Phosphinidene Complexes
COMMUNICATION
[3] K. D. Dillon, F. Mathey, J. F. Nixon, Phosphorus: The Carbon Copy,
Wiley, New York, 1998.
tained with ethylene either as buffer or as collision gas (see
the Supporting Information), and with 1,4-dioxene to yield
phosphirane 7a (Figure 3B).
The ESI-MS/MS experiments also offer insight into the
stability of the three-membered reaction products, which
may either undergo decomplexation of the transition-metal
group to afford unique phosphirane ligands[23] or serve as
precursors to phosphinidenes by [1+2] retroaddition.[24]
CID of mass-selected propene adduct 6a with 70 mTorr
argon caused complete loss of the W(CO)5 unit to render
metal-free phosphirane 8a (Figure 3C), thereby simultane-
ously confirming that 6a is not a loosely bound ion–mole-
cule complex. On the other hand, CID of bicyclic 7a with
argon gas led exclusively to regeneration of phosphinidene
3a by elimination of 1,4-dioxene (Figure 3D). These obser-
[7] a) A. Marinetti, F. Mathey, J. Fischer, A. Mitschler, J. Am. Chem.
[8] a) M. L. G. Borst, R. E. Bulo, C. W. Winkel, D. J. Gibney, A. W.
Ehlers, M. Schakel, M. Lutz, A. L. Spek, K. Lammertsma, J. Am.
D. J. Gibney, Y. Alem, F. J. J. de Kanter, A. W. Ehlers, M. Schakel,
vations are supported by B3PW91/6-311+GACTHUNRTGNEUNG(d,p) calcula-
tions (LANL2DZ for W)[15,16] that indicate a much higher
endothermicity for propene dissociation from 6a (36.0 kcal
molꢀ1) than liberation of 1,4-dioxene from 7a (22.0 kcal
molꢀ1), but an equally demanding demetalation of W(CO)5
from the PCC rings (6a: DE=34.0, 7a: 36.4 kcalmolꢀ1). Evi-
dently, the energy required for [1+2] retroaddition is
strongly dependent on the ring substituents, just as the
metal[25] and phosphorus substituents[24] can influence this
process, thereby pointing to new opportunities for the devel-
opment of efficient phosphinidene precursors.
[11] 31P NMR chemical shifts in acetonitrile at d=692.9 (R=Ph) and d=
766.4 ppm (R=Mes) have been attributed to the free, transient
ꢀ
phosphinidene [R P=W(CO)5], see: a) Y. G. Budnikova, T. V.
[12] We rather ascribed these signals (ref. [11]) to a base-stabilised phos-
In summary, the transient electrophilic phosphinidene
phinidene, namely P,N-ylide [(CO)5W(R)P N=CMe]; see for exam-
ꢀ
complex [R P=W(CO)5], carrying a cationic p-trimethylam-
6523–6524; for solvent adducts of nucleophilic phosphinidenes, see:
c) H. Aktas, J. Mulder, F. J. J. de Kanter, J. C. Slootweg, M. Schakel,
A. W. Ehlers, M. Lutz, A. L. Spek, K. Lammertsma, J. Am. Chem.
moniumphenyl substituent, was detected by gas-phase mass
spectrometric experiments and was shown to give [1+2] cy-
cloadducts with olefins. These observations, supported by
density functional calculations and solution-phase bench-
marking, give credence to the claimed intermediacy of neu-
tral phosphinidene complexes involved in the synthesis of
numerous organophosphorus compounds. The gas-phase
studies further illustrate that W(CO)5-complexed PCC-rings
can undergo demetalation or [1+2] retroaddition depending
on the nature of the phosphirane ring and its substituents,
which expands the chemistry of low-valent phosphorus inter-
mediates.
[13] F. Mathey, Multiple Bonds and Low Coordination in Phosphorus
Chemistry, Thieme, Stuttgart, 1990, p. 34.
[15] See the Supporting Information for details.
[16] Gaussian 03, Revision C.02, M. J. Frisch, G. W. Trucks, H. B. Schle-
gel, G. E. Scuseria, M. A. Robb, J. R. Cheeseman, J. A. Montgom-
AHCTUNGTREGeNNUN ry, Jr., T. Vreven, K. N. Kudin, J. C. Burant, J. M. Millam, S. S.
Iyengar, J. Tomasi, V. Barone, B. Mennucci, M. Cossi, G. Scalmani,
N. Rega, G. A. Petersson, H. Nakatsuji, M. Hada, M. Ehara, K.
Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda,
O. Kitao, H. Nakai, M. Klene, X. Li, J. E. Knox, H. P. Hratchian,
J. B. Cross, V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R. E.
Stratmann, O. Yazyev, A. J. Austin, R. Cammi, C. Pomelli, J. W.
Ochterski, P. Y. Ayala, K. Morokuma, G. A. Voth, P. Salvador, J. J.
Dannenberg, V. G. Zakrzewski, S. Dapprich, A. D. Daniels, M. C.
Strain, O. Farkas, D. K. Malick, A. D. Rabuck, K. Raghavachari,
J. B. Foresman, J. V. Ortiz, Q. Cui, A. G. Baboul, S. Clifford, J. Cio-
slowski, B. B. Stefanov, G. Liu, A. Liashenko, P. Piskorz, I. Komaro-
mi, R. L. Martin, D. J. Fox, T. Keith, M. A. Al-Laham, C. Y. Peng,
A. Nanayakkara, M. Challacombe, P. M. W. Gill, B. Johnson, W.
Chen, M. W. Wong, C. Gonzalez, J. A. Pople, Gaussian, Inc., Wall-
ingford CT, 2004.
Acknowledgements
This work was partially supported by the Council for Chemical Sciences
of the Netherlands Organisation for Scientific Research (NWO/CW). We
thank Dr. M. Smoluch and J. W. H. Peeters for measuring the high-reso-
lution mass spectra.
Keywords: carbenes · cycloaddition · phosphorus · tungsten
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cupied and lowest unoccupied molecular orbitals (HOMO and
Chem. Eur. J. 2010, 16, 1454 – 1458
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