Bis(trifluoromethyl)phosphane and bis(pentafluorophenyl)phosphane and their pentacarbonyl tungsten complexes: Improved synthesis and an experimental and density functional study

Article abstract of DOI:10.1021/ic034166n

The use of Bu₃SnH and Me₃SnH in the synthesis of HP(CF₃)₂ and HP(C₆F₅)₂ from the corresponding bromides leads to a high-yield synthesis, which additionally provides these compounds in large quantities. The pentacarbonyl tungsten complexes [W(CO)₅PH(CF₃)₂] and [W(CO)₅PH(C₆F₅)₂] were synthesized reacting the corresponding phosphanes with [W(CO)₅THF] and characterized by X-ray and elemental analysis as well as multinuclear NMR and mass spectroscopy. The vibrational analyses of HP(CF₃)₂ and HP(C₆F₅)₂ and their tungsten pentacarbonyl complexes were achieved in combination with hybrid DFT calculations. The optimized structures of [W(CO)₅PH-(CF₃)₂] and [W(CO)₅PH(C₆F₅)₂] at the B3PW91 level of theory using a LanL2DZ basis and ECP at the tungsten atom and a 6-311G(3d,p) and 6-311G(d,p) basis set for the nonmetal atoms, respectively, yield an impressively good agreement between experimental and theoretical geometric parameters. An increased π-acidity of HP(CF₃)₂ in comparison with HP(C₆F₅)₂ and HPPh₂ is discussed in the context of vibrational analysis, X-ray structural investigations, and theoretical calculations.

Full text of DOI:10.1021/ic034166n

Inorg. Chem. 2003, 42, 3623−3632
Bis(trifluoromethyl)phosphane and Bis(pentafluorophenyl)phosphane
and Their Pentacarbonyl Tungsten Complexes: Improved Synthesis and
an Experimental and Density Functional Study
Berthold Hoge,* Tobias Herrmann, Christoph Tho1sen, and Ingo Pantenburg
Institut fu¨r Anorganische Chemie, UniVersita¨t zu Ko¨ln, D-50939 Ko¨ln, Germany
Received February 14, 2003
The use of Bu3SnH and Me3SnH in the synthesis of HP(CF ) and HP(C F ) from the corresponding bromides
3 2
6 5 2
leads to a high-yield synthesis, which additionally provides these compounds in large quantities. The pentacarbonyl
tungsten complexes [W(CO)5PH(CF ) ] and [W(CO)5PH(C F ) ] were synthesized reacting the corresponding
3 2
6 5 2
phosphanes with [W(CO)5THF] and characterized by X-ray and elemental analysis as well as multinuclear NMR
and mass spectroscopy. The vibrational analyses of HP(CF ) and HP(C F ) and their tungsten pentacarbonyl
3 2
6 5 2
complexes were achieved in combination with hybrid DFT calculations. The optimized structures of [W(CO)5PH-
(CF ) ] and [W(CO)5PH(C F ) ] at the B3PW91 level of theory using a LanL2DZ basis and ECP at the tungsten
3 2
6 5 2
atom and a 6-311G(3d,p) and 6-311G(d,p) basis set for the nonmetal atoms, respectively, yield an impressively
good agreement between experimental and theoretical geometric parameters. An increased π-acidity of HP(CF )
3 2
in comparison with HP(C F ) and HPPh2 is discussed in the context of vibrational analysis, X-ray structural
6
5 2
investigations, and theoretical calculations.
Introduction
and elemental mercury in the presence of an excess of HI is
suitable for the synthesis of small quantities of HP(CF3)2.5
The reaction of (CF3)2PI with an excess of Me3SnH produces
larger amounts of HP(CF3)2 but requires a fractional con-
densation of the very air sensitive mixture.6
Bis(trifluoromethyl)phosphane, HP(CF3)2, and bis(pen-
tafluorophenyl)phosphane, HP(C6F5)2, are important com-
pounds for the synthesis of nucleophilic bis(trifluoromethyl)-
phosphanide and bis(pentafluorophenyl)phosphanide synthons,1
which are essential in the synthesis of chiral bidentate bis-
(perfluoroorganyl)phosphane ligands.
The synthesis of pentafluorophenylphosphanes is based
on the reaction of C6F5MgBr and phosphorus halides.7,8 Bis-
(pentafluorophenyl)phosphane was first synthesized by react-
8
Trifluoromethylphosphanes have been known since 1953
and have been synthesized by an autoclave reaction of white
phosphorus and CF3I.2 A more convenient access is based
on the Ruppert procedure3 which was improved for the
synthesis of Et2NP(CF3)2 by Ro¨schenthaler and co-workers.4
Several methods for the synthesis of bis(trifluoromethyl)-
phosphane have been published.5 The reaction of (CF3)2PI
ing (C6F5)2PX (X ) Cl, Br) with LiAlH4 in Et2O as a
solvent, followed by aqueous workup.9 A less practical
reaction is based on the reduction of (C6F5)2PCl with PH3
in a sealed glass tube.10
In this paper convenient, large-scale and high-yield
syntheses for HP(CF3)2 and HP(C6F5)2 are presented. Al-
(5) Cavell, R. G.; Dobbie, R. C. J. Chem. Soc. A 1967, 1308-1310 and
literature cited therein.
* Author to whom correspondence should be addressed. Fax: 049-221-
470-5196. E-mail: b.hoge@uni-koeln.de.
(6) Ansari, S.; Grobe, J. Z. Naturforsch. 1975, 30b, 651-652. Grobe, J.;
Le Van, D.; Demuth, R. J. Fluorine Chem. 1988, 39, 385-395.
(7) Wall, L. A.; Donadio, R. E.; Pummer, W. J. J. Am. Chem. Soc. 1960,
82, 4846-4848. Fild, M.; Glemser, O.; Christoph, G. Angew. Chem.
1960, 76, 953. Cowley, A. H.; Pinnell R. P. J. Am. Chem. Soc. 1966,
88, 4533-4534.
(1) (a) Hoge, B.; Tho¨sen, C. Inorg. Chem. 2001, 40, 3113-3116. (b) Hoge,
B.; Tho¨sen, C.; Pantenburg I. Inorg. Chem. 2001, 40, 3084-3088.
(c) Hoge, B.; Tho¨sen, C.; Herrmann, T.; Pantenburg I. Inorg. Chem.
2002, 41, 2260-2265.
(2) Bennett, F. W.; Emele´us, H. J.; Haszeldine, R. N. J. Chem. Soc. 1953,
1565-1571.
(3) Ruppert, W.; Ruppert, I. Tetrahedron Lett. 1983, 24, 5509-5512.
(4) Kolomeitsev, A.; Go¨rg, M.; Dieckbreder, U.; Lork, E.; Ro¨schenthaler,
G.-V. Phosphorus, Sulfur Silicon Relat. Elem. 1996, 109-110, 597-
600.
(8) Fild, D.; Glemser, O.; Hollenberg, I. Z. Naturforsch. 1966, 21B, 920-
923.
(9) Goerlich, J. R.; Plack, V.; Schmutzler, R. J. Fluorine Chem. 1996,
76, 29-35.
(10) Cooke, M.; Green, M.; Kirkpatrick, D. J. Chem. Soc. A 1968, 1507-
1510.
10.1021/ic034166n CCC: $25.00 © 2003 American Chemical Society
Published on Web 05/06/2003
Inorganic Chemistry, Vol. 42, No. 11, 2003 3623

Hoge et al.
mL of THF was added 5.03 g (13.7 mmol) of HP(C6F5)2. After
stirring for 10 h at room temperature, the red solution was
concentrated in vacuo, giving a green oily residue, which was
extracted with 200 mL of hexane. The pale green solution was
concentrated in vacuo and stored at -20 °C for 1 day, yielding
6.44 g (9.3 mmol, 68%) of colorless crystals (mp 87 °C, dec at 90
°C in a molten glass capillary). Single crystals were obtained by
sublimation at 65 °C in vacuo (5 × 10-4 mbar). Elemental anal.
(calcd for C17HF10O5PW): C 29.52 (29.59); H 0.25 (0.15). NMR
data (THF; rt): δ(31P) -100.1 ppm; δ(19Fo) -131.2 ppm (m, 2F);
δ(19Fm) -160.3 ppm (m, 2F); δ(19Fp) -148.5 ppm (m, 1F);
δ(13COtr) 196.3 ppm (d); δ(13COcis) 194.0 ppm (d); δ(13Ci) 103.6
ppm (m), δ(13Co/m) 146.5 ppm (d; 1J(FC) 251 Hz, m), respectively.
though HP(CF3)2 and HP(C6F5)2 have been known for a long
time, no X-ray structural data of these compounds or their
transition metal complexes have been reported. They are
described here in order to gain insight into the coordination
ability of these ligands.
Experimental Section
Materials and Apparatus. Chemicals were obtained from
commercial sources and used without further purification. Bromo-
bis(pentafluorophenyl)phosphane was synthesized by the reaction
of C6F5MgBr and PBr3 according to the literature procedure.8
Bromobis(trifluoromethyl)phosphane was synthesized by treating
neat (CF3)2PNEt24 with gaseous HBr at -78 °C. CAUTION! The
toxic compounds (CF3)2PBr and HP(CF3)2 react violently with air.
Solvents were purified by standard methods.11 Standard high-
vacuum techniques were employed throughout all preparative
procedures; nonvolatile compounds were handled in a dry N2
atmosphere by using Schlenk techniques.
Infrared spectra were recorded on a Nicolet-5PC-FT-IR spec-
trometer as KBr pellets or in a 10 cm gas cell. Raman spectra were
measured on a Bruker FRA-106/s spectrometer with a Nd:YAG
laser operating at λ ) 1064 nm.
The NMR spectra were recorded on Bruker model AMX 300
(13C, 75.47 MHz; 31P, 121.50 MHz; 19F, 282.35 MHz) and Bruker
AC200 spectrometers (31P, 81.01 MHz; 19F 188.31 MHz; 13C, 50.32
MHz; 1H, 200.13 MHz) with positive shifts being downfield from
the external standards 85% orthophosphoric acid (31P), CCl3F (19F),
and TMS (13C and 1H). Calculations of NMR spectra were carried
out with the program gNMR.12 Quantum chemical hybrid density
functional calculations were performed with the Gaussian 98
program package.13
1
1
137.6 ppm (d; J(FC) 258 Hz, m); δ(13Cp) 143.6 ppm (d; J(FC)
1
1
261 Hz, m); δ(1H) 7.6 ppm; J(PH) 380.5 Hz; J(WP) 249.9 Hz;
1J(W(13CO)tr) 174.6 Hz; 1J(W(13CO)cis) 125.6 Hz; 2J(P(13CO)tr) 29.6
Hz; J(P(13CO)cis) 5.7 Hz. Mass spectrum (EI, 20 eV) {m/z (%)
2
[assignment]}: 690 (18) [W(CO)5PH(C6F5)2]+; 662 (20) [W(CO)4PH-
(C6F5)2]+; 634 (18) [W(CO)3PH(C6F5)2]+; 606 (1) [W(CO)2PH-
(C6F5)2]+; 578 (3) [W(CO)PH(C6F5)2]+; 550 (3) [WPH(C6F5)2]+;
532 (100) [P(C6F5)3]+; 365 (17) [P(C6F5)2]+; 198 (8) [P(C6F5)]+.
Preparation of Bis(trifluoromethyl)phosphane. (CF3)2PBr
(7.33 g, 29.4 mmol) was condensed onto 9.90 g (34.0 mmol) of
Bu3SnH which was degassed in advance at room temperature in
vacuo. After stirring for 45 min at 0 °C, the only volatile compound
HP(CF3)2 was condensed into a stopcock vessel, yielding 4.984 g
(29.3 mmol, 99.9%) of HP(CF3)2 as a colorless liquid. NMR data
(CDCl3; rt): δ(1H) 5.3 (d, sep) ppm; δ(31P) -48.0 (d, sep) ppm;
1
δ(19F) -47.3 ppm (d, d); δ(13C) 128.5 ppm (q, mult); J(CF) 317
1
2
3
Hz; J(PH) 240.7 Hz; J(PF) 60.6 Hz; J(FH) 10.0 Hz.
PreparationofPentacarbonyl[bis(trifluoromethyl)phosphane]-
tungsten, [W(CO)5PH(CF3)2].15 HP(CF3)2 (2.55 g, 15.0 mmol) was
condensed onto a freshly prepared, intensely red solution of 4.80 g
(12.1 mmol) of [W(CO)5THF] in 200 mL of THF. After the mixture
was stirred for 10 h at room temperature, the red solution was
concentrated to 5 mL to give a green oil. The residue was extracted
with 200 mL of hexane. The slight green solution was concentrated
in vacuo and stored at -20 °C for 1 day, yielding 2.69 g (5.4 mmol,
45%) of colorless crystals. Single-crystals were obtained by
sublimation at room temperature in a nitrogen atmosphere. El-
emental anal. (calcd for C7HF6O5PW): H 0.28 (0.20); C 17.13
(17.02). NMR data (CDCl3): δ(31P) 1.7 ppm (d, sep); δ(19F) -54.9
ppm (d,d); δ(13COtr) 193.7 ppm (d); δ(13COcis) 191.4 ppm (d);
δ(13CF3) 124.5 ppm (q,d,q); δ(1H) 6.5 ppm; 1J(PH) 359.5 Hz;
1J(WP) 268.8 Hz; 1J(FC) 319.1 Hz; 1J(PC) 65.8 Hz; 1J(W(13CO)tr)
not observed; 1J(W(13CO)cis) 124.5 Hz; 2J(PF) 75.9 Hz; 2J(P(13CO)tr)
32.3 Hz; 2J(P(13CO)cis) 6.7 Hz; 3J(FC) 3.5 Hz; 3J(FH) 6.4 Hz. Mass
spectrum (EI, 20 eV) {m/z (%) [assignment]}: 494 (100)
[W(CO)5PH(CF3)2]+; 466 (8) [W(CO)4PH(CF3)2]+; 425 (6)
[W(CO)5PH(CF3)]+; 397 (7) [W(CO)4PH(CF3)]+; 369 (5) [W(CO)3-
PH(CF3)]+; 354 (16) [WPH(CF3)2]+; 324 (12) [W(CO)5]+; 296 (24)
[W(CO)4]+; 268 (22) [W(CO)3]+; 240 (4) [W(CO)2]+; 151 (15)
[HP(CF3)CF2]+; 131 (8) [CF3PCF]+; 113 (6) [CF3PCH]+; 69 (4)
[CF3]+.
Preparation of Bis(pentafluorophenyl)phosphane. Me3SnH
(1.98 g, 12.0 mmol) was condensed onto a solution of 4.33 g (9.7
mmol) of (C6F5)2PBr in 20 mL of hexane. The colorless solution
was stirred for 30 min at room temperature. Removal of all volatile
compounds in vacuo yielded 3.55 g (9.7 mmol, 100%) of HP(C6F5)2
as a white powder (mp 49-51 °C). Elemental anal. (calcd for C12-
HF10P): H 0.35 (0.28); C 39.26 (39.37). NMR data (CDCl3; rt):
δ(1H) 5.4 (d, quin) ppm; δ(31P) -137.7 (d) ppm; δ(19Fo) -128.3
ppm (m, 2F); δ(19Fm) -159.6 ppm (m, 2F); δ(19Fp) -149.3 ppm
4
1
(m, 1F); J(HF) 4.3 Hz; J(PH) 236.5 Hz. Mass spectrum (EI, 20
eV) {m/z (%) [assignment]}: 366 (98) [HP(C6F5)2+]; 198 (100)
[PC6F5+].
Preparation of Pentacarbonylbis(pentafluorophenyl)phos-
phanetungsten, [W(CO)5PH(C6F5)2].14 To a freshly prepared,
intensely red, solution of 6.00 g (15.1 mmol) [W(CO)5THF] in 200
(11) Perrin, D. D.; Armarego, W. L. F.; Perrin, D. R. Purification of
Laboratory Chemicals; Pergamon Press: Oxford, England, 1980.
(12) Budzelaar, P. H. M.; gNMR, version 4.1; Cherwell Scientific: Oxford,
U.K., 1998.
(13) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb,
M. A.; Cheeseman, J. R.; Zakrzewski, V. G.; Montgomery, J. A., Jr.;
Stratmann, R. E.; Burant, J. C.; Dapprich, S.; Millam, J. M.; Daniels,
A. D.; Kudin, K. N.; Strain, M. C.; Farkas, O.; Tomasi, J.; Barone,
V.; Cossi, M.; Cammi, R.; Mennucci, B.; Pomelli, C.; Adamo, C.;
Clifford, S.; Ochterski, J.; Petersson, G. A.; Ayala, P. Y.; Cui, Q.;
Morokuma, K.; Malick, D. K.; Rabuck, A. D.; Raghavachari, K.;
Foresman, J. B.; Cioslowski, J.; Ortiz, J. V.; Baboul, A. G.; Stefanov,
B. B.; Liu, G.; Liashenko, A.; Piskorz, P.; Komaromi, I.; Gomperts,
R.; Martin, R. L.; Fox, D. J.; Keith, T.; Al-Laham, M. A.; Peng, C.
Y.; Nanayakkara, A.; Gonzalez, C.; Challacombe, M.; Gill, P. M. W.;
Johnson, B.; Chen, W.; Wong, M. W.; Andres, J. L.; Gonzalez, C.;
Head-Gordon, M.; Replogle, E. S.; Pople, J. A. Gaussian 98, revision
A.9; Gaussian, Inc.: Pittsburgh, PA, 1998.
X-ray Crystallography. One suitable single crystal of each
compound was carefully selected under a polarizing microscope
and mounted in a glass capillary. The scattering intensities were
collected by an imaging plate diffractometer (IPDSII, STOE & CIE)
equipped with a normal focus, 1.75 kW, sealed tube X-ray source
(Mo KR, λ ) 71.073 pm) operating at 50 kV and 40 mA. Intensity
(14) Green, M.; Taunton-Rigby, A.; Stone, F. G. A. J. Chem. Soc. A 1968,
1875-1878.
(15) Grobe, J.; Le Van, D.; Meyring, W. Z. Anorg. Allg. Chem. 1990, 586,
149-158.
3624 Inorganic Chemistry, Vol. 42, No. 11, 2003

Bis(trifluoromethyl)- and Bis(pentafluorophenyl)phosphane
data for HP(C6F5)2 were collected at room temperature by ω-scans
in 100 frames (0° e ω e 180°, ψ ) 0°; 0° e ω e 20°, ψ ) 90°;
∆ω ) 2°, exposure time of 10 min) in the 2θ range 2.3-59.5°.
Intensity data for [W(CO)5PH(C6F5)2] were collected at 170 K by
ω-scans in 123 frames (0° e ω e 180°, ψ ) 0°; 0° e ω e 66°,
ψ ) 90°; ∆ω ) 2°, exposure time of 5 min) in the 2θ range 2.3-
59.5°. The intensity data for [W(CO)5PH(CF3)2] were collected at
260 K by ω-scans in 120 frames (0° e ω e 180°, ψ ) 0°; 0° e
ω e 60°, ψ ) 90°; ∆ω ) 2°, exposure time of 2 min) in the 2θ
range 2.3-59.5°. Cooling down to temperatures lower than 260 K
caused damage of the crystal, probably due to a phase transition.
Structure solutions and refinements were carried out using the
programs SHELXS-9716 and SHELXL-93.17 The H atom positions
were taken from the difference Fourier card at the end of the
refinement. Due to the presence of heavy atoms in the crystal
structures of [W(CO)5PH(C6F5)2] and [W(CO)5PH(CF3)2], numer-
ical absorption corrections were applied after optimization of the
crystal shapes (X-RED18 and X-SHAPE19). The last cycles of
refinement included atomic positions for all atoms, anisotropic
thermal parameters for all non-hydrogen atoms, and isotropic
thermal parameters for all hydrogen atoms. Details of the refine-
ments are given in Table 2.
gene phosphanes is striking. For example, Ph2PH melts at
-14 °C, 30 °C lower than Ph2PCl. The boiling point of Ph2-
PH is 40 °C lower than that of chlorodiphenylphosphane.
To find out whether intermolecular fluorine‚‚‚hydrogen
bridges are responsible for the unexpected higher melting
point of HP(C6F5)2 a structural investigation was undertaken.
Previous investigations showed that hybrid density func-
tional theory B3PW91 is a reliable tool for structural as well
as vibrational predictions for perfluoroorganyl phosphorus
derivatives.1a,c The experimental IR and Raman spectroscopic
data of HP(C6F5)2 are listed in Table 1 and compared to
theoretical data calculated at the B3PW91/6-311G(d,p) level
of theory. It should be noted that no vibrational data of HP-
(C6F5)2 have been previously published. The optimized
structure of HP(C6F5)2 exhibits a pyramidal arrangement
around the central phosphorus atom with the sum of bond
angles being 290.2°. The two C6 planes of the C6F5 rings
are twisted, as depicted in Figure 1, resulting in two rotational
enantiomers of the HP(C6F5)2 molecule. Depending on the
spatial difference of the two C6F5 groups, the theoretical
model predicts two sets of C6F5X fundamental vibrations.
Depending on the minor spatial difference of the two C6F5
groups, the two sets of C6F5X fundamentals could not be
completely resolved in the experimental spectra. To fit the
theoretical vibrational frequencies to experimental infrared
and Raman data, a scaling factor of 0.98 was used. After
this operation theoretical and experimental frequencies agreed
excellently, cf. Table 1. The P-H valence mode exhibits a
difference of less than 40 cm-1 between the predicted mode
of an isolated HP(C6F5)2 molecule and the experimental
frequency of polyatomic material, which might be interpreted
in terms of only weak intermolecular interactions.
Bis(pentafluorophenyl)phosphane sublimes upon gentle
warming (35 °C) on a water bath at a pressure of 5 × 10-4
mbar yielding colorless crystals. The X-ray structure analysis
results in a monoclinic space group (P21/c) with four HP-
(C6F5)2 molecules per unit cell, Table 2. The molecular
structure of HP(C6F5)2 is depicted in Figure 1, and selected
bond lengths and angles are listed in Table 3. The experi-
mental molecular dimensions of the HP(C6F5)2 molecule are
in good agreement with the optimized structure at the
B3PW91/6-311G(d,p) level of theory, for example, [calcu-
lated]/X-ray d(PH) [141.5]/142(16) pm, d(PC) [184.9]/183.2-
(6) pm; [184.8]/183.5(6) pm, d(CF)L [133.1]/134.5 pm,
(CPC) [99.9]/100.1(3)°. Even the calculated and experi-
mental CCPC dihedral angles, C21-P1-C11-C16 and
C11-P1-C21-C22, Figure 1, which specify the torsion of
the C6F5 groups, exhibit comparable values of [70.2]/66.2°
and [63.2]/65.1°, respectively. As to be expected for a
centrosymmetric space group, both rotational enantiomers
are present in the unit cell.
Results and Discussion
Several attempts to synthesize HP(C6F5)2 by reduction of
(C6F5)2PCl or (C6F5)2PBr with LiAlH4 gave H2PC6F5 as a
byproduct, even at -90 °C in THF solution. After filtration
and evaporation of the solvent, it was possible to remove
H2PC6F520 in vacuo, yielding crude HP(C6F5)2 contaminated
with lithium and aluminum salts. To remove the salt
contaminations, an aqueous workup was necessary as previ-
ously reported.9 Our own experiments revealed (C6F5)2P-
(O)H21 and (C6F5)2P(O)OH21,22 as major impurities after
aqueous workup. Therefore, we investigated the use of
triorganylstannanes, R3SnH, as reducing reagents. Due to its
different volatility, Me3SnH turned out to be the reagent of
choice for the transformation of (C6F5)2PBr into HP(C6F5)2.
The treatment of (C6F5)2PBr with an excess of Me3SnH in
hexane solution at room temperature selectively yields HP-
(C6F5)2. The product is obtained in a quantitative yield as
an analytically pure white powder, after evaporation of all
volatile compounds in vacuo.
rt
Me3SnH + (C6F5)2PBr hexane8 Me3SnBr + HP(C6F5)2
In comparison with (C6F5)2PBr or (C6F5)2PCl, which both
are liquids at room temperature, HP(C6F5)2 melts at 49-51
°C (lit.8 mp 52 °C). The higher melting point of this
phosphane compared with those of the corresponding halo-
(16) Sheldrick, G. M. SHELXS-97, Program for Crystal Structure Analysis;
University of Go¨ttingen: Go¨ttingen, 1998.
(17) Sheldrick, G. M. SHELXL-93, Program for the Refinement of Crystal
Structures; University of Go¨ttingen: Go¨ttingen, 1993.
(18) X-RED 1.22, STOE Data Reduction Program; Darmstadt, 2001.
(19) X-SHAPE 1.06, Crystal Optimization for Numerical Absorption
Correction; Darmstadt, 1999.
(20) Furin, G. G.; Krupoder, S. A.; Rezvukhin, A. I.; Kilina, T. M.;
Yakobson, G. G. J. Fluorine Chem. 1983, 22, 345-376.
(21) A selective synthesis combined with experimental and spectroscopic
data of (C6F5)2P(O)H and (C6F5)2P(O)OH will be published elsewhere.
(22) Oliver, K. W.; Rettig, S. J.; Thompson, R. C.; Trotter, J.; Xia, S. J.
Fluorine Chem. 1997, 83, 47-50.
The crystal structure of HP(C6F5)2 exhibits intermolecular
H‚‚‚F interactions (H1-F13′, cf. Figures 1-3) of 251(2) pm,
forming two sets of polymeric chains each with one rotational
enantiomer along the crystallographic axis b, Figure 2. Figure
3 depicts the unit cell in the a, c plane, looking along the
polymeric chains oriented on the b axis. The unit cell exhibits
a very tight packing of the polymeric chains, which are
Inorganic Chemistry, Vol. 42, No. 11, 2003 3625

Hoge et al.
Table 1. Calculated Vibrational Frequencies and Observed Infrared and Raman Spectra of Solid HP(C6F5)2 and the Data of the HP(C6F5)2 Moiety in
the Complex [W(CO)5PH(C6F5)2]a
a The vibrational frequencies of the W(CO)5 unit are summarized in Table 7. b B3PW91 functional and 6-311G(d,p) basis set, frequencies are scaled by
a factor of f ) 0.98. c Relative intensities are given. d B3PW91 functional and a LanL2DZ basis and ECP on tungsten and a 6-311G(d,p) basis set for the
nonmetal atoms. The frequencies are scaled by a factor of f ) 0.98.
geared by terminal C6F5 groups. The very good fit of the
polymeric chains may be the reason for the unexpected high
melting point of HP(C6F5)2 rather than the very weak
intermolecular H‚‚‚F contacts. This is also supported by the
3626 Inorganic Chemistry, Vol. 42, No. 11, 2003

Bis(trifluoromethyl)- and Bis(pentafluorophenyl)phosphane
Table 2. Crystal Data and Structure Refinement Parameters of
HP(C6F5)2 (I), [W(CO)5PH(C6F5)2] (II), and [W(CO)5PH(CF3)2] (III)
I
II
III
empirical formula HP(C6F5)2
[W(CO)5PH(C6F5)2] [W(CO)5PH(CF3)2]
cryst syst
space group
a [pm]
b [pm]
c [pm]
R [deg]
â [deg]
γ [deg]
vol [nm3]
Z
monoclinic
P21/c (No. 14) P21/n (No. 14)
939.0(4)
741.0(6)
1951.6(5)
monoclinic
triclinic
P1h (No. 2)
661.3(2)
708.4(2)
1545.5(4)
77.22(2)
89.87(2)
67.98(2)
0.6519(3)
2
1596.7(2)
747.8(1)
1715.1(3)
110.73(1)
107.36(1)
1.2700(13)
4
1.9544(5)
4
formula mass
366.10
1.915
0.335
690.00
2.345
6.116
493.90
2.516
9.069
F
calc [g cm-3
]
µ [mm-1
]
Figure 1. Molecular structure of HP(C6F5)2 and the atom-numbering
scheme; 50% probability amplitude displacement ellipsoids are shown.
abs correction
transm max/min
θ range [deg]
none
-/-
2.23-24.99
numerical
0.3942/0.6118
2.08-27.00
20001
numerical
0.1175/0.4299
2.71-29.58
7571
total data collected 5545
index range
-13 e h e 12 -20 e h e 22
-10 e k e 10 -8 e k e 10
-27 e l e 26 -23 e l e 23
-9 e h e 9
-8 e k e 9
-21 e l e 21
3492
unique data
obsd data
diffractometer
radiation
2199
813
4271
2789
1965
STOE image plate diffraction system
Mo KR (graphite monochromator, λ ) 71.073 pm)
temp [K]
Rmerg
298(2)
0.1163
170(2)
0.1000
260(2)
0.0550
R indexesa
[I > 2σ(I)]
R indexes
(all data)
R1 ) 0.0612
R1 ) 0.0321
R1 ) 0.0356
wR2 ) 0.0653
R1 ) 0.0832
wR2 ) 0.0749
0.949
0.799
186
452
-2.183/1.148
Figure 2. View showing a polymeric chain of HP(C6F5) molecules,
connected by H-F contacts.
wR2 ) 0.1307 wR2 ) 0.0411
R1 ) 0.1711 R1 ) 0.0660
wR2 ) 0.1876 wR2 ) 0.0453
1.163
0.876
213
analysis of the vibrational data in comparison with quantum
chemical calculations.
To exclude a probable influence of the intermolecular
H‚‚‚F interaction on geometric or vibrational data, a sterically
demanding group, i.e., pentacarbonyl tungsten, was coordi-
nated to HP(C6F5)2.
Bis(pentafluorophenyl)phosphane reacts with a freshly
prepared solution of [W(CO)5THF] in THF within 8 h at
room temperature to give [W(CO)5PH(C6F5)2].
GOF (Sobs
GOF (Sall
)
)
0.945
0.825
312
no. of variables
F(000)
712
1288
largest diff map
hole/peak
-0.253/0.284 -1.177/0.974
[e 10-6 pm-3
]
a R1 ) ∑||Fo| - |Fc||/∑|Fo|, wR2 ) [∑w(|Fo| - |Fc| )2/∑w(|Fo| )2]1/2
.
2
2
2
Table 3. Selected Bond Lengths (pm) and Angles (deg) of HP(C6F5)2
P1 H1 142(16)
P1 C11 183.2(6)
P1 C21 183.5(6)
F12 C12 134.7(7)
F13 C13 133.9(7)
F14 C14 134.6(7)
F15 C15 134.9(7)
F16 C16 136.0(7)
F22 C22 135.1(7)
F23 C23 136.1(8)
F24 C24 133.5(8)
F25 C25 132.9(7)
F26 C26 133.6(7)
C11 P1 C21 100.1(3)
C16 C11 C12 115.3(5)
C16 C11 P1 122.6(5)
C12 C11 P1 121.9(4)
F12 C12 C13 117.7(6)
F12 C12 C11 119.6(5)
C13 C12 C11 122.7(6)
F13 C13 C14 120.9(6)
F13 C13 C12 120.5(6)
C14 C13 C12 118.6(6)
F14 C14 C13 119.6(6)
F14 C14 C15 120.0(6)
C13 C14 C15 120.4(6)
F15 C15 C16 120.9(6)
F15 C15 C14 119.6(6)
C16 C15 C14 119.5(6)
C15 C16 F16 117.7(5)
C15 C16 C11 123.5(6)
F16 C16 C11 118.8(5)
C26 C21 C22 114.2(6)
C26 C21 P1 123.2(5)
C22 C21 P1 122.5(6)
rt
[W(CO)5THF] + HP(C6F5)2 THF8
THF + [W(CO)5PH(C6F5)2]
After removal of all volatiles and recrystallization from
hexane, colorless crystals of [W(CO)5PH(C6F5)2] were
isolated in 70% yield, whereas the thermal reaction of HP-
(C6F5)2 with W(CO)6 gave the monosubstituted complex in
only 34% yield.14 The product, [W(CO)5PH(C6F5)2], crystal-
lizes in the monoclinic space group, P21/n, Table 2. The
molecular structure of [W(CO)5PH(C6F5)2] is depicted in
Figure 4, and selected bond lengths and angles are sum-
marized in Table 4. The packing of the unit cell in the a, c
plane is shown in Figure 5. The crystal structure of
[W(CO)5PH(C6F5)2] exhibits no intermolecular H-F contacts
below 300 pm. Geometric data of the HP(C6F5)2 moiety in
the complex [W(CO)5PH(C6F5)2] are closely related to those
of crystalline HP(C6F5)2 and theoretical data of an isolated
molecule. Only the P-H distance in the complex [W(CO)5PH-
(C6F5)2] differs from the values for HP(C6F5)2, but it overlaps
within the error margin. Even the vibrational data of the HP-
(C6F5)2 moiety in the complex [W(CO)5PH(C6F5)2], Table
1, are nearly identical with those of HP(C6F5)2 and prove
that neither weak intermolecular H-F contacts in solid HP-
(C6F5)2 nor the complexation by tungsten pentacarbonyl has
a major influence on structural or vibrational data.
At first sight, the small difference between the P-H
valence mode of the complex [W(CO)5PH(C6F5)2] and solid
HP(C6F5)2 is surprising because the P-H valence mode of
Ph2PH is shifted by nearly 200 cm-1 to higher frequencies
by complexation with pentacarbonyl tungsten.23 Depending
on the σ-donation of electron density from the phosphorus
atom of Ph2PH to the metal center, a more strongly polarized
P-H bond results, indicated by a shift of the P-H valence
(23) Smith, J. G.; Thompson, D. T. J. Chem. Soc. A 1967, 1694-1697.
Inorganic Chemistry, Vol. 42, No. 11, 2003 3627

Hoge et al.
Figure 3. Unit cell packing of HP(C6F5)2 in the a, c plane.
Figure 5. Unit cell packing of [W(CO)5PH(C6F5)2] in the a, c plane.
W-P distance24 by about 5 pm in the corresponding tungsten
pentacarbonyl complexes and also is furthermore supported
by a shift of the C-O valence modes to higher frequencies.
The highest C-O valence mode of the complex [W(CO)5PH-
(C6F5)2] at 2183 cm-1 is shifted by about 10 cm-1 to higher
frequencies in comparison with [W(CO)5PHPh2].23
Figure 4. Molecular structure of [W(CO)5PH(C6F5)2] and the atom-
numbering scheme; 50% probability amplitude displacement ellipsoids are
shown.
Bis(trifluoromethyl)phosphane, commonly synthesized
from halogeno bis(trifluoromethyl)phosphanes and trimeth-
yltin hydride and isolated via fractional condensation, is
conveniently prepared by substitution of the volatile Me3-
SnH by the nonvolatile and commercially available Bu3SnH.
After the reaction of (CF3)2PBr with a slight excess of Bu3-
SnH at 0 °C without any solvent, pure HP(CF3)2 can be
removed from the reaction mixture in vacuo as the only
volatile compound in quantitative yield.
Table 4. Selected Bond Lengths (pm) and Angles (deg) of
[W(CO)5PH(C6F5)2]
P1 C21 182.7(6)
P1 C11 182.9(5)
P1 W1 247.7(1)
P1 H1 129(4)
W1 C51 201.1(6)
W1 C31 202.2(7)
W1 C71 202.3(7)
W1 C41 203.6(6)
W1 C61 205.1(7)
C31 O31 116.3(7)
C41 O41 115.7(6)
C51 O51 115.8(6)
C61 O61 113.6(7)
C71 O71 116.2(7)
C11 C16 138.7(7)
C11 C12 139.4(7)
C12 F12 134.4(6)
C12 C13 137.9(8)
C13 F13 134.0(6)
C13 C14 136.1(8)
C14 F14 134.5(6)
C14 C15 137.4(8)
C21 P1 C11 100.4(2)
C21 P1 W1 113.5(2)
C11 P1 W1 127.8(2)
C21 P1 H1 101(2)
F16 C16 C11 120.1(5)
C15 C16 C11 123.2(5)
C51 W1 C31 89.5(2)
C51 W1 C71 86.8(2)
C31 W1 C71 91.6(3)
C51 W1 C41 93.4(2)
C31 W1 C41 86.8(3)
C71 W1 C41 178.4(3)
C51 W1 C61 90.1(2)
C31 W1 C61 176.5(3)
C71 W1 C61 91.8(3)
C41 W1 C61 89.8(2)
C51 W1 P1 173.1(2)
C31 W1 P1
C71 W1 P1
C41 W1 P1
C61 W1 P1
O31 C31 W1 177.7(6)
O41 C41 W1 178.1(5)
O51 C51 W1 179.8(5)
O61 C61 W1 176.7(6)
O71 C71 W1 177.3(6)
C11 P1 H1
94(2)
W1 P1 H1 114(2)
C16 C11 C12 115.2(5)
C16 C11 P1 125.1(4)
C12 C11 P1 119.7(4)
F12 C12 C13 117.8(5)
F12 C12 C11 119.3(5)
C13 C12 C11 122.9(6)
F13 C13 C14 120.9(5)
F13 C13 C12 120.1(5)
C14 C13 C12 119.0(5)
F14 C14 C13 119.3(5)
F14 C14 C15 119.9(5)
C13 C14 C15 120.8(5)
F15 C15 C16 120.9(5)
F15 C15 C14 120.2(5)
C16 C15 C14 118.9(5)
F16 C16 C15 116.7(5)
Bu3SnH + (CF3)2PBr 0 °C8 Bu3SnBr + HP(CF3)2
neat
The experimental infrared and Raman data of HP(CF3)2
are identical with literature data25,26 and in excellent agree-
ment with theoretical data at the B3PW91/6-311G(3d,p) level
of theory without using a scaling factor, Table 5. Only the
calculated P-H valence mode deviates by about 80 cm-1
from the experimental value. The predicted geometric
parameters of HP(CF3)2 with Cs symmetry are as follows:
d(PH) 141.5 pm, d(PC) 188.8 pm, d(CF)L 134.0 pm, (CPC)
99.3°, ∑ (P) 287.5°. The assignment and approximate mode
description of the fundamental modes, as outlined in Table
5, are based on the calculated vibrational race and displace-
ment vectors, respectively.
87.7(2)
86.9(2)
92.7(1)
93.1(2)
mode to higher frequencies for the complex [W(CO)5PHPh2].
The π-back-bonding effect of Ph2PH does not compensate
the electron density transfer via the σ-donation. The increased
π-acidity of perfluoroorganyl phosphanes compensates the
electron transfer via the σ-donation from the phosphorus to
the metal atom. As a consequence, complexation by pen-
tacarbonyl group VI metals exhibits no significant influence
on structural and vibrational data of perfluoroorganyl phos-
phanes.
In analogy to bis(pentafluorophenyl)phosphane, bis(tri-
fluoromethyl)phosphane reacts with a freshly prepared solu-
(24) Reibenspies, J. H.; Darensborg, D.; Atnip, E. Z. Kristallogr. 1994,
209, 759-760.
(25) Bu¨rger, H.; Cichon, J.; Grobe, J.; Demuth, R. Spectrochim. Acta 1973,
29A, 47-54.
The increased π-acidic character of HP(C6F5)2 in com-
parison with Ph2PH is also indicated by a shortening of the
(26) Dobbie, R. C.; Straughan, B. P. J. Chem. Soc., Dalton Trans. 1973,
2754-2756.
3628 Inorganic Chemistry, Vol. 42, No. 11, 2003

Bis(trifluoromethyl)- and Bis(pentafluorophenyl)phosphane
Table 5. Calculated Vibrational Frequencies and Observed Infrared and Raman Spectra of HP(CF3)2 and the Data of the HP(CF3)2 Moiety in the
Complex [W(CO)5PH(CF3)2]a
a The vibrational frequencies of the W(CO)5 unit are summarized in Table 7. b B3PW91 functional and 6-311G(3d,p) basis set. c Relative intensities are
given. d B3PW91 functional and a LanL2DZ basis and ECP on tungsten and a 6-311G(3d,p) basis set for the nonmetal atoms.
tion of [W(CO)5THF] in THF within 8 h at room temperature
to [W(CO)5PH(CF3)2].
rt
[W(CO)5THF] + HP(CF3)2 THF8
THF + [W(CO)5PH(CF3)2]
Removal of all volatiles and recrystallization from hexane
results in colorless crystals of [W(CO)5PH(CF3)2] in 45%
yield. In contrast to neat HP(CF3)2, which reacts violently
with air, [W(CO)5PH(CF3)2] exhibits no reaction upon short
contact with air. In an earlier paper [W(CO)5PH(CF3)2] was
described as a thermal sensitive oil.15 However, no obvious
decomposition of the solid material was apparent during a
period of 2 weeks at room temperature. The erroneous notice,
that [W(CO)5PH(CF3)2] decomposes at 40 °C in vacuo, may
Figure 6. Molecular structure of [W(CO)5PH(CF3)2] and the atom-
numbering scheme; 50% probability amplitude displacement ellipsoids are
shown.
be attributed to the high sublimation pressure of the complex.
Colorless single crystals were obtained by room temper-
ature sublimation. The X-ray structure analysis results in a
triclinic space group, P1h, Table 2. The molecular structure
of [W(CO)5PH(CF3)2] is shown in Figure 6, and selected
bond lengths and angles are summarized in Table 6. The
unit cell packing in the a, c plane is depicted in Figure 7.
The complex molecules are oriented in such a manner that
they form fluorous layers in the a, b plane, with inter-
molecular H‚‚‚O contacts (H1-O18′, cf. Figures 6 and 7)
of 249(3) pm.
The vibrational frequencies of the HP(CF3)2 moiety in the
complex [W(CO)5PH(CF3)2] are comparable with those of
noncomplexed HP(CF3)2, except for the P-H valence and
one hydrogen deformation mode. The H-P-W deformation
mode of approximately A′ symmetry involves a back and
forth moving of the hydrogen atom to the tungsten atom,
while the hydrogen deformation mode of approximately A′′
symmetry involves a sidelong moving of the hydrogen atom
to the tungsten atom and is therefore less influenced in
comparison to noncomplexed HP(CF3)2. The PH valence
mode of HP(CF3)2 is shifted by around 30 cm-1 to higher
frequencies by complexation with tungsten pentacarbonyl.
This comparably small shift may be attributed to the
increased π-acidity of HP(CF3)2 as already discussed for the
corresponding Ph2PH and HP(C6F5)2 complexes.
The carbonyl stretching frequencies of [W(CO)5PH(C6F5)2]
and [W(CO)5PH(CF3)2] indicate a higher π-acidity of HP-
(CF3)2, as it is evaluated by an increased shift of the C-O
valence modes to higher frequencies, Table 7. The W-P
distances of [W(CO)5PH(C6F5)2] and [W(CO)5PH(CF3)2],
247.7 and 242.3 pm, respectively, agree with the increased
π-back-bonding effect for the HP(CF3)2 ligand.
The 31P NMR resonances of HP(C6F5)2 and HP(CF3)2 are
shifted by about 37 and 50 ppm, respectively, to lower field
by coordination to pentacarbonyl tungsten, while the 1J(PH)
Inorganic Chemistry, Vol. 42, No. 11, 2003 3629

Hoge et al.
Table 6. Selected Bond Lengths (pm) and Angles (deg) of
[W(CO)5PH(CF3)2]
W1 C14 200(1)
W1 C11 202(1)
W1 C13 203.0(7)
W1 C15 204(1)
W1 C12 204.9(7)
W1 P1 242.3(2)
C11 O11 115(1)
C12 O12 113.6(7)
C13 O13 113.4(8)
C14 O14 115(1)
C15 O15 114(1)
P1 C2 186.8(9)
P1 C1 188(1)
P1 H1 135(8)
C1 F13 130(1)
C1 F12 130(1)
C1 F11 133(1)
C2 F21 131(1)
C2 F22 131(1)
C2 F23 131.4(1)
C14 W1 C11 90.2(4)
C14 W1 C13 87.9(3)
C11 W1 C13 89.2(3)
C14 W1 C15 89.8(4)
C11 W1 C15 179.3(3)
C13 W1 C15 91.5(3)
C14 W1 C12 89.7(3)
C11 W1 C12 89.7(3)
C13 W1 C12 177.3(4)
C15 W1 C12 89.6(3)
C14 W1 P1 178.9(3)
C2 P1 C1
99.4(5)
C2 P1 W1 117.3(3)
C1 P1 W1 118.8(3)
C2 P1 H1 103(3)
C1 P1 H1
92(3)
W1 P1 H1 121(3)
F13 C1 F12 109(1)
F13 C1 F11 106.7(8)
F12 C1 F11 106.7(9)
F13 C1 P1 115.0(8)
F12 C1 P1 110.6(6)
F11 C1 P1 108.4(8)
F21 C2 F22 108.2(9)
F21 C2 F23 108(1)
F22 C2 F23 105.6(9)
F21 C2 P1 111.6(7)
F22 C2 P1 109.1(8)
F23 C2 P1 113.9(7)
C11 W1 P1
C13 W1 P1
C15 W1 P1
C12 W1 P1
90.5(3)
91.3(3)
89.4(3)
91.1(2)
O11 C11 W1 178.7(8)
O12 C12 W1 178.9(7)
O13 C13 W1 177.9(8)
O14 C14 W1 178.6(7)
O15 C15 W1 178.7(8)
coupling constant is increased by 144 and 119 Hz, respec-
tively. The 31P NMR spectrum of [W(CO)5PH(CF3)2] is
shown in Figure 8 (upper trace), compared with a calculated
spectrum in the lower trace, exhibiting a large doublet
splitting caused by the 1J(PH) coupling and a further septet
Figure 7. Unit cell packing of [W(CO)5PH(CF3)2] in the a, c plane
indicating O-H contacts of 249(3) pm.
(CF3)2] at the BP86 level of theory, using a LanL2DZ basis
and ECP at the tungsten atom and a 6-311G(d,p) and a
6-311G(3d,p) basis set, respectively, for the ligand atoms,
result in an unexpectedly good agreement between experi-
mental and calculated harmonic frequencies for the M(CO)5
moiety without the necessity of scaling factors, Table 7. On
the other hand, the calculated vibrational frequencies of the
phosphane ligands exhibit major deviations in comparison
to experimental data. The underlying optimized structures
overestimate the tungsten phosphorus and carbon phosphorus
distances by means of 5 and 3 pm, respectively.
2
splitting by the J(PF) coupling by two CF3 groups. Each
septet is surrounded by a set of tungsten satellites as well as
sets of 13C satellites. The iteration of the experimental
spectrum exhibits a 13C isotopic shift of the phosphorus
nuclei of ∆(δ(P(12C)2 - δ(P(12C13C)) ) 0.01 ppm to higher
field. The 13C NMR spectra of [W(CO)5PH(C6F5)2] and
[W(CO)5PH(CF3)2] exhibit each two resonances in the CO
region. One resonance of one CO group trans oriented to
2
the phosphorus containing ligand and a large trans J(PC)
The use of a Becke’s three-parameter functional with the
nonlocal Perdew-Wang 91 correlation (B3PW91) gives a
reasonably good agreement between experimental X-ray and
theoretical structures, using the same basis functionals and
ECP. The calculated bond lengths are slightly overestimated
and agree within a range of less than 3 pm with the
experimental value. The only exceptions are the P-H
distances for which experimental values are naturally un-
certain. The theoretical value of the P-H distance in
[W(CO)5PH(CF3)2] of 141.2 pm compares with the experi-
mental value of 135(8) pm within the error bars. Further
geometric parameters of the optimized structure of [W(CO)5-
PH(CF3)2] with C1 symmetry are as follows: [calculated]/
X-ray d(PW) [244.6]/242.3(2) pm, d(PC)L [189.4]/187.4 pm,
d(CF)L [133.6]/131.1 pm, d(WCtr) [202.5]/200(1) pm,
d(WCcis)L [205.4]/203.4 pm, d(CO)L [114.1]/114.2 pm,
(CPC) [100.0]/99.4(5)°, (CPW) [120.0]/118.8(3)°, and
[119.8]/117.3(3)°. The calculated structure of [W(CO)5PH-
(C6F5)2] with C1 symmetry is described by the following
data: [calculated]/X-ray d(PH) [140.8]/129(4) pm, d(PW)
[250.5]/247.7(1) pm, d(PC)L [184.4]/182.8 pm, d(CF)L
[132.9]/134.3 pm, d(WCtr) [201.1]/201.1(6) pm, d(WCcis)L
[204.8]/203.3 pm, d(CO)L [114.4]/115.5 pm, (CPC) [101.9]/
100.4(2)°, (CPW) [124.8]/127.8(2)°, and [118.3]/113.5(2)°.
The calculated values for the torsion of the C6F5 groups
toward the C11P1C21 plane are specified by the dihedral
angles C21-P1-C11-C12 and C11-P1-C21-C26. The
coupling of about 30 Hz and one resonance for the four CO
groups cis oriented, with a considerably smaller J(PC)
coupling of less than 10 Hz. The more intense 13C NMR
signals of the cis-oriented CO groups exhibit nearly equal
1J(WC) coupling constants of 125.6 and 124.5 Hz of the
C6F5 and CF3 derivative, respectively.
To assign the experimental vibrational spectra of the
pentacarbonyl tungsten complexes of HP(C6F5)2 and HP-
(CF3)2 we optimized their structures at different DFT levels.
The pioneering comprehensive study of monometal car-
bonyls by Jonas and Thiel found the BP86 functional to be
well suited for predictive purposes of vibrational and
geometric parameters.27 The BP86 functional tends to
underestimate the C-O stretching modes rather uniformly
by some 20-40 cm-1 while the M-C stretching modes were
accurate to within 20 cm-1.28 A recent study also uses this
method for mixed phosphane carbonyl group VI metal
complexes.29
2
Structural optimizations and frequency analysis of the
phosphane complexes [W(CO)5PH(C6F5)2] and [W(CO)5PH-
(27) For example: Jonas, V.; Thiel, W. J. Chem. Phys. 1995, 102, 8474-
8484. Jonas, V.; Thiel, W. J. Chem. Phys. 1996, 105, 3636-3648.
Jonas, V.; Thiel, W. Organometallics 1998, 17, 353-360. Jonas, V.;
Thiel, W. J. Phys. Chem. A 1999, 103, 1381-1393.
(28) Koch, W.; Holthausen, M. C. A Chemist’s Guide to Density Functional
Theory, 2nd ed.; Wiley-VCH: Weinheim, 2001; pp 130-136.
(29) Frenking, G.; Wichmann, K.; Fro¨hlich, N.; Grobe, J.; Golla, W.; Le
Van, D.; Krebs, B.; La¨ge, M. Organometallics 2002, 21, 2921-2930.
3630 Inorganic Chemistry, Vol. 42, No. 11, 2003

Bis(trifluoromethyl)- and Bis(pentafluorophenyl)phosphane
Table 7. Calculated Vibrational Frequencies on the BP86 and B3PW91 Levels of Theory and Observed Infrared and Raman Spectra of the W(CO)5
Unit of the Complexes [W(CO)5PH(CF3)2] and [W(CO)5PH(C6F5)2]
a LanL2DZ basis and ECP on tungsten and a 6-311G(3d,p) basis set for the nonmetal atoms. b Relative intensities are given. c LanL2DZ basis and ECP
on tungsten and a 6-311G(d,p) basis set for the nonmetal atoms.
Figure 8. Experimental (a, upper trace) and simulated (b, lower trace) proton decoupled 31P NMR spectrum of [W(CO)5PH(CF3)2].
comparison of the calculated values with experimental X-ray
values exhibits significant deviations: [77.7]/60.45(1)° and
[61.3]/57.91(1)°, respectively. This deviation is not surprising
because the torsions of the C6F5 groups are strongly affected
by packing effects.
If the B3PW91 functional is used, very good agreement
between calculated and experimental vibrational frequencies
of the phosphane ligands, and even the WC valence, the
WCO deformation, and CWC deformation frequencies of
the W(CO)5 moiety, is achieved. The only exceptions are
the CO valence modes, which are overestimated by 60-
100 wavenumbers. Scott and Radom, 1996, investigated the
performance of a variety of DFT functionals (BLYP, BP86,
B3LYP, B3P86, and B3PW91) and developed a set of scaling
factors for predicting vibrational frequencies. The use of
Becke’s one-parameter functionals BLYP and BP86 results
in vibrational frequencies close to experimental data, i.e.,
scaling factors of 0.9945 and 0.9914, respectively, while the
use of the Becke’s three-parameter functionals, B3LYP,
B3P86, and B3PW91, results in theoretical frequencies which
have to be fitted by scaling factors of around f ) 0.95.30
Using the scaling factor of 0.9573 for the B3PW91 functional
(30) Scott, A. P.; Radom, L. J. Phys. Chem. 1996, 100, 16502-16513.
Inorganic Chemistry, Vol. 42, No. 11, 2003 3631

Hoge et al.
with a 6-311G(d) basis, provided by Scott and Radom, we
found a very good agreement between experimental and
theoretical CO valence mode frequencies for the W(CO)5
moiety, Table 7. The W-P valence mode of the complex
[W(CO)5PH(CF3)2] could be assigned in the expected range31
at 210 cm-1 in the Raman spectrum, while the comparable
mode of the C6F5 derivative could not be assigned with
absolute certainty.
To achieve a better comparability of the calculated
frequencies of the phosphane ligands with the calculated
modes of the noncomplexed molecules, the frequencies of
the HP(CF3)2 ligand are listed as calculated in Table 5, while
the frequencies of the HP(C6F5)2 ligand are scaled by the
same scaling factor already used for the noncomplexed
molecule, Table 1. The theoretical vibrational modes of the
complexed phosphanes are nearly identical with those
calculated for the free molecules, as it is already observed
for the experimental data. The unexpected weak influence
on the P-H valence mode of HP(CF3)2 and HP(C6F5)2 by
complexation with tungsten pentacarbonyl is supported by
theoretical calculations. Additionally, as a result of the
increased π-acidity of HP(CF3)2 compared with HP(C6F5)2,
the calculated W-P distances of the pentacarbonyl tungsten
complexes are shortened by 5.9 pm (B3PW91) for the HP-
(CF3)2 derivative, which is in impressively good agreement
with the experimental value of 5.4 pm.
Acknowledgment. We are grateful to Prof. Dr. D.
Naumann for his generous support and the Fonds der
Chemischen Industrie for financial support. We thank Dr.
W. Tyrra and Dr. K. Glinka for helpful discussions. Dr. L.
Packschies is acknowledged for providing a Perl-script
program, g98 frequency finder.32
Supporting Information Available: Crystallographic files in
CIF format for the compounds HP(C6F5)2, [W(CO)5PH(C6F5)2], and
[W(CO)5PH(CF3)2]. This material is available free of charge via
the Internet at http://pubs.acs.org. Crystallographic data for the
structures of HP(C6F5)2, [W(CO)5PH(C6F5)2], and [W(CO)5PH-
(CF3)2] reported in this paper have been deposited with the
Cambridge Crystallographic Data Centre as supplementary publica-
tions CCDC-200227, CCDC-200228, and CCDC-200229, respec-
tively. Copies of the data can be obtained free of charge on
application to CCDC, 12 Union Road, Cambridge CB2 1EZ, U.K.
(fax, (+44)1223-336-033; e-mail, deposit@ccdc.cam.ac.uk).
(31) Guns, M. F.; Claeys, E. G.; van der Kelen, G. P. J. Mol. Struct. 1980,
65, 3-17.
(32) Program available at http://www.uni-koeln.de/themen/Chemie/software/
g98ff/.
IC034166N
3632 Inorganic Chemistry, Vol. 42, No. 11, 2003