fluorescence and dilute the amount of Raman scatterer present
(= number of scattering P5I2 cations per volume). Therefore the
Acknowledgements
ϩ
intensity of the signals in the spectrum is low. For comparison:
the 100% peak in the Raman spectrum of 3 spans only 0.1 Raman
units while P4 and PI3 with the same conditions (laser power, sample
sealed in NMR tube) have intensities of 3.0 to 5.0 Raman units for
their 100% bands. This shows that already very small impurities of
P4, PI3 or other intense Raman scatterers show in the obtained
spectrum.
We thank Prof. H. Schnöckel and Prof. J. Passmore for valuable
discussions and advice, Dipl. Chem. G. Stößer and Dipl. Chem.
J. Bahlo for recording the Raman spectra and H. Berberich and
Dr. E. Matern for recording the many low temperature NMR
spectra. Financial support from the German science foundation
DFG and the Fond der Chemischen Industrie are gratefully
acknowledged.
19 Excess P2I4 is insoluble at Ϫ90 ЊC and, therefore, invisible in the
31P-NMR at Ϫ90 ЊC.
20 We could independently verify this assignment by directly
synthesising and characterising P2I5[Al(OR)4]. We found that
P2I5ϩ[Al(OR)4]Ϫ is rapidly formed from 2 PI3 and Ag(CH2Cl2)-
[Al(OR)4], however, this is subject to ongoing research and will be
published elsewhere.
21 S. Pohl, Z. Anorg. Allg. Chem., 1983, 498, 20.
22 C. Aubauer, G. Engelhardt, T. M. Klapötke and A. Schulz, J. Chem.
Soc., Dalton Trans., 1999, 1729.
References and notes
1 (a) T. P. Martin, Z. Phys. D: At., Mol. Clusters, 1986, 3, 211;
(b) R. Huang, H. Li, Z. Lin and S. Yang, J. Phys. Chem., 1995,
99, 1418; (c) R. B. Huang, Z. Y. Liu, P. Zhang, Y. B. Zhu, F. C. Lin,
J. H. Zhao and L. S. Zheng, Chin. J. Struct. Chem., 1993, 180;
(d ) Z. Y. Liu, R. B. Huang and L. S. Zheng, Z. Phys. D: At., Mol.
Clusters, 1996, 38, 171.
23 M. Hesse, H. Maier and B. Zeeh, Spektroskopische Methoden in der
Organischen Chemie, 4th edn., 1991, Georg Thieme Verlag,
Stuttgart–New York, p. 96.
2 J. A. Zimmerman, S. B. H. Bach, C. H. Watson and J. R. Eyler,
J. Phys. Chem., 1990, 95, 98.
3 L.-S. Wang, B. Niu, Y. T. Lee and D. A. Shirley, J. Chem. Phys.,
1990, 93, 6318.
24 Although many crystals were tried and three full data sets were
recorded at 170 K none of them gave a fully satisfactory result and
the agreement factors were never better than 12.98%. However, the
crystal system and space group are well determined and the thermal
ellipsoids are normal. All trace electron density (about 1.0 to 1.3 e
4 (a) Pn and Pnϩ, n = 1–8, R. O. Jones and D. Hohl, J. Chem. Phys.,
1990, 92, 6710; (b) Pn and Pnϩ, n = 1–11, R. O. Jones and G. Seifert,
J. Chem. Phys., 1992, 96, 7564; (c) En and Enϩ, n = 1–11, E = P, As,
R. O. Jones and P. Ballone, J. Chem. Phys., 1994, 100, 4941.
5 See for example: (a) D. D. Wagman, W. H. Evans, V. B. Parker,
R. H. Schumm, I. Halow, S. M. Bailey, K. L. Churney and R. L.
Nuttal, J. Phys. Chem. Ref. Data, Suppl., 1982, 11, 2; (b) S. G. Lias,
J. E. Bartmess, J. F. Liebman, J. L. Holmes, R. D. Levin and
W. G. Mallard, J. Phys. Chem. Ref. Data, Suppl., 1988, 17, 1;
(c) CRC Handbook of Chemistry and Physics, 76th edn., editor-in-
chief D. R. Lide, CRC Press, Boca Raton, FL, 1986; (d ) http://
www.nist.gov/chemistry.
Å
Ϫ3) appeared in the vicinity of the 18 CF3 groups which suggested
manifold rotational disorder as the reason for the bad agreement
factors.
25 The Cl2P(CHCl2)2ϩ cation was fully optimised in C2 symmetry at the
MP2/TZVPP level and all structural parameters of the cation in 1
could be reproduced in the gas phase within ϩ0.02 Å and 1Њ, i.e. P–
Cl = 1.953 Å, P–C = 1.830 Å, C–Cl = 1.751, 1.758 Å, Cl–P–Cl =
110.9Њ, C–P–C = 110.4Њ. For energies see ref. 26.
ϩ
26 For the geometry of Cl2P(CHCl2)2 see ref. 25; total energy:
6 J. D. Corbett, in Progress in Inorganic Chemistry, vol. 21, editor
S. J. Lippard, John Wiley, New York, 1976, pp. 129–158.
7 S. M. Ivanova, B. G. Nolan, Y. Kobayashi, S. M. Miller, O. P.
Anderson and S. H. Strauss, Chem. Eur. J., 2001, 7, 503.
8 I. Krossing, Chem. Eur. J., 2001, 7, 490.
9 (a) I. Krossing, J. Am. Chem. Soc., 2001, 123, 4603; (b) I. Krossing
and L. van Wüllen, Chem. Eur. J., 2002, 8, 700.
Ϫ3176.10253 a.u., ZPE: 0.04672, G: Ϫ0.00544. CHCl3 (C3v):
d(C–H) = 1.087 Å; d(C–Cl) = 1.763 Å, total energy: Ϫ1417.71307
a.u.; ZPE = 0.02027, G = Ϫ0.01092.
27 S. Brownridge, H. D. B. Jenkins, I. Krossing, J. Passmore and
H. K. Roobottom, Coord. Chem. Rev., 2000, 197, 397.
28 J. A. Zimmerman, S. B. H. Bach, C. H. Watson and J. R. Eyler,
J. Chem. Phys., 1990, 95, 98.
10 I. Krossing and I. Raabe, Angew. Chem., 2001, 113, 4544.
11 Data employed for the Born–Fajans–Haber cycle calculations (all
enthalpies in kJ molϪ1): (a) Lattice potential enthalpies were taken
from the literature (AgI: 890.3)5c or estimated by Jenkins and
Passmore’s volume based modified Kapustinskii equation:12
Ag[Al(OR)4] = 364, P5[Al(OR)4] = 345, P3I6[Al(OR)4] = 334,
P2I5[Al(OR)4] = 340, P3I6[(RO)3Al–F–Al(OR)3] = 311, P2I5[(RO)3-
Al–F–Al(OR)3] = 314, P2I5[AlI4] = 398, P3I6[AlI4] = 386. The
29 It was shown convincingly that iodine substituents at tetra-
coordinate phosphorus atoms lead to a very pronounced upfield
shift due to relativistic spin–orbit coupling mediated to the nucleus
by an effective Fermi contact mechanism.30 Therefore only
relativistic 31P-NMR shifts give meaningful answers as may be
illustrated by the calculated non relativistic (NR) and relativistic (R)
ϩ 30
chemical shift of PI4
which differ by over 700 ppm: δ31PNR
=
ϩ211 and δ31PNR = Ϫ520! At present no routine for the standard
calculation of relativistic NMR shifts is implemented in the current
program codes.
Ϫ
Ϫ
thermochemical volume of Al(OR)4 is 725 Å3, Agϩ (4 Å3), AlI4
ϩ
ϩ
(244 Å3). The volumes of P5 [≈120 Å3, with S3N2ϩ(97) < P5
<
)
S3Cl3ϩ(146)],12 P2I5ϩ [=261 Å3, from V(P2I5AlI4) = 50521 and V(AlI4
30 M. Kaupp, C. Aubauer, G. Engelhardt, T. M. Klapötke and
O. Malkina, J. Chem. Phys., 1999, 110, 3897.
Ϫ
above], P3I6 [≈330 Å3, with V(P3I6ϩ) ≈ 1.5*V(P2I4)] and (RO)3Al–
ϩ
F–Al(OR)3 [=1129 Å3, from V(P3I6[(RO)3Al–F–Al(OR)3]) = 1459
31 A search of the chemical abstracts data base with Scifinder and the
Cambridge structural database CSD with the program Conquest
did not reveal a precedent for this P5-cage. However, similar C2v
symmetric MP4 units (i.e. M = Zr, Hf ) formally containing a
P42Ϫ unit are known (see ref. 34).
Ϫ
and V(P3I6ϩ) above] were assessed/estimated; (b) Enthalpies of
sublimation were taken from the literature (P4: 54.4, I2: 62.4) or were
assessed [P2I4: ∆Hsubl(P2I4) = 83.0; by computing the enthalpy of
reaction for the process: 0.5 P4 (g) ϩ 2 I2 (g)
P2I4 (g); ∆rH =
ϩ
Ϫ156.7 at the MP2/TZVPP level. ∆fH(P4 (g)), ∆fH(I2 (g)) (see below)
and ∆fH(P2I4 (s)) = Ϫ87.7 are known]; (c) Enthalpies of formation
were taken from the literature (Agϩ (g): 1017, IϪ (g): Ϫ188.6, P4
32 The chemical shifts of the naked or solvated P5 cation can be
meaningfully computed since it bears no heavy iodine atoms.
33 If not restrained by symmetry, the calculations always lead to C4v-
ϩ
ϩ
(g): 54.4, I2 (g): 62.4, P3 (g): 1006, AgI (g): 135) or assessed (P2I4
P5ϩ. Species containing C4v-P5 (and solvates) are true minima
(g): Ϫ4.7, MP2/TZVPP see above; P5ϩ (g): 913; see text).
12 H. K. Roobottom, H. D. B. Jenkins, J. Passmore and L. Glasser,
Inorg. Chem., 1999, 38, 3609.
without imaginary frequencies and are lower in relative energy.
34 O. J. Scherer, M. Swarowsky and G. Wolmershäuser, Angew. Chem.,
Int. Ed. Engl., 1988, 27, 694.
35 I. Krossing, Habilitation thesis, University of Karlsruhe, 2002.
36 C. Aubauer, M. Kaupp, T. M. Klapötke, H. Nöth, H. Pietrowski,
W. Schnick and J. Senker, J. Chem. Soc., Dalton Trans., 2001, 1880.
37 J. E. Huheey, Inorganic Chemistry, 4th edn., Harper and Collins,
New York, 1993.
13 We optimised the known4 global minima of the Pnϩ cations (n = 3, 5,
7) at the BP86/SVP, B3LYP/TZVPP and MP2/TZVPP levels and
also calculated the vibrational frequencies and Raman intensities
(only BP86) of these species. The observed new P–P stretches (480
to 630 cmϪ1) fell into a range calculated to be typical for these
cations.
38 H. Schnöckel and S. Schunck, Phosphorus, Sulfur, Silicon Relat.
Elem., 1988, 39, 89.
14 Zdirad Zak and M. Cernik, Acta Crystallogr., Sect. C, 1996, 52,
290.
39 Solvation energies were obtained from the MP2/TZVPP geometries
using the COSMO model at the BP86/SVP level and dielectric
constants for CS2 and CH2Cl2 of 2.63 and 8.92 respectively.
40 Thermal and entropic contributions to the enthalpy and free energy
were obtained by fully optimising all the species in question with
Gaussian98W at the semiempirical PM3 level. All these species also
represented true minima without imaginary frequencies at the PM3
level. ZPE’s were taken from the MP2 calculation. Since statistical
15 Similarly CS2 was used to remove excess S8 in highly electrophilic
and oxidising sulfur cation or S2Nϩ chemistry.
16 We showed that solid P4 is also visible in a conventional solution
NMR spectrometer due to the high local symmetry of the cubic
solid P4 (see ref. 9b).
17 B. W. Tattershall and N. L. Kendall, Polyhedron, 1994, 13, 1517.
Ϫ
18 As observed earlier, large counterions such as Al(OR)4 lead to
J. Chem. Soc., Dalton Trans., 2002, 500–512
511