Novel chiral 1,5-diaza-3,7-diphosphacyclooctane ligands and their transition metal complexes

Article abstract of DOI:10.1039/b300754e

Reaction of bis(hydroxymethyl)phenylphosphine with (R)- or (S)-α-methylbenzylamine leads to the novel cyclic chiral bisphosphine ligands 1,5-(R,R)- and 1,5-(S,S)-bis(α-methylbenzyl)-3,7-diphenyl-1,5- diaza-3,7-diphosphacyclooctane (1r or 1s). Novel chiral chelate complexes of Pt^II (2r, 3r and 3s), Pd^II (4s, 5s) and Re^I (6r) have been obtained by reaction of 1r or 1s with [MCl₂(cod)] (M = Pt, Pd; cod = 1,5-cyclooctadiene) and [{ReBr(CO)₃(thf )} ₂]. Compounds 1-6 were characterised by multinuclear NMR ( ¹H, ¹³C, ³¹P) and IR spcctroscopy. The former technique revealed the presence of two inequivalent phosphorus atoms in 6r. The molecular structure of 1r confirmed the absolute configuration of the chiral centers and a chair-chair conformation of the heterocycle with equatorial orientation of the substituents on phosphorus and axial on nitrogen atoms. Compound Is was used to form a palladium catalyst for the co-polymerisation of carbon monoxide and norbornadiene. The structures of the co-polymers obtained were characterised by GPC, ¹H and ¹³C NMR spectroscopy and elemental analysis. The Royal Society of Chemistry 2003.

Full text of DOI:10.1039/b300754e

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Novel chiral 1,5-diaza-3,7-diphosphacyclooctane ligands and their
transition metal complexes
Andrey A. Karasik,*a Roman N. Naumov,a Oleg G. Sinyashin,a Gennadii P. Belov,c
Helena V. Novikova,c Peter Lönneckeb and Evamarie Hey-Hawkins*b
a A. E. Arbuzov Institute of Organic and Physical Chemistry, Russian Academy of Sciences,
Kazan Scientific Center, Arbuzov str. 8, Kazan, Russian Federation, 420088.
E-mail: karasik@iopc.knc.ru; Fax: (007)8432752253; Tel: (007)8432752392
b Institut für Anorganische Chemie der Universität Leipzig, Johannisallee 29, D-04103 Leipzig,
Germany. E-mail: hey@rz.uni-leipzig.de; Fax: (0049)3419739319; Tel: (0049)3419736151
c Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka,
Moscow Region, Institutsky Str. 18, Russian Federation, 142432.
E-mail: gbelov@cat.icp.ac.ru; Fax: (007)0965155420; Tel: (007)0965222642
Received 20th January 2003, Accepted 28th March 2003
First published as an Advance Article on the web 16th April 2003
Reaction of bis(hydroxymethyl)phenylphosphine with (R)- or (S)-α-methylbenzylamine leads to the novel
cyclic chiral bisphosphine ligands 1,5-(R,R)- and 1,5-(S,S)-bis(α-methylbenzyl)-3,7-diphenyl-1,5-diaza-3,7-
diphosphacyclooctane (1r or 1s). Novel chiral chelate complexes of PtII (2r, 3r and 3s), PdII (4s, 5s) and ReI (6r)
have been obtained by reaction of 1r or 1s with [MCl2(cod)] (M = Pt, Pd; cod = 1,5-cyclooctadiene) and
[{ReBr(CO)3(thf )}2]. Compounds 1–6 were characterised by multinuclear NMR (1H, 13C, 31P) and IR spectroscopy.
The former technique revealed the presence of two inequivalent phosphorus atoms in 6r. The molecular structure
of 1r confirmed the absolute configuration of the chiral centers and a chair-chair conformation of the heterocycle
with equatorial orientation of the substituents on phosphorus and axial on nitrogen atoms. Compound 1s was
used to form a palladium catalyst for the co-polymerisation of carbon monoxide and norbornadiene. The structures
of the co-polymers obtained were characterised by GPC, 1H and 13C NMR spectroscopy and elemental analysis.
Introduction
Experimental
Design of chiral ligands has been a central subject in the
development of catalytic and stoichiometric asymmetric
reactions. As tertiary phosphines are highly efficient ligands in
these reactions, syntheses of new chiral phosphines, especially
chelating phosphines, have received considerable attention.1–3
Mannich-type reactions of various phosphines, formalde-
hyde and optically active amines were demonstrated to be a
powerful method of constructing chiral, air-stable amino-
methylphosphines, which are promising ligands for the design
of enantioselective homogeneous catalysts.4–6 The main route
is the reaction of oxymethyldiphenylphosphines with chiral
primary amines to give a number of chelate ligands with P–
CH2N(R*)CH2–P bisphosphine fragments. Starting from the
work of Markl et al.7,8 and Tzschach and co-workers9,10 a wide
variety of chelate complexes of this type has been obtained,
including phosphines with cyclodextrin,11 dendrimer,12,13 amino
acid and peptide14 moieties. However changes in the steric
and/or electronic properties of the ligands are known to
dramatically influence the selectivity and the reactivity of
transition metal complexes. We are interested in preparing new
polydentate heterocyclic ligands and their transition metal
complexes, especially chiral ones.15–17 It has been shown that
1,5-diaza-3,7-diphosphacyclooctanes are air-stable crystalline
ligands that form predominantly chelate complexes with trans-
ition metals. A distinguishing feature of these complexes is a
chair-boat conformation of the metal-containing bicyclo-
[3.3.1]nonane backbone with one nitrogen atom situated near
the metal atom.18–20 Attempts to prepare optically active
1,5-diaza-3,7-diphosphacyclooctanes from amino acids failed;
instead, 1,3-diaza-5-phosphorinanes were formed.21–23 Here we
describe the novel cyclic chiral bisphosphine ligands 1,5-(R,R)-
and 1,5-(S,S)-bis(α-methylbenzyl)-3,7-diphenyl-1,5-diaza-3,7-
diphosphacyclooctane (1r and 1s) and novel chiral chelate
complexes of PtII (2r, 3r and 3s), PdII (4s, 5s) and ReI (6r).
General
All manipulations were carried out with standard high-vacuum
and dry-nitrogen techniques. Norbornadiene was purchased
from Aldrich, and CO was 99.5% pure. NMR spectra: Avance
DRX 400 (Bruker), standards: 1H NMR (400 MHz): C6H6, 13
C
NMR (100.6 MHz): internal solvent, 31P NMR (162 MHz):
external 85% H3PO4; CXP-200 (Bruker): 1H NMR (200 MHz),
13C NMR (50.4 MHz). The IR spectra were recorded as KBr
mulls on a Perkin-Elmer System 2000 FT-IR spectrometer
in the range 350–4000 cmϪ1 and on an IFS-113v FT-IR
spectrometer in the range 100–450 cmϪ1. The melting points
were determined in sealed capillaries and are uncorrected.
Specific rotation was determined on a Perkin Elmer Model 341
Polarimeter at 589 nm.
Molecular weights and molecular weight distributions of
co-polymers in tetrahydrofuran were measured relative to
polystyrene standards by a Waters GPC instrument at 25 ЊC.
X-Ray crystallography
X-ray diffraction data were collected on a Siemens SMART
CCD diffractometer (radiation: Mo-Kα, λ = 0.71073 Å; method:
ω scans rotation). Absorption correction was performed using
the program SADABS.24 1200 reflections were used for refine-
ment of the unit cell. The structure was solved by direct
methods, and all non-hydrogen atoms were refined aniso-
tropically (SHELX97).25 H atoms were refined isotropically.
The phenyl protons were calculated on idealised positions.
Crystal data, structure refinement for compound 1r, selected
bond lengths (Å) and angles (Њ) for the conformers 1rЈ and 1rЉ
are given in Tables 1 and 2.
CCDC reference number 200855.
See http://www.rsc.org/suppdata/dt/b3/b300754e/ for crystal-
lographic data in CIF or other electronic format.
T h i s j o u r n a l i s © T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 3
D a l t o n T r a n s . , 2 0 0 3 , 2 2 0 9 – 2 2 1 4
2209

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Table 1 Crystal data and structure refinement for compound 1r
Compound 1s was prepared similarly to 1r from (S)-α-meth-
ylbenzylamine. Yield: 75%; α = Ϫ44 for 1s (c = 0.19, CHCl3).
Formula
C32H36N2P2
510.57
Monoclinic
C2
Formula weight
Crystal system
Space group
Unit cell dimensions
a/Å
b/Å
c/Å
Bis[1,5-(R,R)-bis(ꢀ-methylbenzyl)-3,7-diphenyl-1,5-diaza-
3,7-diphosphacyclooctane]platinum(II) dichloride (3r). [PtCl2-
(cod)] (0.43 g, 1.2 mmol) in 20 mL of CH2Cl2 was added to a
solution of 1r (1.18 g, 2.3 mmol) in 10 mL of CH2Cl2. The next
day the solvent was removed in vacuum, 3r was crystallised
from chloroform and white crystals were collected by filtration,
washed with chloroform and dried under vacuum. Yield: 1.35 g,
23.052(12)
5.472(3)
22.567(12)
100.552(10)
2.80(1)
4
223(2)
0.71073
1.212
0.179
0.20 × 0.10 × 0.05
0.92–26.37
1088
Ϫ21 to 28, Ϫ6 to 6, Ϫ28 to 27
8210
5349 (0.0678)
99.4
β/Њ
V/nm3
1
3
Z
91%, mp 192–194 ЊC. H NMR (CDCl3): δ 1.58 (d, JHH = 6.8
Hz, 6H, CH3), 3.40–3.45 (br m, 2JHH = 13.2 Hz, 4H, PCHA2N),
Temperature/K
Wavelength/Å
Dc/g cmϪ3
4.03–4.06 (br m, 2JHH = 13.2 Hz, 4H, PCHB N), 4.38 (br q, 3JHH
2
= 6.8 Hz, 2H, C*H), 7.07–7.54 (m, 20H, C6H5). 13C{1H} NMR
(DMF-d7): δ 15.20 (br s, CH3), 46.25 (br s, C1), 51.72 (br s, C2),
Absorption coefficient/mmϪ1
Crystal size/mm3
θ Range for data collection/Њ
F(000)
66.53 (t, JCP = 13.2 Hz, C*H), 128.21 (s, C10), 128.98 (s, C8),
3
129.21 (s, C9), 129.47 (br s, C5), 131.21 (br s, C6), 131.30 (br s,
C4) 141.08 (s, C7). C3 was not observed. 31P{1H} NMR
Index ranges, hkl
Reflections collected
Independent reflections (Rint
Completeness to θ = 26.37Њ (%)
Absorption correction
Max., min. transmission
Refinement method
(CH2Cl2): δ Ϫ12.5 (1JPtP = 2400 Hz); (DMF): δ Ϫ10.6 (1JPtP
=
)
2368 Hz). α = Ϫ35 for 3r (c = 0.07, DMF). Anal. Calc. for
C64H72Cl2N4P4Pt (M = 1286): C, 59.72; H, 5.60; N, 4.36; P, 9.64.
Found: C, 60.1; H, 5.3; N, 4.6; P, 9.6%.
Complex 2r was not obtained in the pure state, and was
characterised only in the reaction mixture by 31P NMR
spectroscopy.
SADABS
0.9911, 0.9652
Full-matrix least-squares on F 2
5349/1/367
Data/restraints/parameters
Goodness-of-fit on F 2
1.018
Final R indices [I > 2σ(I )]
R indices (all data)
R1 = 0.0718, wR2 = 0.1428
R1 = 0.1378, wR2 = 0.1758
Ϫ0.01(17)
Complex 3s was prepared similarly to 3r from 1s. Yield: 90%,
α = ϩ35 for 3s (c = 0.07, DMF).
Absolute structure parameter
Largest diff. peak, hole/e ÅϪ3
0.266, Ϫ0.240
[1,5-(S,S )-Bis(ꢀ-methylbenzyl)-3,7-diphenyl-1,5-diaza-3,7-
diphosphacyclooctane]dichloropalladium(II) (4s). [PdCl2(cod)]
(0.17 g, 0.6 mmol) in 20 mL of CH2Cl2 was added to a solution
of 1s (0.30 g, 0.6 mmol) in 10 mL of CH2Cl2. The next day the
solvent was removed in vacuum, 4s was crystallised from
chloroform and white crystals were collected by filtration,
washed with chloroform and dried under vacuum. Yield: 0.2 g,
Table 2 Selected bond lengths (Å) and angles (Њ) for conformers
1rЈand 1rЉ
1rЈ
1rЉ
P(1A)–C(1A)
P(1A)–C(2A)
P(1A)–C(3A)
N(1A)–C(2AЈ)
N(1A)–C(1A)
N(1A)–C(9A)
1.887(7) P(1B)–C(1B)
1.906(6) P(1B)–C(2B)
1.819(6) P(1B)–C(3B)
1.447(7) N(1B)–C(2BЈ)
1.450(7) N(1B)–C(1B)
1.467(8) N(1B)–C(9B)
1.915(6)
1.889(6)
1.838(5)
1.457(7)
1.461(7)
1.474(7)
1
3
50%, mp 144–146 ЊC. H NMR (CDCl3): δ 1.56 (d, JHH = 7.2
2
2
Hz, 6H, CH3), 3.28 (dd, JHH = 13.8 Hz, JPH = 6.7 Hz, 2H,
PCH1A2N), 3.38 (dd, JHH = 13.8 Hz, JPH = 7.2 Hz, 2H,
2
2
PCH2A2N), 3.77 (d, JHH = 13.8 Hz, 2H, PCH1B2N), 3.97 (d,
2
2JHH = 13.8 Hz, 2H, PCH2B2N), 4.78 (br s, 2H, C*H), 6.95–7.45
(m, 20H, C6H5). 13C{1H} NMR (DMF-d7): δ 16.73 (s, CH3),
C(3A)–P(1A)–C(1A)
C(3A)–P(1A)–C(2A)
C(1A)–P(1A)–C(2A)
C(2AЈ)–N(1A)–C(1A) 113.6(5) C(2BЈ)–N(1B)–C(9B)
C(2AЈ)–N(1A)–C(9A) 113.0(5) C(2BЈ)–N(1B)–C(1B)
C(1A)–N(1A)–C(9A)
N(1A)–C(1A)–P(1A)
N(1AЈ)–C(2A)–P(1A)
101.4(3) C(3B)–P(1B)–C(1B)
97.2(3) C(3B)–P(1B)–C(2B)
100.6(3) C(2B)–P(1B)–C(1B)
99.3(3)
102.1(3)
99.2(3)
111.7(5)
113.9(4)
118.2(5)
117.4(4)
116.0(4)
46.72 (d, JPC = 33.6 Hz, C1), 49.50 (d, JPC = 38.9 Hz, C2),
63.74 (br s, C*H), 127.50 (s, C10), 127.90 (d, 3JPC = 5.1 Hz, C5),
128.02 (s, C8), 128.39 (s, C9), 130.48 (s, C6), 132.04 (s, C4) 141.74
(s, C7). C3 was not observed. 31P{1H} NMR (CH2Cl2–DMF):
δ Ϫ6.9. α = ϩ34 for 4s (c = 0.03, CH2Cl2). Anal. Calc. for
C32H36Cl2N2P2Pd (M = 687): C, 55.90; H, 5.24; N, 4.08; P, 9.03.
Found: C, 55.7; H, 4.9; N, 4.2; P, 8.9%.
1
1
115.7(5) C(1B)–N(1B)–C(9B)
116.9(5) N(1B)–C(1B)–P(1B)
118.2(4) N(1BЈ)–C(2B)–P(1B)
Preparations
1,5-(R,R)-Bis(ꢀ-methylbenzyl)-3,7-diphenyl-1,5-diaza-3,7-
diphosphacyclooctane (1r). A solution of bis(hydroxymethyl)-
phenylphosphine (2.69 g, 16 mmol) and (R)-α-methylbenzyl-
amine (1.91 g, 16 mmol) in 40 mL of ethanol was refluxed for
6 h. White crystals were collected by filtration, washed with
ethanol and dried under vacuum. Yield: 3.28 g, 80%; mp 170–
172 ЊC. 1H NMR (CDCl3): δ 1.11 (d, 3JHH = 6.4 Hz, 6H, CH3),
Bis[1,5-(S,S )-bis(ꢀ-methylbenzyl)-3,7-diphenyl-1,5-diaza-3,7-
diphosphacyclooctane]palladium(II) dichloride (5s). [PdCl2(cod)]
(0.14 g, 0.5 mmol) in 20 mL of CH2Cl2 was added to a solution
of 1s (0.54 g, 1.1 mmol) in 10 mL of CH2Cl2. The next day the
solvent was removed in vacuum, 5s was crystallised from
chloroform, and white crystals were collected by filtration,
washed with chloroform and dried under vacuum. Yield: 0.56 g,
2
2
1
3.09 (br d, JHH = 14 Hz, 2H, PCH1A2N), 3.37 (br d, JHH = 14
88%, mp 157–159 ЊC. H NMR (DMF-d7): δ 1.58 (br s, 12H,
2
Hz, 2H, PCH1B2N), 3.53 (br d, JHH = 14 Hz, 2H, PCH2A2N),
CH3), 3.27 (br d, 2JHH = 12 Hz, 8H, PCHA2N), 3.95 (br d, 2JHH
=
3.73 (br d, 2JHH = 14 Hz, 2H, PCH2B2N), 4.54 (br q, 3JHH = 6.4
Hz, 2H, C*H), 7.04–7.33 (m, 20H, C6H5). 13C NMR (DMF-d7):
12 Hz, 8H, PCHB N), 4.39 (br q, 3JHH = 6 Hz, 4H, C*H), 7.11–
2
7.52 (m, 40H, C6H5). 13C NMR (DMF-d7): δ = 15.31 (q, 1JCH
=
1
1
1
δ 20.67 (d, JCH = 126.5 Hz, CH3), 57.35 (tt, JCH = 136.7 Hz,
1JCP ≈ 3JCP ≈ 9 Hz, C1), 61.14 (dt, 1JCH = 130.3 Hz, 3JCP ≈ 9 Hz,
126.0 Hz, CH3), 47.21 (br t, JCH = 147.3 Hz, C1), 50.99 (br t,
1JCH = 147.3 Hz, C2), 66.58 (dt, 1JCH = 138.3 Hz, 3JCP = 5.3 Hz,
C*H), 128.23 (d, 1JCH = 165.7 Hz, C10), 129.01 (d, 1JCH = 159.2
C*), 61.41 (tt, JCH = 134.6 Hz, JCP ≈ JCP ≈ 9 Hz, C2), 127.64
1
1
3
(d, 1JCH = 152.0 Hz, C10), 128.36 (d, 1JCH = 157.7 Hz, C6), 129.12
Hz, C8), 129.23 (d, JCH = 159.2 Hz, C9), 129.50 (br d, JCH
=
1
1
(m, JCH ≈ 160 Hz, C5,8,9), 133.28 (dd, JCH = 160.2 Hz, JCP
=
160.6 Hz, C5), 131.04 (br d, 1JCH = 160.6 Hz, C6), 131.30 (br d,
1JCH = 163.2 Hz, C4) 141.03 (s, C7). C3 was not observed.
31P{1H} NMR (DMF): δ 0.3. α = ϩ43 for 5s (c = 0.02, DMF).
Anal. Calc. for C64H72Cl2N4P4Pd (M = 1197): C, 64.16; H, 6.02;
N, 4.68; P, 10.36. Found: C, 63.7; H, 6.2; N, 4.2; P, 10.0%.
1
1
3
10.2 Hz, C4), 141.19 (d, JCP = 7.6 Hz, C3), 145.92 (s, C7).
31P{1H} NMR (CDCl3): δ Ϫ64.4 (br s). α = ϩ44 for 1r (c = 0.21,
CHCl3). Anal. Calc. for C32H36N2P2 (M = 510): C, 75.29; H,
7.06; N, 5.49; P, 12.16. Found: C, 75.5; H, 7.0; N, 5.6; P, 12.6%.
1
D a l t o n T r a n s . , 2 0 0 3 , 2 2 0 9 – 2 2 1 4
2210

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[1,5-(R,R)-Bis(ꢀ-methylbenzyl)-3,7-diphenyl-1,5-diaza-3,7-
diphosphacyclooctane]bromotricarbonylrhenium(I) (6r). [{ReBr-
(CO)3(thf )}2] (0.19 g, 0.23 mmol) in 3 mL of DMF was added
to a solution of 1r (0.23 g, 0.45 mmol) in 7 mL of DMF. The
next day the solvent was removed in vacuum, 6r was crystallised
from chloroform and white crystals were collected by filtration,
washed with chloroform and dried under vacuum. Yield: 0.23 g,
59%, mp 150 ЊC (decomp.). 1H NMR (CDCl3): δ 1.32 (d, 3JHH
=
6.8 Hz, 3H, CH3), 1.64 (d, 3JHH = 6.8 Hz, 3H, CЈH3), 2.62 (dd,
Scheme 1
2
2JHH = 12.0 Hz, JPH = 12.9 Hz, 1H, PCH1B2N), 3.16 (m, 2H,
2
PCH2AB2N), 3.41 (d, JHH = 12.7 Hz, 1H, PCH2ЈB2N), 3.70 (d,
2
2JHH = 12.0 Hz, 1H, PCH1A2N), 3.73 (d, JHH = 11.7 Hz, 1H,
(CHCl3, CH2Cl2), in contrast to 1,5-diaza-3,7-diphosphacyclo-
octanes described previously.5
PCH1ЈB2N), 3.76 (q, 3JHH = 6.8 Hz, 1H, C*H), 4.10 (q, 3JHH = 6.8
31P, H, 13C NMR and elemental analysis data are in good
1
2
2
Hz, 1H, C*ЈH), 4.16 (dd, JHH = 12.7 Hz, JPH = 6.8 Hz, 1H,
PCH1ЈA2N), 4.59 (dd, JHH = 11.7 Hz, JPH = 6.4 Hz, 1H,
2
2
agreement with the proposed structure.
In the H and 13C NMR spectra of 1 (1r or 1s) the ring
1
PCH2ЈA2N), 6.93–7.59 (m, 20H, C6H5). 13C{1H} NMR (DMF-
d7): δ 13.31 (br s, CH3), 18.96 (br s, CЈH3), 42.38 (br dd, 1JPC
=
methylene groups are inequivalent due to the presence of
asymmetric substituents in the 1- and 5-positions of the hetero-
cycle. In the 1H NMR spectrum they are registered as two
(AAЈ)X spin systems and in the 13C spectra as two AMMЈXY
spin systems. The asymmetric substituents on the nitrogen
atoms are equivalent. The protons of the CH and CH3 groups
of the α-methylbenzyl moieties appear as a broad quartet and a
doublet, respectively.
X-Ray crystallography confirmed the formation of chiral 1,5-
(R,R)-bis(α-methylbenzyl)-3,7-diphenyl-1,5-diaza-3,7-diphos-
phacyclooctane (1r) (Figs. 1 and 2, Tables 1 and 2). The absolute
configuration is known due to the R configuration of the
starting material, although the large esd of the Flack value
[Ϫ0.01(17)] does not allow an unambiguous assignment of the
configuration.
33 Hz, 3JPC = 6 Hz, C1), 46.15 (br dd, 1JPC = 35 Hz, 3JPC = 8 Hz,
C2Ј), 48.55 (br dd, 1JPC = 31 Hz, 3JPC = 7 Hz, C2), 52.72 (br dd,
1JPC = 36 Hz, JPC = 6 Hz, C1Ј), 67.47 (t, JCP = 10.3 Hz, C*),
3
3
67.57 (t, JCP = 12.0 Hz, C*Ј), 128.18 (s, C10), 128.44 (s, C10Ј),
3
128.54 (s, C8), 128.74 (s, C8Ј), 128.96 (s, C9), 129.24 (s, C9Ј),
129.75 (d, JCP = 7.9 Hz, C5), 129.90 (d, JCP = 8.3 Hz, C5Ј),
3
3
130.87 (d, JCP = 7.5 Hz, C4), 131.11 (d, JCP = 7.4 Hz, C4Ј),
131.31 (s, C6,6Ј), 140.93 (s, C7), 141.56 (s, C7Ј), 189.88, 191.30,
191.73 (CO). C3 was not observed. 31P{1H} NMR (CDCl3):
δ Ϫ16.6 (d), Ϫ16.9 (d) (2JPP = 57.8 Hz). α = ϩ13 for 6r (c = 0.07,
CHCl3). IR: ν(CO) = 2028, 1946, 1897 cmϪ1. Anal. Calc. for
C35H36BrN2O3P2Re (M = 860): C, 48.84; H, 4.19; N, 3.26; P,
7.21. Found: C, 49.0; H, 4.3; N, 3.1; P, 6.9%.
2
2
Co-polymerisation of norbornadiene (nbd) and CO. The
procedure for studying the kinetics of co-polymerisation of
nbd and CO has already been described.26
A solution of Pd(CH3COO)2 (11.25 mg, [Pd(CH3COO)2] =
7.2 × 10Ϫ4 mol lϪ1), ligand (38 mg, [1s/Pd(CH3COO)2] = 1.5),
CF3COOH (0.008 ml) or p-CH3C6H4SO3H (0.48 mg) in
CH2Cl2–CH3OH (58 : 2 ml) and nbd (10 ml) were placed in a
200 ml mechanically stirred steel autoclave, which was then
charged with carbon monoxide (pCO = 4.0 MPa).
The reaction mixture was stirred at 54 ЊC for 6 h, and then
the remaining carbon monoxide was vented off, and the
co-polymer precipitated by addition of heptane, collected by
filtration and dried under vacuum. After co-polymerisation the
surface of the autoclave was coated with black Pd. The nbd/CO
co-polymer was soluble in chloroform and THF, and insoluble
in methanol and acetone. Anal. Calc. for nbd–CO: C, 80.0; H,
6.5. Found: C, 80.0; H 6.5 (co-polymer 7); C, 80.4; H 6.6
1
(co-polymer 8). H NMR (CDCl3) (co-polymer 7): δ 0.9–2.1
(br m, 6.7H, H1,4,7), 2.1–3.5 (br m, 4.7 H, H2,3), 5.8–6.0 (br m,
0.6H, H2(B)), 6.0–6.3 (br s, 1.4H, H2,3(A) and H3(B)) (Fig. 4).
13C{H} NMR (CDCl ) (co-polymer 7): δ 209.7 (br s, C᎐O),
Fig. 1 An ORTEP view of the conformer 1rЈ.
᎐
3
208.7 (br s, C᎐O), 138.1 (br m, C5,6(A)), 128.6 (br m, C5,6(B)),
᎐
10–55 (m, C1–4,7). IR (KBr) (co-polymer 7): 1778(w), 1730(w),
1710(s), 1700(s), 1695(w) cmϪ1. 1H NMR (CDCl3) (co-polymer
8): δ 0.9–2.1 (br m, 4.6H, H1,4,7), 2.1–3.5 (br m, 2.6 H, H2,3), 6.0–
6.3 (br s, 2H, H2,3). 13C{H} NMR (CDCl3) (co-polymer 8):
δ 210.6 (br s, C᎐O), 209.2 (br s, C᎐O), 176 (br s, C–O ethereal),
᎐
᎐
175 (br s, C–O lactone), 135.9 (br m, C5,6) 113.5 (br s, C–O
spiroketal), 10–54 (m, C1–4,7). IR (KBr) (co-polymer 8): 1778(s),
1730(w), 1710(w), 1700(s), 1695(s) cmϪ1
.
Results and discussion
Optically active (R)- or (S)-α-methylbenzylamine underwent
condensation reactions with bis(hydroxymethyl)phosphine to
give chiral 1,5-(R,R)- or 1,5-(S,S)-bis(α-methylbenzyl)-3,7-
diphenyl-1,5-diaza-3,7-diphosphacyclooctane (1r or 1s) in
good yield (Scheme 1). Compounds 1r and 1s are white, air-
stable crystalline solids and soluble in common organic solvents
Fig. 2 An ORTEP view of the conformer 1rЉ.
D a l t o n T r a n s . , 2 0 0 3 , 2 2 0 9 – 2 2 1 4
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Two independent half-molecules are present in the asym-
metric unit. Compound 1r exists as a 1 : 1 mixture of two
conformational isomers due to the inequivalence of the
P–CH2–N fragments of the molecule. In conformer 1rЈ (Fig. 1)
the phenyl ring on the phosphorus atom is almost eclipsed with
the P–C2 bond (torsion angle C(4A)–C(3A)–P(1A)–C(2A) =
19.9Њ), and in the second conformer 1rЉ (Fig. 2) with the P–C1Ј
bond (torsion angle C(8B)–C(3B)–P(1B)–C(1B) = 23.1Њ). The
eclipsed cyclic P–C bond is slightly shorter than the uneclipsed
one (1.906 and 1.887 Å for 1rЈ, and 1.915 and 1.889 Å for 1rЉ).
Both isomers have the same “chair-chair” conformation of the
bisphosphine heterocycles with nearly parallel phosphorus lone
pairs. The P–P distance depends on the conformation along the
exocyclic P–C bonds and is noticeably shorter in isomer 1rЉ
(3.128 Å) in comparison with 1rЈ (3.279 Å). The lone pairs of
the nitrogen atoms are situated in the equatorial positions.
Thus, in the conformation existing in the solid state, only
the lone pairs of the phosphorus atoms are situated in
positions suitable to trap soft transition metal ions in a
chelating fashion.
Scheme 3
ligand are equivalent and occupy identical positions above and
below the plane of the metallocycle. The P–CH2–N methylene
groups are inequivalent and are observed as two groups of
1
multiplets (broad doublets) in the H NMR spectra and two
broad singlets in the 13C{1H} spectra of 3r and 5s. Signals for
the carbon atoms of the phenyl substituent on phosphorus C4
and C6 exhibited high- and low-field shifts, respectively, relative
to 1, in accordance with quaternisation of the phosphorus
atoms. The signal for C3 was not observed, perhaps due to the
usual low intensity and broadening of signals of carbon atoms
connected to phosphorus and coupling with four different
phosphorus atoms. The multiplicities of the signals in the
coupled 13C NMR spectrum of 5s confirm the assignments of
signals, that is, the heterocyclic ligand in the square-planar
complexes 2–5 retains the configuration of the starting
phosphine 1.
The high solubility of 1r or 1s in organic solvents is
unusual for 1,5-diaza-3,7-diphosphacyclooctanes and opens the
possibility of designing different chiral complexes of transition
metals and catalysts in situ. In the reaction mixture of 1r with
one equivalent of [PtCl2(cod)] (cod = cyclooctadiene) in
CH2Cl2, two signals were observed in the 31P NMR spectrum.
One signal was situated close to the signals of cis-(1,5-dibenz-
yl-3,7-diphenyl-1,5-diaza-3,7-diphosphacyclooctane)dichloro-
1
platinum() (δ 31P Ϫ26.3, JPtP = 2950 Hz) and the other close
to the signals of bis(1,5-dibenzyl-3,7-diphenyl-1,5-diaza-3,7-
diphosphacyclooctane)platinum() dichloride (δ 31P Ϫ17.4,
1JPtP = 2302 Hz) described previously.18,20 The signal of the
chelate complex 2r (δ 31P Ϫ24.2, 1JPtP = 2960 Hz) was the minor
one (20%), and that of the sterically hindered ionic complex
The noticeable decrease in the stereospecific coupling
constants 2JPH for the PCHA2N protons of 5s (2J(PHA) ≈ 0 Hz)
in comparison with neutral complex 4s (2J(PHA2) = 7.2,
2J(PHA1) = 6.7 Hz) could be explained in terms of different
conformational behaviour of the heterocyclic ligand in the
crowded (5s) and less crowded (4s) transition metal com-
plexes. The same picture was observed for analogous cationic
and neutral platinum complexes of 1,5-dibenzyl-3,7-diphenyl-
1,5-diaza-3,7-diphosphacyclooctane.20
1
3r (δ 31P Ϫ10.6, JPtP = 2368 Hz) the major one (80%)
(Scheme 2). Unconsumed [PtCl2(cod)] crystallised from the
reaction mixture.
Reaction of bisphosphine 1r with [{ReBr(CO)3(thf )}2] in
DMF leads to the formation of thin white needles of complex
6r (Scheme 4). In the IR spectrum of 6r strong CO absorption
bands of the fac-ReBr(CO)3 fragment coordinated with the
bisphosphine were observed.27,28 In contrast to complexes 2–5
two signals with relatively large coupling constant (2JPP = 57.8
Hz) were registered in the 31P NMR spectrum of 6r.
Scheme 2
To obtain 2r in pure form, a solution of 1r was added
to [PtCl2(cod)] (10% excess) dropwise. In the resulting mixture
2r was the predominant product (75%), but could not be
isolated without 3r. The salt 3r could be obtained in high yield
in the presence of two equivalents of 1r or on adding one
equivalent of 1r to the reaction mixture containing 2r.
Reactions of 1s with [PdCl2(cod)] gave slightly different
results (Scheme 3). In the 31P NMR spectrum of the reaction
mixture signals of two complexes were registered. However, the
neutral 1 : 1 complex 4s was the predominant product and
could be isolated from the reaction mixture in a pure state.
Scheme 4
The signals are situated close to each other (δ Ϫ16.6, Ϫ16.9)
in the low-field region relative to 1. We suppose that the differ-
ence between the two phosphorus atoms in the chelate complex
6r is connected with the different apical ligands (CO and Br) of
the octahedrally coordinated central ion. In accordance with
this assumption, the two chiral 1-methylbenzyl substituents on
the nitrogen atoms are inequivalent. The CH3 groups of the
α-methylbenzyl moieties are registered as two doublets and the
CH groups as two broad quartets in the 1H NMR spectrum of
1
In the H NMR spectrum of 4s two independent (AB)X spin
systems for the P–CH2–N protons were observed, in accordance
with inequivalence of C1 and C2.
The cationic palladium complex 5s was synthesised using two
equivalents of 1s and one equivalent of [PdCl2(cod)].
1H and 13C NMR data of the cationic complexes 3r and 5s
are similar. The chiral substituents on the nitrogen atoms of the
D a l t o n T r a n s . , 2 0 0 3 , 2 2 0 9 – 2 2 1 4
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Table 3 Co-polymerisation activities and MWD of co-polymers nbd–CO
Acid
[Acid]/[Pd]
W/g gPdϪ1 hϪ1
Conv. (%)
Mn
Mw
Mw/Mn
7
8
a
b
2
5
10
127
3.4
42.8
820
540
1100
680
1.34
1.26
6r. The NMR signals for the protons of the PCH2N fragments
are more complex than those of 1–5. The methylene protons
represent four (AB)X systems (one spin system for each proton)
in the co-polymerisation. In the 13C NMR spectrum of
co-polymer 7 only one broad signal for carbonyl groups was
registered, and for co-polymer 8 this signal was accompanied by
signals for ethereal (δ 176), lactone (δ 175) and spiroketal
(δ 113.5) groups.35
1
in the H NMR spectrum, and four doublets of doublets with
3
1J(PC) and J(PC) coupling in the 13C{1H} spectrum due to
the asymmetrical environments of the phosphorus atoms. In
addition, there are two sets of lines for each type of phenyl
group in the 1H and 13C NMR spectra of 6r.
1
The complexity of the H NMR spectrum of 6r prevented
a correct conformational analysis. However, the appearance
2
of noticeable J(PH) (6.4–12.9 Hz) coupling constants in most
of the (AB)X spin systems of the P–CH2–N protons indicates
that the conformational behaviour of the heterocyclic ligand
in compound 6r is similar to that of 4s and differs from that
of the cationic complexes 3r and 5s.
Fig. 4
The alternating co-polymerisation of ethylene and carbon
monoxide has attracted considerable interest from both
academia and industry over the last few decades.29–33 The
presence of carbonyl groups in the polyolefin chain increases
the ability of polymers to undergo photo- and biodegradation
(at least for the statistical co-polymers) and provides the
opportunity to modify the chains to give polymers with unusual
combinations of properties. Chiral co-polymers of propene and
styrene have been already studied.34 There is no information
about chiral co-polymers of norbornadiene (nbd) and CO.
Catalysts obtained in situ from 1s, Pd(CH3CO2)2 and CF3-
CO2H or p-CH3C6H4SO3H catalysed the co-polymerisation of
norbornadiene and carbon monoxide. Fig. 3 shows kinetic
curves for the co-polymerisation of norbornadiene and carbon
monoxide in the presence of two promoters: CF3COOH or
p-CH3C6H4SO3H.
The appearance of black palladium in the reaction mixture
and relatively low efficiency of the catalysts could be explained
by the formation of ionic complexes [PdL2]2ϩ (cf. 5s) in the
Ϫ
presence of a weakly nucleophilic anion (CF3CO2 or p-CH3-
C6H5SO3Ϫ). The excess of palladium acetate then decomposes
to give black palladium. The activity and selectivity of cationic
complexes are low due to the steric hindrance around the
palladium atom in cationic complexes.
On the whole, the catalyst systems on the basis of 1s
described here demonstrate rates of co-polymerisation and
co-polymer MWDs comparable or higher than those of
the best already known catalysts.36–38 The catalyst affords
co-polymers with predominantly cis-(R,S)-norbornene units.
Acknowledgements
Financial support from the INTAS (N 00–00677) and RFBR
(N 01–03–33248) is gratefully acknowledged. A. A. K. thanks
the Sächsisches Ministerium für Wissenschaft und Kunst
(SMWK, Az.: 4–7531.50–04–0361–01/11) and DFG (Az.: 436
RUS 17/60/01) for research grants.
References
1 Homogeneous Catalysis with Metal Phosphine Complexes, ed. L. H.
Pignolet, Plenum Press, New York, 1983.
2 Applied Homogeneous Catalysis with Organometallic Compounds,
ed. B. Cornils and W. A. Herrmann, VCH, Weinheim, 1996.
3 H. Brunner and W. Zettlmeier, Handbook of Enantioselective
Catalysis with Transition Metal Compounds, VCH, Weinheim, 1993.
4 K. Kellner and A. Tzschach, Z. Chem., 1984, 24, 365.
5 B. A. Arbuzov and G. N. Nikonov, Adv. Heterocycl. Chem., 1994, 61,
60.
6 O. A. Erastov and G. N. Nikonov, Functional Phosphines and their
Derivatives, Moscow, Nauka, 1986.
7 G. Markl and G. Yu Jin, Tetrahedron Lett., 1981, 22, 223.
8 G. Markl, G. Yu Jin and Ch. Schoerner, Tetrahedron Lett., 1980, 21,
1845.
Fig. 3 Kinetic curves of nbd–CO co-polymerisation in the presence of
two promoters: CF3COOH (a) and p-CH3C6H4SO3H (b)
The reaction rate and yield of co-polymer (see Table 3) are
noticeably higher for p-CH3C6H4SO3H b (co-polymer 8) than
for CF3COOH a (co-polymer 7). However the molecular weight
of the co-polymer in this case is lower (Table 3).
9 K. Kellner, W. Hanke and A. Tzschach, Z. Chem., 1984, 24,
193.
1H and 13C NMR data give some additional information
about co-polymer structures. Co-polymer 8 has mainly cis
structure A (δ H5,6 6.2), and co-polymer 7 is a mixture of cis
(A) and trans (B) structures (δ H5,6 6.2, 5.9) (Fig. 4). Thus,
co-polymerisation in the presence of p-CH3C6H4SO3H pro-
ceeds stereoselectively to produce only optically inactive,
symmetric (R,S)-norbornene units. The ratio of integral inten-
sities of aliphatic (H1–4 and H7) and olefinic (H5,6) protons (ca. 6
for 7 and ca. 4 for 8) are higher than the expected value (3),
perhaps due to the participation of both double bonds of nbd
10 K. Kellner, A. Tzschach, Z. Nagy-Magos and L. Marko,
J. Organomet. Chem., 1980, 193, 307.
11 M. T. Reetz and S. R. Waldvogel, Angew. Chem., 1997, 109, 870.
12 D. Astruc and F. Chardac, Chem. Rev., 2001, 101, 2991.
13 P. Arya, N. V. Rao and J. Singkhonrat, J. Org. Chem., 2000, 65, 1881.
14 D. E. Berning, K. Katti, C. L. Barnes and W. A. Volkert, J. Am.
Chem. Soc., 1999, 121, 1658.
15 S. V. Bobrov, A. A. Karasik and O. G. Sinyashin, Phosphorus, Sulfur
Silicon, 1999, 144–146, 289.
16 A. A. Karasik and G. N. Nikonov, Z. Obsch. Khim., 1993, 63, 2775
(in Russian).
D a l t o n T r a n s . , 2 0 0 3 , 2 2 0 9 – 2 2 1 4
2213

View Online
17 A. A. Karasik, O. G. Sinyashin, J. Heinicke and E. Hey-Hawkins,
Phosphorus, Sulfur Silicon, 2002, 177, 1469.
18 B. A. Arbuzov, A. A. Karasik and G. N. Nikonov, Bull. Acad. Sci.,
Div. Chem. Sci., 1992, 41, 253.
27 D. H. Gibson, H. He and M. S Mashuta, Organometallics, 2001, 20,
1456.
28 R. Schibli, K. V. Katti, W. A. Volkert and C. L. Barnes, Inorg. Chem.,
2001, 40, 2358.
19 A. A. Karasik, G. N. Nikonov and A. S. Dokuchaev, Russ. J. Coord.
Chem., 1994, 20, 300.
20 A. A. Karasik, S. V. Bobrov and G. N. Nikonov, Russ. J. Coord.
Chem., 1995, 21, 574.
21 A. A. Karasik, I. O. Georgiev, R. I. Vasiliev and O. G. Sinyashin,
Mendeleev Commun., 1998, 140.
22 A. A. Karasik, I. O. Georgiev, O. G. Sinyashin and E. Hey-Hawkins,
Polyhedron, 2000, 19, 1455.
29 C. Bianchini and A. Meli, Coord. Chem. Rev., 2002, 225,
35.
30 E. Drent and P. H. M. Budzelaar, Chem. Rev., 1996, 96, 663.
31 G. P. Belov, Polym. Sci., Ser. B., 1998, 40, 89.
32 G. P. Belov, Polym. Sci., Ser. C., 2001, 43, 46.
33 G. P. Belov, Kinet. Catal., 2001, 42, 301.
34 W. R. Pousch, J. M. Hawkins and R. H. Grubbs, Chemtracts: Org.
Chem., 1988, 1, 21.
23 A. A. Karasik, I. O. Georgiev, E. I. Musina, J. Heinicke and
O. G. Sinyashin, Polyhedron, 2001, 20, 3321.
35 M. D. E. Forbes, S. R. Ruberu, D. Nachtigallova, K. D. Jordan and
J. C. Barborak, J. Am. Chem. Soc., 1995, 117, 3946.
36 T. Kawaguchi, M. Kanno, T. Yanagihara and Y. Inoue, J. Mol.
Catal., 1999, 143, 253.
37 D.-J. Liaw and J.-S. Tsai, J. Polym. Sci. Part A. Polym. Chem., 1997,
35, 1157.
24 SADABS: G. M. Sheldrick, SADABS, Program for Scaling and
Correction of Area-detector Data, Göttingen, 1997.
25 SHELX97: SHELXS97 and SHELXL97 – Programs for Crystal
Structure Analysis. G. M. Sheldrick, University of Göttingen, 1998.
26 G. P. Belov, E. G. Chepaikin, A. P. Bezruchenko and V. I. Smirnov,
Vysokomol. Soedin. Ser. A, 1993, 35, 1585.
38 S.-W. Zhang, T. Kaneko and S. Takahashi, Macromolecules, 2000,
33, 6930.
D a l t o n T r a n s . , 2 0 0 3 , 2 2 0 9 – 2 2 1 4
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