Preparation of carbonyltungsten(0) complexes of 2-chloro-3,3-diphenyl-1-(2,4,6-tri-tert-butylphenyl)-1,3-diphosphapropene

Article abstract of DOI:10.1039/b102810n

(Z)-2-Chloro-3,3-diphenyl-1-(2,4,6-tri-tert-butylphenyl)-1,3-diphosphapropene was prepared from chlorodiphenylphosphine and 1-chloro-2-(2,4,6-tri-tert-butylphenyl)-2-phospha-ethenyllithium and used for metal complex formation as a ligand to provide carbonyltungsten(0) complexes.

Full text of DOI:10.1039/b102810n

Preparation of carbonyltungsten(0) complexes of 2-chloro-3,3-
diphenyl-1-(2,4,6-tri-tert-butylphenyl)-1,3-diphosphapropene
Shigekazu Ito and Masaaki Yoshifuji*
Department of Chemistry, Graduate School of Science, Tohoku University, Aoba, Sendai 980-8578,
Japan. E-mail: yoshifj@mail.cc.tohoku.ac.jp
Received (in Cambridge, UK) 27th March 2001, Accepted 10th May 2001
First published as an Advance Article on the web 13th June 2001
(Z)-2-Chloro-3,3-diphenyl-1-(2,4,6-tri-tert-butylphenyl)-1,3-
diphosphapropene was prepared from chlorodiphenylphos-
phine and 1-chloro-2-(2,4,6-tri-tert-butylphenyl)-2-phospha-
ethenyllithium and used for metal complex formation as a
ligand to provide carbonyltungsten(0) complexes.
was made to prepare E-2. Although NMR signals due to E-2
were observed in the reaction mixture (dP 325.1, 3.0, JPP
15 Hz), E-2 was isomerized to Z-2 after the usual work-up
procedure, probably due to large repulsion between the Mes*
group and the Ph2P group.
2
Next we investigated the coordination property of Z-2
towards tungsten(0). Initially, Z-2 was allowed to react with an
equivalent amount of W(CO)5(thf) for 6 h at room temperature
to afford the corresponding pentacarbonyltungsten(0) complex
3 in 39% yield as yellow prisms after recrystallisation from
hexane (Scheme 1).‡ The coordination on tungsten seemed to
occur at the Ph2P phosphorus atom as suggested by a satellite
signal due to the tungsten atom in the 31P NMR spectrum of 3.
The reason for this type of coordination might be explicable
taking the stronger basicity of the Ph2P group into account,12
while Bertrand and coworkers reported an NMR study to
suggest the coordination at the low-coordinated l s -phospho-
rus atom in a 1,3-diphosphapropene system.4 In the 13C NMR
spectrum, the chemical shift of the PNC carbon atom is similar
to that for Z-2, but the two 1JPC values are quite different (79 and
4 Hz) indicating low electronic interaction between the PPh2
group and the PNC carbon atom. The structure of 3 was
unambiguously determined by X-ray crystallography and Fig. 1
displays an ORTEP drawing.§ The P2–W distance is
2.540(1) Å, which is similar to that for W(CO)5(PPh3)
[2.545(1) Å].13 The P1–C(1) distance is 1.675(4) Å, which is a
normal value for the PNC bond.1 The P1, P2, C1, Cl, W atoms
are almost coplanar and the tungsten atom is located on the same
side of lone pairs of the P1 atom with a P1…W distance of
3.97 Å. Complex 3 did not react with an excess amount of
W(CO)5(thf) to afford the bis-tungsten complex, probably due
to steric congestion around the PNC phosphorus atom.4
The 1,3-diphosphapropene system is an attractive ligand system
for metal complex formation because two different types of
phosphorus atoms are included within the system; i.e. a low-
3
2
3 3
coordinated l s -phosphorus atom1,2 and a common l s -
phosphorus atom. However, research on coordination of the
1,3-diphosphapropene derivatives toward transition metals has
3
been limited, whereas several metal complexes of h -1,3-di-
phosphaallyl ligands have been reported so far.3,4 Indeed, the
only reported example concerns the X-ray structural analysis of
an iron(0) complex of 1,3-diphosphapropene prepared through
an intramolecular cyclization of a bulky 1,3-diphosphaallene by
ourselves.5 There have been no reports on X-ray structural
analysis of transition metal complexes of 1,3-diphosphapropene
itself. Furthermore, the catalytic abilities of transition metal
complexes of low-coordinated phosphorus compounds are of
current interest,6–10 and thus detailed study of the coordination
chemistry of the 1,3-diphosphapropene system is crucial. Here
we report the preparation and X-ray structural determination of
carbonyltungsten complexes of a 1,3-diphosphapropene deriva-
tive kinetically stabilized by the 2,4,6-tri-tert-butylphenyl
group (Mes*) including a selective coordination reaction of
either the monodentate or chelate form.
3
2
A kinetically stabilized (Z)-1-chloro-2-(2,4,6-tri-tert-butyl-
phenyl)-2-phosphaethenyllithium (Z-1) was prepared from
2,2-dichloro-1-(2,4,6-tri-tert-butylphenyl)-1-phosphaethene
and butyllithium, and was allowed to react with chloro-
diphenylphosphine (Scheme 1)11 to afford the corresponding
2-chloro-1,3-diphosphapropene (Z-2) in good yield (78%) after
silica-gel column chromatographic purification (hexane–tolu-
ene, v/v = 5/1). Compound Z-2 was characterized spectroscop-
ically.† In the 31P NMR spectrum, a peak due to the PNC
phosphorus atom appeared at low field (dP 302.4) with a large
2JPP value (277 Hz), suggesting an E-configuration. Similarly,
starting from E-1 and chlorodiphenylphosphine,11a an attempt
The structure of 3 indicates that Z-2 is a good chelating
ligand, and therefore we tried to prepare a chelate complex of Z-
2 by use of W(CO)4(cod) (cod = cycloocta-1,5-diene) at room
Fig. 1 An ORTEP drawing of 3 with 50% probability ellipsoids. Hydrogen
atoms are omitted for clarity. Bond lengths (Å) and angles (°): W–P(2)
2.540(1), C(1)–Cl 1.740(4), P(1)–C(1) 1.675(4), P(1)–Cipso(Mes*)
1.840(4), C(1)–P(2) 1.829(4), P(2)–Cipso(Ph) 1.828(4), P(2)–Cipso(PhA)
1.835(4); C(1)–P(1)–Cipso(Mes*) 103.1(2), W–P(2)–C(1) 119.3(1), W–
P(2)–Cipso(Ph) 110.6(1), W–P(2)–Cipso(PhA) 116.5(1), C(1)–P(2)–Cipso(Ph)
104.6(2), C(1)–P(2)–Cipso(PhA) 99.8(2), Cipso(Ph)–P(2)–Cipso(PhA) 104.3(2),
Cl–C(1)–P(1) 124.9(2), Cl–C(1)–P(2) 115.4(2), P(1)–C(1)–P(2) 119.2(2).
Scheme 1
1208
Chem. Commun., 2001, 1208–1209
This journal is © The Royal Society of Chemistry 2001
DOI: 10.1039/b102810n

o-Mes*), 150.8 (p-Mes*), 136.2 (dd, 1JPC 62, 3JPC 27 Hz, ipso-Mes*), 135.8
(dd, 1JPC 16, 3JPC 11 Hz, ipso-Ph), 133.6 (d, 2JPC 20 Hz, o-Ph), 128.8 (p-Ph),
122.0 (m-Mes*), 37.8 (d, 3JPC 1 Hz, o-CMe3), 35.1 (p-CMe3), 32.9 (d, 4JPC
7 Hz, o-CMe3), 31.4 (p-CMe3); 31P{1H} NMR (81 MHz, CDCl3) d 302.4
(PNC), 13.4 (PPh2), 2JPP 277 Hz.
‡ Spectroscopic data: for 3: yellow prisms (hexane), mp 196–198 °C
(decomp.); 1H NMR (200 MHz, CDCl3) d 7.6–7.7 (4H, arom.), 7.4–7.5 (6H,
4
arom.), 7.36 (2H, d, JPH 2 Hz, m-Mes*), 1.35 (18H, o-But), 1.29 (9H, p-
But); 13C{1H} NMR (50 MHz, CDCl3) d 199.3 (d, 2JPC 23 Hz, COax), 197.0
(dd, 2JPC 7, 2JPC 7 Hz, COeq), 163.5 (dd, 1JPC 79, 1JPC 4 Hz, PNC), 153.3 (d,
2JPC 3 Hz, o-Mes*), 151.3 (p-Mes*), 135.1 (dd, 1JPC 61, 3JPC 18 Hz, ipso-
Mes*), 134.5 (dd, 1JPC 44, 3JPC 10 Hz, ipso-Ph), 132.7 (d, 2JPC 12 Hz, o-Ph),
4
3
130.2 (d, JPC 2 Hz, p-Ph), 128.6 (d, JPC 10 Hz, m-Ph), 122.3 (m-Mes*),
37.5 (o-CMe3), 35.0 (p-CMe3), 32.6 (d, 4JPC 7 Hz, o-CMe3), 31.2 (p-CMe3);
31P{1H} NMR (81 MHz, CDCl3) d 328.0 (PNC), 1JPW 187 Hz, 34.2 (PPh2),
2JPP 187 Hz; IR (KBr) n 2071, 1988, 1936, 1919 cm21, FAB-MS m/z 804
(M+ 2 CO; 53%), 692 (M+ 25CO; 79%), 275 (Mes*P+ 2 1; 100%). Anal.
Calc. for C36H39ClO5P2W: C, 51.91; H, 4.72; Cl, 4.26. Found: C, 51.92; H,
4.78; Cl, 4.30%. For 4: red prisms (hexane), mp 220–222 °C (decomp.); 1H
NMR (200 MHz, CDCl3) d 7.6–7.7 (4H, arom.), 7.4–7.5 (8H, arom.), 1.61
(18H, o-But), 1.34 (9H, p-But); 13C{1H} NMR (50 MHz, CDCl3) d 208.4
(dd, 2JPC 36, 2JPC 6 Hz, COeq), 207.7 (dd, 2JPC 25, 2JPC 12 Hz, COeq), 203.2
(dd, 2JPC 10, 2JPC 7 Hz, COax), 156.4 (dd, 1JPC 23, 1JPC 9 Hz, PNC), 155.6
(d, 2JPC 2 Hz, o-Mes*), 153.6 (d, 4JPC 2 Hz, p-Mes*), 132.5 (d, 2JPC 14 Hz,
o-Ph), 131.5 (dd, 1JPC 38, 3JPC 16 Hz, ipso-Ph), 130.9 (d, 4JPC 2 Hz, p-Ph),
Fig. 2 An ORTEP drawing of 4 with 50% probability ellipsoids. Hydrogen
atoms are omitted for clarity. Bond lengths (Å) and angles (°): W–P(1)
2.489(3), W–P(2) 2.526(3), C(1)–Cl 1.73(1), P(1)–C(1) 1.651(10), P(1)–
Cipso(Mes*) 1.82(1), C(1)–P(2) 1.82(1), P(2)–Cipso(Ph) 1.83(1), P(2)–
Cipso(PhA) 1.81(1), C(1)–P(1)–Cipso(Mes*) 108.6(5), P(1)–W–P(2) 65.1(1),
W–P(2)–C(1) 93.5(3), W–P(1)–C(1) 99.4(4), W–P(1)–Cipso(Mes*)
152.0(3), W–P(2)–Cipso(Ph) 115.6(4), W–P(2)–Cipso(PhA) 127.6(4), C(1)–
P(2)–Cipso(Ph) 109.7(5), C(1)–P(2)–Cipso(PhA) 104.5(5), Cipso(Ph)–P(2)–
Cipso(PhA) 103.9(5), Cl–C(1)–P(1) 131.2(6), Cl–C(1)–P2 126.8(6), P(1)–
C(1)–P(2) 101.8(5).
3
1
3
130.8 (d, JPC 11 Hz, m-Ph), 125.7 (dd, JPC 26, JPC 26 Hz, ipso-Mes*),
122.5 (d, 3JPC 6 Hz, m-Mes*), 38.3 (d, 3JPC 1 Hz, o-CMe3), 35.3 (d, 5JPC
1
Hz, p-CMe3), 33.2 (d, 4JPC 3 Hz, o-CMe3), 31.0 (p-CMe3); 31P{1H} NMR
(81 MHz, CDCl3) d 263.7 (PNC), 1JPW 213 Hz, 19.1 (PPh2), 1JPW 202 Hz,
2JPP 116 Hz; IR (KBr) n 2019, 1923, 1903, 1890 cm21, FAB MS m/z 804
(M+; 59%), 692 (M+ 2 4CO; 96%), 275 (Mes*P+ 2 1; 90%), 154 (PhPCCl+
2 1; 100%). Anal. Calc. for C35H39ClO4P2W: C, 52.23; H, 4.88; Cl, 4.40.
Found: C, 52.50; H, 4.95; Cl, 4.52%.
§ Crystal data: for 3: C36H39ClO5P2W, M = 832.95, monoclinic, P21/c (no.
14), a = 10.062(5), b = 25.244(3), c = 13.845(2) Å, b = 93.920(3)°, V =
3508(1) Å3, Z = 4, Dc = 1.577 g cm2 3, m = 3.504 mm21, T = 120(1) K,
2qmax = 50.1°, 5861 total reflections, 5487 observed reflections [I >
1s(I)], R1 = 0.031, Rw = 0.073, S = 0.96 for 562 parameters, CCDC
159934.
temperature. After 12 h, 4 was obtained in 19% yield as red
crystals together with 63% recovery of Z-2, after purification by
gel permeation chromatographic separation (Scheme 1).‡ A
trace amount of 4 was also obtained by the reaction of Z-2 and
W(CO)5(thf). In the 31P NMR spectrum of 4, a peak due to the
PNC phosphorus atom is observed at a higher field than that for
Z-2, and both of the two phosphorus atoms show satellite peaks
due to the presence of the tungsten atom. Moreover, the
coupling constant between the PNC phosphorus and the tungsten
(213 Hz) is reasonable for a complex with an end-on
coordinating mode.14 On the other hand, Appel and coworkers
reported a side-on coordination with Fe(0) on the PNC moiety in
the 1,3-diphosphapropene system.3 In the 13C NMR spectrum
of 4, a peak due to the PNC carbon atom has a higher chemical
shift than that for Z-2, and the two 1JPC values are small (23 and
9 Hz). Two different chemical shifts were observed for COeq
carbons together with two different 2JPC values, probably due to
the coordination by two different types of phosphorus atoms.
The structure of 4 was unambiguously determined by X-ray
crystallography and Fig. 2 depicts an ORTEP drawing.§ The
PNC phosphorus atom coordinates in the end-on mode which
For 4: C35H39ClO4P2W, M = 804.94, orthorhombic, P212121 (no. 19), a
= 16.687(2), b = 21.984(3), c = 9.310(3) Å, V = 3415(1) Å3, Z = 4, Dc
= 1.565 g cm21, m = 3.594 mm21, T = 125(1) K, 2qmax = 50.1°, 3318
total reflections, 3132 observed reflections [I > 2s(I)], R1 = 0.049, Rw
0.110, S = 1.27 for 389 parameters, CCDC 159933.
=
See http://www.rsc.org/suppdata/cc/b1/b102810n/ for crystallographic
data in CIF or other electronic format.
1 M. Regitz and O. J. Scherer, Multiple Bonds and Low Coordination in
Phosphorus Chemistry, Georg Thieme Verlag, Stuttgart, 1990; K. B.
Dillon, F. Mathey and J. F. Nixon, Phosphorus: The Carbon Copy, John
Wiley & Sons, Chichester, 1998.
2 M. Yoshifuji, I. Shima, N. Inamoto, K. Hirotsu and T. Higuchi, J. Am.
Chem. Soc., 1981, 103, 4587; M. Yoshifuji, I. Shima, N. Inamoto, K.
Hirotsu and T. Higuchi, J. Am. Chem. Soc., 1982, 104, 6167.
3 R. Appel and W. Schuhn, J. Organomet. Chem., 1987, 329, 179.
4 D. Bourissou, Y. Canac, M.-I. Collado, A. Baceiredo and G. Bertrand,
Chem. Commun., 1997, 2399; D. Bourissou, Y. Canac, H. Gornitzka,
C. J. Marsden, A. Baceiredo and G. Bertrand, Eur. J. Inorg. Chem.,
1999, 1479.
5 C. A. Akpan, P. B. Hitchcock, J. F. Nixon, M. Yoshifuji, T. Niitsu and
N. Inamoto, J. Organomet. Chem., 1988, 338, C35.
6 W. Keim, R. Appel, S. Gruppe and F. Knoch, Angew. Chem., Int. Ed.
Engl., 1987, 26, 1012.
7 K. Toyota, K. Masaki, T. Abe and M. Yoshifuji, Chem. Lett., 1995,
221.
1
leads to a large JPW value in the NMR spectrum. The P1–W
distance [2.489(3) Å] is shorter than the P2–W distance
[2.526(3) Å], and the P1–C(1) distance [1.651(10)] is normal
for the PNC bond. The P1–W–P2 angle is small with a value of
65.1(1)°. The P1–C(1)–P2 and C(1)–P2–W angles, 93.5(3) and
101.8(5)°, respectively, are smaller than the corresponding
angles for 3.
Chelate complex 4 was also derived by photo-irradiation of 3.
A THF solution of 3 was irradiated with a medium-pressure
mercury lamp at 5 °C for 16 h in an NMR tube to afford 4 almost
quantitatively. No E/Z isomerization of 3 was observed
probably due to the steric hindrance between the Mes* and Ph2P
moieties.15
8 B. Breit, J. Mol. Catal. A, 1999, 143, 143.
9 R. Shintani, M. M.-C. Lo and G. C. Fu, Org. Lett., 2000, 2, 3695.
10 S. Ikeda, F. Ohhata, M. Miyoshi, R. Tanaka, T. Minami, F. Ozawa and
M. Yoshifuji, Angew. Chem., Int. Ed., 2000, 39, 4512.
11 (a) M. Yoshifuji, S. Ito, K. Toyota and M. Yasunami, Bull. Chem. Soc.
Jpn., 1995, 68, 1206; (b) M. van der Sluis, F. Bickelhaupt, N. Neldman,
H. Kooijman, A. L. Spek, W. Eisfeld and M. Regitz, Chem. Ber., 1995,
128, 465.
Compound 2 contains a chlorine atom at the sp2-carbon atom
which can potentially be substituted. We are now attempting to
prepare various types of 1,3-diphosphapropenes from 2, as well
as metal complexes of the type 3 and 4.
This work was supported in part by a Grant-in-Aid for
Scientific Research (No. 12042208) from the Ministry of
Education, Science, Sports and Culture, Japan.
12 T. C. Klebach, R. Lourens and F. Bickelhaupt, J. Organomet. Chem.,
1981, 210, 211.
13 M. J. Aroney, I. E. Buys, M. S. Davies and T. W. Hambley, J. Chem.
Soc., Dalton Trans., 1994, 2827.
14 M. Yoshifuji, Bull. Chem. Soc. Jpn., 1997, 70, 2881.
15 M. Yoshifuji, K. Toyota and N. Inamoto, Tetrahedron Lett., 1985, 26,
1727.
Notes and references
† NMR data for 2: 1H NMR (200 MHz, CDCl3) d 7.4–7.5 (4H, arom.),
7.3–7.4 (8H, arom.) 1.41 (18H, o-But), 1.31 (9H, p-But); 13C{1H} NMR (50
MHz, CDCl3) d 169.0 (dd, 1JPC 72, 1JPC 54 Hz, PNC), 153.2 (d, 2JPC 2 Hz,
Chem. Commun., 2001, 1208–1209
1209