1,3,6-azadiphosphacycloheptanes: A novel type of heterocyclic diphosphines

Article abstract of DOI:10.1002/hc.20397

The novel type of seven-membered cyclic diphosphines, namely 1,3,6-azadiphosphacycloheptanes, has been synthesized by condensation of 1,2-bis(phenylphosphino)ethane, formaldehyde, and primary amines (aniline, p-toluidine, benzylamine, and 5-aminoisophthalic acid) as a mixture of rac-and meso-stereoisomers. The structures of rac-stereo-isomers of N-tolyl and N-(3′,5′-dicarboxyphenyl)-substituted diphosphines were investigated by X-ray crystal structure analyses. The stereoisomers of N-(3′,5′- dicarboxyphenyl)-substituted compound were separated at a preparative scale, and their platinum(II) dichloride complexes were obtained. The corresponding meso-isomer readily forms P,P-chelate complex with [PtCl₂(cod)], whereas the rac-stereoisomer forms oligomeric complex.

Full text of DOI:10.1002/hc.20397

Heteroatom Chemistry
Volume 19, Number 2, 2008
1,3,6-Azadiphosphacycloheptanes: A Novel
Type of Heterocyclic Diphosphines
Andrey A. Karasik, Anna S. Balueva, Elvira I. Moussina,
Roman N. Naumov, Alexey B. Dobrynin, Dmitry B. Krivolapov,
Igor A. Litvinov, and Oleg G. Sinyashin
A. E. Arbuzov Institute of Organic and Physical Chemistry, Russian Academy of Sciences,
Kazan Scientific Center Arbuzov str. 8, Kazan 420088, Russian Federation
Received 3 October 2006; revised 17 November 2006
INTRODUCTION
ABSTRACT: The novel type of seven-membered
cyclic diphosphines, namely 1,3,6-azadiphosphacyclo-
heptanes, has been synthesized by condensation of
1,2-bis(phenylphosphino)ethane, formaldehyde, and
primary amines (aniline, p-toluidine, benzylamine,
and 5-aminoisophthalic acid) as a mixture of rac-
and meso-stereoisomers. The structures of rac-stereo-
isomers of N-tolyl and N-(3ꢀ,5ꢀ-dicarboxyphenyl)-
substituted diphosphines were investigated by X-ray
crystal structure analyses. The stereoisomers of N-
(3ꢀ,5ꢀ-dicarboxyphenyl)-substituted compound were
separated at a preparative scale, and their platinum(II)
dichloride complexes were obtained. The correspond-
ing meso-isomer readily forms P,P-chelate complex
with [PtCl2(cod)], whereas the rac-stereoisomer forms
Phosphine ligands are an excellent tool to ob-
tain metal complexes with tailor-made properties,
and they have been widely used in several fields
such as water-soluble and asymmetric metal com-
plexes [1,2]. The chelating diphosphines draw the
special attention because of the stability of their
metal complexes. However, to date, studies involv-
ing diphosphine ligands and especially hybrid func-
tional diphosphines have mostly been focused on
linear compounds [1,2]. In contrast, heterocyclic
diphosphines in which the phosphorus atoms are
incorporated into the ring have not been exten-
sively investigated, though such incorporation leads
to essential differences in the structures and the
properties of acyclic and cyclic compounds [3]. The
main specific feature of the cyclic diphosphines is
the appearance of the cis–trans isomers of the sub-
stituents on the phosphorus atoms [3]. Indeed, 1,3-
and 1,4-diphosphacyclohexanes [4], -cycloheptanes
[5], and 1,4- and 1,5-diphosphacyclooctanes [6]
exist as a mixture of cis- and trans- (or meso-
and rac-)stereoisomers, only cis-isomers being able
to act as chelating ligands as it was shown for
1,5-diphosphacyclooctanes [7]. In total, the eight-
membered diphosphines are the most studied type
of such ligands. A wide range of bidentate cyclic
eight-membered aminomethylphosphines, namely
1,5-diaza-3,7-diphosphacyclooctanes ligands, has
been synthesized by the Mannich-like reactions of
arylphosphine, formaldehyde, and primary amines
ꢁ
C
oligomeric complex. 2008 Wiley Periodicals, Inc. Het-
eroatom Chem 19:125–132, 2008; Published online in
Wiley InterScience (www.interscience.wiley.com). DOI
10.1002/hc.20397
Correspondence to: Andrey A. Karasik; e-mail: karasik@iopc.
knc.ru.
Contract grant sponsor: VolkswagenStiftung Foundation.
Contract grant number: I/82 020.
Contract grant Sponsor: Russian Foundation for Basic
Research.
Contract grant number: 06-03-32754-a.
Contract grant sponsor: President’s of Russian Federation
Grant for the Support of Leading Scientific Schools.
Contract grant number: 5148.2006.3.
Contract grant sponsor: Russian Science Support Foundation.
2008 Wiley Periodicals, Inc.
c
ꢀ
125

126 Karasik et al.
[8–14]. It should be mentioned that only cis-
stereoisomers (or meso-stereoisomers) of these
diphosphines are formed. The similar approach
was also successfully used for the synthesis of
1,3,5-azadiphosphacyclohexanes [15] on the basis
of the secondary bis(arylphosphino)methane, but
only a few examples of the seven-membered cyclic
aminomethylphosphines were described. Most of
these compounds include only one phosphorus cen-
ter [16–18], but the condensation of hydroxymethyl
derivatives of 1,2-diphosphinoethane and 1,2-
diphosphinobenzene with amino acids led to the bi-
cyclic diphosphines, where bridgehead phosphorus
atoms are included simultaneously into the seven-
and eight-membered heterocycles [19]. The com-
plexes of 1,5-diaza-3,7-diphosphacyclooctanes with
different transition metals (CuI[9,20,21], ReI[12],
PtII[9,12,13,22], and PdII [9,12–14]) were synthe-
sized, and the structure of these complexes in
the solid state and dynamic processes in solu-
tion as well as catalytic activity in the hydrogena-
tion of alkynes [23], copolymerization of alkenes
and carbon monoxide [24] have been studied. Al-
though the chelating type of the coordination was
predominant [9,12–14,20–22], these diphosphines
appeared to be also able to form the binuclear
complexes as the bridging ligands in spite of the
cis-mutual orientation of the electron lone pairs
on the phosphorus atoms [9,22]. For relatively
small and rigid 1-aza-3,5-diphosphacyclohexanes,
only the formation of oligonuclear complexes with
bridging ligand was found for both trans- and
cis-stereoisomers [15]. It indicates that inclusion
of donor atoms in heterocyclic structures re-
duces their chelation ability, and sometimes the
oligomerization becomes the predominant process.
In this connection, the synthesis and study of
the complexation properties of the intermediate-
sized seven-membered N-containing diphosphines
is of special interest, so that we assumed that
the use of 1,2-bis(phenylphosphino)ethane [25]
as a starting reagent will give possibly seven-
membered cyclic diphosphines. Unlike unchelat-
ing bicyclic diphosphine ligands described in [19],
the cis- (or meso-) stereoisomers of the monocyclic
N-containing diphosphines may probably form
chelate complexes whereas trans- (or rac-) ones may
become the basis for the formation of polynuclear
structures.
SCHEME 1
diastereomers. Its interaction with paraformalde-
hyde at 100–110◦C smoothly led to the mixture of
rac- and meso-1,2-bis[(hydroxymethyl)phenylphos-
phino)ethanes 1, which was further used without
additional purification. Condensations of 1 with pri-
mary arylamines, namely aniline, p-toluidine and
5-aminoisophthalic acid, and benzylamine, were
carried out in ethanol. The 31P NMR spectra of the
final reaction mixtures showed two prevailing peaks
at δP − 25 and −27 ppm in the case of arylamines and
at −33.5 and −31.8 ppm in the case of benzylamine.
The spontaneous crystallization led to the isolation
of the crystalline products 2–5 (Scheme 1), which
were air stable and soluble in benzene, chloroform,
acetone, and DMF. The compound 4 with a dicar-
boxyphenyl substituent was satisfactorily soluble in
water in the presence of 2 equivalents of inorganic
base.
The structure elucidation of these compounds
was based on 31P and 1H NMR, IR and mass spectra,
and elemental analysis. The absence of the absorp-
tion bands of hydroxyl (excluding dicarboxyphenyl-
substituted compound 4) and amino groups in the IR
spectra of 2–4 indicated the formation of the cyclic
compounds. The mass spectra of 4 and 5 showed
the peak for the molecular ion of the correspond-
ing 1,3,6-azadiphosphacycloheptanes with m/z 451.2
and 377.2, respectively. The 31P NMR spectra of
crude compounds 2–4 showed two narrow singlets
in the region between −25 and −27 ppm that co-
incided with the main signals of reaction mixture’s
spectra and indicated the crystallization of a mix-
ture of meso- and rac-stereoisomers. In the case
of N-benzyl-substituted compound 5, the spectrum
RESULTS AND DISCUSSION
The starting 1,2-bis(phenylphosphino)ethane con-
tained two asymmetric phosphorus centers, so
that it was, in fact, a mixture of rac- and meso-
Heteroatom Chemistry DOI 10.1002/hc

1,3,6-Azadiphosphacycloheptanes: A Novel Type of Heterocyclic Diphosphines 127
TABLE 1 The Selected Torsional Angles of the Molecules
showed only one signal at δP −33.5 ppm due to spon-
rac-3 and rac-4
taneous crystallization of the individual stereoiso-
mer from the reaction mixture. Concentration of
the filtrate gave rise to the stereoisomeric mixture,
and along with the predominant signal of the first
stereoisomer the minor peak of the second stereoiso-
mer was also observed at δP −31.8 ppm. The intensity
Molecule 3
Molecule 4
Torsion Angle
Torsion Angle
τ (deg)
τ (deg)
C4P3C2N1
C2P3C4C5
P3C4C5P6
C7P6C5C4
C5P6C7N1
C2N1C7P6
C7N1C2P3
58.5(4)
−69.5(5)
106.5(4)
−67.6(4)
−12.7(5)
88.6(6)
N1C2P3C4
C2P3C4C5
P3C4C5P6
C4C5P6C7
C5P6C7N1
P6C7N1C2
C7N1C2P3
99.72
−69.77
73.79
−84.94
1
ratio was 5:1. The H NMR spectra of crude com-
pounds 2–4 also showed the double set of signals
for the expected groups of protons and indicated the
formation of 1,3,6-azadiphosphacycloheptanes.
The fractional crystallization of 4 from the DMF–
acetone mixture led to the isolation of its individual
stereoisomer. Only one peak at δP −25.7 ppm was
observed in its 31P NMR spectrum. On the contrary,
the corresponding filtrate appeared to be essentially
enriched by another meso-stereoisomer (δP −26.7
ppm), its content was about 80%. The X-ray anal-
ysis of the monocrystal of the isolated individual
stereoisomer showed that it was rac-stereoisomer
(Fig. 1).
Henderickson [26,27] proposed variants of
the assignment of the carbocycle conformations
according to the sequence of the signs of torsional
angles of the cycle. This sequence allows one to de-
scribe the conformation of the cycle 4 as twist-chair
(Table 1). The cycle includes the planar five-atom
fragment N1C2P3C5P6. The atoms C4 and C7 are
deviated from this planar fragment to the opposite
sides (Fig. 2). The phenyl substituents on the phos-
phorus atoms are in pseudoequatorial positions and
directed to the opposite sides of the medium plane
of the cycle, so that the electron lone pairs are in
axial positions and have the opposite directions. The
nitrogen atom is coordinated in a near trigonal-
79.45
−16.30
−73.62
−97.4(5)
planar fashion (the sum of its bond angles is
353.84◦) due to conjugation of its electron lone pair
with the π-systems of the aryl substituent, which is
pseudoaxial.
Both isomers of 4 are stable in 5% aqueous so-
lution of sodium hydroxide and do not undergo the
oxidation or the hydrolysis according to their 31P and
1H NMR spectra.
In the case of compounds 2 and 3, the anal-
ogous fractional crystallization led only to enrich-
ment of the mixture by one of stereoisomers. The
successful separation of rac- and meso-isomers of 4
allowed us to attribute the signals of both stereoiso-
mers for all compounds 2–4 because their proton
signal’s pictures of P CH2 N fragments were sim-
ilar. In all cases for rac-stereoisomers, the signals
of one proton are doublet of doublets with coupling
2
2
constants JHH 13.7–13.8 Hz and JPH 9.2–11.2 Hz,
whereas the signals of another proton are doublets
of multiplets with small pseudocoupling constants
JPH 0–5 Hz due to the presence of complex and par-
tially degenerated AAꢀBBꢀXXꢀ spin system. For the
meso-stereoisomers of these compounds, the corre-
sponding signals are two doublets of doublets with
2
2
the coupling constants JHH 14.4–14.9 Hz and JPH
5.3–5.6 and 21.95–24.9 Hz. The unusually high value
of one of stereospecific geminal constants indicates
the eclipse of the phosphorus lone electron pair and
FIGURE 2 The conformation of the cycle of rac-(SS) isomer
of 4 (the substituents on the heteroatoms and hydrogen atoms
are omitted for clarity).
FIGURE 1 An ORTEP view of rac-(SS) isomer 4.
Heteroatom Chemistry DOI 10.1002/hc

128 Karasik et al.
FIGURE 3 An ORTEP view of rac-(SS) isomer 3.
FIGURE 4 The conformation of the cycle of rac-(SS) isomer
of 3 (the substituents on the heteroatoms and hydrogen atoms
are omitted for clarity).
one of the C H bonds in the predominant conforma-
tions of meso-isomers 2–4 (the torsion angles must
not be more than 20◦ [28]). The spectra give the ev-
idence that for 2 and 3 rac-isomers were predom-
inant after the recrystallization (the ratios of rac-
and meso-isomers were about 2:1); in the case of
compound 3, the monocrystal of the predominant
rac-isomer was isolated.
also the rac-stereoisomer of the heterocycle 5, but its
predominant conformation probably differed from
those of N-aryl-substituted compounds.
The structure of the rac-isomer of compound 3
was investigated by X-ray analysis (Fig. 3). The phos-
phorus atoms configurations in the studied crystal
of 3 corresponded to (SS)-enantiomer. According to
the method [26,27], the conformation of the cycle of
the compound 3 may also be described as twist-chair
(Table 1). The fragment N1P3C4P6C7 is near planar.
The atoms C2 and C5 are located on the opposite
sides of this plane (Fig. 4). Like the rac-isomer of
4, the phenyl substituents on the phosphorus atoms
are in pseudoequatorial positions and are directed
to the opposite sides of the medium plane of the
cycle, and the tolyl group on the nitrogen atom is
pseudoaxial. The nitrogen atom is coordinated in a
trigonal-planar fashion (the sum of the bond angles
is 359.48◦).
It is possible to expect that the type of com-
plexation of transition metals by rac- and meso-
stereoisomers of 1,3,6-azadiphosphacycloheptanes
is completely different because their rac-isomers
with opposite-directed electron lone pairs may
act only as bridging ligands, whereas the meso-
isomers may form chelate complexes. However, in
the case of 1,3,5-azadiphosphacyclohexanes, both
stereoisomers acted only as bridging ligands to
form oligonuclear complexes with Pt(II) dichlo-
ride because of the high-sterical strain of four-
membered chelate complexes and the rigidity of
six-membered cycle [15]. Since the most com-
plete isomer’s separation was provided in the case
of 1,3,5-azadiphosphacycloheptane 4, the complex-
ation reactions of its both stereoisomers were
studied. The reaction of meso-isomer of 4 with
(cyclooctadiene)platinum(II) dichloride in DMF led
to the formation of two types of complexes. The
31P NMR spectrum of the reaction mixture showed
two peaks at δP 37.5 and 42.4 ppm with the ra-
tio 1:1 and indicated the formation of two differ-
ent metal complexes. The unusually high-downfield
shifts of both signals in comparison with the sig-
nal of ligand (ꢀδ = 64.2 and ꢀδ = 69.1 ppm, re-
spectively) indicated that both complexes formed
chelate five-membered cycles. The corresponding
In the case of the isolated stereoisomer of N-
benzyl substituted compound 5, the proton spec-
trum picture of P CH2 N fragments in the region
of 3–4 ppm looks slightly different from those ones
of both stereoisomers of the compounds 2–4: the sig-
2
nals are broad doublet (the coupling constants JHH
13.8 Hz and 2 JPH near 0 Hz) and the doublet of mul-
2
tiplets (the coupling constants JHH = 13.8 Hz and
pseudoconstants JPH 0–4 Hz). Since the values of the
coupling constants were closer to the corresponding
values of the rac-stereoisomers of the compounds
2–4, we concluded that the isolated compound was
1
coupling constants JPtP are strongly different (3342
Heteroatom Chemistry DOI 10.1002/hc

1,3,6-Azadiphosphacycloheptanes: A Novel Type of Heterocyclic Diphosphines 129
SCHEME 3
some cyclic oligomer, but the satisfactory solubil-
ity of the complex indicates that the cyclic struc-
ture is more probable. On keeping of the starting
ligand conformation, the geometrical parameters of
the subunits (namely the antiparallel electron pair’s
direction of the ligand and the turning angles of the
metal centers of about 90◦) make the formation of
tetranuclear macrocyclic complex 8 the most proba-
ble [30]; however, one cannot exclude the formation
of other oligomers (Scheme 3).
The results obtained show that the condensation
of 1,2-bis[(hydroxymethyl)aryl-phosphino]ethanes
with primary amines may be considered as a
general and convenient method of the synthe-
sis of a novel type of cyclic diphosphines—1,3,6-
azadiphosphacycloheptanes, which are formed as
the mixtures of meso- and rac-stereoisomers. These
stereoisomeric mixtures may be separated, and the
different stereoisomers act as different types of lig-
ands: the meso-isomers are chelating P,P-ligands,
and the rac-isomers are bridging ones to form
oligonuclear metal complexes.
SCHEME 2
and 2195.4 Hz) perhaps due to the formation of cis-
LPtCl2 and [L2Pt]2+·2Cl− structures 6 and 7 (Scheme
2). A low-field peak of the complex 7 disappears
in the 31P NMR spectrum of the reaction mixture,
when treating the crude product with the excess
of (cyclooctadiene)platinum(II) dichloride in DMF
at 70◦C. The crystallization of the product from
DMSO led to the isolation of individual complex 6
with metal–ligand ratio 1:1. Its 31P NMR spectrum
showed only the upfield peak at δP 37.5 with coupling
1
constant JPtP 3342 Hz, which was typical for cis-
chelate P,P-complexes of cyclic aminomethylphos-
phines. The proton signals of P CH2 N fragments
are two broad doublets with coupling constant JPH
2
near 0 Hz, which correspond to torsion angles
Pt P C H values of 70◦–80◦. These data give the ev-
idence that the compound 6 is typical mononuclear
cis-P,P-chelate complex. So, on the contrary to 1,3,5-
azadiphosphacyclohexanes, the meso-isomers of
1,3,6-azadiphosphacyclooctanes are chelating P,P-
ligands. It should be mentioned that the formation
of chelate complexes 6 and 7 additionally confirmed
the structure attribution of the stereoisomers.
The interaction of rac-isomer of 4 with (cyclooc-
tadiene)platinum(II) dichloride led to the formation
of the crystalline product with the metal–ligand ra-
tio 1:1. One very broad peak at δP 1.2 ppm with the
EXPERIMENTAL
All manipulations involving 1,2–bis(phenylphos-
phino)ethane and 1,2-bis[(hydroxymethyl)phenyl-
phosphino]ethane were carried out under an inert
atmosphere. NMR-spectra: MSL-400 (Bruker), stan-
dards: 31P NMR (161 MHz): external 85% H3PO4; 1H
MNR (400 MHz): internal solvent; 13C NMR (100.6
1
1
coupling constant JPtP 3519 Hz was observed in its
MHz); WM-250 (Bruker): H NMR (250 MHz): in-
31P NMR spectrum. The relatively low complexation
shift of the signal in the comparison with the lig-
and’s signal (ꢀδ 27 ppm) and the typical coupling
constant value for cis-nonchelate P,P-complexes of
aminomethylphosphines [29] proves the formation
of the oligomeric polynuclear complexes with the
bridging P,P-ligands. The absence of the signals
of uncomplexed three-coordinated terminal phos-
phorus atoms may correspond to the formation of
both linear oligomers of high-molecular weights and
ternal solvent; CXP-100: 31P NMR (36.47 MHz): ex-
ternal 85% H3PO4. The IR spectra were recorded as
Nujol mulls on a Specord M-80 spectrometer in the
range 400–4000 cm−1. The EI mass spectra were ob-
tained on a TRACE MS “Finnigan MAT” spectrom-
eter (electron energy 70 eV, ion source temperature
200◦C, the direct injection system). The treatment of
mass spectral data was carried out with the use of
“Xcalibur” program. The melting points were done
on a Boetius apparatus and are uncorrected.
Heteroatom Chemistry DOI 10.1002/hc

130 Karasik et al.
Crystal Data
Synthesis
1,2-Bis(phenylphosphino)ethane. The solution
The X-ray data for crystals 3 and 4 were collected
on a CAD-4 Enraf–Nonius automatic diffractometer
at 20◦C. The stability of crystal and of experimental
conditions was checked every 2 h using three control
reflections, whereas the orientation was monitored
every 200 reflections by centering two standards.
Decay corrections were not necessary. Corrections
for Lorentz and polarization effects were applied.
Twenty five centered reflections were used to deter-
mine unit cell dimensions.
of 1,2-bis[(isopropyloxy)phenyl-phosphoryl]ethane
[35] (31 g, 0.07 mol) in dry ether (200 mL) was added
dropwise with the vigorous stirring to the suspen-
sion of lithium aluminum hydride (5.9 g, 0.15 mol)
in dry ether (150 mL) at 0◦C. The reaction mixture
was then heated under reflux with vigorous stirring
for 4 h, cooled to the ambient temperature, and 15%
aqueous hydrochloric acid (70 mL) was added drop-
wise up to pH 2. The organic layer was separated,
the aqueous layer was extracted by ether (100 mL),
and the combined organic extracts were dried with
sodium sulfate for 3 days. The solvent was removed
in vacuum; the residue was distilled to give 8.5 g
(44%) of 1,2-bis(phenylphosphino)ethane [25] with
Crystals 3: C23H25NP2, M 377.38, F(000) 800,
˚
monoclinic, a 10.577(1), b 14.212(4), c 14.685(3) A,
◦
3
β 110.100(5) , V 2073.0(14) A , dcalc 1.21 g cm−3, Z
4, space group P21/a. A total of 4192 unique reflec-
tions were measured in the range 2◦ ≤ θ ≤ 26◦ using
graphite monochromated λ Mo Kα radiation and
ω/2θ scan mode, of which 1667 were with I > 2σ.
Empirical absorption correction was not applied
(µ Mo 2.16 cm−1).
˚
1
the boiling point 160◦C/0.05 mm. H NMR (CDCl3):
1.86–2.2 (m, 4H, CH2), 3.95 (d, 1 JPH = 209.7 Hz, 2H,
PH), 7.19–7.45 (m, 10H, C6H5). 31P NMR (CDCl3):
−46.91 (1 JPH = 209.7 Hz), −47.10 (1 JPH = 209.7 Hz).
Crystals 4: C27H30N2O5P2, M 524.47, F(000)
1104, monoclinic, a 9.919(4), b 10.691(7), c 24.65(2)
1,2-Bis[(hydroxymethyl)phenylphosphino]ethane
(1). Solid paraformaldehyde (0.24 g, 8.1 mmol)
was added to 1,2-bis(phenylphosphino)ethane (1 g,
4.1 mmol), and the reaction mixture was heated at
90◦C until the mixture became homogeneous. The
◦
3
A, β 96.24(6) , V 2599(3) A , dcalc 1.34 g cm−3, Z 4,
space group P21/c. A total of 5050 unique reflec-
tions were measured in the range 2◦ ≤ θ ≤ 26◦ using
graphite monochromated λ Mo Kα radiation and
ω/2θ scan mode, of which 2098 were with I > 2σ.
Empirical absorption correction was not applied
(µ Mo 2.08 cm−1).
˚
˚
1
yield of 1 was 1.24 g (100%). 31P{ H} NMR (C6D6):
–18.1, –19.43.
The structure was solved by the direct method
using the SIR [31] program and refined by the full
matrix least-squares using SHELXL97 [32] program.
All non-hydrogen atoms were refined anisotropi-
cally. The hydrogen atoms were included in calcu-
lated position with thermal parameters 30% larger
than atom to which they attached. The final agree-
ment factors are R 0.058, Rw 0.115 based on 4192
reflections with F2 > 3σ for crystal 3 and R 0.098,
Rw 0.252 based on 5050 reflections with F2 > 3σ
for crystal 4. All calculations were performed on
PC using WinGX [33] program. Cell parameters,
data collection, and data reduction were performed
on Alpha Station 200 computer using MoLEN [34]
program.
CCDC no. 622121 and 622122 contains
the supplementary crystallographic data (exclud-
ing structure factors) for this paper. These
data can be obtained free of charge via
www.ccdc.cam.ac.uk/conts/retrieving.html (or from
the Cambridge Crystallographic Data Centre, 12
Union Road, Cambridge CB2 1 EZ, UK; fax: +44-
1223 336033 or deposit@ccdc.cam.ac.uk).
General Procedure for the Synthesis of (2)–(5)
The solution of 1 (3.0 mmol) and the corresponding
primary amine (3.0 mmol) in ethanol (10–30 mL)
was stirred at 80◦C for 2–4 h and cooled to the am-
bient temperature. In the case of compound 2, the
solvent was partially removed in vacuum, in the case
of compound 3 the reaction mixture was allowed
to stand for 2 days at 0◦C for the crystallization.
The precipitate formed was filtered off, washed by
ethanol, and dried at 0.1 Torr for 2–4 h.
1,3,6-Triphenyl-1-aza-3,6-diphosphacycloheptane
(2). Recrystallized from ethanol. Yield 0.32 g, 29%;
mp 80–82◦C. 1H NMR (C6D6): 1.91–2.13 (m, 4H
2
+ 4H, P CH2, meso + rac), 3.26 (dd, JHH = 14.7
2
Hz, JPH = 5.4 Hz, 2H, P CHA2 N, meso), 3.85 (dd,
2
2 JHH = 13.7 Hz, JPH = 11.2 Hz, 2H, P CHA2 N,
2
2
rac), 4.09 (dm, JHH = 13.7 Hz, JPH ≈ 5.0 Hz, 2H,
P CHB2 N, rac), 4.17 (dd, 2 JHH = 14.7 Hz, 2 JPH = 24.9
Hz, 2H, P CHB2 N, meso), 6.69–6.95 (m, 3H +3H,
o-H + p-H in NC6H5, meso + rac), 7.00–7.45 (m,
12H + 12H, PC6H5 + m-H in NC6H5, meso + rac).
Heteroatom Chemistry DOI 10.1002/hc

1,3,6-Azadiphosphacycloheptanes: A Novel Type of Heterocyclic Diphosphines 131
1
31P{ H} NMR (C6D6): –25.8 (meso), –26.6 (rac). IR (ν˜
(cm−1), Nujol): 1593 (aryl), 3050 (aryl). Anal. Calcd
for C22H23NP2 [363]: C, 72.70; H, 6.33; N, 3.85; P,
17.07. Found: C, 72.93; H, 6.57; N, 3.65; P 16.65.
63.86; H, 5.10; N, 3.10; P, 13.75. Found: C, 63.28; H,
4.7; N, 3.00; P, 13.18.
The concentration of the filtrate after the re-
crystallization of 4 gave precipitate, which was fil-
tered off, washed with ethanol, and dried at 0.1 Torr
for 3 h. The precipitate was the mixture of meso-4
(80%) and rac-4 (20%). Yield 0.31 g (21%). Spectral
1-p-Tolyl-3,6-diphenyl-1-aza-3,6-diphosphacyclo-
heptane (3). Recrystallized from ethanol: acetone
(20:1). Yield 0.30 g, 27%; mp 80–84◦C. 1H NMR
(CDCl3): 2.24 (s, 3H, CH3, meso), 2.28 (s, 3H, CH3,
rac), 2.36–2.51 (m, 4H + 4H, P CH2, meso +
1
data for meso-4: H NMR (DMF-d7): 2.11–2.25 (m,
2H, P CHA2 ), 2.44–2.66 (m, 2H, P CHB2 ), 4.11 (dd,
2
2 JHH = 14.9 Hz, JPH = 5.3 Hz, 2H, P CHA2 N), 4.49
(dd, 2 JHH = 14.9 Hz, 2 JPH = 21.95 Hz, 2H, P CHB2 N),
7.39–7.55 (m, 6H, o-H + p-H in C6H5), 7.60–7.65
(m, 6H, m-H in C6H5+ o-H in C6H3), 8.01 (s, 1H,
p-H in C6H3). 1H NMR (D2O): 1.54 (m, 2H, P CHA2 ),
1.75 (m, 2H, P CH2B), 2.85–3.05 (m, 2H, P CHA2 N),
3.88–4.07 (m, 2H, P CHB2 N), 6.80–7.70 (m, 13H,
2
2
rac), 3.63 (dd, JHH = 15.04 Hz, JPH = 5.6 Hz, 2H,
P CHA2 N, meso), 3.93 (dd, 2 JHH = 13.8 Hz, 2 JPH = 9.9
Hz, 2H, P CHA2 N, rac), 4.20 (m, JHH = 13.8 Hz,
2
2H, P CHB2 N, rac), 4.34 (dd, JHH = 15.04 Hz,
2
2 JPH = 24.0 Hz, 2H, P CHB2 N, meso), 6.72 (d,
3 JHH = 8.6 Hz, 2H, o-C6H4, rac), 6.93 (d, JHH = 8.6
3
1
Ar). 13C{ H} NMR (DMF-d7): 18.74 (s, P CH2), 57.22
3
Hz, 2H, o-C6H4, meso), 7.00 (d, JHH = 8.6 Hz, 2H,
(br s, P CH2 N), 118.24 (s, o-C in C6H3), 118.91
(s, p-C in C6H3), 129.06 (s, p-C in C6H5), 129.28 (d,
3
m-C6H4, rac), 7.11 (d, JHH = 8.6 Hz, 2H, m-C6H4,
meso), 7.26–7.60 (m, 10H + 10H, C6H5, meso + rac).
2
3 JPC = 2.44 Hz, m-C in C6H5), 132.07 (d, JPC = 17.10
1
31P{ H} NMR (CDCl3): −25.3 (meso), −26.2 (rac).
Hz, o-C in C6H5), 132.97 (s, m-C in C6H3), 138.0 (d,
1 JPC = 15.3 Hz, i-C in C6H5), 147.53 (s, i-C in C6H3),
IR (ν˜ (cm−1), Nujol): 1612 (aryl), 3060 (aryl). Anal.
Calcd for C23H25NP2 [377]: C, 73.21; H, 6.63; N, 3.71;
P 16.44. Found: C, 72.83; H, 6.19; N, 3.50; P, 16.02.
1
167.95 (s, COOH). 31P{ H} NMR (DMF-d7): −26.7.
1
31P{ H} NMR (D2O): –27.34.
1-(3ꢀ,5ꢀ-Dicarboxyphenyl)-3,6-diphenyl-1-aza-3,6-
1-Benzyl-3,6-diphenyl-1-aza-3,6-diphosphacyclo-
heptane (5). Yield of rac-5 0.45 g, 39%; mp 86–88◦C.
1H NMR (CDCl3): 2.25–2.51 (m, 4H, P CH2), 3.25
diphosphacycloheptane (4). Yield 0.98 g, 67%.
1
31P{ H} NMR (CDCl3): −25.7 (rac), −26.7 (meso),
2
2
the intensity ratio 1:1. IR (ν˜ (cm−1), Nujol): 1598
(aryl), 1696 (CO), 3060 (aryl), 3312 br (OH).
(br d, JHH = 13.8 Hz, JPH ≈ 0 Hz, 2H, P CHA2 N),
2
3.81 (m, JHH = 13.8 Hz, 2H, P CHB2 N), 3.95
2
The crude 4 was recrystallized from the DMF–
acetone mixture (1:1), washed with ethanol and
dried at 0.1 Torr for 3 h to give 0.35 g (24%) of
stereoisomerically pure rac-4, mp 232–236◦C. 1H
NMR (DMF-d7): 2.44–2.64 (m, 4H, P CH2), 4.10 (dd,
(m, JHH = 12.9 Hz, Ph CH2 N), 7.22–7.46 (m,
1
15H, C6H5). 31P NMR { H} (CDCl3): −33.5. IR
(ν˜ (cm−1), Nujol): 1588 (aryl), 3060 (aryl). MS EI
(m/z): 377.2 (23) [M]+, 349.2 (25) [M C2H4]+, 286.2
(35)) [M CH2Ph]+, 258.2 (30) [M CH2NCH2Ph]+,
230.2 (32) [M C2H4 CH2NCH2Ph]+, 133.2 (62)
[M–PhPCH2CH2PPh]+, 108.2 (38) [PhP]+, 91.1 (100)
[PhCH2]+. Anal. Calcd for C23H25NP2 [377]: C, 73.21;
H, 6.63; N, 3.71; P 16.44. Found: C, 72.77; H, 6.27;
N, 3.56; P 16.00.
2
2 JHH = 13.8 Hz, JPH = 10.2 Hz, 2H, P CHA2 N), 4.30
2
(m, JHH = 13.8 Hz, 2H, P CHB2 N), 7.40–7.55 (m,
6H, o-H + p-H in C6H5), 7.60–7.75 (m, 6H, m-H
in C6H5 + o-H in C6H3), 8.02 (s, 1H, s, 1H, p-H in
C6H3). 1H NMR (D2O): 1.65–2.0 (m, 4H, P CH2),
3.61–3.70 (m, 2H, P CHA2 N), 3.76 (d, J = 12.4 Hz,
2H, P CHB2 N), 7.01–7.60 (m, 12H, C6H5 + o-H
The concentration of the filtrate of the reaction
mixture gave the mixture of rac-5 and meso-5 in the
in C6H3), 8.34 (s, 1H, p-H in C6H3). 13C{ H} NMR
ratio 5:1. Spectral data for meso-5: 31P NMR { H}
1
1
1
3
(DMF-d7): 25.14 (dd, JPC = 15.3 Hz, JPC = 15.0 Hz,
P CH2), 53.98 (d, 1 JPC = 15.3 Hz, P CH2 N), 118.37
(s, o-C in C6H3), 119.39 (s, p-C in C6H3), 129.36 (d,
3 JPC = 6.54 Hz, m-C in C6H5), 129.64 (s, p-C in C6H5),
(CDCl3): −31.8.
cis-(RS)-[P,P-1-(3ꢀ,5ꢀ -Dicarboxyphenyl)-3,6-di-
phenyl-1-aza-3,6-diphosphacycloheptane]-platinum
(II) Dichloride (6). The solution of (cyclooctadi-
ene)platinum(II) dichloride (0.13 g, 0.3 mmol) in
DMF (10 mL) was added dropwise to the solution
of meso-4 (0.17 g, 0.3 mmol, contained about 20%
2
132.46 (d, JPC = 18.53 Hz, o-C in C6H5), 132.92 (s,
1
m-C in C6H3), 138.08 (d, JPC = 15.3 Hz, i−C in
C6H5), 150.20 (s, i-C in C6H3), 167.81 (s, COOH).
1
31P{ H} NMR (DMF-d7): −25.7. 31P NMR (D2O): δp
−27.14. MS EI (m/z): 451.2 (20) [M]+, 423.2 (22)
[M C2H4]+, 258.2 (40) [M CH2NC6H3(COOH)2]+,
230.2 (77) [M C2H4 CH2NC6H3(COOH)2]+, 108.2
(85) [PhP]+. Anal. Calcd for C24H23NO4P2 [451]: C,
of rac-4) in DMF (5 mL).31P{ H} NMR (DMF): δp
1
37.51 (1 JPtP = 3342.2 Hz), 42.46 (1 JPtP = 2195 Hz),
the intensity ratio 1:1. (Cyclooctadiene)platinum(II)
dichloride (0.02 g, 0.05 mmol) was added to the
Heteroatom Chemistry DOI 10.1002/hc

132 Karasik et al.
reaction mixture, and it was stirred at 70◦C for
10 h and cooled. The precipitate formed was
filtered off and recrystallized from DMSO to give
individual 6. Yield 0.05 g (28%), mp >260◦C. 1H
NMR (DMSO-d6): 2.50 (m, 4H, P CH2), 4.15 (d,
[8] Ma¨rkl, G.; Jin, G. Yu.; Scho¨rner, Ch. Tetrahedron Lett
1980, 21, 1409–1412.
[9] Bobrov, S. V.; Karasik, A. A.; Sinyashin, O. G. Phos-
phorus, Sulfur, Silicon 1999, 144–146, 289–292.
[10] Arbuzov, B. A.; Nikonov, G. N. Adv Heterocycl Chem
1994, 61, 59–140 and references therein.
[11] Karasik, A. A.; Georgiev, I. O.; Musina, E. I.; Heinicke,
J.; Sinyashin, O. G. Polyhedron 2001, 20, 3321–3331.
[12] Karasik, A. A; Naumov, R. N.; Sinyashin, O. G.; Belov,
G. P.; Novikova, H. V.; Lo¨nnecke, P.; Hey-Hawkins,
E. Dalton Trans 2003, 2209–2214.
[13] Karasik, A. A.; Naumov, R. N.; Sommer, R.;
Sinyashin, O. G.; Hey-Hawkins, E. Polyhedron 2002,
21, 2251–2256.
2
2 JHH = 14.9 Hz, 2H, P CH2A N), 4.80 (d, JHH = 14.9
1
Hz, 2H, P CHB2 N), 7.59–8.02 (m, 13H, Ar). 31P{ H}
NMR (DMSO-d6): 37.51 (1 JPtP = 3342.2 Hz). Anal.
Calcd for C24H23Cl2NP2PtO4 [717]: C, 40.17; H, 3.21;
N, 1.95; P, 8.64. Found: C, 39.32; H, 2.97; N, 1.72; P
8.03.
[14] Kane, J. C.; Wong, E. H.; Yap, G. P. A.; Rheingold,
A. L. Polyhedron 1999, 18, 1183–1188.
[15] Karasik, A. A.; Bobrov, S. V.; Akhmetzyanov, A. I.;
Naumov, R. N.; Nikonov, G. N.; Sinyashin, O. G.
Koordinatzionnaya Khim 1998, 24, 530–535.
[16] Issleib, K.; Oehhme, H.; Mohr, K. Z Chem 1973, 19,
139–141.
[17] Ma¨rkl, G.; Jin, G. Yu. Tetrahedron Lett 1981, 22,
3467–3470.
[18] Arbuzov, B. A.; Erastov, O. A.; Romanova, I. P.;
Efremov, Yu. Ya.; Musin, R. Z. Izv Akad Nauk SSSR,
Ser Khim 1982, 440–443.
The Interaction of rac-4 with (Cyclooctadi-
ene)platinum(II) Dichloride. The solution of (cy-
clooctadiene)platinum(II) dichloride (0.14 g, 0.3
mmol) in DMF (10 mL) was added dropwise to the
solution of rac-4 (0.17 g, 0.3 mmol) in DMF (5 mL).
The precipitate formed was filtered off and washed
1
by ethanol. Yield 0.13 g (48.1%), mp >260◦. 31P{ H}
NMR (DMF): 1.26 (br s, 1 JPtP ≈ 3519 Hz). Anal. Calcd
for [C24H23Cl2NP2PtO4]n [717]: C, 40.17; H, 3.21; N,
1.95; P, 8.64. Found: C, 39.46; H, 2.88; N, 1.78; P,
8.12.
[19] Berning, D. E.; Katti, K.; Barnes, C. L.; Volkert, W. A.
J Am Chem Soc 1999, 121, 1658–1664.
[20] Karasik, A. A.; Nikonov, G. N.; Dokuchaev, A. S.;
Litvinov, I. A. Russ J Coord Chem 1994, 20, 300–303.
[21] Karasik, A. A.; Krashilina, A. V.; Gubaidullin, A. T.;
Litvinov, I. A.; Cherkasov, V. K.; Sinyashin, O. G.;
Abakumov, G. A. Russ Chem Bull 2000, 49, 1782–
1788.
[22] Karasik, A. A.; Bobrov, S. V.; Nikonov, G. N.;
Pisarevskii, A. P.; Litvinov, I. A.; Dokuchaev, A. S.;
Struchkov, Yu. T.; Enikeev, K. M. Russ J Coord Chem
1995, 21, 574–584.
REFERENCES
[1] (a) Beller, M.; Kumar, K. In Transition Metals for
Organic Synthesis; Beller, M.; Bolm, C.; (Eds); Wiley-
VCH: Berlin, 2004; Vol. 1, Ch. 2.1, pp. 29–55; (b) Au-
Yeung, T. T.-L.; Chan, S.-S.; Chan, A. S. C. In Transi-
tion Metals for Organic Synthesis; Beller, M.; Bolm,
C.; (Eds); Wiley-VCH: Berlin, 2004; Vol. 2, Ch. 1.1.2,
pp. 14–27; (c) Ohkuma, T.; Noyori, R. In Transition
Metals for Organic Synthesis; Beller, M.; Bolm, C.;
(Eds); Wiley-VCH: Berlin, 2004; Vol. 2, Ch. 1.1.3, pp.
29–113.
[2] (a) Stelzer, O.; Rossenbach, S.; Hoff, D. In
Aqueous-Phase Organometallic Catalysis; Cornils, B.;
Herrmann, W. A. (Eds).; VCH: Berlin, 2004; Ch. 3.2.1,
pp. 100–120; (b) Goedheijt, M. S.; Kamer, P. C.,
Reek, N. H.; van Leeuwen, P. W. N. M. In Aqueous-
Phase Organometallic Catalysis; Cornils, B.; Her-
rmann, W. A. (Eds).; VCH: Berlin, 2004; Ch. 3.2.2,
pp. 121–136.
[23] Khairullina, R. Z.; Karasik, A. A.; Musakova, E. Yu.
Neftekhimiya, 1994, 34, 332 – 335.
[24] Novikova, E. V.; Karasik, A. A.; Hey-Hawkins, E.;
Belov, G. P. Russ J Coord Chem 2005, 31, 280–288.
[25] Butler, I. R.; Licence, P.; Coles, S. J.; Hursthouse,
M. B. J Organomet Chem 2000, 598, 103–107.
[26] Henderickson, J. B. J Am Chem Soc 1964, 86, 4854–
4866.
[27] Henderickson, J. B. J Am Chem Soc 1967, 89, 7036–
7043.
[28] Samitov, Yu. Yu. Atlas spektrov YaMR prostranstven-
nyh izomerov; Izd. Kazanskogo Universita: Kazan,
Russian Federation, 1978; pp. 8–24.
[3] Mathey, F. In Phosphorus-Carbon Heterocyclic
Chemistry: The Rise of a New Domain; Mathey,
F.; (Ed); Pergamon: London, 2001; Ch. 1,
pp. 1–15.
[29] Alt, H. G.; Baumgartner, R. R.; Brune, H. A. Chem
Ber 1986, 119, 1694–1703.
[4] Hackney, M. L. J.; Schubert, D. M.; Brandt, P. F.;
Haltiwanger, R. C.; Norman, A. D. Inorg Chem 1997,
36, 1867–1872.
[5] Pabel, M.; Wild, S. B. In Phosphorus-Carbon Hetero-
cyclic Chemistry: The Rise of a New Domain; Mathey,
F. (ed); Pergamon: London, 2001; Ch. 6.1, pp. 631–
669.
[30] Swiegers, G. F.; Malefeste, T. J. Coord Chem Rev
2002, 225, 91–121.
[31] Altomare, A.; Cascarano, G.; Giacovazzo, C.; Viterbo,
D. Acta Crystallogr Sec A 1991, 47, 744–748.
[32] Sheldrick, G. M. SHELXL97: A Computer Program
for Crystal Structure Determination; University of
Gottingen: Gottingen, Germany, 1997.
[6] Toto, S. D.; Arbuckle, B. W.; Bharadwaj, P. K.; Doi,
J. T.; Musker, W. K. Phosphorus, Sulfur, Silicon, Re-
lat Elem 1991, 56, 27–38.
[7] Arbuckle, B. W.; Musker, W. K. Polyhedron 1991, 10,
415–419.
[33] Farrugia, L. J. J Appl Cryst 1999, 32, 837–838.
[34] Straver, L. H.; Schierbeek, A. J. MolEN Structure
Determination System, Program Description, Vol. 1;
Nonius B.V., Delft, 1994; p. 180.
[35] Mastalerz, P. Roczniki Chem 1965, 39, 33–37.
Heteroatom Chemistry DOI 10.1002/hc