Step Dance on a Pentagon: Copper(I) and Copper(I)-Tungsten(0) Triphospholyl Triphenylphosphane Complexes

Article abstract of DOI:10.1021/om030570i

[(3,5-di-teri-butyl-1,2,4-triphospholyl)Cu(PPh₃)] (8) is, in contrast to the related dinieric complex [(3,5-di-teri-butyl-1,2,4- triphospholyl)Cu(PMe₃)₂]₂, monomeric and thighly fluxional in solution. 3 is synthesized from the corresponding trimethylstannyl 1,2,4-triphosphole la and [ClCu(PPh₃)]₄. Evidence for a three-sided rearrangement process between different molecular structures in solution could be obtained from dynamic ³¹P NMR spectroscopy. An η⁵-π coordination mode (3a) of the copper ion is preferred at room temperature. The equilibrium shifts to the two spectroscopically distinguishable, but almost isoenergetic, σ complexes 3b and 3c at low temperature, which interconvert with the activation barrier ΔG? = 37 kJ/mol. The σ-donor orbitals of the triphospholyl ligand are believed to be an sp³ hybrid P orbital in the case of 3b and an sp² P lone pair for 3c. The reaction of 3 with [(THF)W(CO)₅] leads to the binuclear CuW complex 4 and the trinuclear W²Cu complex 5 with σ-phosphorus-coordinated W(CO)⁵ moieties. 5 bears an additional η⁵-π coordinated W(CO) ₃ unit and a unique W-Cu-P bridge, as established by X-ray crystallography. Both complexes are fluxional in solution, and the activation barriers of their rearrangement processes have been established.

Full text of DOI:10.1021/om030570i

Organometallics 2004, 23, 1689-1697
1689
Step Da n ce on a P en ta gon : Cop p er (I) a n d
Cop p er (I)-Tu n gsten (0) Tr ip h osp h olyl
Tr ip h en ylp h osp h a n e Com p lexes†
Frank W. Heinemann, Matthias Zeller,‡ and Ulrich Zenneck*
Institut fu¨r Anorganische Chemie, Universita¨t Erlangen-Nu¨rnberg, Egerlandstrasse 1,
91058 Erlangen, Germany
Received August 8, 2003
[(3,5-di-tert-butyl-1,2,4-triphospholyl)Cu(PPh3)] (3) is, in contrast to the related dimeric
complex [(3,5-di-tert-butyl-1,2,4-triphospholyl)Cu(PMe3)2]2, monomeric and highly fluxional
in solution. 3 is synthesized from the corresponding trimethylstannyl 1,2,4-triphosphole 1a
and [ClCu(PPh3)]4. Evidence for a three-sided rearrangement process between different
molecular structures in solution could be obtained from dynamic 31P NMR spectroscopy. An
η5-π coordination mode (3a ) of the copper ion is preferred at room temperature. The
equilibrium shifts to the two spectroscopically distinguishable, but almost isoenergetic, σ
complexes 3b and 3c at low temperature, which interconvert with the activation barrier
∆Gq ) 37 kJ /mol. The σ-donor orbitals of the triphospholyl ligand are believed to be an sp3
hybrid P orbital in the case of 3b and an sp2 P lone pair for 3c. The reaction of 3 with
[(THF)W(CO)5] leads to the binuclear CuW complex 4 and the trinuclear W2Cu complex 5
with σ-phosphorus-coordinated W(CO)5 moieties. 5 bears an additional η5-π coordinated
W(CO)3 unit and a unique W-Cu-P bridge, as established by X-ray crystallography. Both
complexes are fluxional in solution, and the activation barriers of their rearrangement
processes have been established.
In tr od u ction
examples, the heterocycles cannot be viewed as simple
analogues of their carbocyclic parent compounds any
longer.
Phosphorus atoms can be incorporated in unsaturated
heterocycles to replace CR fragments as isovalent and
isolobal building blocks, which results in the formation
of numerous organophosphorus and organometallic
phosphorus compounds in which the phosphorus atom
can often be viewed as a close relative of the element
carbon.1 On the other hand, each phosphorus atom
supplies a lone pair to the ring molecules, causes a
decrease of the frontier π-orbital energies, and expands
its ring size with respect to the pure carbon ring
analogues. All three aspects modify the ligand proper-
ties of such heterocycles; however, the differences are
not dominant for compounds having less than half of
the CR fragments substituted by phosphorus atoms.
That changes significantly when the number of ring
phosphorus atoms equals or exceeds that of the carbon
atoms as in the case of 1,3,5-triphosphinine,1b-d 1,2,4-
triphospholyl,3-7 or 1,3-diphosphete2 ligands. In these
Unlike cyclopentadienyl (Cp) derivatives, not only are
the ligand properties of 1,2,4-triphospholyl ligands
therefore governed by the delocalized π-system but also
the phosphorus lone pairs play a comparably active role.
In principle, they can be utilized independently from
the π-electrons as phosphine-like σ-donor functions
toward metal centers. On the other hand, they allow
intra- and intermolecular σ-/π-rearrangement processes
with low activation barriers. The 1,5-sigmatropic shift
of the tin atoms of triorganylstannyl-1,2,4-triphosphole
derivatives (1), for example, requires an activation
energy of only 31 kJ mol-1,3 and a related rearrange-
ment for bis(1,2,4-triphospholyl)mercury occurs even in
the solid state.4 Novel structural features have been
observed for the molecular structures of 1,2,4-triphos-
pholyl complexes of Ni, Pd, and Pt, which are not known
for Cp ligands. This includes a reversible equilibrium
(2) Topf, C.; Clark, T.; Heinemann, F. W.; Hennemann, M.; Kummer,
S.; Pritzkow, H.; Zenneck, U. Angew. Chem. 2002, 114, 4221-4226;
Angew. Chem., Int. Ed. 2002, 41, 4047-4052.
* To whom correspondence should be addressed. Fax: Int. code
+(9131)852-7367. E-mail: zenneck@chemie.uni-erlangen.de.
† Dedicated in honor of Professor Dr. Otto Scherer on the occasion
of his 70th birthday.
(3) Elvers, A.; Heinemann, F. W.; Wrackmeyer, B.; Zenneck, U.
Chem. Eur. J . 1999, 5(11), 3143-3153.
‡ Current address: Youngstown State University, Department of
Chemistry, 1 University Plaza, Youngstown, OH 44555-3663. E-mail:
mzeller@cc.ysu.edu.
(4) Al-Ktaifani, M. M.; Bauer, W.; Bergstra¨sser, U.; Breit, B.;
Francis, M. D.; Heinemann, F. W.; Hitchcock, P. B.; Mack, A.; Nixon,
J . F.; Pritzkow, H.; Regitz, M.; Zeller, M.; Zenneck, U. Chem. Eur. J .
2002, 8, 2622-2633.
(1) (a) Dillon, K. B.; Mathey, F.; Nixon, J . F. Phosphorus, The Carbon
Copy; Wiley: Chichester, U.K., 1998. (b) Vlaar, M. J . M.; Ehlers, A.
W.; Schakel, M.; Clendenning, S. B.; Nixon, J . F.; Lutz, M.; Spek, A.
L.; Lammertsma, K. Angew. Chem., Int. Ed. 2001, 40(23), 4412-4415.
(c) Peters, C.; Disteldorf, H.; Fuchs, E.; Werner, S.; Stutzmann, S.;
Bruckmann, J .; Kruger, C.; Binger, P.; Heydt, H.; Regitz, M. Eur. J .
Org. Chem. 2001, 18, 3425-3435. (d) Hofmann, M.; Schleyer, P. v. R.;
Regitz, M. Eur. J . Org. Chem. 1999, 12, 3291-3303.
(5) Heinemann, F. W.; Pritzkow, H.; Zeller, M.; Zenneck, U. Orga-
nometallics 2000, 19, 4283-4288.
(6) Heinemann, F. W.; Hofmann, M.; Zenneck, U. J . Organomet.
Chem. 2002, 643-644, 357-362.
(7) Clark, T.; Heinemann, F. W.; Hennemann, M.; Zeller, M.;
Zenneck, U. Angew. Chem. 2000, 112, 2174-2178; Angew. Chem., Int.
Ed. 2000, 39, 2087-2091.
10.1021/om030570i CCC: $27.50 © 2004 American Chemical Society
Publication on Web 03/19/2004

1690 Organometallics, Vol. 23, No. 8, 2004
Heinemann et al.
Sch em e 1
Sch em e 2
crystalline material of 3 failed up to now. Room-
temperature 1H NMR spectra of 3 exhibit phenyl
multiplets and one sharp tert-butyl resonance. The 13C
between a Ni σ-complex dimer and its mononuclear
π-derivative.5 The removal of only one phosphorus atom
from the triphospholyl ring skips these effects almost
completely. Neither triorganylstannyl-1,3-diphospholes
nor (η5-1,3-diphospholyl)copper triphenylphosphine shows
any sign of dynamic effects at ambient temperature.8
With the aim of learning more about the specific
ligand properties of the 3,5-di-tert-butyl-1,2,4-triphos-
pholyl ligand, we investigated its complex chemistry
with respect to the coinage metals gold and copper. In
a first communication on the gold complexes, we re-
ported about highly dynamic mixtures of interchanging
isomers of [(3,5-di-tert-butyl-1,2,4-triphospholyl)Au-
(PPh3)] in solution. In the solid state we observe the
extremely asymmetric σ-complex dimer [(3,5-di-tert-
butyl-1,2,4-triphospholyl)Au(PPh3)]2 (2) with a remark-
able range of different metal-triphospholyl interac-
tions6 (Scheme 1).
If the PPh3 ligand is just replaced by PEt3, a com-
pletely different dinuclear species, [{Au(PEt3)2}{Au(3,5-
di-tert-butyl-1,2,4-triphospholyl)2}], is observed in the
solid state.9 These results indicate shallow energetic
minima for 1,2,4-triphospholyl gold species. Packing
might influence the molecular structures in the solid
state, and several monomer-dimer and monomer-
monomer equilibria exist for 2 in solution which are too
complex to be analyzed unambiguously by NMR tech-
niques. Nixon and co-workers reported about two static
binuclear (µ,σ-3,5-di-tert-butyl-1,2,4-triphospholyl)nCu2-
(PMe3)4 (n ) 1, 2) complexes,9 whose L2M(µ,σ-1,2,4-
triphospholyl)ML2 moieties are isostructural with the
dimeric Ni(II) species [(µ,σ-3,5-di-tert-butyl-1,2,4-tri-
phospholyl)2Ni2(NO)2(PPh3)2].5
NMR signals of the triphospholyl ligand are split by 31
P
coupling into pseudotriplets. These findings are in line
with both a symmetrical η5-coordinated or a highly
fluxional η1-coordinated triphospholyl ligand. The 31P-
{1H} NMR spectrum consists of three signals at 204,
1
188, and 8 ppm, respectively. Unlike H and 13C NMR,
the room-temperature 31P{1H} NMR signals of 3 indi-
cate dynamic processes on the time scale of NMR
spectroscopy, as they are significantly broadened. Vari-
able-temperature 31P{1H} NMR measurements proved
this assumption. Slow-exchange-limit spectra of two
different η1 isomers are observable at low temperatures
(Figure 1).
When the sample is warmed to +48 °C, the general
appearance of the spectrum remains constant, but the
2
line width decreases and a J P,P coupling between the
two types of ring phosphorus atoms becomes visible. Its
value of 55 Hz gives a hint of the significant participa-
tion of a η5 coordination mode (3a ) with a delocalized π
system at elevated temperatures. The position of the
two triphospholyl signals around 200 ppm are compat-
ible with this assumption as well. In contrast to that,
the room-temperature observations in solution for the
known 1,2,4-triphospholyl Au(I) and Cu(I) complexes
strongly favor η1-bonding modes of the heterocycle.6,9
When the 31P NMR sample is cooled, the line widths
of the signals increase and reach a maximum around
-10 °C. At lower temperatures, new signals grow in and
those which are observable at the high-temperature lose
intensity, move slightly, and sharpen at the same time.
At -70 °C they are no longer broadened and, as
expected for a pure η5-bonding mode, the doublet and
triplet signals of an AB2 partial spin system are
observed for the ring phosphorus atoms (2J P,P ) 49.6
Hz) while the PPh3 signal remains unsplit.
In this paper we report on our results on the prepara-
tion and dynamic NMR spectroscopy of a monomeric
copper analogue of 2, [(3,5-di-tert-butyl-1,2,4-triphos-
pholyl)Cu(PPh3)] (3). With the aim of reducing the
highly dynamic effects of 3 in solution by blocking the
phosphorus lone pairs, we utilized it as a ligand of
tungsten carbonyl complexes. To our surprise, the
resulting di- and trinuclear bimetallic CuW complexes
are as fluxional as mononuclear 3.
Around -30 °C a new set of resonances arises, which
form an AB2X spin system as well. The A and B signals
of this set are separated by almost 100 ppm, and the A
resonance is shifted to a remarkably low field value (277
ppm). Related chemical shifts are indicative of phos-
phaalkenes. A fluxional η1-coordination of the copper
atom would be in line with the data. As proven for
triorganylstannyl triphospholes (1), a fast 1,5-sigma-
tropic rearrangement of the metal can explain this part
of the observations. If so, the AB2X spin system should
be transformed into an ABCX system at very low
temperature. This is indeed the case; however, two
ABCX sets of the same intensity are observed at -90
°C and the AB2X spin system of η5 complex 3a is present
at this temperature in only very small intensity. The
two ABCX spin system signals are relatively broad;
Resu lts
The target complex [(3,5-di-tert-butyl-1,2,4-triphos-
pholyl)Cu(PPh3)] (3) is formed in good yield through the
reaction of 1-Me3Sn-3,5-di-tert-butyl-1,2,4-triphosphole
(1a ) with the tetrameric copper complex [ClCu(PPh3)]4
(Scheme 2).
The triphospholyl complex 3 forms orange to yellow
microcrystalline solids. All attempts to prepare single-
(8) Zeller, M. Ph.D. Thesis, University of Erlangen-Nu¨rnberg, 2000.
(9) Al-Ktaifani, M. M.; Hitchcock, P. B.; Nixon, J . F. J . Organomet.
Chem. 2003, 665, 101-106.
1
thus, only one J PP coupling of approximately 357 Hz is

CuI Triphospholyl Triphenylphosphane Complexes
Organometallics, Vol. 23, No. 8, 2004 1691
F igu r e 1. Variable-temperature 31P{1H} NMR spectra of 3 (161.7 MHz, [D8]toluene).
resolved. Two of the signals arising from the loss of
equivalence of the two neighboring P ring atoms are not
detectable between -50 and -70 °C, a hint of an
additional dynamic process.
a free delocalized π6 system as in 3c is impossible for
cyclopentadienyl ligands but requires a phosphorus
atom or another element with a lone pair as a ring
element. Examples of the postulated structure type 3c
have been characterized for some triphospholyl Pt and
Pd11 complexes. Dimeric Ni(II) and Cu(II) triphospholyl
complexes share the σ M-L interaction and the delo-
calized π system.5,9
The kinetic and thermodynamic parameters, which
can be extracted from the observed coalescence temper-
atures and the relative concentrations of the three
isomers 3a -c, give hints in the same direction (Scheme
3). The activation energy for the 1,5-sigmatropic shift
of the copper atom of 3b can be estimated at 31(2) kJ /
mol (coalescence of 31P signals at 235 and 122 ppm at
-70 °C).12 An almost identical value was determined
for the respective process of triorganylstannyl triphos-
pholes 1.3 For the more complex rearrangement equi-
librium between 3b and 3c, which is associated with
localization and delocalization of the π electrons and the
rehybridization of the metal bonding P-orbitals from sp3
into sp2, the activation barrier is estimated to be 37(2)
kJ /mol (coalescence of 31P signal pairs at 292/267 and
This complicated NMR spectroscopic behavior could
be explained principally by the formation of an asym-
metric dimer at low temperatures, as observed for 1. A
symmetric dimer such as [(µ,σ-3,5-di-tert-butyl-1,2,4-
triphospholyl)2Cu2(PMe3)4] is definitely incompatible
with the spectra.9 On the basis of the observed coales-
cence phenomena, such a dimer would have to be highly
dynamic, and two independent rearrangement processes
with different activation barriers are required to fit to
the dynamic spectra.
A low-temperature equilibrium between two different
but almost isoenergetic monomeric complexes is the
second possibility. The experimental findings can be
more easily and completely explained by an NMR
spectroscopic slow rearrangement between the η5 com-
plex 3a and the two σ-bonded isomers 3b and 3c and a
fast equilibrium between the σ complexes. 3b is char-
acterized by an η1 σ-sp3(P)-Cu interaction and a local-
ized ring π system. An sp2(P) lone pair binds to the
copper atom of 3c, and a free delocalized π6 system is
formed by the ring elements of the coordinated triphos-
pholyl ligand, as shown in Scheme 3.
(10) Werner, H.; Otto, H.; Ngo-Khac, T.; Burschka, C. J . Organomet.
Chem. 1984, 262, 123-136.
(11) (a) Bartsch, R.; Carmichael, D.; Hitchcock, P. B.; Meidine, M.
F.; Nixon, J . F.; Sillet, G. J . D. J . Chem. Soc., Chem. Commun. 1988,
1615-1617. (b) Nixon, J . F.; Sillet, G. J . D. J . Organomet. Chem. 1993,
461, 237-245.
The ligand-metal bonding mode of isomer 3b is
believed to be closely related to that of triorganylstannyl
triphospholes 1.3,8 The η1 coordination of cyclopentadi-
enyl ligands, when bonded to gold(I), is an alternative
model.10 The combination of a lone pair coordination and
(12) Friebolin, H. Ein- und Zweidimensionale NMR-Spektroskopie
und ihre Anwendungen in der Chemie, 2nd ed.; Georg Thieme Verlag:
Stuttgart, Germany, 1983.

1692 Organometallics, Vol. 23, No. 8, 2004
Heinemann et al.
Sch em e 3
Sch em e 4
193/168 ppm around -50 °C). The observation of a
higher activation barrier for this process seems to make
sense; however, such an equilibrium is a rare case, as
we did not find comparable observations in the litera-
ture. From the temperature dependence of the relative
concentration of 3a versus 3b plus 3c we can estimate
the thermodynamic parameters for the η5 T η1 rear-
rangements 3a versus interchanging 3b and 3c.8
Cop p er -Tu n gsten Tr ip h osp h olyl Com p lexes. As
we failed to obtain crystals of suitable quality, no X-ray
structural analysis and thus no direct proof of the
postulated molecular structures 3a -c was possible.
With the aim of increasing the crystallization properties
and reducing the complexity of the dynamic NMR
spectra by blocking one phosphorus lone pair at the
minimum, we modified complex 3 by complexation to a
suitable metal carbonyl fragment. When 3 is reacted
with in situ generated [(THF)W(CO)5] in THF, the
binuclear CuW complex 4 and trinuclear W2Cu complex
5 are formed. Chromatography on water-deactivated
silica and recrystallization from CH2Cl2/n-hexane leads
to their separation in single-crystalline form (Scheme
4)
Bright yellow 4 crystallizes in the monoclinic space
group P21/n with approximately 0.8 equiv of CH2Cl2 per
complex molecule. The solvent molecules are disordered
in channels parallel to the b axis of the elemental cell.
A pentacarbonyltungsten fragment is attached to one
of the two adjacent phosphorus atoms of the triphos-
pholyl ring, and the copper atom is in bonding contact
with all five ring atoms as proposed for 3a . This
represents 18-valence-electron (VE) bonding situations
for both metal atoms (Figure 2 and Tables 1 and 3).
Due to the influence of the three phosphorus atoms
and the attached W(CO)5 moiety, there are some dif-
ferences between corresponding molecular structure
data of the tungsten-complexed [(1,2,4-triphospholyl)-
Cu(PPh3)] compound 4 and its [CpCu(PR3)] analogues.
The phosphine-Cu bond length P(4)-Cu(1) ) 2.180(3)
Å is elongated by 4.5 pm, and the distance between the
Cu atom and the center of the planar ring ligand is
shortened by 6 and 10 pm, respectively, with regard to
the CpCu complexes [CpCu(PPh3)] and [CpCu(PEt3)].13
In contrast to the Cp complexes, the angle between the
two bond vectors of the Cu atom (Cu(1)-P(4) vs Cu(1)-
center of the ring ligand) equals 170.3(2)° and thus
deviates by nearly 10° from linearity. Almost the same
deviation from the idealized rectangular arrangement
is found for the angle between the vectors Cu(1)-P(4)
and P(3)-W(1), 102.2(2)°. The increase of 12° with
respect to 90° fits the observed deviation from a linear
orientation of both ligands.
(13) (a) Cotton, F. A.; Takats, J . J . Am. Chem. Soc. 1970, 92, 2353-
2358. (b) Delbaere, L. T. J .; McBride, D. W.; Ferguson, R. B. Acta
Crystallogr., Sect. B 1970, 26, 515-521.

CuI Triphospholyl Triphenylphosphane Complexes
Organometallics, Vol. 23, No. 8, 2004 1693
Ta ble 3. Cr ysta l Da ta a n d Str u ctu r e Refin em en t
Deta ils for 4 a n d 5
4
5
empirical formula
C
33.8H34.6Cl1.6
CuO5P4W
-
C36H33CuO8P4W2
formula wt
solvent
948.80
1148.74
n-hexane/CH2Cl2 n-hexane/CH2Cl2
cryst habit
temp, K
yellow needle
298(2)
orange plate
220(2)
cryst syst
space group
unit cell dimens
a, Å
b, Å
c, Å
monoclinic
P21/n
monoclinic
P21/c
15.598(6)
10.842(4)
24.242(13)
90
92.72(4)
90
4095(3)
4
1.539
16.120(2)
10.727(2)
22.954(6)
90
98.14(2)
90
3929(2)
4
1.942
R, deg
â, deg
γ, deg
V, Å3
Z
calcd density, g/cm3
abs coeff, mm-1
F(000)
3.622
1870
6.588
2200
F igu r e 2. Molecular structure of 4 in the solid state.
Hydrogen atoms are omitted for clarity.
cryst size, mm
θ range for data collecn, 2.06-27.06
deg
0.40 × 0.15 × 0.10 0.42 × 0.18 × 0.08
1.79-26.01
Ta ble 1. Selected Bon d Len gth s (Å) a n d
An gles (d eg) for 4
index ranges
-19 e h e 19
-1 e k e 13
-1 e l e 31
16 002
-19 e h e 1
-13 e k e 1
-28 e l e 28
9531
W-P(3)
2.532(2)
2.113(3)
1.751(8)
1.754(8)
1.788(8)
1.740(8)
1.987(10)
2.010(11)
2.027(10)
2.004(11)
2.077(10)
C(35)-O(35)
C(31)-O(31)
C(32)-O(32)
C(33)-O(33)
C(34)-O(34)
Cu-P(4)
1.158(9)
1.138(10)
1.123(9)
1.161(10)
1.124(9)
2.180(3)
2.274(8)
2.277(8)
2.417(3)
2.473(3)
2.438(3)
P(3)-P(2)
P(2)-C(2)
C(2)-P(1)
P(1)-C(1)
C(1)-P(3)
W-C(35)
W-C(31)
W-C(32)
W-C(33)
W-C(34)
no. of rflns collected
no. of indep rflns
8949 (R(int) )
0.0657)
7713 (R(int) )
0.0841)
no. of rflns with I > 2σ(I) 2935
4950
completeness, %
(to θ, deg)
99.6 (27.06)
99.9 (26.01)
Cu-C(1)
Cu-C(2)
abs cor
ψ scan
integration
0.556 and 0.280
7713/0/466
Cu-P(1)
max and min transmissn 0.168 and 0.118
Cu-P(2)
no. of data/restraints/
params
8949/5/424
Cu-P(3)
goodness of fit on F2
0.678
1.056
C(2)-P(1)-C(1)
P(1)-C(1)-P(3)
C(1)-P(3)-P(2)
P(3)-P(2)-C(2)
100.1(4)
P(2)-C(2)-P(1)
W-P(3)-C(1)
W-P(3)-P(2)
121.8(5)
141.0(3)
116.9(1)
final R indices (I > 2σ(I)) R1 ) 0.0466,
R1 ) 0.0666,
wR2 ) 0.1419
R1 ) 0.1198,
wR2 ) 0.1671
118.0(5)
102.1(3)
97.8(3)
wR2 ) 0.0651
R1 ) 0.1812,
wR2 ) 0.0868
R indices (all data)
largest diff peak and
hole, e Å-3
0.658 and -0.899 2.367 and -3.754
Ta ble 2. Selected Bon d Len gth (Å) a n d
An gles (d eg) for 5
W(1)-Cu
Cu-P(4)
2.646(2)
2.238(4)
2.390(4)
2.498(4)
2.138(5)
1.82(2)
1.73(2)
1.81(2)
1.75(2)
1.96(2)
W(1)-C(32)
W(1)-C(33)
C(31)-O(31)
P(2)-W(1)
P(1)-W(1)
P(3)-W(1)
C(1)-W(1)
C(2)-W(1)
C(32)-O(32)
C(33)-O(33)
1.97(2)
1.97(2)
1.17(2)
2.623(4)
2.561(4)
2.576(4)
2.37(2)
2.44(2)
1.17(2)
1.16(2)
Cu-P(2)
W(2)-P(3)
P(3)-P(2)
P(2)-C(1)
C(1)-P(1)
P(1)-C(2)
C(2)-P(3)
W(1)-C(31)
W(1)-Cu-P(4)
W(1)-Cu-P(2)
P(2)-Cu-P(4)
C(1)-P(1)-C(2)
P(1)-C(2)-P(3)
154.3(2)
62.5(1)
143.1(2)
100.0(7)
118.3(9)
C(2)-P(3)-P(2)
P(3)-P(2)-C(1)
P(2)-C(1)-P(1)
C(2)-P(3)-W(2)
P(2)-P(3)-W(2)
102.6(6)
95.9(5)
122.7(8)
140.9(6)
115.9(2)
5 forms orange plates. The space group of the crystal
is P21/c. Not only is the targeted σ-bonded (CO)5W
fragment present but also an additional W(CO)3 moiety
completes the trinuclear complex 5. Tungsten atom W(1)
and the (Ph3P)Cu(1) moiety form a bridge to one of the
two adjacent phosphorus atoms P(2) of the triphospholyl
ring. Its neighbor P(3) binds the W(2)(CO)5 fragment
(Figure 3 and Tables 2 and 3). Both tungsten atoms,
W(1) and W(2), exhibit 18-VE shells, but, as usual for
trigonal coordinated coinage metals, the VE sum of Cu
equals 16. To the best of our knowledge, the molecular
structure of 5 is without precedence in copper complex
F igu r e 3. Molecular structure of 5 in the solid state.
Hydrogen atoms are omitted for clarity.
chemistry; only a dimeric Pt-W triphospholyl complex
shares some of its features.14
The 1,2,4-triphospholyl ligand of 5 is markedly dis-
torted. The angle P(3)-P(2)-C(1) is reduced to only
(14) Bartsch, R.; Meidine, M. F.; Nixon, J . F.; Sillet, G. J . D. J . Chem.
Soc., Chem. Commun. 1990, 317-319.

1694 Organometallics, Vol. 23, No. 8, 2004
Heinemann et al.
F igu r e 4. Variable-temperature 31P{1H} NMR spectra of 4 (161.7 MHz; 25 to -70 °C, CD2Cl2; 60 to 90 °C, [D8]toluene).
95.9(5)°, and the intra-ring P-C bond lengths are
alternating. The differences of adjacent P-C bond
lengths of 5-8 pm are very close to those observed for
the stannyl triphospholes 1, which exhibits an unques-
tionable diene character in the solid state.3 The ring
distortion of 5, however, is most probably caused by the
asymmetrical coordination of Cu(1) and η5-bonded W(1).
The two bond distances W(1)-P(1) and W(1)-P(3) equal
2.561(4) and 2.576(4) Å, respectively, whereas the Cu-
(1)-bound P(2) enhances its distance to W(1) to signifi-
cantly at 2.623(4) Å. The bond distance Cu(1)-W(1) is
in the normal range observed for other Cu-W single
bonds (2.646(2) Å).
explanation for this low activation energy has been
given. A direct 1,2-shift seems to be unlikely, as it
should be high in energy for metal atoms being bonded
at such divergent σ-orbitals. In the case of copper
complex 4, however, it may be related to the specific
properties of copper(I) triphospholyl compounds, as
observed for 3. Transferring the experimental results
on 3 to binuclear 4, a low activation barrier for π,σ
rearrangements of the Cu-triphospholyl interaction can
be assumed. This causes at least a transient localization
of the ring π system, which is no longer occupied directly
by the copper atom and may be utilized by the tungsten
atom as an alternative electron reservoir. The formation
of the σ(Cu),σ(W) complex 4a may happen in one or two
steps (Scheme 5).
If the tungsten atom of 4a moves from its position at
a phosphorus pz orbital to the equivalent position of the
neighbor P atom to form 4a ′, it may stay in constant
contact with the π-electron density above the ring plane.
This consideration fits better to the observed low
activation energy of the whole process than a direct 1,2-
shift of the tungsten atom.
In contrast to our expectations, both 4 and 5 are
fluxional in solution. For 4 a 1,2-shift of the tungsten
atom is observed by variable-temperature 31P NMR
spectroscopy (Figure 4).
At -70 °C the spectrum of 4 is well resolved, including
1
31P and 183W coupling patterns. The J (183W,31P) cou-
1
pling constant is 213 Hz, J (31P,31P) is 424.5 Hz, and
the two 2J (31P,31P) coupling constants are 49.3 and 54.2
Hz, respectively. Around 60 °C the signals of the two
adjacent phosphorus atoms coalesce and an activation
barrier of 55.6(9) kJ /mol results for the 1,2-shift of the
tungsten atom.12 This value is remarkably small. Most
studies on triphospholyl π-complexes with an additional
metal fragment being bonded to a phosphorus lone pair
do not mention dynamic effects. An exception are two
metal pentacarbonyl complexes of triphosphaferrocene,
[(η5-Cp*)Fe(η5-(3,5-di-tert-butyl-1,2,4-triphospholyl)M-
(CO)5] (M ) Cr, W). The 1,2-shifts of the metals have
activation barriers similar to those of 4.15 Unluckily, no
Despite a crowded situation of three metal atoms
around one triphospholyl ring, as indicated by the
molecular structure in the solid state, even the ditung-
sten complex 5 is fluxional in solution. 31P NMR spectra
at ambient temperature exhibit only broad lines; when
the sample is cooled to -80 °C, a well-resolved spectrum
is observed (Figure 5).
(15) Mueller, C.; Bartsch, R.; Fischer, A.; J ones, P. G. Polyhedron
1993, 12(11), 1383-90.

CuI Triphospholyl Triphenylphosphane Complexes
Organometallics, Vol. 23, No. 8, 2004 1695
F igu r e 5. Variable-temperature 31P{1H} NMR spectra of 5 (161.7 MHz, CD2Cl2).
Sch em e 5
31P and 183W coupling patterns are completely re-
solved in the low-temperature 31P{1H} NMR spectrum
of 5 and allow an unambiguous analysis. The spectrum
consists of two sets of four signals each, which can be
associated with the two isomeric compounds 5a and 5b.
The spectrum of 5a is in line with the bonding mode
observed in the solid state, as indicated by the transoid
2J (31Pc31Pd) coupling constant of 59.6 Hz. The spectrum
of 5b is closely related, but the cross metal coupling
2J (31Pa31Pd) ) 50.1 Hz gives clear evidence for the
coordination of the single ring phosphorus atom Pa to
the copper atom. Connectivity and coupling constants
of both isomers 5a and 5b are depicted in Figure 6.
5b is a unique case. All known 1,2,4-triphospholyl
complexes with η1-coordinated metal fragments bind
them through one of the two adjacent phosphorus
atoms. The existence of 5b points to the fact that the
general preference of the coordination toward one of the
neighboring phosphorus atoms seems to be not only
governed by the basicity of the lone pairs but also
modified by steric effects and entropy. The available
space for a metal atom which is attached to one of the
lone pairs of the ring phosphorus atoms P(1) or P(2) is
almost the same for 5. As a result, both isomers should
be close to isoenergetic and the concentrations of 5a and
5b are almost identical, due to the integration values

1696 Organometallics, Vol. 23, No. 8, 2004
Heinemann et al.
dienylmetal complexes. These experimental results
define some of the specific ligand properties of unsatur-
ated P-rich phosphorus heterocycles.
Exp er im en ta l Section
Gen er a l Con sid er a tion s. All experiments were conducted
under a nitrogen atmosphere by using standard Schlenk and
cannula techniques. Solvents were dried according to the
described procedures and used freshly distilled from the drying
agent. [ClCu(PPh3)]4 was prepared according to the litera-
ture.16 1-(Trimethylstannyl)-3,5-di-tert-butyl-1,2,4-triphosphole
(1a ) was prepared as described previously3 and distilled under
oil pump vacuum for purification. 31P{1H} NMR spectrum
simulation of 5 was carried out using the program Nuts 2D
Version 5.084 (NMR Data Processing Program, Acorn NMR,
1995).
F igu r e 6. Connectivity and 31P coupling constants in Hz
of 5a and 5b in solution.
of their 31P NMR spectra at low temperature. This
accidental but helpful coincidence allows the determi-
nation of the activation energy of the rearrangement
process ∆Gqexchange ) 44(2) kJ /mol simply by determining
the coalescence temperatures of the 31P NMR signals
[(3,5-d i-ter t-bu tyl-1,2,4-tr ip h osp h olyl)Cu (P P h 3)] (3). A
0.428 g (0.296 mmol) portion of [ClCu(PPh3)]4 was dissolved
in 40 mL of CH2Cl2, and 0.498 g (1.261 mmol) of 1-(trimeth-
ylstannyl)-3,5-di-tert-butyl-1,2,4-triphosphole (1a ) in 10 mL
CH2Cl2 was added at -40 °C. The reaction mixture was
warmed to room temperature and was stirred for an additional
3 h. All volatile components of the reaction mixture were
removed under oil pump vacuum. The yellow residue was
dissolved in 50 mL of n-hexane, and the solution was filtered
and concentrated under vacuum down to ca. 30 mL. 3 crystal-
lized at -18 °C. The solid was washed twice at -60 °C with
small amounts of n-hexane and dried in vacuo. Chromatog-
raphy on SiO2/5% H2O with toluene as the eluent led to a
luminous yellow fraction, which was recrystallized from n-
hexane at -30 °C to yield 0.545 g (0.98 mmol, 82.6%) of 3 as
a microcrystalline yellow to orange solid.
even in the case of two different species12 (Tcoalescence
)
0 ( 5 °C for P(a) and P(c) and -10 ( 5 °C for P(b)).
When it moves from P(2) to P(1), the copper atom has
to pass ring carbon atom C(1). This may create a
temporal bonding situation C(1)-Cu(1) with a local
energetic minimum or a transition state; thus, ∆Gq
exchange
can to be regarded as the upper limit for the difference
in bond energy for the two cases Cu(I)-Cring and Cu-
(I)-Pring of 5. As a result, the activation energy repre-
sents an experimental hint of the specific contribution
of phosphorus atoms toward the π bonding of unsatur-
ated P-heterocycles.
1
Sp ectr oscop ic Da ta for 3. H NMR (269.7 MHz, CDCl3,
room temperature): δ 1.48 (s, 18H, CH3), 7.31-7.45 (m, 15H,
C6H5). 13C{1H} NMR (67.83 MHz, CDCl3, room temperature):
δ 194.14 (dpt (doublet/pseudo triplet), 1J (31P,13C) ) 73.7 Hz,
∑[1J (31P,13C) + 2J (31P,13C)] ) 99.2 Hz, Cring), 133.70 (d,
2J (31P,13C) ) 16.2 Hz, o-Ph C), 133.17 (d, 1J (31P,13C) ) 26.1
Hz, i-Ph C), 129.83 (s, p-Ph C), 128.53 (d, 3J (31P,13C) ) 9.3
Hz, m-Ph C), 40.08 (dpt, 2J (31P,13C) ) 19.1 Hz, ∑[2J (31P,13C) +
3J (31P,13C)] ) 12.2 Hz, C(CH3)3), 36.87 (br (broad signal), no
coupling resolved, C(CH3)3). 13C{1H} NMR (100.4 MHz, [D8]-
toluene, -90 °C): δ 39.2 (br, C(CH3)3), 38.1 (br, C(CH3)3), 34.5
(br, C(CH3)3), 135-122 (Ph C, not assigned due to overlapping
solvent signals). 31P{1H} NMR (161.7 MHz, [D8]toluene,
+48 °C): rapid exchange of isomers, [AB2X] spin system, δ
Con clu sion s
When the coinage metal ions Au(I) and Cu(I) are
combined with the ligand 3,5-di-tert-butyl-1,2,4-triphos-
pholyl, a wide variety of complexation modes are
observed, ranging from monomeric η5-π to different
forms of mono- and dimeric η1 bonding with localized
and delocalized ring π-electron systems, respectively.
Most of the compounds are highly fluxional, thus
indicating low activation barriers between the different
bonding modes which connect metal atoms and the
unsaturated P-heterocyclic ligands. The features are
unprecedented for the otherwise closely related cyclo-
pentadienyl Au(I) and Cu(I) complexes. Qualitatively,
the results can be rationalized by a combination of two
complementary flexible building blocks. The relative
small difference in energy for the Cu(I) ion in bonding
situations with 18 or 16 VE and the possibility to go as
far as 14-VE species gives rise to a remarkable struc-
tural manifold in copper complex chemistry. On the
other hand, the 1,2,4-triphospholyl ligand not only
exhibits a cyclopentadienyl-like π-electron system but
also combines it with the phosphorus lone pairs, which
are sources of three almost ball-shaped centers of
electron density. They are thus accessible for soft Lewis
acids such as Cu(I) and Au(I) not only in the plane of
the ring but from the side as well. This way the lone
pairs bridge the horizontal node of the π-system and
give freedom to metals which are capable of utilizing
the complete electron density around the ring to stabi-
lize transition, intermediate, and even ground states
outside the standard bonding situations of cyclopenta-
2
204.08 (br, 1P, P(A) ) Pring), 187.62 (d, J (31P,31P) ) 55.0 Hz,
2P, P(B) ) Pring), 8.24 (br, 1P, P(X) ) P(C6H5)3). 31P{1H} NMR
(161.7 MHz, [D8]toluene, -30 °C): [(η5-t-Bu2C2P3)(PPh3)Cu]
(3a ), [AB2X] spin system, δ 197 (br, 1P, P(A) ) Pring), 182 (br,
2P, P(B) ) Pring), 17 ((br, 1P, P(X) ) PPh3); [(η1-t-Bu2C2P3)-
(P(C6H5)3)Cu] (rapidly interchanging isomers 3b and 3c),
[AX2Y] spin system, δ 275 (br, 1P, P(A) ) Pring), 176.5 (br, 2P,
P(X) ) Pring), -6 (br, P(Y) ) PPh3). 31P{1H} NMR (161.7 MHz,
[D8]toluene, -90 °C): mixture of isomers 3b and 3c, [(η1-t-
Bu2C2P3)(PPh3)Cu], two independent [ABCD] spin systems, δ
290.5 (br, 1P, P(A1 or A2) ) Pring), 256.0 (br, 1P, P(A2 or 1) )
P
ring), 235 (br, 1P, P(B1 or B2) ) Pring), 192.7 (br, d, 1J (31P-
(B),31P(C)) ) 357 Hz, 1P, P(B2 or B1) ) Pring), 168.1 (br, d,
1J (31P(B),31P(C)) ) 357 Hz, 1P, P(C2 or C1) ) Pring), 122.3 (br,
1P, P(C1 or C2) ) Pring), 1.1 ((br, 1P, P(D1 or D2) ) P(C6H5)3),
-3.7 ((br, 1P, P(D2 or D1) ) PPh3). MS (FD+, toluene): m/z
(%) 262 (100) [PPh3]+, 556 (14) [(t-Bu2C2P3)(PPh3)Cu]+, 588 (5)
[{PPh3}2Cu]+, 884 (25) [(t-Bu2C2P3)2(PPh3)Cu2]+, 1114 (1.5)
[(t-Bu2C2P3)2 (PPh3)2Cu2]+. Mp: 142 °C.
[(µ,η(1):η(1-5)-(3,5-d i-ter t-b u t yl-1,2,4-t r ip h osp h olyl)-
{W(CO)5}{Cu (P P h 3)}] (4) a n d [(µ,η(1):η(1-5):η(1)-(3,5-d i-
(16) Costa, G.; Reisenhofer, E.; Stefani, L. J . Inorg. Nucl. Chem.
1965, 27, 2581-2584.

CuI Triphospholyl Triphenylphosphane Complexes
Organometallics, Vol. 23, No. 8, 2004 1697
ter t-bu t yl-1,2,4-t r ip h osp h olyl){W(CO)5}{W(CO)3}{Cu (P -
P h 3)}](W-Cu ) (5). A 0.269 g (0.76 mmol) portion of W(CO)6
in 120 mL of THF was irradiated for 1 h with a high-pressure
mercury lamp. At -40 °C 0.311 g (0.56 mmol) of [(3,5-di-tert-
butyl-1,2,4-triphospholyl)Cu(PPh3)] (3) in 20 mL of THF was
added. The solution was warmed to room temperature, and
all volatile components of the mixture were removed under
vacuum. The residue was extracted six times with 10 mL of
n-hexane, the combined solutions were filtered, and the solvent
was removed again in vacuo. The remaining solid was dis-
solved in a few milliliters of CH2Cl2 and covered with a layer
of n-hexane. Storage for 5 days at 4 °C led to orange crystalline
material. It was isolated, washed with benzene and n-hexane,
and dried in vacuo to obtain 45 mg (0.040 mmol, 7.1%) of 5.
All liquid phases were combined, and the solvents were
removed in vacuo. The orange residue was chromatographed
on SiO2/5% H2O with a toluene/n-hexane mixture (1/2). The
color of the first fraction was yellow to orange. After removal
of the solvent the residue was redissolved in CH2Cl2/n-hexane.
n-Hexane was added to the solution at -18 °C until crystal-
lization of 4 started. The crystals contain 4 and CH2Cl2 in the
ratio of ca. 5:4. A total of 174 mg (0.183 mmol, 32.7%) was
isolated as yellow to orange crystals.
2J (31P,13C) ) 2.7 Hz, W(CO)4(CO)), 134.15 (d, J (31P,13C) ) 14.7
Hz, o-Ph C), 131.63 (s, p-Ph C), 129.66 (d, J (31P,13C) ) 10.0
1
Hz, m-Ph C), 129.55 (d, J (31P,13C) ) 41.2 Hz, i-Ph C), 38.77
(dd, 2J (31P,13C) ) 16.0 Hz, 2J (31P,13C) ) 5.0 Hz, C(CH3)3), 38.44
(dd, 2J (31P,13C) ≈ 12.4 Hz, 2J (31P,13C) ≈ 12.4 Hz, C(CH3)3)
36.243 (br, C(CH3)3). 31P{1H} NMR (161.7 MHz, CD2Cl2,
1
23.7 °C): δ 44.5 (br, d, J (31P(A),31P(B)) ) 322 Hz, 1P, P(A) )
P
ring), 32.6 (br, 1P, P(C) ) Pring), 3.7 (br, 1P, P(B) ) Pring), 3.7
(s, 1P, P(D) ) PPh3). 31P{1H} NMR (161.7 MHz, CD2Cl2, -79.9
°C): 5a , [ABCD] spin system, δ 59.41 (d, J (183W,31P) ) 238.1
1
Hz, dd, 1J (31P(A),31P(B)) ) 373.98 Hz, 2J (31P(A),31P(C)) ) 47.66
Hz, 1P, P(A) ) Pring), 57.96 (dd, J (31P(A),31P(C)) ) 47.66 Hz,
2
2J (31P(B),31P(C)) ) 39.48 Hz, 1P, P(C) ) Pring), 3.34 (d,
2J (31P(B),31P(D)) ) 56.95 Hz, 1P, P(D) ) PPh3), -18.37 (d,
1J (183W,31P) ) 18.9 Hz, ddd, 1J (31P(A),31P(B)) ) 372.98 Hz,
2J (31P(B), 31P(C)) ) 39.48 Hz, 2J (31P(B),31P(D)) ) 56.95 Hz,
1P, P(B) ) Pring); 5b, [ABCD] spin system, δ 34.69 (d,
1J (183W,31P) ) 231.2 Hz, dd, 1J (31P(A),31P(B)) ) 391.24 Hz,
2J (31P(A),31P(C)) ) 40.81 Hz, 1P, P(A) ) Pring), 25.05 (dd, 1J (31P-
(A),31P(B)) ) 391.24 Hz, 2J (31P(B),31P(C)) ) 38.98 Hz, 1P,
P(B)
) P ) 9.9 Hz, ddd,
ring), 3.51 (d, 1J (183W,31P)
2J (31P(A),31P(C)) ) 40.81 Hz, 2J (31P(B),31P(C)) ) 38.98 Hz,
2J (31P(C),31P(D)) ) 50.1 Hz, 1P, P(C) ) Pring), 2.64 (d,
2J (31P(C),31P(D)) ) 50.1 Hz, 1P, P(D) ) PPh3); chemical shifts
and coupling constants have been obtained by iterative
spectrum simulation. IR (n-hexane/CH2Cl2): ν(CO) 2075 (m),
2026 (sh), 1966 (s, br), 1945 (s, br), 1898 (m, br), 1860 (m, br),
1864 (m, br), 1824 (m, br) cm-1. Raman (solid): ν(CO) 2073
Sp ectr oscop ic Da ta for 4. 1H NMR (399.65 MHz, CD2-
Cl2, 23.3 °C): δ 1.356 (s, 18H, CH3), 7.25-7.40 (m, 15H, C6H5).
13C{1H} NMR (100.4 MHz, CD2Cl2, 23.3 °C): δ 200.91 (pt,
3
∑[2J (31P,13C) + J (31P,13C)] ) 30.2 Hz, W(CO)4CO), 197.26 (d,
1J (183W,13C) ) 126.3 Hz, W(CO)4CO), 134.0 (d, 2J (31P,13C) )
14.7 Hz, o-Ph C), 131.28 (d, 4J (31P,13C) ) 1.9 Hz, p-Ph C),
(s), 1985 (s), 1953 (m), 1929 (m), 1883 (m), 1867 (m); ν(CCphenyl
)
131.10 (d, 1J (31P,13C)
)
44.0 Hz, i-Ph C), 129.33 (d,
1584 (w), ν(PP) and ν(PC) 900-1100, ν(WC) ) 405-561; ν(WP)
333, 245 cm-1. MS (FD+, CH2Cl2): m/z (%) 262 (30) [PPh3]+,
1149 (100) [M]+. Anal. Calcd for (C36H33CuP4O8W2): C, 37.64;
H, 2.90. Found: C, 37.81; H, 3.05. Mp: 171 °C.
3J (31P,13C) ) 10.9 Hz, m-Ph C), 40.57 (dd, 2J (31P,13C) ) 18.3
Hz, 2J (31P,13C) ) 11.0 Hz, C(CH3)3), 36.45 (dd, 2J (31P,13C) )
2
10.0 Hz, J (31P,13C) ) 8.2 Hz, C(CH3)3). 13C{1H} NMR (100.4
MHz, [D8]toluene, -59.9 °C): δ 200.5 (d, 2J (31P,13C) ) 30.1 Hz,
W(CO)4CO), 197.01 (d, 1J (183W,13C) ≈ 120 Hz, W(CO)4CO),
∼135-129 (Ph C, not assigned due to overlapping solvent
signals), ∼40.1 (br, C(CH3)3), 35.96 (br, C(CH3)3). 31P{1H} NMR
(161.7 MHz, [D8]toluene, 90.0 °C): [AX2Y] spin system, δ 19.10
(s, 1P, PPh3), 149.76 (br, 2P, Pring), 198.90 (dd, 2J (31P,31P) )
51.7 Hz, 1P, Pring). 31P{1H} NMR (161.7 MHz, CD2Cl2, 25.2
°C): δ 18.85 (s, 1P, PPh3), 127.15 (br, 1P, Pring), 163.87 (br,
Cr ysta l Str u ctu r e Deter m in a tion of 4 a n d 5. Intensity
data of 4 were collected on a Nicolet R3m/V (ω scan, 5.0°/min,
Mo KR radiation, graphite monochromator, λ ) 0.710 73 Å)
using the P3/PC software.17 Intensity data of 5 were collected
on a Siemens P4 diffractometer (ω scan, 4.0°/min, Mo KR
radiation, graphite monochromator, λ ) 0.710 73 Å) using the
XSCANS 2.20 software.18 The structures were solved by direct
methods and refined by full-matrix least-squares procedures
against F2 with all reflections using SHELXTL programs.19
All non-hydrogen atoms were refined anisotropically. The
hydrogen atoms are geometrically positioned. Crystal data and
experimental details are listed in Table 3. All significant
residual electron density maxima are in close vicinity of the
tungsten atoms and might be due to an insufficient absorption
correction or break-off effects.
2
1P, Pring), 196.86 (dd, J (31P,31P) ) 50.9 Hz, 1P, Pring). 31P{1H}
NMR (161.7 MHz, CD2Cl2, -69.8 °C): [AXYZ] spin system, δ
18.69 (s, 1P, PPh3), 123.90 (d, 1J (183W,31P) ) 212.6 Hz, dd,
1J (31P,31P) ) 424.5 Hz, 2J (31P,31P) ) 54.2 Hz, 1P, Pring), 159.41
(ddd, 1J (31P,31P)
) ) 49.3 Hz,
424.5 Hz, 2J (31P,31P)
J (31P,31P) ) 7 Hz, 1P, Pring), 192.81 (ddd, 2J (31P,31P) ) 54.2 Hz,
2J (31P,31P) ) 49.3 Hz, J (31P,31P) ) 9.7 Hz, 1P, Pring). IR (n-
hexane/CH2Cl2): ν(CO) 2070 (m), 2042 (s, br), 1925 (sh) cm-1
MS (FD+, toluene): m/z (%) 881 (100) [M]+.
Sp ectr oscop ic Da ta for 5.
.
Ack n ow led gm en t. This work was supported by the
Deutsche Forschungsgemeinschaft and the Fonds der
Chemischen Industrie. M.Z. is grateful for a scholarship
by the DFG-Graduiertenkolleg Phosphorchemie als
Bindeglied verschiedener chemischer Disziplinen, at the
University of Kaiserslautern, Kaiserslautern, Germany.
We also thank Dr. M. Moll for the measurement of
variable-temperature NMR spectra.
Su p p or tin g In for m a tion Ava ila ble: Further details of
the structure determination, including tables of atomic coor-
dinates, bond distances and angles, and thermal parameters.
This material is available free of charge via the Internet at
http://pubs.acs.org.
1H NMR (399.65 MHz, CD2Cl2, 22.9 °C): δ 1.07 (s, 9H, CH3),
1.31 (s, 9H, CH3), 7.35-7.50 (m, 15H, C6H5). 1H NMR (399.65
MHz, CD2Cl2, -79.9 °C): δ 0.99 (s, 9H, CH3), 1.07 (s, 9H, CH3),
1.23 (s, 9H, CH3), 1.40 (s, 9H, CH3), 7.35-7.55 (m, 30H, C6H5).
13C{1H} NMR (100.4 MHz, CD2Cl2, 22.9 °C): δ 212.75 (d,
1J (183W,13C) ) 167.6 Hz, W(CO)3), 198.54 (d, 2J (31P,13C) ) 34.8
Hz, W(CO)4(CO)), 196.49 (d, 1J (183W,13C) ) 127.2 Hz, d,
OM030570I
(17) Siemens Analytical X-ray Instruments Inc., Madison, WI, 1989.
(18) XSCANS 2.20; Siemens Analytical X-ray Instruments Inc.,
Madison, WI, 1996.
(19) Sheldrick, G. M. SHELXTL NT V5.1; Bruker AXS, Madison,
WI, 1999.