The reaction of cyclohexanone azine with PCl3. synthesis of annulated dichlorodiazaphosphole and its unusual transannulation

Article abstract of DOI:10.1002/zaac.201200042

The N, N'-annulated dichlorodiazaphosphole 1 was prepared in 55€‰% yield by the reaction of cyclohexanone azine (c-HA) with two equivalents of PCl₃ in pyridine. Compound 1 revealed one-dimensional chains in crystal with short intermolecular interactions [3.194(1) A] between phosphorus atoms of adjacent molecules. Treatment of c-HA with MeLi (2 equiv. in Et₂O) followed by addition of PCl₃ gave 1 in 33€‰% yield. An amount of c-HA isomerizes in these conditions to form corresponding hexahydroindazole derivative 3, which further reacts with 1 to give diazaphosphole 5 as transannulation product. Copper monochloride forms an (1:1) adduct with 5, which was characterized by its X-ray crystal structure. Only one equivalent of PCl₃ reacts with c-HA in Et ₂O/Et₃N mixture to form diazaphospholium chloride 2 and hexahydroindazole 3.

Full text of DOI:10.1002/zaac.201200042

ARTICLE
DOI: 10.1002/zaac.201200042
The Reaction of Cyclohexanone Azine with PCl3. Synthesis of Annulated
Dichlorodiazaphosphole and its Unusual Transannulation
Alexander N. Kornev,*[a] Olga Y. Gorak,[a] Olga V. Lukoyanova,[a]
Vyacheslav V. Sushev,[a] Julia S. Panova,[a] Evgenii V. Baranov,[a] Georgy K. Fukin,[a]
Sergei Y. Ketkov,[a] and Gleb A. Abakumov[a]
Keywords: Phosphorus heterocycles; Azaphospholes; Ketazines; Phosphorus-nitrogen ligands; X-ray diffraction
Abstract. The N,NЈ-annulated dichlorodiazaphosphole 1 was prepared conditions to form corresponding hexahydroindazole derivative 3,
in 55% yield by the reaction of cyclohexanone azine (c-HA) with two
equivalents of PCl3 in pyridine. Compound 1 revealed one-dimen-
sional chains in crystal with short intermolecular interactions
[3.194(1) Å] between phosphorus atoms of adjacent molecules. Treat-
which further reacts with 1 to give diazaphosphole 5 as transannulation
product. Copper monochloride forms an (1:1) adduct with 5, which
was characterized by its X-ray crystal structure. Only one equivalent
of PCl3 reacts with c-HA in Et2O/Et3N mixture to form diazaphosphol-
ment of c-HA with MeLi (2 equiv. in Et2O) followed by addition of ium chloride 2 and hexahydroindazole 3.
PCl3 gave 1 in 33% yield. An amount of c-HA isomerizes in these
formed can be used for preparation of various organic[17] or
Introduction
organoelement[14,18,19] compounds. Alternatively, direct reac-
tion of a ketazine with PCl3 is also possible. The unique exam-
ple is the reaction of PCl3 with bis(tert-butyl-methyl)ketazine,
which affords 1,2-diaza-3-phosphacyclopenta-3,5-diene and
the 1,5-diaza-2,6-diphospha-bicyclo[3.3.0]octa-3,7-diene in a
2:1 ratio, respectively.[14] The mechanism for the formation of
the latter compounds is not readily apparent. Perhaps it in-
cludes direct interaction of the nitrogen lone pairs of ketazine
with the electrophile PCl3 to form the Lewis acid-base ad-
duct.[20] Such interaction increases the acidity of α-hydrogen
atoms and facilitates the dehydrochlorination process (Scheme
S1, Supporting Information). So, further studies of the related
reactions promise interesting findings in phosphorus-nitrogen
chemistry and, in particular, in the chemistry of heterophos-
pholes. We herein report the reaction between cyclohexanone
azine and phosphorus trichloride in various conditions, which
affords a novel annulated diazaphosphole and demonstrates its
unusual transannulation.
Phosphorus heterocycles are versatile building blocks for the
engineering of ligands used for homogeneous catalysis[1] and
organic π-conjugated materials with potential application in
electronic and optoelectronic devices.[2] Functional heterophos-
pholes are currently receiving increasing attention due to their
potential as precursors for these purposes.[3] Among these heter-
ophospholes, dihydro-1,3,2-diazaphospholes are perhaps the
most widely investigated precursors of phosphorus analogues of
Arduengo carbenes.[4–6] The chemistry of related 1,2,3-diaza-
phospholes and diazaphospholenes has been extensively
studied by Schmidpeter, Bansal and others.[3,7,8] These com-
pounds are known to take part in cycloaddition reactions.[9]
Dialkyl-1H- and -2H-1,2,3-diazaphospholes became available
from ketone hydrazones and PCl3.[10–13] These reactions start
with formation of a P–N bond followed by cyclization involv-
ing substitution of the α-hydrogen atom of the alkyl radical R.
Recently, it has been shown that ketazines may also react with
phosphorus trichloride to form various phosphole derivatives
depending on the reaction conditions.[14] Like ketones, ketaz-
ines are known to be easily deprotonated at the α-C position
by alkyllithium reagents.[15] Since the azine bridge (=N–N=)
prevents conjugation,[16] an excess of alkyllithium reagent usu-
ally results in a dilithium derivative. The 1,6-dianions thus
Results and Discussion
The reaction of cyclohexanone azine with PCl3 in the molar
ratio of 1:2 in pyridine was carried at ambient conditions for
24 h. The abundant precipitate of Py(HCl) was filtered off; a
single phosphorus-containing product (1) of this reaction was
separated by crystallization from MeCN and purified by subli-
mation at 160 °C and 6.66 Pa (Scheme 1). Crystals, suitable
for X-ray analysis, were obtained by crystallization from pyr-
idine. The molecular structure of 1 with selected bond lengths
and angles is shown in Figure 1; crystallographic data are sum-
marized in Table 1.
* Dr. A. N. Kornev
Fax: +7-831-4627497
E-Mail: akornev@iomc.ras.ru
[a] G. A. Razuvaev Institute of Organometallic Chemistry
Russian Academy of Sciences
49 Tropinin Street
603950 Nizhny Novgorod, Russia
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/zaac.201200042 or from the au-
thor.
Z. Anorg. Allg. Chem. 2012, 638, (7-8), 1173–1178
© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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A. N. Kornev et al.
ARTICLE
Table 1. Crystal and structure refinement for compounds 1 and 4.
1
4
Empirical formula
Formula weight
Temperature, K
Crystal system
Space group
C12H16Cl2N2P2
321.11
150(2)
monoclinic
C18H26Cl1.88Cu0.88N2P
423.94
100(2)
triclinic
¯
P21/n
P1
a /Å
b /Å
c /Å
α /°
7.2912(5)
6.9859(5)
14.1252(9)
90
102.2080(10)
90
703.21(8)
2
7.6203(3)
10.2144(4)
12.9043(5)
106.1700(10)
99.1890(10)
93.1020(10)
947.15(6)
2
β /°
γ /°
Volume /Å–3
Z
Crystal size /mm3
Absorption coefficient /mm–1
Absorption correction
Max. /min. transmission
Density (calculated), Mg·m–3
Reflections collected
Independent reflections
Data / restraints / parameters
R indices [I Ͼ 2σ(I)]
R indices (all data)
Largest diff. peak and hole /e·Å–3
0.38ϫ0.16ϫ0.16
0.672
Semi-empirical from equivalents
0.9001 / 0.7843
1.517
0.19ϫ0.09ϫ0.08
1.374
Semi-empirical from equivalents
0.8980 / 0.7803
1.486
7989
3628 [R(int) = 0.0215]
3628 / 0 / 227
R1 = 0.0392, wR2 = 0.0934
R1 = 0.0465, wR2 = 0.0971
0.843 and –0.318
4341
1521 [R(int) = 0.0157]
1521 / 0 / 82
R1 = 0.0314, wR2 = 0.0863
R1 = 0.0333, wR2 = 0.0879
0.604 and –0.239
a tetracyclic system comprising two N,NЈ-annulated 1,2,3-di-
azaphosphole rings both attached to the cyclohexene rings. The
five-membered heterocycles adopts a nearly planar conforma-
tion; mean deviation of the atoms P(1), C(1), C(2), N(1), and
N(1A) from the plane is 0.051 Å; the sum of bond angles at
nitrogen atoms is 358.1(4)°. The lengths of the C–C linkages
in the heterocycles, 1.347(2) Å, are in the range expected for
C(sp2)–C(sp2) bonds. The planar PCCN fragments are also co-
planar. The phosphorus atoms are strongly pyramidalized and
the sum of bond angles is 291.55°. The P–Cl bond length
[2.1762(6) Å] lies in the normal range and is shorter than the
bonds in the related 1,3,2-diazaphospholidines (2.20–
2.30 Å).[21,22] The structural parameters of heterocycles in 1
are very close to those observed in the related diazadiphos-
phole, which was synthesized from the dilithium salt of bi-
s(tert-butylmethyl)ketazine and PCl3.[14] Crystal packing
analysis of 1 revealed short intermolecular interactions be-
tween the phosphorus atoms of adjacent molecules, which
form one-dimensional chains in the crystal structure. Part of
the chain is depicted in Figure 2. The intermolecular distances
P(1A)···P(1AB) and P(1B)···P(1AC) are notably shorter
[3.194(1) Å], than the sum of van-der-Waals radii of the phos-
phorus atoms (3.8 Å[23]). Short intermolecular interactions are
well known for pnicogens and pnicogen compounds;[24] a pos-
sible model for the P···P nonbonding interaction might be a
negative hyperconjugation of the lone pair of electrons at phos-
phorus of one molecule with the anti-bonding orbital σ*PЈNЈ
at the adjacent phosphorus and the substituent along the P···P
Scheme 1. Synthesis of 6,12-dichloro-1,2,3,4,7,8,9,10-octahydro-
6H,12H-[1,2,3]benzodiazaphospholo[2,1-a][1,2,3]benzodiaza-
phosphole (1).
Figure 1. The molecular structure of 1 with ellipsoids of 30% prob-
ability. Hydrogen atoms are omitted for clarity. Selected bond lengths
/Å and angles /° for 1: P(1)–N(1A) 1.693(1), P(1)–C(1) 1.798(2), P(1)–
Cl(1) 2.1762(6), N(1)–C(2) 1.390(2), N(1)–N(1A) 1.413(2), C(1)–C(2)
1.347(2); N(1A)–P(1)–C(1) 88.11(6), N(1A)–P(1)–Cl(1) 104.35(5),
C(1)–P(1)–Cl(1) 99.09(5), C(2)–N(1)–N(1A) 109.5(1). Symmetry
transformations used to generate equivalent atoms A: –x,–y,–z.
axis[24,25]
.
The crystal structure shows that replacement of two α-hy-
drogen atoms in both cyclohexane rings of c-HA occurred.
Compound 1 is centrosymmetric; the inversion center is lo-
The 31P NMR chemical shift of 1 (δ =108.6 ppm) falls in the
expected range for dihydro-1,2,3-diazaphospholes containing
cated in the middle of the N(1)–N(1A) bond. Two PCl units covalent P–Cl bonds at three-coordinate phosphorus
are accommodated in five-membered heterocycles resulting in atom.[14,26] The infrared spectrum of 1, listed in Figure S1
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Dichlorodiazaphosphole and its Unusual Transannulation
cyclohexanone azine with PCl3 in the presence of triethytlam-
ine, a mixture of the products 1 and 2 was observed. It thus
became obvious that the solvent plays a crucial role in this
reaction.
Additionally, the reaction of PCl3 with the dilithium deriva-
tive of cyclohexanone azine was carried out. Lithiation of c-
HA was performed by addition of MeLi to a diethyl ether solu-
tion of c-HA. The first equivalent of MeLi reacted for a few
minutes; the process was accompanied by a fast methane evol-
ution. Reaction with the second equivalent of MeLi was com-
pleted after 48 h. The dilithium derivative of c-HA further re-
acted with two equivalents of PCl3 in diethyl ether to give a
yellow solution and precipitated LiCl. Compound 1 was sepa-
rated from the reaction mixture in 33% yield. Note, that only
two P–Cl groups are consumed by the dilithium derivative.
This may be one of the reasons of the smaller yield of 1 com-
pared to the reaction in pyridine. The remaining two P–Cl frag-
ments may react with c-HA due to its basic properties. Actu-
ally, c-HA hydrochloride was found in the reaction products
in a small amount, together with the hydrochloride of its iso-
mer 3. Furthermore, the 31P NMR spectrum of the oily residue
showed two novel signals at δ = 199.8 and 196.7 ppm. The
chromatography-mass spectrometry measurements (Figure S5
and Figure S6, Supporting Information) revealed formation of
two novel compounds with highest mass peaks at 301 and 140
m/z. The CuCl adduct 4 of one of the products (5), having
highest mass peak at 301 m/z was isolated and fully charac-
terized. According to the X-ray analysis it turned to be the
transannulation product, which was formed by side reaction
of the dichloro derivative 1 with hexahydroindazole 3. The
molecular structure of 4 with selected bond lengths and angles
is shown in Figure 3. The crystallographic data of 4 are sum-
marized in Table 1.
Figure 2. Crystal packing fragment of 1 with ellipsoids of 30% prob-
ability. Hydrogen atoms are omitted for clarity.
(Supporting Information), was in agreement with the found
structure. An intense absorbance between 1100 and 1300 cm–1
was observed. This is a characteristic of the PN skeleton of
cyclic phosphorus-nitrogen compounds.[27] The bands at 465
and 480 cm–1 in this spectrum were assigned to the P–Cl
stretching vibrations.
The reaction of cyclohexanone azine with PCl3, was carried
out in diethyl ether in the presence of triethylamine. It gave
another organophosphorus product with a chemical shift at δ
= 214.0 ppm in the 31P NMR spectrum. In these conditions
only one equivalent of PCl3 reacts with c-HA to form diaza-
phospholium chloride 2 (Scheme 2). Microanalytical data for
2 were satisfactory and the mass spectrum gave the expected
parent ion (m/z = 221.1) and fragmentation patterns (Figure
S2, Supporting Information). Note that the reaction proceeds
very slowly (one week) giving the hexahydroindazole deriva-
tive 3 as a side product in 15% yield (Scheme 3).
Scheme 2. Reaction of c-HA with PCl3 in diethyl ether. Formation of
2-cyclohexylidene-4,5,6,7-tetrahydro-2H-1,2,3-benzodiazaphosphol-2-
ium chloride (2).
Scheme 3. Isomerization of c-HA into 2Ј,3aЈ,4Ј,5Ј,6Ј,7Ј-hexahydrospiro-
[cyclohexane-1,3Ј-indazole] (3).
Figure 3. The molecular structure of 4 with ellipsoids of 30% prob-
ability. Hydrogen atoms are omitted for clarity. Selected bond lengths /
Å and angles /° for 4: P(1)–N(1) 1.686(2), P(1)–C(1) 1.731(2), N(1)–
N(2) 1.364(2), N(1)–C(7) 1.500(2), N(2)–C(2) 1.349(3), N(2)–C(14)
1.414(2), C(1)–C(2) 1.397(3), C(13)–C(14) 1.326(3), Cu(1)–Cl(2)
2.0762(6), Cu(1)–Cl(1) 2.0982(7); Cl(2)–Cu(1)–Cl(1) 179.47(3),
N(1)–P(1)–C(1) 89.73(9), N(2)–N(1)–C(7) 109.3(2), N(2)–N(1)–P(1)
113.8(1), C(7)–N(1)–P(1) 136.9(1), C(2)–N(2)–N(1) 112.9(2), C(2)–
N(2)–C(14) 137.0(2), N(1)–C(7)–C(13) 100.1(2).
Cyclohexanone azine can be converted into 4,5-dihydropyr-
azoles by reaction in acidic conditions, as reported by Stolle
and Hanusch in 1930.[28] The hydrochloride of 3 was isolated
in crystalline form and characterized by 1H NMR spec-
troscopy, elemental analysis and mass spectrometry. It demon-
strated some differences in comparison with the spectrum of
isomeric c-HA (Figures S3 and S4, Supporting Information).
The organic (cationic) component of compound 4 may be
By using tetrahydrofurane instead of Et2O in the reaction of considered as hexahydroindazole 3, attached to a half part of
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A. N. Kornev et al.
ARTICLE
compound 1. The polycyclic system of 4 includes two five- contact [3.311(1) Å] is substantially shorter than the sum of
membered N,NЈ-annulated heterocycles (C3N2 and C2N2P) corresponding van der Waals radii (3.7 Å).[23] Schematic repre-
both attached to the cyclohexene rings. The phosphole ring sentation of the formation of 5 is shown in Scheme 4. Tenta-
exhibits planar conformation whereas the C3N2 ring is nearly tively, the first step of the reaction between the chlorophos-
planar. The mean deviation of the atoms N(1), N(2), C(14), phine 1 and the secondary amine 3 is the P–N bond formation
C(13), C(7) from the mean plane C3N2 is 0.022 Å. The angle resulting in the intermediate product 6, which undergoes sub-
between the C2N2P and C3N2 planes is 2.9°; the sums of bond sequent fragmentation. The nitrogen (sp2) atom of hexahy-
angles at the nitrogen atoms are 360.0° (N1) and 359.9° (N2). droindazole part of 6 coupled with the carbon (sp2) atom of
The nitrogen–nitrogen bond length in 4 [1.364(2) Å] is notably the diazadiphosphole fragment. This interaction is facilitated
shorter than that [1.413(2) Å] in 1. The C(1)–C(2) distance of in transition state by positive charge transfer from phosphorus
1.397(3) closely resembles the aromatic C–C bond. These data to conjugated sp2-carbon, as depicted in structure 6b. Presum-
are indicative of better cyclic conjugation in the positively ably, the hydrogen atom at the tertiary carbon atom of the
charged diazaphosphole ring of 4 relative to that in 1. Note hexahydroindazole part is transferred to the nitrogen atom of
that the C(13)–C(14) distance of 1.326(3) Å is close to a nor- the diazadiphosphole fragment followed by cleavage of the N–
mal carbon–carbon double bond in alkenes. The presence of a P and N–C bonds to form two novel diazaphospholes 5 and 7.
quaternary carbon atom [C(7), Figure 3] impedes the cyclic It seems that compound 5 may easily extrude the halide anion
conjugation in the C3N2 heterocycle. The anionic part of 4 is to form diazaphospholium cation with a highest mass peak at
the linear [CuCl2]– anion, which is formed by chloride ion 301 m/z in the mass spectrum. This is in agreement with the
transfer from dihydrodiazaphosphole 5 to CuCl. In the crystal 6e-aromatic delocalization found in similar C2N2P+ five mem-
of 4, the short intermolecular interaction occurs between the bered heterocycles.[11,29]
P(1) atom of the organic cation and the Cl(2) atom of the
The transannulation reaction described above seems to be
[CuCl2]– anion. The distance of intermolecular P(1)···Cl(2) energetically favorable since two non-aromatic molecules after
interaction gave the aromatic diazaphosphole 7 and compound
5, which is the precursor of the aromatic diazaphosphonium
cation. It should also be noted that the control reaction of
dichlorodiazaphosphole 1 with cyclohexanone azine gave no
products. The structure of the intermediate 6 was fully opti-
mized by the B3LYP/6-31G(d) method and characterized as
energy minimum on the hypersurface by means of a vibrational
analysis. The arrangement and selected bond lengths for 6 are
shown in Figure 4 and Table 2 respectively. Notably, that the
P26–N23 (1.787 Å) and N22–C24 (1.400 Å) bonds are signifi-
cantly elongated, whereas the nitrogen atom (N8) of the pyr-
azolyl fragment is coordinated to the positively charged sp2
Scheme 4. Schematic representation of the proposed mechanism for
the reaction of 1 with hexahydroindazole 3.
Figure 4. The molecular structure of the intermediate 6 optimized at
the B3LYP/6-31G(d) level.
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Dichlorodiazaphosphole and its Unusual Transannulation
quency computations. For the geometry optimization we used the full
structure without simplification and the B3LYP/6-31G(d) level of
theory. The structure corresponds to an energy minimum.
carbon atom (C24) of diazadiphosphole, which explains the
ease of the transformation to 5 and 7. The Cl31–P21 bond is
quite long (2.312 Å) that may be explained by hyperconjuga-
tion effects between the six π electrons in the C2N2 unit and
the σ*(P-Cl) orbital.[4] The Mulliken charges for the intermedi-
ate 6 are shown in Figure S7 (Supporting Information).
X-ray Crystallography: Intensity data for 1 and 4 were collected with
a Smart Apex diffractometer with graphite monochromated Mo-Kα ra-
diation (λ = 0.71073 Å) in the ω-φ scan mode (ω = 0.3°, 10 sec on
each frame). The intensity data were integrated by SAINT program.[31]
SADABS[32] was used to perform area-detector scaling and absorption
corrections. The structures of 1 and 4 were solved by direct methods
and were refined on F2 using all reflections with SHELXTL pack-
age.[33] All non-hydrogen atoms were refined anisotropically. Hydro-
gen atoms were placed in calculated positions and refined in the “ri-
ding-model” and refined isotropically. In crystal of 4 the [CuCl2]–
anion is disordered with Cl– anion occupancies of disordered anions
of 0.88 and 0.12, respectively.
Table 2. Calculated bond lengths in 6.
Cl31–P21
P21–N22
N22–N23
N23–P26
P26–N7
C19–N23
C24–N22
C18–C19
C24–C25
N22–C24
N23–C19
2.312
1.727
1.408
1.787
1.726
1.368
1.400
1.370
1.349
1.400
1.368
Crystallographic data (excluding structure factors) for the structures in
this paper have been deposited with the Cambridge Crystallographic
Data Centre, CCDC, 12 Union Road, Cambridge CB21EZ, UK. Copies
of the data can be obtained free of charge on quoting the depository
numbers CCDC-848933 (1) and CCDC-848934 (4) (Fax: +44-1223-
336-033; E-Mail: deposit@ccdc.cam.ac.uk, http://www.ccdc.cam.a-
c.uk).
Surprisingly, a better yield of 4 was observed when a solu-
tion of Cu(MeCN)4BF4 was added to the mother liquor con-
taining diazaphospholes 5 and 7. This is possibly due to fast
ion exchange and better solubility of copper(I) tetrafluorobor-
ate unlike CuCl.
Reaction of c-HA with PCl3 in Pyridine. Synthesis of 1: Phosphorus
trichloride (1.09 g,7.9 mmol) was added to a solution of cyclohexa-
none azine (0.46 g, 2.4 mmol) in pyridine (15 mL) at 0 °C. The color
immediately turned to yellow. The resulting solution was allowed to
stand at room temperature for 24 h, upon which pyridine hydrochloride
precipitated. The mixture was filtered; the solvent was evaporated un-
der reduced pressure and changed for acetonitrile. Soon after dissol-
ution in acetonitrile, yellow crystals of the crude product precipitated.
Sublimation at 160 °C (2.67 Pa) gave 0.42 g (55%) of 1.
C12H16Cl2N2P2: calcd. C 44.88; H 5.02; N 8.72; P 19.29%; found C
44.82; H 5.08; N 8.69; P 19.32%. 1H NMR (CDCl3, 295 K): δ = 1.50–
2.10 (m, 8 H, CH2 at 2,3,8,9 C-atoms); 2.32–2.56 (m, 4 H, CH2 at 4
and 10 C-atoms), 2.65–2.80 (m, 4 H, CH2 at 1 and 7 C-atoms) ppm.
13C NMR (CDCl3, 295 K): δ = 23.1–23.6 [m, 2C (4, 10)], 22.1–22.6
[m, 2C (1,7)]; 21.3–22.1 [m, 4C-(2,3,8,9)]; 144.9 [m, 2C, (4a, 10a)];
116.6 [m, 2C, (6a, 12a)] ppm. 31P{1H} NMR: δ = 108.6 ppm. IR
(nujol): ν˜ = 1589 m, 1347 w, 1287 m, 1247 m, 1181 m, 1161 m, 1130
w, 1025 m, 960 m, 920 m, 854 w, 807 m, 756 w, 723 w, 684 m, 610
w, 589 m, 545 s, 480 m, 466 w cm–1.
Conclusions
The results of our study illustrate that the annulated dichlor-
odiazaphosphole 1 may be easily synthesized by reaction of
cyclohexanone azine with two equivalents of PCl3 in pyridine
in 55% yield. The reaction of dilithiated cyclohexanone azine
with PCl3, which gives a 33% yield of 1, is a complicated
process that is accompanied by isomerization of c-HA into 4,5-
dihydropyrazole. The latter further reacts with 1 to give the
product of re-annulation 5, in which one of the diazaphosphole
rings replaced by the dihydropyrazole fragment. Copper(I)
chloride reacts with 5 to form the adduct 4, which could be
structurally characterized.
Experimental Section
Reaction of c-HA with PCl3 in Et2O. Formation of 2 and 3: Phos-
phorus trichloride (1.13 g, 8.2 mmol) was added to a mixture of cyclo-
hexanone azine (1.00 g, 5.2 mmol) and Et3N (1.99 g, 19.7 mmol) in
Et2O (20 mL) at 0 °C. The resulting solution was allowed to stand at
room temperature for a week, upon which triethylamine hydrochloride
precipitated. The mixture was filtered and concentrated under reduced
pressure. Pale yellow crystals of 2 were obtained overnight from a
concentrated solution at 0 °C. Yield 0.65 g (49%). C12H18N2PCl (2):
calcd. C 56.14; H 7.07; N 10.91; P 12.07; Cl 13.81%; found C 56.08;
General Remarks: Solvents were purified following standard meth-
ods.[30] Toluene and pyridine were thoroughly dried with sodium hy-
dride and distilled prior to use. Diethyl ether and THF were dried and
distilled over Na/benzophenone. Phosphorus trichloride and cyclo-
hexanone azine were purchased from Sigma-Aldrich Chemical Co. and
distilled before use. All manipulations were performed in a vacuum or
in an argon atmosphere using standard Schlenk techniques. NMR spec-
tra were recorded in CDCl3 or C6D6 solutions with a Bruker DPX-
200 device. Infrared spectra were recorded with a Perkin-Elmer 577
spectrometer from 4000 to 400 cm–1 in nujol or with a Perkin-Elmer
FT-IR spectrometer System 2000 as KBr mulls. GC-MS spectra were
recorded with an “Trace GC Ultra”-“Polaris Q” device with ion trap
mass analyzer.
1
H 7.11; N 10.88; P 12.10; Cl 13.76%. H NMR (CDCl3, 295 K): δ =
3.0–2.5 (m, 4H, (CH2 at 9 and 13 C-atoms), 2.5–1.4 (m, 14H, CH2 at
4,5,6,7,10,11,12 C-atoms) ppm. 31P{1H} NMR: δ = 214.0 (s) ppm.
MS, m/z (%): 221.1 (16) [M]+-Cl, 220.1 (100) [M]+-HCl, 192.3 (60),
141.2 (37).
Computational Details: DFT calculations performed in this work The Remaining solvent was fully removed from the mother liquor un-
were carried out at the B3LYP/6-31G(d) level of theory with the der reduced pressure, and CH2Cl2 was added. Colorless crystals of
Gaussian 03 package (Supporting general information). The optimized
geometry of 6 corresponds to energy minima, as indicated by fre-
3·HCl were precipitated overnight. Yield 0.15 g (15%). C12H21ClN2
(3·HCl): calcd. C 63.00; H 9.25; Cl 15.50; N 12.25%; found C 62.93;
Z. Anorg. Allg. Chem. 2012, 1173–1178
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www.zaac.wiley-vch.de
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A. N. Kornev et al.
ARTICLE
1
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H 9.30; Cl 15.47; N 12.21%. H NMR (CDCl3, 295 K): δ = 11.8 (s,
broad, 2 H, HN+), 3.0–2.6 (2 H, N = CCH2), 2.50–1.10 (m, 17 H, CH
and 7 CH2) ppm. MS: m/z (%):192.3 (20) [M]+, 149.4 (100) [M-
C3H7]+, 136.3 (60), 107.2 (32). IR (nujol): ν˜ = 2613 s, 2495 s, 1398
m, 1270 w, 1240 m, 1173 m, 1036 m, 1007 m, 954 w, 877 w, 807 m
cm–1.
Reaction of Lithiated c-HA with PCl3. Synthesis of 1 and 4: A
solution of MeLi in diethyl ether (1 m, 20.0 mL) was added dropwise
at 0 °C to a solution of cyclohexanone azine (1.92 g, 10 mmol) in the
same solvent. The mixture was allowed to stand for a 43 h, at room
temperature for completing the reaction, afterwards PCl3 (2.75 g,
72 mmol) in E2O (20 mL) was added at 0 °C under vigorous stirring.
The mixture was filtered and the solvent was evaporated under reduced
pressure. Yellow crystals of 1, precipitated overnight were collected.
The yield of the crude product 1 was 33%. The mother liquor was
separated from the crystals of 1, and allowed to react with an excess
of Cu(MeCN)4BF4 (3.14 g, 10.0 mmol) in THF solution. Colorless
crystals of 4 were precipitated overnight. Yield 1.22 g (28%).
C18H26Cl2CuN2P: calcd. C 49.60; H 6.01; Cl 16.27; N 6.43%; found
C 49.22; H 6.12; Cl 16.31; N 5.39%. IR (nujol): ν˜ = 1285 m, 1270
w, 1247 w, 1180 m, 1138 m, 1096 m, 1040 w, 1012 w, 962 w, 922 m,
873 w, 839 w, 817 w, 772 m, 722 s, 578 m, 542 m, 500 w cm–1.
The compound 4 decomposed at 190 °C (0.1 Torr) to give pure 5 and
copper(I) chloride.
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Supporting Information (see footnote on the first page of this article):
Nomenclature and atom numbering schemes for the polycyclic com-
pounds 1, 2, 3, 5, and 7. IR spectrum of 1; mass spectra for compounds
2, 3, 5, and 7; Mulliken charges for the intermediate 6.
Acknowledgement
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This work was supported by The Russian President’s program “Lead-
ing scientific Schools” (No. 4182.2008.3), State contract No.
16.740.11.0015, and RFBR regional grant No. 11–03–97029. We thank
Drs. O. V. Kouznetsova and N. M. Khamaletdinova for IR measure-
ments and Dr. V. I. Faerman for the chromatography-mass spectrome-
try analysis.
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Received: February 02, 2012
Published Online: June 04, 2012
1178
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© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2012, 1173–1178