Cationic dimetallic gold hydride complex stabilized by a xantphos-phosphole ligand: Synthesis, X-ray crystal structure, and density functional theory study

Article abstract of DOI:10.1021/ic901014r

The bis-2,5-diphenylphosphole xantphos ligand (XDPP) 1 reacts with the [AuCI(tht)] complex to afford the monocoordinated [Au(XDPP)CI] 2 and the dicoordinated chelate species [Au(XDPP)CI] 3. Addition of AgOTf on this mixture, at room temperature, affords t

Full text of DOI:10.1021/ic901014r

Inorg. Chem. 2009, 48, 8415–8422 8415
DOI: 10.1021/ic901014r
Cationic Dimetallic Gold Hydride Complex Stabilized by a Xantphos-Phosphole
ligand: Synthesis, X-ray Crystal Structure, and Density Functional Theory Study
†
†
‡
†
†
,†
ꢀ
ꢀ
Aurelie Escalle, Guilhem Mora, Fabien Gagosz, Nicolas Mezailles, Xavier F. Le Goff, Yves Jean,* and
Pascal Le Floch*,†
†
‡
ꢀ ꢀ ꢀ ꢀ
ꢁ
Laboratoire “Heteroelements et Coordination”, and Laboratoire de Synthese Organique,
Ecole Polytechnique, CNRS, 91128 Palaiseau Cedex, France
Received May 26, 2009
The bis-2,5-diphenylphosphole xantphos ligand (XDPP) 1 reacts with the [AuCl(tht)] complex to afford the
monocoordinated [Au(XDPP)Cl] 2 and the dicoordinated chelate species [Au(XDPP)Cl] 3. Addition of AgOTf on
this mixture, at room temperature, affords the cationic [Au(XDPP)][OTf] complex 4 which was fully characterized. An
X-ray crystal structure analysis confirms the bent structure of this 14 VE [ML2]þ complex. Reaction of 4 with HSiMe2Ph
in tetrahydrofuran at -78 °C yields the dinuclear [(XDPP)Au-H-Au(XDPP)]þ cationic complex 5, in which the
hydride bridges the two [Au(XDPP)]þ metal fragments. In 5, the Au-P bond lengths are different and the
phosphorus atoms which are located nearly trans to the hydride ligand exhibit significantly shorter P-Au bond
lengths. Reaction of 4 with DSiMe2Ph to form the [(XDPP)Au-D-Au(XDPP)]þcomplex 6 allowed to unambiguously
ascribe the chemical shift of the deuteride in 2H NMR (δ = 7.0 ppm with a 2JDP = 8.4 Hz. The electronic structure of the
[(XDPP)Au-H-Au(XDPP)]þ complex was studied through density functional theory calculations. An orbital analysis
is developed in which complex 5 is viewed as the combination of two 12 electrons fragments [Au(XDPP)]þ with H-.
This analysis reveals that the hydride interacts in a bonding way with the σ MO between the two gold atoms and in an
antibonding way with a combination of d orbitals at the metal centers. This simple description allows to rationalize the
inequivalence of the two types of P-Au bonds in 5.
Introduction
precursor of these P-functional compounds, the 1,2,5-triphe-
nylphosphole, easily available on a multigram scale from the
simple condensation of dichlorophenylphosphine with 1,4-
diphenyl-1,3-butadiene.4 A few years ago, we launched a
program aimed at evaluating the 2,5-diphenylphosphole
(DPP) motif in catalytic transformations of synthetic rele-
vance. Various mixed ligands such as those featuring either
pyridine derivatives5a-c or an ancillary olefin ligand5d were
produced and already proved to be very efficient in catalytic
transformations such as hydrogen transfer processes,5e C-C
and C-B coupling reactions,5a-c,e and hydroformylation.6
Much more recently we focused our researches on a new
Phospholes, unsaturated phosphorus-containing five-
membered heterocycle, exhibit a very rich chemistry that
makes them very useful building blocks in phosphorus
chemistry.1 Their reactivity and properties have been exten-
sively exploited in different contexts to elaborate new phos-
phorus structures such as phosphametallocenes,2 new
heterocycles, precursors of materials,3 and so forth. Thanks
to the readily modified backbone, which allows fine-tuning of
the electronic properties of the phosphorus atom, they have
also been widely used as ligands in homogeneous catalysis.
Among these, the 2,5-diphenyl derivative is particularly
attractive to elaborate robust catalysts because of its very
good stability toward air oxidation. Furthermore, the
(4) Mora, G.; Deschamps, B.; van Zutphen, S.; Le Goff, X. F.; Ricard, L.;
Le Floch, P. Organometallics 2007, 26, 1846–1855.
(5) (a) Thoumazet, C.; Melaimi, M.; Ricard, L.; Mathey, F.; Le Floch, P.
Organometallics 2003, 22, 1580–1581. (b) Melaimi, M.; Thoumazet, C.; Ricard,
L.; Le Floch, P. J. Organomet. Chem. 2004, 689, 2988–2994. (c) Thoumazet,
*To whom correspondence should be addressed. E-mail: pascal.lefloch@
polytechnique.edu (P.L.F.), yves.jean@polytechnique.edu (Y.J.). Fax: þ33-
169334440 (P.L.F.). Phone: þ33-169334401 (P.L.F).
(1) (a) Quin, L. D. Phosphorus-Carbon Heterocyclic Chemistry: The Rise
of a New Domain; Mathey, F., Ed.; Pergamon: Amsterdam, 2001; p 219. (b) Quin,
L. D. In Phosphorus-Carbon Heterocyclic Chemistry: The Rise of a New
Domain; Mathey, F., Ed.; Pergamon: Amsterdam, 2001; p 307.
C.; Melaimi, M.; Ricard, L.; Le Floch, P. C. R. Chimie 2004, 7, 823–832.
::
(d) Thoumazet, C.; Ricard, L.; Grutzmacher, H.; Le Floch, P. Chem. Commun.
2005, 1592–1594. (e) Thoumazet, C.; Melaimi, M.; Ricard, L.; Mathey, F.;
Le Floch, P. Organometallics 2003, 22, 1580.
(2) (a) Mathey, F. Coord. Chem. Rev. 1994, 137, 1–52. (b) Le Floch, P.
Coord. Chem. Rev. 2006, 250, 627–681.
(6) Mora, G.; van Zutphen, S.; Thoumazet, C.; Le Goff, X. F.; Ricard, L.;
Grutzmacher, H.; Le Floch, P. Organometallics 2006, 25, 5528–5532.
(7) (a) Mora, G.; Piechaczyk, O.; Le Goff, X. F.; Le Floch, P. Organo-
metallics 2008, 27, 2565–2569. (b) Mora, G.; van Zutphen, S.; Klemps, C.;
Ricard, L.; Jean, Y.; Le Floch, P. Inorg. Chem. 2007, 46, 10365–10371.
ꢀ
(3) (a) Baumgartner, T.; Reau, R. Chem. Rev. 2006, 106, 4681. (b) Crassous,
ꢀ
J.; Reau,R. DaltonTrans. 2008, 6865–6876. (c) Hobbs, M. H.; Baumgartner, T. Eur.
J. Inorg. Chem. 2007, 3611–3628.
r
2009 American Chemical Society
Published on Web 08/03/2009
pubs.acs.org/IC

8416 Inorganic Chemistry, Vol. 48, No. 17, 2009
Scheme 1. XDPP Ligand
Escalle et al.
Scheme 2. Palladium and Platinum Catalysts Used in the Allylation of
Amines and Featuring the XDPP Ligand
derivative (XDPP) 1 of this DPP compound featuring the
Xantphos backbone (Scheme 1).7
This molecule proved to be a remarkable bidentate ligand
for group 10 metals, and the corresponding reduced
[M(XDPP)2] complexes (M=Pd, Pt) were found to exhibit
unusual catalytic properties. Thus, Pd(allyl) complexes such
as I or the dimeric species II act as very efficient precursors of
14 VE Pd and Pt catalysts which can achieve allylation of
primary arylamines (Pd)8 and arylamines (Pt)9 with allylal-
cohols under mild conditions (Scheme 2).
same study, the authors also isolated and structurally char-
acterized an interesting triangular cationic gold hydride
dimer V, isolobal of H3þ, with a short intramolecular Au-
(I)-Au(I) interaction (Scheme 3). Unfortunately, no infor-
mation from the Au-H bond could be retrieved since the
hydride could not be structurally localized. We reasoned that
the peculiar electronic and geometrical properties of our
XDPP ligand (wide bite angle þ acceptor properties) could
allow the stabilization of the elusive “phosphine-AuH” like
species, and the precise analysis of the Au-H interaction.
Our results in this endeavor are presented herein.
As part of our investigations, we recently extended our
studies to cationic derivatives of group 11 metals and therein
we wish to report on the case of Au(I) complexes. Our interest
in the Au(I) chemistry is two-fold. First, only a few 14 VE
chelated Au(I) complexes have been reported so far, and their
chemistry, as well as their catalytic properties, remains largely
unexplored.10 Second, even if Au-H has been observedinthe
gas phase,11 mono metallic Au-H fragments characterized
from solution phase are very rare, yet phosphine-Au-H
species have been postulated as catalytic intermediates.12
In fact, when this study was undertaken, no simple
[(ligand)Au-H] complex had been reported. It is clearly
related to the only synthetic strategy available, namely, the
reaction of a Au-Cl moiety with a hydride source. Indeed, it
is well-known that [(R3P)AuCl] is readily reduced to Au
clusters or even phosphine stabilized Au nanoparticles by
such sources. The characterization/isolation of [(R3P)AuH]
species was therefore a challenge. While our work was in
progress, the first [L-AuH] complex was reported, with
L being a NHC (N-heterocyclic carbene) ligand.13 In the
Results and Discussion
Synthesis of Complexes. In a first series of experiments,
we explored the coordinating behavior of ligand 1 to-
ward the Au(I) source [AuCl(tht)] (tht=tetrahydrothio-
phene). Reactions of 1 with this complex at room tem-
perature in dichloromethane affords two complexes that
are formed in a 1:1 ratio. Indeed, examination of the 31P
NMR spectrum of the crude mixture reveals the presence
of three signals: one at 11.6 ppm and two of similar
intensity at δ=30.3 ppm and δ=-13.3 ppm. No attempts
were made to isolate and separate these two complexes,
but on the basis of these data one may propose that their
complex 2 is a gold dicoordinated species (δ = 11.6 ppm)
whereas complex 3 is a monocoordinated species with one
pendant phosphole unit (signal at δ = 30.3 ppm, δ =
-13.3 ppm for the coordinated and non-coordinated
phosphorus atoms of the ligand, respectively). As a
comparison, the shift of phosphorus in the free ligand 1
is -15.9 ppm. These two complexes result from the
complexation of the two conformations of the free ligand
1 which are in equilibrium at room temperature.14 Addi-
tion of 1 equiv of a chloride abstractor (AgOTf) then
(8) Piechaczyk, O.; Thoumazet, C.; Jean, Y.; Le Floch, P. J. Am. Chem.
Soc. 2006, 128, 14306–14317.
ꢀ
(9) Mora, G.; Piechaczyk, O.; Houdard, R.; Mezailles, N.; Le Goff, X. F.;
Le Floch, P. Chem. Eur. J. 2008, 14, 10047–10057.
ꢀ
(10) (a) Mezailles, N.; Avarvari, N.; Maigrot, N.; Ricard, L.; Mathey, F.; Le
Floch, P.; Cataldo, L.; Berclas, T.; Geoffroy, M. Angew. Chem., Int. Ed. 1999,
38(21), 3194–3196. (b) Deschamps, E.; Deschamps, B.; Dormieux, J. L.; Ricard, L.;
ꢀ
Mezailles, N.; Le Floch, P. Dalton Trans. 2006, 594–602. (c) Heuer, B.; Pope, S. J.
A.; Reid, G. Polyhedron 2000, 19, 743–749. (d) Chan, W.-H.; Mak, T. C. W.; Che,
C. M. Dalton Trans. 1998, 2275–2276. (e) Ainscough, E. W.; Brodie, A. M.;
Chaplin, A. B.; O'Connor, J. M.; Otter, C. A. Dalton Trans. 2006, 1264–1266.
(f) Xu, F.-B.; Li, Q.-S.; Wu, L.-Z.; Leng, X.-B.; Li, Z.-C.; Zeng, X.-S.; Chow, Y. L.;
Zhang, Z.-Z. Organometallics 2003, 22, 633. (g) Poorters, L.; Armspach, D.; Matt,
D.; Toupet, L.; Choua, S.; Turek, P. Chem. Eur. J. 2007, 9448–9461. (h) Gibson, A.
M.; Reid, G. J. Chem. Soc., Dalton Trans. 1996, 1267.
(14) Theoretical calculations carried out at the B3PW91/6-311þþG(d,
p)//B3PW91 6-31 G(d) level of theory have demonstrated that both con-
formation of Xantphos-phosphole 1 have nearly the same energy (ΔE =
þ2.9 kcal/mol) at the same energy. In the first conformation the two
phosphorus atom lone pair point towards the plane of symmetry of the
ligand (to form a chelate ligand) whereas in the second conformation (þ2.9
kcal/mol) one phosphorus atom lone pair points outside the ligand explain-
ing why a monodentate is formed when [Au-Cl] is reacted. The two
conformations are in equilibrium through the inversion of one phosphorus
atom of one phosphole ring. DFT calculations indicate that the inversion
barrier in this type of 1,2,5-tris aryl substituted phosphole is about 16 kcal/
mol (RB3PW 6-311þþG(d,p) level of theory).
::
::
(11) (a) Ringstrom, U. Nature 1963, 198, 981. (b) Ringstrom, U. Ark. Fys.
1964, 27, 227–265. (c) Raubenheimer, H. G.; Cronje, J. Gold, Progress in
Chemistry, Biochemistry and Technology;Schmidbaur, H., Ed.; Wiley:Chischester,
::
1999; pp 557-632. (d) Pyykko, P. Angew. Chem., Int. Ed. 2004, 116, 4512–4557.
::
Pyykko, P. Angew. Chem., Int. Ed. 2004, 43, 4412–4456, and references therein.
(12) For a comprehensive review on catalysis by gold complexes or
nanoparticles see: (a) Hashmi, A. S. K.; Hutchings, G. J. Angew. Chem.,
Int. Ed. 2006, 45, 7896–7936; and references therein. For pertinent references in
which Au-H bonds are postulated in catalytic cycles, see for example:
(b) Gonzalez-Arellano, C.; Corma, A.; Iglesias, M.; Sanchez, F. Chem. Commun.
2005, 3451–3453. (c) Ito, H.; Takagi, K.; Miyahara, T.; Sawamura, M. Org. Lett.
(15) One reviewer of this article suggested that complex 3 could be
obtained in pure form by submitting complex 4 to a metathesis with chloride
salts. Several attempts were thus made using LiCl as salt in different solvents
but each attempt resulted in the formation of 2 and 3 as a mixture.
2005, 7, 3001–3004.
::
(13) Tsui, E. Y.; Muller, P.; Sadighi, J. P. Angew. Chem., Int. Ed. 2008, 47,
8937–8940.

Article
Inorganic Chemistry, Vol. 48, No. 17, 2009 8417
Scheme 3. Known Au-H Fragments (Homo Metallic Au Complexes)
and Our Working Hypothesis
Scheme 4. Synthesis of the Cationic Derivative 4
Figure 1. Solid-state structure of the cation of complex 4. Thermal
ellipsoids are set at the 50% probability level. For clarity, phenyl groups
of phospholes have been omitted and only the ipso carbon is represented.
˚
Selected bond lengths[A] and angles [deg]: Au(1)-P(1), 2.301(1); Au(1)-
P(2), 2.300(1); P(1)-Au(1)-P(2), 146.97(4); P(1)-C(2), 1.820(4); P(2)-
C(12), 1.801(5); C(2)-P(1)-Au(1), 108.1(1); C(41)-P(2)-C(38), 93.4(2).
Scheme 5. Synthesis of the Complex 5
cleanly afforded a single signal in 31P NMR at δ=14.9
ppm corresponding to complex 4 which was isolated as a
very air-stable yellow solid in a quantitative yield
(Scheme 4).15
spectroscopy. After washings with diethyl ether and
filtration at room temperature, complex 5 was isolated
as a very air-stable yellow solid with a 98% yield
(Scheme 5).
The formulation of 4 was established on the basis
of 1H and 13C NMR data and elemental analysis. Addi-
tional evidence on its formulation was given by an
X-ray crystallographic study since single crystals of 4
could be grown by slow diffusion of hexanes (mixture of
isomers) into a dichloromethane solution of the com-
plex at room temperature. A view of one molecule of 4 is
presented in Figure 1, and the most significant metric
parameters are listed in the corresponding legend.
Notably, the formation of complex 4 does not require
the prior isolation of complexes 2 and 3. Complex 4 can
be straightforwardly obtained by reaction of 1 equiv of
the XDPP ligand in dichloromethane at room tempera-
ture with 1 equiv of [AuCl(tht)] and 1 equiv of [AgOTf].
Apart from the excepted wide P-Au-P bite angle of
146.97(4)° and the Au-P bond distances (2.301(1) and
The structure of 5 could not be simply established on
the basis of 1H and 13C NMR data which show no
apparent hydride and only exhibit vinylic and aromatic
signals of the phosphole and Xantphos units. Note that in
the (NHC) Au-H complex IV, the hydride resonance
was observed at δ=5.11 ppm in C6D6 and 3.38 ppm in
CD2Cl2. However, the 31P NMR spectrum of 5 shows a
2
very characteristic doublet at 23.8 ppm with a JHP
coupling constant of 54.0 Hz attesting that each phos-
phorus atom in 5 is coupled with a hydrogen atom. To
definitely establish the structure of 5 the hydride was
replaced by a deuteride. Reaction of D-SiMe2Ph16 with
complex 4 afforded under the same experimental condi-
tions complex 6 which was isolated after usual workup in
96% yield as a yellow powder (Scheme 6).
˚
2.300(1) A) which fall in the usual range for this type of
complexes, the structure of 4 does not deserve further
comments.
2
Importantly, the H NMR spectrum of complex 6 is
Several attempts were made to generate a gold-hydride
complex from 4 upon reaction with various hydrides.
However, in most cases, whatever the experimental con-
ditions used (solvent, temperature), these reactions essen-
tially led to the formation of colloidal mixtures. The most
satisfying result was obtained upon reacting HSiMe2Ph in
tetrahydrofuran (THF) at -78 °C. Reaction of 0.5 equiv
of HSiMe2Ph with 4 cleanly resulted in the formation of a
single signal, centered at δ = 23.8 ppm in 31P NMR
very characteristic and exhibits a signal which appears as
a quintet at δ=7.0 ppm (2JDP = 8.4 Hz) attesting that the
deuterium atom is surrounded by four equivalent phos-
phorus nuclei. Moreover, the 31P{1H}-NMR spectrum
shows a pseudo triplet with a coupling constant (JDP) of
(16) Pawlenko S. In Houben Weyl, Methoden der Organischem Chemie
::
Muller, E., Bayer, O., Eds.; Thieme Verlag: Stuttgart, NY, 1980; Bd. 13/5, p 90.

8418 Inorganic Chemistry, Vol. 48, No. 17, 2009
Scheme 6. Synthesis of the Deuterated Complex 6
Escalle et al.
Figure 2. Solid-state structure of the cation of complex 5. Thermal
ellipsoids are set at the 50% probability level. For clarity, phenyl groups
of phospholes have been omitted and only the ipso carbon is represented.
Complex 5 presents a C2 axis (H(1) and the middle of Au(1)-Au(10) bond
˚
are on the axis). Selected bond lengths [A] and angles [deg]: Au(1)-P(1),
2.308(1); Au(1)-P(2), 2.446(1); Au(1)-Au(10), 2.7542(3); Au(1)-H(1),
1.70(3); P(1)-Au(1)-P(2), 124.77(3); P(2)-Au(1)-Au(10), 117.24(2);
P(1)-Au(1)-Au(10), 117.08(2); P(1)-Au(1)-H(1), 144.9(8); P(2)-Au-
(1)-H(1), 89(1); Au(10)-Au(1)-H(1), 36(1); P(2)-Au(1)-Au(10)-P(20),
82.63(2); P(1)-Au(1)-Au(10)-P(10), 61.82(2); P(1)-Au(1)-Au(10)-
P(20), 72.23(2).
8.4 Hz. The final proof of the similarity of the hydride and
the deuteride is given by the ratio of the coupling con-
stants (JHP/JDP=54/8.4=6.43) which is essentially equal
to the ratio of the gyromagnetic factors (γproton/γdeuterium
=
26.753/4.107= 6.51). These important informations sug-
gest that complexes 5 and 6 are not monomeric but
dinuclear. This chemical shift is not common for hydride
species which in most case for others metals are in nega-
tive shifts. Note that in the case of the dimer complex V,
Sadighi et al. reported that the hydride resonates at
0.42 ppm. So far, no studies were undertaken to rationa-
lize the important deshielding observed in the case of our
complex 5 but taking into account the important electro-
nic capacities between the two ligands, one may propose
that this could result from the strong π-accepting capacity
of the XDPP ligand which would increase the acidity of
the bridged hydride.
Fortunately, single crystals of complex 5 were obtained
by slowly diffusing a mixture of hexanes into a dichloro-
methane solution of the dimer at room temperature. A
view of one molecule of 5, which presents a C2 axis, is
presented in Figure 2, and the most significant bond
lengths and angles are listed in the corresponding legend.
A second view of 5 showing the deviation between the two
P-Au-P planes and the positioning of the hydrogen
atom is presented in Figure 3.
Figure 3. Other view of 5 restricted to the [Au2P4H]þ core showing the
deviation between the two P-Au-P planes.
bond is particularly short at 1.616 A,17 whereas it is verþy
˚
2
˚
long at 1.976 A in the [(dppm)2Ru(μ -H)2Au(PPh3)]
complex18 (dppm = bis-diphenylhosphinomethane).19
Another important observation concerns the respective
arrangement of the two [(XDPP)Au]þ fragments. As can
be easily seen in Figure 3, the two fragments are not
coplanar and adopt a twist angle. Most probably, this
deviation results from the steric congestion due to the
diphenylphosphole substituents rather than to electronic
effects. Undoubtedly, the most intriguing structural fea-
ture arises from the P-Au bonds which are markedly
˚
The structure of 5 deserves further comments. First, as
expected an hydrido ligand symmetrically binds in μ2-
fashion the two [(XDPP)Au] fragments which are sepa-
different. Thus the P(1)-Au bond lengths (2.308(1)A) are
˚
found to be shorter than the P(2)-Au bonds (2.446(1)A)
in each [Au(XDPP)]þ unit. This result is quite unexpected
if one takes into account that the two P1 atoms are nearly
trans to the hydrido ligand which is well-known to display
a strong trans influence.
˚
rated by a distance of 2.7542(3) A. Note that, in the
dinuclear complex V, the similar separation was found to
˚
be significantly shorter at 2.7099(4) A. A second impor-
tant piece of data is given by the Au-H bond distance of
1.70(3) A. Comparison with other species is made difficult
The reactivity of dimer 5 was briefly explored. A first
interesting remark concerns its stability in solution.
Though poorly soluble in common organic solvents, such
as hexanes, toluene, and ethers, 5 is fairly soluble in
chlorinated solvents but decomposes overnight in di-
chloromethane to afford colloidal gold and a new com-
plex 7 whose structure could be straightforwardly esta-
˚
since in the corresponding NHC based dimer V attempts
to locate the gold-bound hydrogen atom in the difference
Fourier synthesis failed because of a too-noisy environ-
ment around the two gold atoms.13 In the case of the
complex NHC Au-H IV the hydrogen atom was posi-
tioned on the basis of a second residual density max-
imum.13 Furthermore, no direct comparison can be
drawn with [AuHM] complexes since in these latter the
Au-H bond lengths vary considerably. Thus, in the
[(PPh3)3(CO)Ru(μ2-H)2Au(PPh3)]þ complex the Au-H
blished on the basis of the 31P NMR spectrum. Indeed,
2
the presence of a triplet at δ = 40.7 ppm with JPP
=
2
196 Hz, a doublet at δ = 16 ppm with JPP = 196 Hz
and of a singlet at -12.4 pm is very characteristic of a
(19) For a selection Au-H bond distances in [M-H-Au]þ complexes,
see: (a) Lehner, H.; Matt, D.; Pregosin, P. S.; Venanzi, L. M.; Albinati, A.
J. Am. Chem. Soc. 1982, 104, 6825–6827. (b) Albinati, A.; Chaloupka, S.; Currao,
A.; Klooster, W. T.; Koetzle, T. F.; Nesper, R.; Vananzi, L. M. Inorg. Chim. Acta
2000, 300-302, 903–911. (c) Alexander, B. D.; Johnson, B. J.; Johnson, S. M.;
Casalnuovo, A. L.; Pignolet, L. H. J. Am. Chem. Soc. 1986, 108, 4409–4417.
(17) Alexander, B. D.; Gomez-Sal, M. P.; Gannon, P. R.; Blaine, C. A.;
Boyle, P. D.; Mueting, A. M.; Pignolet, L. H. Inorg. Chem. 1988, 27, 3301.
(18) Alexander, B. D.; Johnson, B. J.; Johnson, S. M.; Boyle, P. D.; Kann,
N. C.; Mueting, A. M.; Pignolet, L. H. Inorg. Chem. 1987, 26, 3506.

Article
Inorganic Chemistry, Vol. 48, No. 17, 2009 8419
Scheme 7. Synthesis of the Complex 7
Figure 4. Solid-state structure of the cation of complex 7. Thermal
ellipsoids are set at the 50% probability level. For clarity, phenyl groups
of phospholes have been omitted and only the ipso carbon is represented.
˚
Selected bond lengths [A] and angles [deg]: Au(1)-P(1), 2.37(1); Au(1)-
P(3), 2.37(1); Au(1)-P(2), 2.42(1); P(1)-Au(1)-P(3), 125.7(5); P(1)-
Au(1)-P(2), 120.6(5); P(3)-Au(1)-P(2), 112.8(5).
tricoordinated mononuclear Au(I) complex (Scheme 7).
This assumption was further confirmed by detailed ana-
1
lyses of the H and 13C NMR spectra as well as by
elemental analysis.
Definitive evidence was given by an X-ray crystal
structure analysis of 7, single crystals being obtained by
diffusion of a solution of hexanes into a dichloromethane
solution of the complex. A view of one molecule of 7 is
presented in Figure 4, and the most relevant bond dis-
tances and angles are listed in the corresponding legend.
This structure does not deserve special comment except
for the P(1)-Au(1)-P(2) bond angle. Indeed, it is sig-
nificantly smaller than in complex 4 (120.58(3) in 7 versus
146.97(4) in 4), reflecting here again a significant flex-
ibility of the XDPP bite angle. One may also note the
different coordination mode from that of the Xantphos
ligand which can form the homoleptic tetracoordinated
cationic 18 VE complex.20
Figure 5. View of the optimized structure of complex 5. The phenyl
groups on phosphole units have been drawn in wireframe for sake of
clarity. Selected bond lengths[A] and angles [deg]: Au(1)-P(1), 2.357,
Au(1)-P(2) 2.517, Au(1)-Au(2) 2.824, Au(1)-H(1) 1.763, Au(2)-H(1)
1.758, P(1)-Au(1)-P(2) 121.2, P(2)-Au(1)-Au(2) 119.1, P(1)-Au(1)-
Au(2) 118.5, P(1)-Au(1)-H(1) 89.9, P(2)-Au(1)-H(1) 89.9, and Au-
(2)-Au(1)-H(1) 36.7.
In their article, Sadighi et al. reported that their di-
nuclear [Au2H]þ complex could serve as a source of the
monomeric species [Au-H] upon reaction with NaOtBu.
Unfortunately, addition of KOtBu led to a rapid decom-
position of complex 5, and careful monitoring of the
progress of the reaction by 31P NMR did not allow to
establish the formation of any [(XDPP)Au-H] complex.
Density Functional Theory (DFT) Calculations. To shed
some light on the electronic structure of dimer 5, theore-
tical calculations were carried out within the framework
of DFT (see Experimental Section for further details).
Calculations were carried out on the whole structure
including all substituents except the two methyl groups
of the Xantphos backbone which were replaced by hydro-
gen atoms. The geometry of the [(XDPP)2Au2(μ2-H)]þ
dimer 5 was optimized without any symmetry con-
straint.21 A view of the optimized structure is reported
in Figure 5, and the most significant metric parameters
are listed in the corresponding legend. On the whole, the
main features of the experimental structure were properly
reproduced by these calculations, the hydride ligand
˚
˚
(exp.: 1.70 (3) A) and the twisted arrangement of the
two XDPP ligands (see P-Au-Au-P dihedral angles).
The bond distances around the metal centers were over-
˚
estimated at most by 0.07 A. Noteworthy, like in the
experimental structure, the two Au-P distances asso-
ciated with a XDPP ligand differ by 0.16 A (difference of
˚
˚
0.14 A in the experimental structure). Surprisingly, the
longest Au-P distances are those approximately cis with
the hydride ligand. Finally a mean deviation of 2° was
found for the bond angles. Berger et al.,22 in a recent
theoretical study on [Au2H]þ, obtained an Au-Au bond
˚
˚
distance of 2.60 A and an Au-H bond distance of 1.69 A.
These distances are much shorter than the Au-Au dis-
˚
˚
tance of 2.824 A and Au-H distance of 1.763 A calcu-
lated here for complex 5. The differences are obviously
due to the presence of the π-acceptor ligands on the
[Au2H]þ fragment in the real system.
˚
bridging the two metal centers with Au-H = 1.76 A
To understand the way the hydride ligand binds the two
metal centers, a molecular orbital analysis was performed
on the whole complex and on various fragments. The
[(XDPP)2Au2(μ2-H)]þ complex can be seen as resulting
from the interaction of an hydride H- with the
(20) (a) Pintado-Alba, A.; de la Riva, H.; Nieuwhuyzen, M.; Bautista, D.;
Raithby, P. R.; Sparkes, H. A.; Teat, S. J.; Lopez-de-Luzuriaga, J. M.;
Lagunas, M. C. Dalton Trans. 2004, 3459. (b) Deak, A.; Megyes, T.; Tarkanyi,
G.; Kiraly, P.; Biczok, L.; Palinkas, G.; Stang, P. J. J. Am. Chem. Soc. 2006, 128,
12668–12670.
(21) Despite many attempts, we could not avoid the presence of one very
small imaginary frequency at -9.7650 corresponding mainly to the rotation
of a phenyl group on one phosphole part of the ligand.
(22) Berger, R. J. F. Z. Naturforsch. 2009, 64b, 388–394.

8420 Inorganic Chemistry, Vol. 48, No. 17, 2009
Escalle et al.
Scheme 8. Frontier Orbitals of the Bent [L2Au]þ Monomer B (Left-
Hand Side) and MOs of the [L2AuAuL2]2þ Dicationic Dimer A (Right-
hand Side) Relevant for the Interaction Diagram Reported on Scheme 6
Figure 6. HOMO of complex 5 as given by DFT calculations.
˚
Table 1. Bond Distances (A) and Angles (deg) of the Complex 5 in the Crystal
Structurea and As Calculated by DFT
Scheme 9. Three-Orbital Interaction Diagram Explaining the Inter-
action between H- and the [L2AuAuL2]2þ Fragment and the Shape of
the HOMO
bond/angle
exp.
DFT
Au(1)-P(1)
2.308(1)
2.446(1)
2.7542(3)
1.70(3)
2.357
2.517
2.824
1.763
1.758
Au(1)-P(2)
Au(1)-Au(2)
Au(1)-H(1)
Au(2)-H(1)
1.70(3)
P(1)-Au(1)-P(2)
P(2)-Au(1)-Au(2)
P(1)-Au(1)-Au(2)
P(1)-Au(1)-H(1)
P(2)-Au(1)-H(1)
Au(2)-Au(1)-H(1)
124.77(3)
117.24(2)
117.08(2)
144.9(8)
89(1)
121.2
119.1
118.5
147.3
89.9
36(1)
36.7
P(2)-Au(1)-Au(2)-P(10)
P(2)-Au(1)-Au(2)-P(20)
P(1)-Au(1)-Au(2)-P(10)
P(1)-Au(1)-Au(2)-P(20)
72.23(2)
82.63(2)
61.82(2)
72.23(2)
69.8
82.6
57.5
70.3
[(XDPP)2Au2]2þ fragment (A). This dicationic dimer A
can in turn be decomposed into two identical mono-
nuclear [(XDPP)Au]þ fragments (B) which are d10-ML2
complexes adopting a bent geometry. The lowest unoc-
cupied molecular orbital (LUMO; mainly s-p hybrid
orbital on the metal center with a contribution on the
ligands) and the highest occupied d orbital of B are
schematically pictured in Scheme 8.23 Thus the LUMO
of dimer A results from the bonding combination of the
LUMOs of the B fragments (see Scheme 8). This molec-
ular orbital (MO, σ) is widely developed between the two
metal centers, and its pseudo-cylindrical symmetry
around the Au-Au axis allows an interaction with the
1s orbital of the incoming hydride (stabilizing two-orbital
two-electron interaction). As can be seen, the bonding
combination of the occupied d orbitals on fragments B,
yields the MO dþ of dimer A (Scheme 8) which also has
the appropriate symmetry to interact 1sH- through a
destabilizing two-orbital four-electron interaction.
a For a better comparison of X-ray and theoretical data, Au(10) in the
X-ray data was renamed as Au(2) in the table.
The actual shape of the HOMO pictured in Figure 6
confirms this analysis. There is a three-center (Au-H-
Au) bonding interaction resulting from the bonding mix-
ing of 1sH- and σ fragment orbitals. Small antibonding
Au-H interactions also appear which involve a d com-
ponent on the metal centers (antibonding mixing between
1sH- and dþ). Finally antibonding components on the P
ligands appear only on the ligands cis to the hydride. This
nicely rationalizes the lengthening of the two Au-P
bonds located approximately cis to the hydride
(Table 1), an unexpected result with respect to the usual
trans influence exerted by a hydride ligand.
Conclusion
In conclusion we have shown that the XDPP ligand
belongs to the class of rare bidentate ligands that allow the
stabilization of 14 VE chelate gold cationic complexes of
general formula [Au(L2)]þ. Though formation of the neutral
16 VE gold-hydride complex [Au(XDPP)(H)] could not be
observed, a cationic dimetallic gold hydride complex [Au2-
(XDPPP)2(H)]þ, formally resulting from the stabilization of
the gold hydride complexby the [Au(XDPP)]þ complex could
be synthesized and successfully structurally and spectrosco-
pically characterized. DFT calculations carried out on the real
model establish that this dimetallic complex can be viewed as
the interaction of H- with the dimetallic dicationic [Au2-
(XDPPP)2]2þ fragment. Importantly, a detailed MO ana-
lysis reveals that bonding between H and Au in [Au2-
(XDPPP)2(H)]þ does not simply results from the two orbital
On the whole, a three-orbital four-electron interaction
scheme has to be considered (Scheme 9). The shape of the
highest occupied molecular orbital (HOMO) of the whole
complex thus results from the combination of a bonding
interaction between 1sH- and σ and from an antibond-
ing interaction between 1sH- and dþ.24 Consequently,
according to the way the σ and dþ fragment orbitals
participate in the HOMO, the antibonding contributions
on P ligands are predicted to vanish on the ligands trans to
the hydride and to add on the cis ligands.
(23) Jean Y. Molecular Orbitals of Transition Metal Complexes; Oxford
University Press: London, 2005; pp 83-84.
(24) Jean Y.; Volatron, F. An Introduction to Molecular Orbitals; Oxford
University Press: New York, 1996; Chapter 6.

Article
Inorganic Chemistry, Vol. 48, No. 17, 2009 8421
interaction between H- and an empty σ Au-Au orbital.
A four electron three orbital interaction diagram, also in-
volving the participation of a filled d orbital at gold, is
involved. This particular electronic situation allows to nicely
rationalize the difference observed between P-Au bonds.
Further studies will now focus on the reactivity of this new
class of cationic XDPP gold complexes and their potential use
as catalysts.
CHxanthene), 7.05-7.25 (m, 32H, Hmeta/ortho phenyl), 7.36 (m, 8H,
Hpara phenyl), 7.42-7.50 (dd, 4H, CHxanthene). 13C NMR
(CD2Cl2): δ 31.3 (s, CH3xanthene), 39.34 (s, C(CH3)2xanthene),
115.21 (m,35.6 Hz, CxantheneP), 128.24 (s, CHaromatic), 129.4 (s,
CHaromatic), 131.18 (s, CHaromatic), 131.98 (s, CHaromatic), 132.18
(s,CHaromatic), 134.19 (s, CHaromatic), 137.01 (m, ΣJ = 15 Hz,
Caromatic), 137.81 (m, ΣJ = 15 Hz, Cβ phosphole), 138.19 (m, ΣJ=
5 Hz, Caromatic)149.63 (m, ΣJ=44 Hz, CR phosphole), 159.27 (m,
ΣJ=13 Hz, CO). Anal. Calcd for C95H73Au2F3O5P4S: C, 60.01;
H, 3.87. Found: C, 60.05; H, 3.90.
Experimental Section
Synthesis of Complex 6 [(XDPP)Au-D-Au(XDPP)][OTf]. To
a solution of the complex 4 (152 mg, 0.15 mmol) in THF (2 mL)
was added at -78 °C the silane DSiMe2Ph (11.6 μL, 0.075
mmol). Completion of the reaction was confirmed by 31P NMR.
The mixture was allowed to warm to room temperature. The
title compound, which precipitated, was then filtered under
nitrogen. The corresponding solid was washed with diethyl-
ether. The solvent was removed to afford a yellow-brown solid 6
(190 mg, 67%). 31P{1H} NMR (CD2Cl2): δ 23.8 (pt, JDP=8.4
Hz). 1H NMR (CD2Cl2): δ 1.56 (s, 12H, CH3xanthene), 6.35 (m,
8H, ΣJHP=23 Hz, Hβ phosphole), 6.75 (m,4H, CHxanthene), 6.95 (t,
4H, J = 8.4 Hz, CHxanthene), 7.05-7.25 (m, 32H, Hmeta/ortho phenyl),
7.36 (m, 8H, Hpara phenyl), 7.42-7.50 (dd, 4H, CHxanthene). 2D-
NMR (CH2Cl2): δ 7.0 (q, JDP=8.4 Hz). 13C NMR (CD2Cl2): δ
31.3 (s, CH3xanthene), 39.34 (s, C(CH3)2xanthene), 115.21 (m,35.6
Hz, CxantheneP), 128.24 (s, CHaromatic), 129.4 (s, CHaromatic),
131.18 (s, CHaromatic), 131.98 (s, CHaromatic), 132.18 (s,
CHaromatic), 134.19 (s, CHaromatic), 137.01 (m, ΣJ = 15 Hz,
Synthesis. All reactions were routinely performed under an
inert atmosphere of argon or nitrogen using Schlenk and glove-
box techniques and dry deoxygenated solvents. Dry hexanes and
THF were obtained by distillation from Na/benzophenone.
Dry dichloromethane was distilled on P2O5. Nuclear magnetic
resonance spectra were recorded on a Bruker AC-300 SY
spectrometer operating at 300.0 MHz for 1H, 75.5 MHz for
13C, and 121.5 MHz for 31P. Solvent peaks are used as internal
reference relative to Me4Si for 1H and 13C chemical shifts
(ppm); 31P chemical shifts are relative to an 85% H3PO4 external
reference. Coupling constants are given in hertz. The following
abbreviations are used: s, singlet; d, doublet; t, triplet; m,
multiplet; v, virtual; p, pseudo. XDPP 1 was prepared as
previously reported. [AuCl(tht)] was prepared according to
established procedure.25 Silver trifluoromethanesulfonate and
the silane HSiMe2Ph were obtained from commercial suppliers
and were used as received. The deuterated silane DSiMe2Ph was
prepared according to established procedure.26 Elemental ana-
lyses were performed by the “Service d’analyse du CNRS”, at
Gif sur Yvette, France.
C
aromatic), 137.81 (m, ΣJ = 15 Hz, Cβ phosphole), 138.19 (m,
ΣJ = 5 Hz, Caromatic)149.63 (m, ΣJ = 44 Hz, CR phosphole),
159.27 (m, ΣJ = 13 Hz, CO). Anal. Calcd for C95H72DAu2-
F3O5P4S: C, 59.97; H, 3.92. Found: C, 60.04; H, 3.89.
Synthesis of Complex 4 [Au(XDPP)][OTf]. To a solution of
[AuCl(tht)]] (94.5 mg, 0.29 mmol) in dichloromethane (3 mL)
was added at room temperature the ligand 1 XDPP (200 mg,
0.29 mmol) . The solution was stirred 5 min. Completion of the
reaction was confirmed by 31P NMR. Silver triflate salt (75.7
mg, 0.29 mmol) was then added to the solution at room
temperature. The mixture was stirred 15 min, filtered, and con-
centrated. The corresponding solid was washed with hexanes.
The solvent was removed to afford a yellow solid 4 (295 mg,
98%). 31P{1H} NMR (CD2Cl2): δ 14.9 (s). 1H NMR (CD2Cl2):
δ1.56 (s, 6H, CH3xanthene), 6.99-7.05 (m, 2H, CHxanthene), 7.1 (t,
2H, CHxanthene), 7.14-7.27 (m, 12H, H meta/para phenyl), 7.6 (d,
4H, JHP = 27 Hz, Hβ phosphole), 7.51-7.57 (m, 8H, Hortho phenyl),
7.58-7.62 (m, 2H, CHxanthene).13C NMR (CD2Cl2): δ 29.7 (s,
CH3xanthene), 35.7 (s, C(CH3)2 xanthene), 110.1 (vt, ΣJ = 46.4 Hz,
Synthesis of Complex 7 [Au(XDPP)2][OTf]. A solution of the
complex 5 (30.1 mg, 0.029 mmol) in dichloromethane (1 mL)
was stirred overnight. Completion of the reaction was con-
firmed by 31P NMR. The solvent was removed to afford a
yellow solid 7 (25 mg, 93%). 31P{1H} NMR (CD2Cl2): δ -12.4
(s), 16 (d), 40.7 (t). 1H NMR (CD2Cl2): δ 1.19 (s, 6H,
CH3xanthene), 1.41 (s, 6H, CH3xanthene), 6.28-6.65 (m, 10H,
H
H
aromatic), 6.66-7.18 (m, 32H, Haromatic), 7.2-7.5 (m, 14H,
aromatic), 7.51-7.80 (m, 4H, Haromatic). 13C NMR (CD2-
Cl2): δ 26.9 (s,CH3xanthene), 30.4 (s,CH3xanthene), 33.8 (s,
C(CH3)2xanthene), 35.63 (s,C(CH3)2xanthene), 110.70 (m, ΣJ =
49.7 Hz,CxantheneP), 112.92 (s, ΣJ = 48.2 Hz, CxantheneP),
117.18 (d, J = 13.7 Hz, CxantheneP), 122.52 (d, J = 18.8 Hz,
CHaromatic), 123.58 (s, CHaromatic), 124.73 (d, ΣJ = 8.1 Hz,
CHaromatic), 124.84 (d, J=8 Hz, CHaromatic), 125.02 (m, ΣJ=
9.6 Hz, CHaromatic), 125.42 (vt, ΣJ=8.6 Hz, CHaromatic), 126.23
(s, CHaromatic), 127.13 (s, CHaromatic), 127.87 (s, CHaromatic),
127.93 (s, CHaromatic), 128.51 (s, CHaromatic), 129.04 (d, ΣJ=5.1
Hz, CHaromatic), 130.45 (d, ΣJ= 5.1 Hz, Caromatic), 130.71 (d, J=
11.6 Hz, CHaromatic), 131.10 (m, ΣJ = 6 Hz, CHaromatic), 131.31
(d, J=3.8 Hz, CHaromatic), 131.4 (d, J=3.5 Hz, CHaromatic),
CxantheneP), 125.4(vt, ΣJ=8 Hz, CHaromatic), 125.3 (vt, ΣJ=8 Hz,
CHaromatic), 128.4 (s, CHaromatic), 128.6(s, CHaromatic), 129.2 (s,
CHaromatic), 130.0 (s, CHaromatic), 131.9 (vt, ΣJ = 14.8 Hz,
C
aromatic), 135.3 (vt, ΣJ = 5 Hz, Caromatic), 135.6 (vt, ΣJ = 18
Hz, Cβ phosphole), 144.3 (vt, ΣJ=48 Hz, CR phosphole), 154.6 (vt,
ΣJ=11 Hz, CO). Anal. Calcd for C48H36AuF3O4P2S: C, 56.26;
H, 3.54. Found: C, 56.20; H, 3.57.
Synthesis of Complex 5 [(XDPP)Au-H-Au(XDPP)][OTf].
To a solution of the complex 4 (139 mg, 0.13 mmol) in THF
(2 mL) was added at -78 °C the silane HSiMe2Ph (10.5 μL,
(27) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb,
M. A.; Cheeseman, J. R.; Montgomery, J. A., Jr.; Vreven, T.; Kudin, K. N.;
Burant, J. C.; Millam, J. M.; Iyengar, S. S.; Tomasi, J.; Barone, V.;
Mennucci, B.; Cossi, M.; Scalmani, G.; Rega, N.; Petersson, G. A.;
Nakatsuji, H.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa,
J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Klene, M.; Li,
X.; Knox, J. E.; Hratchian, H. P.; Cross, J. B.; Bakken, V.; Adamo, C.;
Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.;
Cammi, R.; Pomelli, C.; Ochterski, J. W.; Ayala, P. Y.; Morokuma, K.;
Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Zakrzewski, V. G.; Dapprich,
S.; Daniels, A. D.; Strain, M. C.; Farkas, O.; Malick, D. K.; Rabuck, A. D.;
Raghavachari, K.; Foresman, J. B.; Ortiz, J. V.; Cui, Q.; Baboul, A. G.;
Clifford, S.; Cioslowski, J.; Stefanov, B. B.; Liu, G.; Liashenko, A.; Piskorz,
P.; Komaromi, I.; Martin, R. L.; Fox, D. J.; Keith, T.; Al-Laham, M. A.;
Peng, C. Y.; Nanayakkara, A.; Challacombe, M.; Gill, P. M. W.; Johnson,
B.; Chen, W.; Wong, M. W.; Gonzalez, C.; Pople, J. A. Gaussian 03, revision
C.02; Gaussian, Inc.: Wallingford, CT, 2004.
0.065 mmol). Completion of the reaction was confirmed by 31
P
NMR. The mixture was allowed to warm to room temperature.
The title compound, which precipitated, was then filtered under
nitrogen. The corresponding solid was washed with diethyl-
ether. The solvent was removed to afford a yellow-brown solid 5
(180 mg, 70%). 31P{1H} NMR (CD2Cl2): δ 23.8 (s). 1H NMR
(CD2Cl2): δ 1.56 (s, 12H, CH3xanthene), 6.35 (m, 8H, ΣJHP=23
Hz, Hβ phosphole), 6.75 (m,4H, CHxanthene), 6.95 (t, 4H, J=8.4 Hz,
(25) Uson, R.; Laguna, A. In Organometallics Syntheses; King, R. B.,
Eisch, J., Eds.; Elsevier Science, Amsterdam, 1986; Vol. 3 p 324.
(26) Pawlenko, S. Houben Weyl, Methoden der Organischem Chemie;
::
Muller, E., Bayer, O., Eds.; Thieme Verlag, Stuttgart, NY 1980; Bd. 13/5, p. 90.

8422 Inorganic Chemistry, Vol. 48, No. 17, 2009
Escalle et al.
Table 2. Crystallographic Data for Complexes 4, 5, and 7
4
5
7
empirical formula
Mr
C
47H36AuOP2,CF3O3S, 2CH2Cl2
C94H73Au2O2P4,CF3O3S
1901.41
orthorhombic
Pbcn
20.828(1)
15.631(1)
23.608(1)
90.00
90.00
90.00
7685.9(7)
4
1.643
3.988
0.50*0.12*0.12
75831
11204 (0.0573)
0.0316
0.0849
C94H72AuO2P4,CF3O3S, 2CH2Cl2
1194.59
triclinic
P1
1873.28
monoclinic
P21/c
18.430(1)
18.044(1)
31.243(1)
90.00
124.869(1)
90.00
8524.5(7)
4
1.460
2.011
0.24*0.20*0.06
67381
24828 (0.0506)
0.0447
0.1372
crystal system
space group
˚
a [A]
16.447(1)
16.986(1)
17.884(1)
95.103(1)
101.052(1)
99.753(1)
4794.5(5)
4
1.655
3.458
0.28*0.24*0.20
51145
˚
b [A]
˚
c [A]
R [deg]
β [deg]
γ [deg]
˚
volume [A]
Z
F
calcd [g.cm-3
]
μ [mm-1
]
crystal size [mm]
reflections collected
unique reflections (Rint
R [F > 4σ(F)]
RwF (all F2)
)
27699 (0.0448)
0.0481
0.1370
GoF
0.993
1.010
0.967
131.97 (vt, ΣJ=15.2 Hz, Caromatic), 132.16 (s, Caromatic), 134.25
(d, J=16.8 Hz, Caromatic), 134.52 (vt, ΣJ=6 Hz, Caromatic), 135.16
(m, ΣJ = 24.9 Hz, Cβ phosphole), 136.40 (d, J=46 Hz, CR phospole),
138.47(d, J=35.7 Hz, CHaromatic), 145.67 (vt, ΣJ = 43.9 Hz,
CR phosphole), 152.17 (d, ΣJ = 4.3 Hz, CR phospole), 152.64 (d, ΣJ=
8 Hz, CO), 152.73 (s, CO), 155.08 (vt, ΣJ=11.6 Hz, CO). Anal.
Calcd for C95H72AuF3O5P4S: C, 66.98; H, 4.26. Found: C,
67.04; H, 4.30.
X-ray Crystallography for Complexes 4, 5, 7. Yellow blocks of
4, brown needles of 5 and yellow plates of 7 crystallized by slow
diffusion of hexanes into a saturated dichloromethane solution
of respectively 4, 5, and 7. Data were collected on a Nonius
˚
Kappa CCD diffractometer using a Mo KR (λ = 0.71073 A)
X-ray source and a graphite monochromator at 150 K. Experi-
mental details are described in Table 2. The crystal structures
were solved using SIR 9737 and SHELXL97.38 Oak Ridge
Thermal Ellipsoid Plot (ORTEP) drawings were made using
ORTEP III for Windows.39 Crystallographic data can be ob-
tained free of charge at www.ccdc.cam.ac.uk/conts/retrieving.
html [or from the Cambridge Crystallographic Data Center, 12
Union Road, Cambridge CB21EZ, U.K.; fax: (int) þ44-1223/
336-033 ; e-mail: deposit@ccdc.cam.ac.uk] with the deposition
numbers CCDC 731892-731894, respectively, for 4, 5, and 7.
Computational Details. Calculations were performed with the
Gaussian 03 series of program.27 DFT28,29 was applied for the
complex [(XDPP)2Au2(μ2-H)]þ (in which the methyl substitu-
ents on the xanthenes backbone were replaced by hydrogen
atoms) with the B3PW91 functional.30,31 A quasi-relativistic
effective core potential operator was used to represent the 60
innermost electrons of the gold atoms.32 The basis set for the
metal was the quadruple-ζ basis set associated to the pseudo-
potential33 (Def2-QZVP calculations). 6-31Gþ* basis set was
used for the atoms directly bonded to the metal centers (P atoms
and the bridging hydride).34 3-21G* was used for the phosphole
cycles35 and 3-21G for the phenyl groups carried by the phosph-
ole cycles and for the xanthenes backbone.36 The minimum
energy was characterized by vibration frequencies calculations.
Acknowledgment. The CNRS, the Ecole Polytechnique,
and the IDRIS (for computer time, Project No. 090616) are
thanked for supporting this work.
Supporting Information Available: Computational details,
computed Cartesian coordinates, energies, three lower frequen-
cies of all theoretical structures, an X-ray structure and tables
giving crystallographic data for 4, 5, and 7 (including atomic
coordinates, bond lengths and angles, and anisotropic displace-
ment parameters). This material is available free of charge via
the Internet at http://pubs.acs.org.
(28) Ziegler, T. Chem. Rev. 1991, 91, 651–667.
(29) Parr, R. G.; Yang, W. DFT; Oxford University Press: Oxford, U.K.,
1989.
(30) Becke, A. D. J. Chem. Phys. 1993, 98, 5648–5652.
(31) Perdew, J. P.; Wang, Y. Phys. Rev. B 1992, 45, 13244–13249.
::
(32) Andrae, D.; Haussermann, U.; Dolg, M.; Stoll, H.; Preuss, H. Theor.
Chim. Acta 1990, 77, 123–141.
(37) Altomare, A.; Burla, M. C.; Camalli, M.; Cascarano, G.; Giacovazzo,
C.; Guagliardi, A.; Moliterni, A. G. G.; Polidori, G.; Spagna, R. SIR97, an
integrated package of computer programs for the solution and refinement of
crystal structures using single-crystal data.
(38) Sheldrick, G. M., SHELXL-97; Universitat Gottingen: Gottingen,
Germany, 1997.
(33) Weigend, F.; Ahlrichs, R. Phys. Chem. Chem. Phys. 2005, 7, 3297–
3305.
ꢀ
(34) Clark, T.; Chandrasekhar, J.; Spitznagel, G. W.; Von Rague Scleyer,
P. J. Comput. Chem. 1983, 4, 294.
::
::
::
(35) Pietro, W. J.; Francl, M. M.; Hehre, W. J.; Defrees, D. J.; Pople, J. A.;
Binkley, S. J. Am. Chem. Soc. 1982, 104, 5039–5048.
(36) Binkley, S.; Pople, J. A.; Hehre, W. J. J. Am. Chem. Soc. 1980, 102,
939–947.
(39) Farrugia, L. J., ORTEP-3; Department of Chemistry, University of
Glasgow: Glasgow, Scotland, U.K., 2001.