Synthesis of the first 2,3-dihydro-1,2,3-azadiphosphete complex

Article abstract of DOI:10.1039/b206233j

Synthesis of the first 2,3-dihydro-1,2,3-azadiphosphete complex was achieved via thermal reaction of a 2H-azaphosphirene complex in o-xylene, whereby a 2,5-dihydro-1,3-diaza-2,5-diphosphinine complex and a further unidentified byproduct were formed; the structure of the title compound was established through an X-ray singlecrystal diffraction study.

Full text of DOI:10.1039/b206233j

Synthesis of the first 2,3-dihydro-1,2,3-azadiphosphete complex†
E. Ionescu, P. G. Jones and R. Streubel*
Institut für Anorganische und Analytische Chemie der Technischen Universität Braunschweig, Postfach
3329, D-38023 Braunschweig, Germany. E-mail: r.streubel@tu-bs.de; Fax: +531 3915387
Received (in Cambridge, UK) 27th June 2002, Accepted 13th August 2002
First published as an Advance Article on the web 29th August 2002
1
Synthesis of the first 2,3-dihydro-1,2,3-azadiphosphete com-
complex 5 (295.5 (¡ J(183W,31P)¡ = 217.0 Hz) point to a
compound having a low-coordinated phosphorus centre;12
unfortunately, this product decomposed during chromatog-
raphy.
plex was achieved via thermal reaction of a 2H-azaphosphir-
ene
complex
in
o-xylene,
whereby
a
2,5-dihydro-1,3-diaza-2,5-diphosphinine complex and a fur-
ther unidentified byproduct were formed; the structure of
the title compound was established through an X-ray single-
crystal diffraction study.
It seems plausible that the primarily formed terminal
phosphinidene complex 7 reacts with complex 3 to yield the
betaine-type intermediate 8 in the first reaction step, which then
rearranges with loss of pentacarbonyltungsten to the final
product 4 (Scheme 3).cf.13–15
The composition of complex 4 in solution was unambigu-
ously deduced from NMR data.‡ The 31P{1H} and 13C{1H}
NMR data of complex 4 are characteristic of four-membered
phosphorus heterocycles such as 1,2-dihydro-1,2-diphos-
phetes.2 For example, the carbon atom of the imine moiety
The short communication of W. Mahler on the first synthesis of
1,2-dihydro-1,2-diphosphete and 1,2,3-triphospholene deriva-
tives1 is one of the landmarks in the chemistry of phosphorus
carbon heterocyclic chemistry.2 For example, the isomeric
C2P2R4 heterocycles I,1 II,3 III4 or IV5 (Scheme 1) have
fascinated phosphororganic and coordination chemists and
spurred experimental and theoretical studies, especially with
regard to rearrangements of I–IV. Surprisingly, none of the
related CNP2R3 heterocycles in which one CR moiety in I–IV
is replaced by a nitrogen atom has been experimentally or
theoretically investigated.
Scheme 1 Monocyclic isomers of C2P2R4 I–IV (lines denote organic or
elementorganic substituents).
Scheme 3 Proposed reaction course for the formation of the 2,3-dihydro-
1,2,3-azadiphosphete complex 4.
In previous studies, we showed that 2H-azaphosphirene
complexes are new versatile building blocks6 for unsaturated
phosphorus heterocycles. We also provided proof that two
highly reactive species were involved in such thermal reactions
in solution: electrophilic terminal phosphinidene complexes7
and nitrilium phosphane-ylide complexes.8 Very recently, we
reported the synthesis of the first 1,2,3,4-azatriphospholene
complex, having a heterocyclic ligand that is related to
compound 2.9
Here, we report the synthesis of complex 4, having the novel
2,3-dihydro-1,2,3-azadiphosphete as ligand, via thermal reac-
tion of the 2H-azaphosphirene complex 310 in o-xylene.
Complex 4 was obtained as the main product (ca. 45–50% as
determined by 31P NMR spectroscopy) together with complex 5
(ca. 20–25%) and the 2,5-dihydro-1,3-diaza-2,5-diphosphinine
complex 611 (ca. 20–25%) (Scheme 2). The NMR data of
Scheme 2 Reagents and conditions (i) 570 mg (0.92 mmol) of complex 3 in
2 mL of o-xylene, 90 °C, 20 min; column chromatography (SiO2, 250 °C,
n-pentane); 4: yellow solid, yield: 30%, mp 130 °C (decomp.).
Fig. 1 Molecular structure of 4 in the crystal (thermal ellipsoids at 30%
probability level; H atoms are omitted for clarity). Selected bond lengths
[Å] and angles [°]: P(1)–P(2) 2.2577(8), P(2)–C(13) 1.846(2), C(13)–N
1.304(3), N–P(1) 1.7473(18), P(1)–W 2.5257(6); N–P(1)–P(2) 78.51(6),
C(13)–P(2)–P(1) 69.92(7), N–C(13)–P(2) 107.80(15), C(13)–N–P(1)
101.26(14).
† This work is dedicated to Dr Hans-Martin Schiebel on the occasion of his
70th birthday.
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CHEM. COMMUN., 2002, 2204–2205
This journal is © The Royal Society of Chemistry 2002

1
shows a resonance (195.9 (dd, ¡ J(31P,13C)¡ = 33.6 Hz,
suppdata/cc/b2/b206233j/ for crystallographic files in CIF or other
electronic format.
¡ J(31P,13C)¡ = 12.6 Hz). These data are also similar to those of
1
PC(Ph)NN subunits in five-membered heterocycles, such as 2H-
1,4,2-diazaphosphole in complexes.16 The solid state structure
of complex 4 was determined by single-crystal X-ray diffraction
analysis (Fig. 1).§ The bis(trimethylsilyl)methyl groups adopt
trans positions at the slightly folded four-membered ring (N–
P(1)–P(2)–C(13) 8.9°), whereby the torsion angle for C(6)–
P(2)–P(1)–C(20) was determined to be 2136.9°.
1 W. Mahler, J. Am. Chem. Soc., 1964, 86, 2306.
2 F. Mathey (ed.), Chemistry of Phosphorus-Carbon Heterocyclic
Chemistry: The Rise of a New Domain, Pergamon, Amsterdam, 2001.
3 J. Grobe, D. Le Van, B. Broschk, M. Hegemann, B. Lüth, G. Becker, M.
Böhringer and E. Würthwein, J. Organomet. Chem., 1997, 529, 177.
4 M. Sanchez, R. Réau, C. J. Mardsen, M. Regitz and G. Bertrand, Chem.
Eur. J., 1999, 5, 274.
5 O. Schmidt, A. Fuchs, D. Gudat, M. Nieger, W. Hoffbauer, E. Niecke
and W. W. Schoeller, Angew. Chem., 1998, 110, 995; O. Schmidt, A.
Fuchs, D. Gudat, M. Nieger, W. Hoffbauer, E. Niecke and W. W.
Schoeller, Angew. Chem., Int. Ed., 1998, 37, 949.
6 For a review on 2H-azaphosphirene complexes: R. Streubel, Coord.
Chem. Rev., 2002, 227, 175.
We are grateful to the Deutsche Forschungsgemeinschaft and
the Fonds der Chemischen Industrie for financial support; Mr.
A. Weinkauf registered the X-ray data for 4.
Notes and references
‡ Elemental analysis for complex 4: calc: C 38.66, H 5.37, N 1.73; found:
C 38.48, H 5.44, N 1.71. NMR data were recorded in CDCl3 solutions (295
K) at 50.3 MHz (13C) and 81.0 MHz (31P), using TMS and 85% H3PO4 as
standard references; J/Hz. Selected spectroscopic data for 4: 13C{1H}
NMR: d 2.0 (s br, 2 3 SiMe3), 2.5 (s br, SiMe3), 3.3 (d, 3J(P,C) = 2.1 Hz,
SiMe3), 14.7 (dd, J(P,C) = 64.0 Hz, J(P,C) = 17.8 Hz, CH(SiMe3)2), 32.6
(dd, J(P,C) = 11.5 Hz, J(P,C) = 6.6 Hz, CH(SiMe3)2), 127.2 (d, J(P,C) =
2.8 Hz, Carom), 128.2 (d, J(P,C) = 3.5 Hz, Carom), 128.5 (s, Carom), 128.7 (s,
Carom), 132.2 (m, Carom), 138.1 (dd, J(P,C) = 20.9 Hz, J(P,C) = 24.9 Hz,
7 For recent reviews on terminal phosphinidene complexes: (a) K. B.
Dillon, F. Mathey and J. F. Nixon, in Phosphorus: The Carbon Copy,
Wiley, Chichester, 1998, p. 19; (b) K. Lammertsma and M. J. M. Vlaar,
Eur. J. Inorg. Chem., 2002, 1127.
8 For a review on nitrilium phosphane-ylide complexes: R. Streubel, Top.
Curr. Chem., 2002, in press.
9 N. Hoffmann, C. Wismach, P. G. Jones, R. Streubel, N. H. Tran Huy and
F. Mathey, Chem. Commun., 2002, 454.
10 R. Streubel, A. Ostrowski, S. Priemer, U. Rohde, J. Jeske and P. G.
Jones, Eur. J. Inorg. Chem., 1998, 257.
Carom), 195.9 (dd, J(P,C) = 33.6 Hz, J(P,C) = 12.6 Hz, PCNP), 197.8 (dd,
J(P,C) = 8.6 Hz, J(P,C) = 2.2 Hz, cis-CO), 199.6 (d, J(P,C) = 24.6 Hz,
11 R. Streubel, H. Wilkens, F. Ruthe and P. G. Jones, Chem. Commun.,
2000, 2453.
12 R. Appel, in Multiple Bonds and Low Coordination in Phosphorus
Chemistry, ed. M. Regitz and O. J. Scherer, Georg Thieme Verlag,
Stuttgart, 1990, p. 157.
13 A. Marinetti and F. Mathey, Organometallics, 1987, 6, 2189.
14 R. Streubel, L. Ernst, J. Jeske and P. G. Jones, J. Chem. Soc., Chem.
Commun., 1995, 2113.
15 N. H. Tran Huy, L. Ricard and F. Mathey, Heteroat. Chem., 1998, 9,
597.
3
trans-CO). 31P{1H} NM: d 78.7 (d, 1+3J(P,P) = 91.3 Hz, J(W,P) = 3.0
Hz), 79.8 (d, 1J(W,P) = 251.7 Hz).
§ Crystal structure determination of 4, C26H43NO5P2Si4W. Crystal data:
Monoclinic, space group P21/n, a = 14.7253(8), b = 13.0428(8), c =
18.8621(12) Å, b = 97.072(4)°, U = 3595.1 Å3, Z = 4, T = 2140 °C. Data
collection: a crystal ca. 0.14 3 0.13 3 0.08 mm was used to register 73721
intensities (Mo-Ka radiation, 2qmax 60°) on a ‘Bruker SMART 1000 CCD’
diffractometer. An absorption correction was performed with SADABS.
Structure refinement: the structure was refined anisotropically against F2
(program SHELXL-9717) to wR2 0.045, R1 0.022 for 364 parameters, 59
restraints (to displacement parameters of the light atoms) and 10522
independent reflections. Hydrogen atoms were included using a riding
model or rigid methyl groups. CCDC 188876. See http://www.rsc.org/
16 R. Streubel, H. Wilkens and P. G. Jones, Chem. Eur. J., 2000, 21,
3997.
17 G. M. Sheldrick, SHELXL-97, University of Göttingen, Germany,
1997.
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