Preparation, structure, and some coordination properties of 2-chloro-3,3-diphenyl-3-thioxo-1-(2,4,6-tri-t-butylphenyl)-1,3- diphosphapropene

Article abstract of DOI:10.1039/b211230b

A sterically encumbered 3-thioxo-1,3-diphosphapropene, bearing a P=C-P=S skeleton, was prepared, characterised, and allowed to react with a carbonyltungsten(0) reagent and iodine affording the corresponding chelate tungsten(0) complex and charge-transfer complex with iodine, respectively, which were analysed by the X-ray crystallography.

Full text of DOI:10.1039/b211230b

Preparation, structure, and some coordination properties of
2-chloro-3,3-diphenyl-3-thioxo-1-(2,4,6-tri-t-butylphenyl)-
1,3-diphosphapropene
Shigekazu Ito, Hongze Liang 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) 14th November 2002, Accepted 24th December 2002
First published as an Advance Article on the web 13th January 2003
A sterically encumbered 3-thioxo-1,3-diphosphapropene,
bearing a PNC–PNS skeleton, was prepared, characterised,
and allowed to react with a carbonyltungsten(0) reagent and
iodine affording the corresponding chelate tungsten(0)
complex and charge-transfer complex with iodine, re-
spectively, which were analysed by the X-ray crystallog-
raphy.
A 3-sulfide Z-2 was isomerised to afford the E-isomer, E-2,
as a Z+E ratio of 4+1 upon irradiation, whereas no E/Z
isomerisation of Z-2 was observed by heating in the refluxing
toluene, in contrast to the case of 1 showing no E/Z
isomerisation. In the 31P NMR spectrum, the PNC phosphorus of
E-2 appeared at dP 344.0 in a lower field than that of the Z-
isomer and the P(S)Ph2 phosphorus appeared at dP 42.1.† The
2JPP value of E-2 (53 Hz) is smaller than that of the Z-isomer,
which supports the E-configuration.1
Recently we have reported the coordination properties of the
kinetically stabilised 1,3-diphosphapropene 1 on the carbo-
nyltungsten(0) moieties.1 Compound 1 possesses two different
types of phosphorus atoms within the system; an unsaturated
To estimate the coordination properties of Z-2, at first, the
reactions with carbonyltungsten(0) reagents were performed.
Compound Z-2 was allowed to react with W(CO)4(cod) (cod =
cycloocta-1,5-diene) affording the corresponding chelate com-
plex 4 almost quantitatively. In the 31P NMR spectrum, the
P = C phosphorus of 4 was observed at dP 319.0 with the
satellite peaks for 183W (1JPW 290 Hz), whereas the P(S)Ph2
phosphorus was observed at dP 48.4 without the satellite peaks
for 183W.† On the other hand, Z-2 was allowed to react with
W(CO)5(thf) to give 4 in 20% yield through the unstable
monocoordinated complex, where the sulfur solely coordinates
on the tungsten (dP 331.7, 54.6, 2JPP 96 Hz). The structure of 4
was analysed by X-ray crystallography as shown in Fig. 2.‡ The
two independent molecules were found in the unit cell and one
of them is displayed. The PNC–PNS system forms the five-
membered chelate ring with the tungsten. The P1–C1–P2–S
torsion angle is 26.7(7)°, whereas the W–P1–C1–P2 skeleton is
almost planar with the angle of 0.8(7)°. Such an envelope
3
2
3 3
l s -phosphorus atom2 and a common l s -phosphorus atom,
3
3
possibly regarded as a difunctional ligand. The l s -phospho-
rus atom in 1 predominantly coordinated on the tungsten due to
the higher basicity than the unsaturated phosphorus atom,
besides 1 could behave as a chelating ligand. On the other hand,
there are a number of heterofunctional ligands containing
phosphorus and sulfur atoms.3 For example, a diphosphine
sulfide Ph2PCH2P(S)Ph has been employed as catalyst ligand
for methanol carbonylation.4 Additionally, compounds contain-
ing the unsaturated phosphorus atom(s) have been paid
considerable attention as a novel class of ligands for synthetic
catalysts.5–7 Here we report on the sulfurisation of 1 to afford a
3-sulfide 2 possessing the PNC–PNS skeleton (Scheme 1), and
the coordination properties of 2 using carbonyltungsten(0)
reagents or iodine together with their structural determinations
by the X-ray analyses.
structure was reported for a rhodium( ) complex ligated with a
I
1,3-Diphosphapropene 11 was allowed to react with an
equivalent amount of sulfur affording the corresponding
product Z-2 in an excellent yield (88%) without sulfurisation on
the unsaturated 1-phosphorus atom.† In the 31P NMR spectrum,
the PNC phosphorus of Z-2 appeared at dP 322.4 and the P(S)Ph2
phosphorus was observed at dP 49.1 with a 2JPP value of 104 Hz.
Alternatively, Z-2 was obtained by a reaction of 3 with
Ph2P(S)Cl in a poor yield (ca. 10%). The structure of Z-2 was
confirmed by X-ray crystallography and the molecular structure
is shown in Fig. 1.‡ The PNC(Cl)–PNS skeleton displays almost
a planar s-cis conformation, which is similar to the case of
diphenylvinylphosphine sulfide.8 The distances of the P1–C1
and the P2–S are close to the average values for the PNC and
PNS bonds, respectively.2,8
diphosphine sulfide Ph2PCH2P(S)Ph2.4 The S–W distance is
similar to that of the tetracarbonyltungsten(0) complex of [o-
(methylsulfanyl)phenyl]diphenylphosphine [2.527(2) Å].9 The
P–W distance is comparable to that of the tetracarbonyltung-
sten(0) complex of 1,3-diphosphapropene 1 [2.489(3) Å].1
Compared with Z-2, the PNS bond of 4 is elongated due to the
coordination by the tungsten atom and accordingly the n(PNS)
value of 4 becomes lower (604 cm21) than that of Z-2 (646
cm21). The n(C·O) values, 2019, 1913, and 1869 cm21, are
similar to the corresponding complex of Ph2PCH2P(S)Ph2.10
The charge-transfer complexes of phosphine chalcogenide
with halogens have been paid considerable attention, because
Fig. 1 An ORTEP drawing of Z-2 with 30% probability ellipsoids.
Hydrogen atoms are omitted for clarity. Selected bond lengths (Å) and
angles (°): P1–C1 1.675(4), C1–Cl 1.737(3), P1–CMes* 1.852(4), P2–C1
1.821(4), P2–S 1.946(1), C1–P1–CMes* 101.7(2), P1–C1–P2 119.1(2), P1–
C1–Cl 126.5(2), P2–C1–Cl 114.1(2), S–P2–C1 112.5(1).
Scheme 1 Reagents and Conditions: (a) 1/8·S8, toluene, reflux, 12 h; (b)
Ph2P(S)Cl, THF, 278 °C; (c) Medium pressure Hg lamp (100 W), CDCl3,
0 °C, 36 h; (d) W(CO)4(cod), THF, 20 °C, 12 h; (e) I2, Et2O:hexane 1+1, 0
°C.
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Notes and references
1
† Physical data: Z-2: Colourless crystals, mp 111–112 °C, H NMR (400
MHz, CDCl3) d = 7.93 (4H, m, arom), 7.50 (2H, m, arom), 7.46 (4H, m,
arom), 7.42 (2H, m, arom), 1.45 (18H, s, o-t-Bu), 1.34 (9H, s, p-t-Bu);
13C{1H} NMR (100 MHz, CDCl3) d = 159.4 (dd, 1JPC 84 Hz, 1JPC 62 Hz,
PNC), 154.0 (d, 2JPC 2 Hz, o-Mes*), 151.7 (s, p-Mes*), 134.7 (dd, 1JPC 62
Hz, 3JPC 13 Hz, ipso-Mes*), 132.9 (d, 2JPC 11 Hz, m-Ph), 132.4 (d, 4JPC
3
Hz, p-Ph), 132.0 (dd, 1JPC 88 Hz, 3JPC 3 Hz, ipso-Ph), 128.8 (d, 3JPC 13 Hz,
o-Ph), 123.0 (brs, m-Mes*), 38.3 (brs, o-CMe3), 35.5 (s, p-CMe3), 33.5 (d,
4JPC 7 Hz, o-CMe3), 31.8 (s, p-CMe3). E-2: 1H NMR (400 MHz, CDCl3) d
= 7.75 (4H, m, arom), 7.38 (8H, m, arom), 1.51 (18H, s, o-t-Bu), 1.39 (9H,
s, p-t-Bu). 4: Deep red prisms (hexane), mp 173 °C (decomp); 1H NMR (400
MHz, CDCl3) d = 7.74 (4H, m, arom), 7.62 (2H, m, arom), 7.53 (6H, m,
arom), 1.63 (18H, s, o-t-Bu), 1.35 (9H, s, p-t-Bu); 13C{1H} NMR (100
MHz, CDCl3) d = 209.4 (dd, 2JPC 46 Hz, 3JPC 6 Hz, COeq), 204.8 (d, 3JPC
2
4 Hz, COeq), 202.4 (d, JPC 10 Hz, COax), 155.5 (s, o-Mes*), 153.5 (s, p-
Mes*), 142.6 (dd, 1JPC 89 Hz, 1JPC 16 Hz, PNC), 133.5 (d, 4JPC 3 Hz, p-Ph),
133.0 (d, 2JPC 11 Hz, m-Ph), 130.1 (m, ipso-Ph), 129.3 (d, 3JPC 13 Hz, o-Ph),
128.3 (dd, 1JPC 87 Hz, 3JPC 5 Hz, ipso-Mes*), 123.5 (d, 3JPC 7 Hz, m-Mes*),
39.1 (brs, o-CMe3), 35.7 (s, p-CMe3), 33.8 (brs, o-CMe3), 31.5 (s, p-CMe3).
Anal. Calc. for C35H39ClO4P2SW: C, 50.23; H, 4.70. Found: C, 50.24, H,
4.66%. 5: Red plates (ether-hexane), mp 102 °C (decomp). Anal. Calc. for
C31H39ClI2P2S: C, 46.83; H, 4.91. Found: C, 46.79; H, 4.84%.
Fig. 2 An ORTEP drawing of 4 with 30% probability ellipsoids. Hydrogen
atoms are omitted for clarity. The p-t-butyl group is disordered and the
atoms with a predominant occupancy factors (0.55), which are refined
isotropically, are shown. Selected bond lengths (Å) and angles (°): W–P1
2.442(2), W–S1 2.566(3), Cl–C1 1.746(9), S–P2 1.990(4), P1–C1 1.65(1),
P1–CMes* 1.82(1), C1–P2 1.81(1), S–W–P1 82.80(9), W–S–P2 102.9(2),
W–P1–C1 115.3(3), W–P–CMes* 143.3(3), C1–P1–CMes* 101.3(4), P1–C1–
P2 117.5(5), P1–C1–Cl 127.4(6), P2–C1–Cl 114.9(6), S–P2–C1 108.2(3).
‡ Crystal data: Z-2: C31H39ClP2S, M = 541.11, colourless prism, 0.50 3
0.50 3 0.20 mm, monoclinic, P21/n (no. 14), a = 16.294(2), b = 11.480(4),
c = 17.142(3) Å, b = 105.38(1)°, V = 3091(4) Å3, Z = 4, T = 288 K,
2qmax = 50.0°, r = 1.163 g cm23, m(Mo-Ka) = 0.312 mm21, 4565
measured reflections, 4520 unique reflections (Rint = 0.052), R1 = 0.062 [I
> 2s(I)], Rw = 0.087 (all data), S = 1.29 for 316 parameters (CCDC-
196480). 4: C35H39ClO4P2SW, M = 837.00, deep red prism, 0.30 3 0.30
they have displayed various intriguing molecular assemblies
which are dependent on the reaction conditions.11 For example,
triphenylphosphine sulfide has been reported to react with
iodine to form charge-transfer complexes11,12 and it prompted
us to investigate the reaction of Z-2 with iodine. Compound Z-2
was mixed with an equivalent amount of iodine in ether at 20 °C
and a deep red solution was obtained after 3 h. This solution was
diluted with hexane and cooled to 0 °C to obtain compound 5 as
red-brown plates. The elemental analysis revealed that 5 is a 1+1
charge-transfer complex of Z-2 and iodine. In the IR spectrum
(KBr), 5 displayed a peak at n(PNS) 611 cm21, which is lower
than that of Z-2. On the other hand, the 31P NMR spectrum in
chloroform-d indicated the value of dP 325.8, 48.4; 2JPP = 106
Hz, which is similar to the corresponding data of Z-2. The
structure of 5 was finally established by the X-ray crystallog-
raphy and the structure is shown in Fig. 3.‡ The I2–I1–S
skeleton is almost straight in shape.12 The S–I1 distance is
longer than that of Ph3PS·I2 [2.753(2) Å], whereas the I1–I2 and
P1–S distances are close to those of Ph3PS·I2.12 The PNC
distance is almost identical with that for Z-2. The molecule
displays a weak intermolecular interaction to form a dimer and
the intermolecular S…S and S…I1 distances, 3.320(4) and
3.838(2) Å respectively, are shorter than the corresponding
sums of the van der Waals radii [S, 1.85 Å; I, 2.15 Å].13
This work was supported in part by Grants-in-Aid for
Scientific Research (No.13303039 and 14044012) from the
Ministry of Education, Culture, Sports, Science and Technol-
ogy, Japan. H. L. is grateful to the Japan Society for the
Promotion of Science for Postdoctoral Fellowships for Foreign
Researchers. We thank Dr Chizuko Kabuto, Tohoku University,
for obtaining the X-ray data of compound 5.
¯
3 0.20 mm, triclinic, P1 (no. 2), a = 17.180(2), b = 20.019(1), c =
10.807(1) Å, a
= 90.023(6), b = 91.993(2), g = 89.968(6)°, V =
3714.6(6) Å3, Z = 4, T = 296 K, 2qmax = 55.0° r = 1.497 g cm23, m(Mo-
Ka) = 3.362 mm21, 28035 measured reflections, 14887 unique reflections
(Rint = 0.119), R1 = 0.064 [I > 2s(I)], Rw = 0.148 (all data), S = 1.28 for
789 parameters (CCDC-196481). 5: C31H39ClI2P2S, M = 794.92, red plate,
0.40 3 0.50 3 0.08 mm, orthorhombic, Pbca (no. 61), a = 11.751(1), b =
38.246(3), c = 15.542(1) Å, V = 6985(1) Å3, Z = 8, T = 243 K, 2qmax
=
55.0°, r = 1.512 g cm23, m(Mo-Ka) = 2.047 mm21, 59303 measured
reflections, 8504 unique reflections (Rint = 0.043), R1 = 0.045 [I > 3s(I)],
Rw = 0.053 (all data), S = 1.19 for 334 parameters (CCDC-196482). See
http://www.rsc.org/suppdata/cc/b2/b211230b/ for crystallographic files in
CIF or other electronic format.
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Fig. 3 An ORTEP drawing of 5 with 30% probability ellipsoids. Hydrogen
atoms are omitted for clarity. Selected bond lengths (Å) and angles (°): I1–
I2 2.8122(9), I1–S 2.809(2), Cl–C1 1.723(8), S–P1 1.990(3), P1–C1
1.822(8), 1.811(9), P2–C1 1.678(8), P2–CMes* 1.843(3), I2–I1–S 174.90(5),
I1–S–P1 98.44(10), S–P1–C1 109.2(3), Cl–C1–P1 112.4(4), Cl–C1–P2
118.7(5), P1–C1–P2 118.7(5), C1–P2–CMes* 100.2(4).
13 J. Emsley, The Elements, 3rd edn, Oxford University Press, NY,
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