
M. G. Gardiner, B. A. Messerle, C. L. Raston, Organometallics
1
À1
,
1
3
17
r
3
colorless cubes, crystal size 0.10 ” 0.09 ” 0.08 mm , orthorhombic,
1
992, 11, 3566 – 3570; c) M. G. Gardiner, C. L. Raston, F. G. N.
Cloke, P. B. Hitchcock, Organometallics 1995, 14, 1339 – 1353.
[15] Important structure principles of 6 are comparable to those of
the N,N’-dilithium-but-2-ene-1,4-diamide [(4-CH C H )-
LiNC(Ph) C(Ph)NLi(4-CH C H )]·3THF
space group Pbca, a = 9.4632(3), b = 11.2806(3), c =
3
2
1
1.7174(7) Š, V= 2318.3(1) Š , T= À908C, Z = 8, 1calcd
=
À3
À1
.073 gcm , m(MoKa) = 0.62 cm , F(000) = 816, 4678 reflections
3
6
4
collected, h(À12/12), k(À14/14), l(À28/28), range 2.868 ꢀ Vꢀ
¼
[6a]
or those of the
[PhLiNCH CH N-
3
6
4
2
7.498, V = 99%, 2641 symmetry-independent reflections,
max
N,N’-dilithium
ethylenediamide
2
2
Rint = 0.033, 1812 observed reflections with F > 4s(F ), 195
o
o
LiPh]·3HMPA
(HMPA = hexamethylphosphoramide),
in
refined parameters, 0 restraints, R1 = 0.047, wR2 = 0.101,
obs
obs
which three HMPA ligands provide coordinative saturation of
the lithium atoms. D. R. Armstrong, D. Barr, A. T. Brooker, W.
Clegg, K. Gregory, S. M. Hodgson, R. Snaith, D. S. Wright,
Angew. Chem. 1990, 102, 443 – 445; Angew. Chem. Int. Ed. Engl.
1990, 29, 410 – 411.
R1all = 0.082, wR2 = 0.117, GOOF = 1.007, max. residual elec-
all
À3
tron density:0.133/ À0.184 eŠ
. 4: C H Li N O , M =
34 54 2 2 2 r
À1
5
0
36.68 gmol
,
colorless cubes, crystal size 0.12 ” 0.12 ”
.10 mm , orthorhombic, space group Pca2 , a = 21.1701(4),
3
1
3
b = 9.7292(2), c = 32.8356(7) Š, V= 6763.1(2) Š , T= À908C,
À3
À1
Z = 8, 1
= 1.054 gcm , m(Mo ) = 0.63 cm , F(000) = 2352,
Ka
calcd
1
3208 reflections collected, h(À27/27), k(À12/12), l(À42/42),
range 1.928 ꢀ Vꢀ 27.488, V = 96.9%, 13208 symmetry-inde-
max
pendent reflections, 8820 observed reflections with F > 4s(F ),
o
o
7
65 refined parameters, 1 restraint, R1 = 0.064, wR2 = 0.168,
obs obs
R1all = 0.093, wR2 = 0.1828, GOOF = 0.974, Flack parameter
all
0
.4(10) (merohedral twin), max. residual electron density:0.420/
À3
À1
À0.247 eŠ . 5: C H Li N O ·0.5C H O, M = 843.97 gmol
,
5
1
81
4
3
3
4
10
r
3
red cubes, crystal size 0.12 ” 0.12 ” 0.10 mm , monoclinic, space
group P2 /n, a = 15.423(3), b = 20.970(4), c = 16.826(3) Š, b =
1
1
1
00.15(3)8, V= 5356.8(19) Š3
.046 gcm , m(MoKa) = 0.63 cm , F(000) = 1840, 17050 reflec-
,
T= À908C, Z = 4, 1calcd
=
À3
À1
tions collected, h(À18/18), k(À25/23), l(À20/20), range 1.948 ꢀ
Angew. Chem. Int. Ed. 2003, 42, 2253 – 2257
www.angewandte.org
ꢀ 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
2257