Zirconaindane phospholanes: Key reagents for the synthesis of mono- or tri-cyclic phosphanes and related species

Article abstract of DOI:10.1039/a702036h

The zirconaindane phospholane 3 reacts either with PhSbCl₂ or Me₂SnCl₂ to give tricyclic systems incorporating phosphorus, antimony or tin; the same reaction involving 3 and R₂PCl (R = Ph, Et) leads to acyclic-c

Full text of DOI:10.1039/a702036h

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Zirconaindane phospholanes: key reagents for the synthesis of mono- or
tri-cyclic phosphanes and related species
M. Zablocka,a A. Igau,b B. Donnadieu,b J.-P. Majoral,*b A. Skowronska*a and P. Meunier*c
a Laboratoire de Chimie de Coordination du CNRS, 205 route de Narbonne, 31077 Toulouse Cedex, France
b Polish Academy of Sciences, Centre of Molecular and Macromolecular Studies, Sienkiewicza 112, 90-363 Lodz, Poland
c Laboratoire de Synthe`se et d’Electrosynthe`se Organome´talliques associe´ au CNRS (UMR 5632), Universite´ de Bourgogne,
Faculte´ des Sciences Gabriel, 6 boulevard Gabriel, 21000 Dijon, France
The zirconaindane phospholane 3 reacts either with
PhSbCl2 or Me2SnCl2 to give tricyclic systems incorporating
phosphorus, antimony or tin; the same reaction involving 3
and R2PCl (R = Ph, Et) leads to acyclic–cyclic diphos-
phanes.
All these reactions proceeded with ring retention. In contrast
an exchange reaction with concomitant ring opening was
observed when 3 was reacted with a chlorophosphane such as
Ph2PCl at 240 °C for 1 h (Scheme 2). The 1,1-diphosphane 8
was obtained as two isomers 8a,b in a 4:1 ratio as shown by 31
P
NMR spectroscopy: two doublets at d 5.1 (PPh) and 212.0
(PPh2) (2JPP 7.8 Hz) for the major compound and d 3.9 (PPh)
and 216.3 (PPh2) (2JPP 19.5 Hz) for the minor one. Mono-
sulfurization occurred regioselectively on the intracyclic phos-
phorus atom by adding 1 equiv. of elemental sulfur to 8a,b and
led to the adducts 9a,b {two isomers in a 4:1 ratio. d(31P): 65.5
There is an extensive literature on the topic of cyclic
phosphanes such as phospholanes, phospholenes or phos-
pholes.1 In contrast only a limited number of fused bicyclic and
tricyclic phosphanes have been prepared and only very recently
a few tricyclic 1,1-diphosphanes were described.2 As far as we
are aware, fused tricyclic systems incorporating phosphorus and
other heavier main group elements, are not known. With this in
mind we became interested in developing synthetic routes to
these species because of the intrinsic interest in phosphane and
polyphosphane derivatives as reagents for mediating organic
transformations or as ligands for complex formation and use in
catalysis.
2
[P(S)Ph] and 29.6 (PPh2), JPP 31.5 Hz (major); d 64.1
[P(S)Ph] and 211.8 (PPh2), 2JPP = 31.5 Hz (minor)}. Further
addition of a second equivalent of sulfur led predominantly to
the formation of the disulfide 10a {d(31P) 65.2 [P(S)Ph] and
2
43.3 [P(S)Ph2], JPP 0 Hz} isolated by silica gel column
chromatography.‡ 13C and 1H NMR spectra coupled with mass
spectrometry and microanalytical data showed clearly that
cleavage of the two zirconium–carbon bonds occurred with
grafting of the diphenylphosphino group in a position to the
intracyclic P–Ph moiety.
This prompted us to initiate the chemistry of the zirconain-
dane phospholane 3 which was regioselectively prepared via the
treatment of 1-phenyl-2-phospholene PhP–CHNCHCH2CH2 1
A similar ring opening process initiated also by an exchange
reaction between 3 and a chlorophosphane was detected when 3
was reacted with Et2PCl. Addition of sulfur to the resulting
1,1-diphosphanes 11a,b (two isomers) led to the 1,1-dithiodi-
phosphanes 12a,b (two isomers in 9:1 ratio). The major isomer
12a was isolated by chromatography and fully characterized by
NMR,† mass spectrometry and elemental analysis.
2
with the transient (benzyne)zirconocene [(h-C5H5)2Zr(h -
C6H4)] 2. 2 Here we will detail the formation, from 3, of unusual
phosphorus and antimony (or tin) tricyclic systems as well as
that of new acyclic–cyclic diphosphanes.
Reactions of 3 with PhSbCl2 in benzene at 5 °C for 1 h led to
the stibaphospholane 4 [d(31P) 5.9] which was isolated in 80%
yield as its sulfide adduct 5 [d(31P) 61.9] (Scheme 1). The
formulation of 5 was confirmed by NMR spectroscopy,3 mass
spectrometry (FAB [M + 1]+ 470) and by elemental analysis.
An analogous exchange reaction performed with 3 and
Me2SnCl2 at 0 °C for 3 h gave the tin–phosphorus containing
tricyclic species 6 [d(31P) 5.6] which was also fully charac-
terized as its sulfide adduct 7 obtained in 75% yield [d(31P)
64.1)] (Scheme 1). NMR data corroborated such an assign-
ment.† Compounds 4–7 are the first examples of fused tricyclic
systems incorporating phosphorus and antimony or phosphorus
and tin in the cyclic skeleton.
X-Ray structures have been obtained for 10a3 and for 12a
(Fig. 1):§ they showed similar features for the two derivatives.
Indeed substituents on the intracyclic carbon atoms C(1)
[P(S)Ph2] and C(2) (Ph) of the phospholane ring are cis in both
cases [P(1)–C(1)–C(2)–C(21) torsion angle: 85.7° for 10a,
73.2° for 12a] while the substituent on C(1) and the phenyl
group on the phosphorus atom P(2) are trans [P(1)–C(1)–
P(2)–C(221) torsion angle: 3.2° for 10a, 14.0° for 12a].
Remarkably the regioselectivity of the reaction of phos-
pholene 1 with a more hindered benzyne zirconocene precursor
5
such as (h -ButC5H4)2ZrPh2 was found to be the same: the
zirconaindane phospholane 3B was formed nearly quantitatively
MCl2
(η-C5H5)2ZrCl2
Zr
Ph
Ph
P
M
P
Ph
(η-C5H5)2
Ph2PCl
S8
S8
Ph
Ph
3
4 M = SbPh
6 M = SnMe2
Ph2P
P
Ph2P
P
Ph2P
P
Ph
Ph
Ph
S
S
S
S8
3
8a,b
9a,b
10a,b
Ph
Ph
Et2PCl
S8
M
P
S
Ph
Et2P
P
Et2P
P
S
12a,b
5 M = SbPh
7 M = SnMe2
Ph
Ph
S
11a,b
Scheme 1
Scheme 2
Chem. Commun., 1997
1239

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129.3 [d, J(CP) 10.3, Ph], 131.4 [d, J(CP) 9.5, Ph], 131.6 [d, J(CP) 3.0, Ph],
135.8, 136.1 (s, C6H4), 136.2 [d, 1J(CP) 68.2, ipso-PPh], 140.9 [d, 1J(CP)
8.9, SbPh), 144.5 [d, 3J(CP) 2.1, ipso-C6H4], 156.7 [d, 3J(CP) 4.5, C6H4].
FABMS (MNBA–DMF): m/z 391 (100, [M 2 S]+). 7 31P{1H} NMR
(C6D6): d 64.1. 1H NMR (C6D6): d 0.73 (s, 6 H, CH3), 1.77–2.16 (m, 4 H,
CH2), 3.42 [dd, 2J(HP) 9.6, 3J(HH) 9.6, 1 H, PCHSn], 4.24 (m, 1 H,
PCHCH), 7.02–7.41, 7.65–7.96 (m, 9 H, Haryl). 13C NMR (C6D6): d 4.9 (s,
CH3), 33.4 [d, 2J(CP) 6.3, PCH2CH2], 35.2 [d, 1J(CP) 49.8, PCH2], 51.7 (s,
PCHCH), 52.1 [d, 1J(CP) 33.7, PCHSn], 127.0 (s, p-Ph), 128.7 [d, J(CP)
11.9, Ph], 130.6 [d, J(CP) 11.4, Ph], 127.0. 127.6, 131.8, 136.0 (s, C6H4),
142.8 (s, ipso-C6H4), 148.1 [d, 3J(CP) 4.5, C6H4]. 10a 31P{1H} NMR (thf):
d 64.2, 43.3. 13C NMR (CDCl3): d 34.2 [dd, 2J(CP) 10.2, 3J(CP) 3.4,
PCH2CH2], 34.7 [d, 1J(CP) 55.1, PCH2], 49.1 [d, 2J(CP) 7.8, PCHPh], 56.2
[dd, 1J(CP) 38.1, 1J(CP) 42.9, PCHP], 127.1, 128.9, 128.6, 128.4, 131.4,
131.3 (s, Ph), 127.5 [d, J(CP) 13.3, Ph], 128.2 [d, J(CP) 12.5, Ph], 130.8 [d,
J(CP) 2.5, Ph], 131.8 [d, J(CP) 9.4, Ph], 132.7 (s, ipso-Ph), 133.8 [d, J(CP)
9.8, ipso-Ph], 134.7 [d, J(CP) 11.6, Ph], 142.9 [d, J(CP) 8.5, ipso-Ph]. 12a
31P{1H} NMR (thf): d 62.8, 55.1 (5.1). 13C NMR (CDCl3): d 6.8 [d, 2J(CP)
4.0, PCH2CH3], 7.1 [d, 2J(CP) 3.8, PCH2CH3], 23.0 [d, 1J(CP) 52.4,
PCH2CH3], 25.9 [dd, 1J(CP) 49.7, 3J(CP) 4.8, PCH2CH3], 34.4 [d, 2J(CP)
11.3, PCH2CH2], 36.8 [d, 1J(CP) 54.1, PCH2], 50.0 [d, 2J(CP) 8.0, PCHPh],
55.1 [dd, 1J(CP) 36.4, 1J(CP) 36.4, PCHP], 128.1, 128.6, 129.4 (s, Ph),
130.3 [d, J(CP) 69.3, ipso-PPh2], 133.0 [d, J(CP) 2.8, Ph], 134.9 [d, J(CP)
11.4, Ph], 142.7 [d, J(CP) 11.6 ipso-PPh].
C(122)
S(1)
C(111)
C(224)
C(225)
C(23)
C(223)
C(121)
P(1)
C(22)
C(112)
C(222)
C(21)
C(1)
C(24)
C(221)
S(2)
C(2)
C(226)
P(2)
C(25)
C(26)
C(3)
C(4)
Fig. 1 Molecular structure (CAMERON6) of 12a with crystallographic
numbering scheme. Selected bond lengths (Å) and angles (°): P(2)–C(1)
1.84 (1), P(2)–C(4) 1.80 (1), C(1)–C(2) 1.56 (1), C(2)–C(3) 1.53 (1),
C(3)–C(4) 1.50 (2), P(2)–C(221) 1.82 (1); C(1)–P(2)–C(221) 112.8 (5),
P(2)–C(1)–C(2) 105.7 (6), P(2)–C(1)–P(1) 124.0 (5).
(η-C5H4But)
(η-C5H4But)
‡ The second disulfide adduct 10b arising from sulfurisation of 9b was not
isolated.
Zr
§ Crystal data for C20H26P2S2 12a: M = 392.49, monoclinic, space group
P21/n, a = 10.944 (1), b = 12.033 (2), c = 16.654 (1) Å, b = 107.114 (8)°,
U = 2096.3 Å3, Z = 4, Dc = 1.24 g cm23, m = 3.94 cm21. Crystal size:
0.35 3 0.15 3 0.35 mm, 1308 measured reflections (2740 independent),
Rav = 0.047, R = 0.0540, Rw = 0.070 from 1344 reflections with I >
1.5s(I). The data collection was performed at 293 K on a I.P.D.S. STOE
diffractometer using graphite-monochromated Mo-Ka radiation for the two
compounds. The structures were solved by direct methods using the
program SIR924 and subsequent Fourier maps. The refinement of models
were performed by using full-matrix least-squares techniques with the aid of
the package CRYSTALS.5 All hydrogen atoms were found on difference
Fourier maps but they were introduced as fixed contributors with
C–H = 0.96 Å and isotropic thermal parameters fixed 20% higher than
those of the carbon atoms to which they were attached their positions were
recalculated after each cyclic of refinement. For the two structures all non-
hydrogen atoms were anisotropically refined. Atomic coordinates, bond
lengths and angles, and thermal parameters have been deposited at the
Cambridge Crystallographic Data Centre (CCDC). See Information for
Authors, Issue No. 1. Any request to the CCDC for this material should
quote the full literature citation and the reference number 182/506.
P
heat
+ (η-C5H4But)2ZrPh2
Ph
3′
–PhH
P
Ph
1
Zr
P
Ph
(η-C5H4But)
(η-C5H4But)
3′′
Scheme 3
and no trace of 3A was detected (Scheme 3). These results can be
explained by considering that, whatever the steric hindrance
encountered on zirconium, the regioselectivity of the reaction of
zirconocene–benzyne complexes with phospholene 1 is gov-
erned by the transient formation of a zirconocene stabilized
phosphorus benzyne complex leading in the final products 3 and
3B to a P–Zr dative bond. Moreover, treatment of 3B with
PhSbCl2 also led to the formation of the stibaphospholane 4.
In conclusion, zirconaindane phospholanes 3 and 3B ap-
peared to be versatile reagents, leading to new mono- and tri-
cyclic heavier main group element compounds via disubsti-
tution reactions with ring retention (formation of 4–7) or
monosubstitution reactions with ring opening (formation of 10,
12).
References
1 See for example: L. D. Quin and A. N. Hughes, in The Chemistry of
Organophosphorus Compounds, ed. F. R. Hartley, Wiley, 1990, vol. 1,
ch. 10.
2 M. Zablocka, N. Ce´nac, A. Igau, B. Donnadieu, J.-P. Majoral,
A. Skowronska and P. Meunier, Organometallics, 1996, 15, 5436.
3 M. Zablocka, A. Igau, B. Donnadieu, J.-P. Majoral and A. Skowronska,
unpublished work.
4 SIR92, a Program for Automatic Solution of Crystal Structures by Direct
Methods. A. Altomore, G. Cascarano, G. Giacovazzo, A. Guargiardi,
M. C. Burla, G. Polidori and M. Camalli, J. Appl. Crystallogr., 1994, 27,
435.
Financial support of this work by the CNRS, France, and by
State Committee for Scientific Research, Poland (KBN grant
No. 3TO9A 03709), is gratefully acknowledged.
5 D. J. Watkin, C. K. Prout, R. J. Carruthers and P. Betteridge, CRYSTALS
Issue 10. Chemical Crystallography Laboratory, University of Oxford,
Oxford, UK, 1996.
6 D. J. Watkin, C. K. Prout and K. Pearce, CAMERON, Chemical
Crystallography Laboratory, University of Oxford, Oxford, 1996.
Footnotes
* E-mail: majoral@lcctoul.lcc-toulouse.fr
† 5 31P{1H} NMR (C6D6): d 61.9. 1H NMR (C6D6) (J/Hz): d 1.69–2.20 (m,
4 H, CH2), 3.26 [dd, J(HP) 8.0, J(HH) 6.1, 1 H, PCHSb], 3.97 (m, 1 H,
CH), 6.89–7.35, 7.75–7.87 (m, 9 H, Haryl). 13C NMR (CDCl3): d 34.8 [d,
2J(CP) 6.6, PCH2CH2], 36.6 [d, 1J(CP) 51.8, PCH2], 51.6 [d, 1J(CP) 46.6,
PCHSb], 58.1 [d, 2J(CP) 8.1, PCHCH], 126.1, 128.2, 128.9, 129.4 (s, Ph),
2
3
Received in Basel, Switzerland, 24th March 1997; Com.
7/02036H
1240
Chem. Commun., 1997