Direct evidence for intermolecular oxidative addition of σ(Si-Si) bonds to gold

Article abstract of DOI:10.1002/anie.201307613

Oxidative addition plays a major role in transition-metal catalysis, but this elementary step remains very elusive in gold chemistry. It is now revealed that in the presence of GaCl₃, phosphine gold chlorides promote the oxidative addition of disilanes at low temperature. The ensuing bis(silyl) gold(III) complexes were characterized by quantitative ³¹P and ²⁹Si NMR spectroscopy. Their structures (distorted Y shape) and the reaction profile of σ(Si-Si) bond activation were analyzed by DFT calculations. These results provide evidence for the intermolecular oxidative addition of σ(Si-Si) bonds to gold and open promising perspectives for the development of new gold-catalyzed redox transformations. Oxidative addition is the most elusive elementary step in reactions with gold. Now, evidence for the intermolecular oxidative addition of σ(Si-Si) bonds is reported. Phosphine gold chlorides readily reacted with disilanes at low temperature in the presence of GaCl₃. The ensuing bis(silyl) gold(III) complexes were characterized by ³¹P and ²⁹Si NMR spectroscopy, and their structures were analyzed by DFT calculations. Copyright

Full text of DOI:10.1002/anie.201307613

Angewandte
Chemie
DOI: 10.1002/anie.201307613
Gold Complexes
ꢀ
Direct Evidence for Intermolecular Oxidative Addition of s(Si Si)
Bonds to Gold**
Maximilian Joost, Pauline Gualco, Yannick Coppel, Karinne Miqueu, Christos E. Kefalidis,
Laurent Maron,* Abderrahmane Amgoune,* and Didier Bourissou*
Abstract: Oxidative addition plays a major role in transition-
metal catalysis, but this elementary step remains very elusive in
gold chemistry. It is now revealed that in the presence of GaCl3,
phosphine gold chlorides promote the oxidative addition of
disilanes at low temperature. The ensuing bis(silyl) gold(III)
complexes were characterized by quantitative 31P and
29Si NMR spectroscopy. Their structures (distorted Y shape)
corroborated for the reaction of alkynes and allenes with
silyl gold(I) complexes.[7] Reductive elimination from
[8,9]
[10–12]
ꢀ
ꢀ
gold(III) complexes to form C C
I, F) bonds has also been confirmed. Furthermore, reductive
elimination from tetrathiolate gold(III) complexes to form
and C X
(X = N,
ꢀ
S S bonds was disclosed by Bachmann and co-workers; this
reaction was found to be reversible.[13]
ꢀ
and the reaction profile of s(Si Si) bond activation were
analyzed by DFT calculations. These results provide evidence
For oxidative addition reactions, however, comparatively
little and generally only indirect information has been
gained.[14,15] Aside from the work of Bachmann et al. on
ꢀ
for the intermolecular oxidative addition of s(Si Si) bonds to
gold and open promising perspectives for the development of
new gold-catalyzed redox transformations.
ꢀ
s(S S) bond activation, direct spectroscopic and crystallo-
graphic evidence for the intramolecular oxidative addition of
[16]
ꢀ
s(Si Si) bonds was reported by our group. In this project,
R
ecently, the scope of gold-catalyzed transformations was
we took advantage of chelating assistance with a phosphine to
spectacularly expanded,[1–3] and our knowledge of gold
reactivity has significantly increased.[4] Fundamental studies
have shown that gold complexes display versatile reactivity,
and examples of all common mechanistic elementary steps
have progressively been documented.
pre-orientate the s(Si Si) bond and to stabilize the ensuing
ꢀ
oxidative addition product. The results obtained substanti-
ated our interest in and the potential of the chelating strategy
for the study of unusual bonding situations and reactivity.[17]
However, at the same time, the role and the importance of the
anchoring sites that are used to promote disilane activation
remain unclear. We therefore asked ourselves to which extent
intramolecular reactions with such an assistance were repre-
sentative of the intrinsic reactivity of gold complexes, and
whether similar transformations could also proceed intermo-
lecularly. Therefore, we explored the reactions of simple
phosphine gold complexes with disilanes; herein, we report
unambiguous evidence for the intermolecular oxidative
The ability of gold to undergo transmetalation has been
illustrated with various main group elements[5] and transition
metals.[5h,6] The feasibility of syn insertion was recently
[*] M. Joost, Dr. P. Gualco, Dr. A. Amgoune, Dr. D. Bourissou
Laboratoire Hꢀtꢀrochimie Fondamentale et Appliquꢀe
Universitꢀ Paul Sabatier/CNRS UMR 5069
118 Route de Narbonne, 31062 Toulouse Cedex 09 (France)
E-mail: amgoune@chimie.ups-tlse.fr
dbouriss@chimie.ups-tlse.fr
Homepage: http://hfa.ups-tlse.fr/LBPB/index_lbpb.htm
ꢀ
addition of s(Si Si) bonds. The ensuing bis(silyl) gold(III)
complexes were characterized by quantitative 31P and
29Si NMR spectroscopy at low temperature, and the reaction
Dr. Y. Coppel
ꢀ
profile of s(Si Si) bond activation was thoroughly analyzed
by DFT calculations.
Laboratoire de Chimie de Coordination, CNRS UPR 8241
205 Route de Narbonne, 31077 Toulouse (France)
In a first control experiment, one equivalent of the
disilane (PhMe2Si)2 was added to the phosphine gold complex
[(Ph3P)AuCl] in toluene. No reaction occurred at room
temperature over several days, and progressive heating up
to 1008C only led to decomposition of the gold precursor.
Neutral [(L)AuCl] complexes are commonly activated with
chloride abstractors, and we thus sought to generate a more
electrophilic gold species using GaCl3.[18] Upon addition of
(PhMe2Si)2 to a 1:1 mixture of [(Ph3P)AuCl] and GaCl3 in
CD2Cl2 at ꢀ908C (Scheme 1), the solution immediately
turned light yellow. Analysis of the reaction mixture by
31P NMR spectroscopy at ꢀ808C indicated the formation of
a new species 1a. The 31P resonance signal was significantly
shifted downfield (d 60.9 ppm) and appeared in the same
region as those of the bis(silyl) phosphine gold(III) complexes
that we had recently generated from chelating phosphine
disilanes.[16] Compound 1a was the major phosphorus-con-
Dr. K. Miqueu
Institut Pluridisciplinaire de Recherche sur l’Environnement et les
Matꢀriaux, Equipe Chimie Physique, Universitꢀ de Pau et des Pays
de l’Adour/CNRS UMR 5254, Hꢀlioparc
2 Avenue du Prꢀsident Angot, 64053 Pau cedex 09 (France)
Dr. C. E. Kefalidis, Dr. L. Maron
Laboratoire de Physique et Chimie des Nano-Objets
Universitꢀ de Toulouse, INSA, UPS, LPCNO
Universitꢀ de Toulouse/CNRS UMR 5215/INSA
135 Avenue de Rangueil, 31077 Toulouse (France)
E-mail: laurent.maron@irsamc.ups-tlse.fr
[**] Financial support from the Centre National de la Recherche
Scientifique, the Universitꢀ de Toulouse, and the Agence Nationale
de la Recherche (ANR-10-BLAN-070901) is gratefully acknowledged.
CalMip and CINES are acknowledged for generously providing
computing time.
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/anie.201307613.
Angew. Chem. Int. Ed. 2014, 53, 747 –751
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
747

.
Angewandte
Communications
These results are consistent with the phosphine bis(silyl) gold
formulation of 1a; for this compound, the presence of a single
signal in the 29Si NMR spectrum and the value of JSi,P suggest
a Y shape structure. Compounds such as 1a are unprece-
dented, but Marko and co-workers have recently disclosed an
isoelectronic N-heterocyclic carbene (NHC) platinum bis-
(silyl) complex.[22]
Scheme 1. Formation of the bis(silyl) gold(III) complex 1a upon
oxidative addition of a disilane.
To obtain further evidence on the formation of phosphine
taining species (ca. 66%). Another resonance in the 31P NMR
spectrum is observed at d 43.7 ppm, which suggests the
formation of the cationic complex [(Ph3P)2Au]+ as a side
product.
gold(III) bis(silyl) species upon oxidative addition of s(Si Si)
ꢀ
bonds, we prepared complex 2 in which one of the phenyl
substituents at the phosphorus atom bears a SiPhMe2 group in
the ortho position (Scheme 2). This spectator silyl group may
According to variable-temperature NMR measurements,
compound 1a is thermally unstable. Decomposition occurred
rapidly above ꢀ608C,[19] and further spectroscopic character-
ization was thus performed at ꢀ808C. The 29Si NMR spectrum
of the reaction mixture displays three resonance signals that
correspond to the starting disilane (d ꢀ21.0 ppm), the chlor-
osilane PhMe2SiCl (d 21.0 ppm) and complex 1a
Scheme 2. Synthesis of the bis(silyl) gold(III) complex 3, which fea-
tures a silicon-labeled phosphine.
(d 40.7 ppm). The signal for 1a appears as a doublet (JSi,P
=
39.8 Hz) and correlates with the 31P NMR signal at
d 60.9 ppm, as established by 2D HMBC(31P–29Si) and
29Si{selective 31P} NMR experiments.[20] The magnitude of
the JSi,P coupling constant that was observed for 1a is not
consistent with a phosphine gold(I) silyl structure (JSi,P
(trans) = 165–210 Hz),[7,21] and may rather be attributed to
the formation of a phosphine bis(silyl) gold(III) complex with
a symmetric Y shape structure. However, at this stage, it was
not possible to unambiguously establish the presence of two
silyl groups per gold center. We thus envisioned to count the
silicon atoms per PPh3 moiety, and hence recorded a 31P NMR
spectrum with a long acquisition time.[20] Apart from the main
signal, three sets of satellites, which correspond to the 29Si and
13C isotopomers of 1a, could be distinguished (Figure 1).
After deconvolution of the overlapping signals, the area of
each satellite was precisely determined, and taking into
account the natural abundance of the 13C (1.11%) and 29Si
(4.70%) isotopes, we found two silyl groups per PPh3 moiety.
be used as an internal standard for 29Si NMR spectroscopy to
enable the direct counting of the silyl groups at the gold
center. For complex 2, the corresponding 29Si NMR signal
appears as a doublet (3JSi,P = 8.0 Hz) at d ꢀ5.5 ppm. Addition
of the disilane (PhMe2Si)2 to a 1:1 mixture of complex 2 and
GaCl3 at ꢀ808C resulted in the instantaneous formation of
complex 3 (ca. 60% yield according to 31P NMR spectrosco-
py), along with some side products.
Complex 3 is thermally unstable and decomposes within
hours at ꢀ808C. As expected, its 29Si NMR spectrum displays
two resonance signals (Figure 2). One signal (d ꢀ7.6 ppm, d,
3JSi,P = 4.6 Hz, 1 Si) appears in the region where the resonan-
ces of ArSiPhMe2 derivatives are usually found and is
analogous to that of the starting complex 2. The second
signal (d 40.2 ppm, d, 2JSiP = 38.3 Hz, 2 Si) appears in the
region of gold silyl species and is similar to those of
complex 1a. The relative integration of these two signals
unequivocally confirmed the formulation of 3 as a phosphine
gold(III) bis(silyl) complex.
Figure 1. Long-acquisition 31P{1H} spectrum of complex 1a that shows
Figure 2. Quantitative 29Si{1H} NMR spectrum after addition of the
disilane (PhMe2Si)2 to a 1:1 mixture of complex 2 and GaCl3.
29
the 13C ( and ) and Si ( ) satellites.
~
&
*
748
www.angewandte.org
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2014, 53, 747 –751

Angewandte
Chemie
The oxidative addition process was then explored with
other disilanes. The reaction proceeded similarly with the
disilane (Ph2MeSi)2, and the ensuing complex 1b (obtained in
[(Ph3P)Au]+ highly unlikely.[24] Upon reaction of II with the
disilane (PhMe2Si)2, the system reaches the transition state of
the oxidative addition, TSII-III. The corresponding activation
barrier is relatively low (11.7 kcalmolꢀ1 from II), which is in
ca. 40% yield according to 31P NMR spectroscopy) displayed
2
a very similar 29Si NMR pattern (d 34.5 ppm, d, JSi,P
=
line with a kinetically facile reaction. The s(Si Si) bond is
ꢀ
39.8 Hz). Interestingly, the non-symmetric disilane
located in the plane that is defined by the phosphorus, gold,
and chlorine atoms, and it is substantially elongated (from
2.38 ꢀ in the free disilane to 2.50 ꢀ in TSII-III). Following the
intrinsic reaction coordinate, TSII-III leads to the oxidative
ꢀ
Ph2MeSi SiMe2Ph was also activated by gold. The resulting
complex 1c is highly unstable even at low temperatures (ca.
12% yield according to 31P NMR spectroscopy), but its
structure could be established by 29Si NMR spectroscopy at
ꢀ808C. As expected from the dissymmetric nature of the
disilane, complex 1c displayed two distinctive 29Si NMR
resonance signals in the region typical for gold–silyl species
ꢀ
addition product III in which the s(Si Si) bond is fully broken
(3.3 ꢀ).[20] Taking into account the residual contact with the
ꢀ
GaCl4 counteranion (Cl···Au: 3.09 ꢀ), the gold center is
tetracoordinated and adopts a distorted square planar geom-
2
ꢀ
that correspond to SiMe2Ph (d 42.8 ppm, d, JSi,P = 27.5 Hz)
etry. Dissociation of GaCl4 from III to give the ion pair
2
and SiMePh2 (d 33.1 ppm, d, JSi,P = 49.6 Hz).
complex IV is exothermic by 3.1 kcalmolꢀ1, which makes the
whole oxidative addition process from [(Ph3P)AuCl] and
GaCl3 slightly thermodynamically favorable.[25] The phos-
phine gold bis(silyl) complex IV adopts a distorted Y shape
geometry (P–Au–Si bond angles of 129.68 and 145.98 on
average). The situation differs somewhat from that encoun-
tered for the isoelectronic NHC Pt bis(silyl) complex.[22,26]
Careful examination of the potential energy surface (PES) of
IV revealed the presence of several rotamers of similar
structure and energy (Figure S28).[20] In all of them, the two
silyl groups are found in different environments. Conversely,
a single 29Si NMR signal was observed experimentally. The
most likely interpretation for the apparent magnetic equiv-
alence of the two silyl groups is a fast isomerization of
complex IV on the NMR time scale. Indeed, a low-energy
To evaluate the role of PPh3 in the oxidative addition
process, other phosphines were tested. The substitution
pattern at phosphorus was found to strongly influence the
stability and reactivity of the [(R3P)AuCl]/GaCl3 ion pairs.
With phosphites, such as P(OPh)3 and P(OMe)3, addition of
(PhMe2Si)2 induced fast degradation and led to a mixture of
unidentified products. Under the same conditions, no reaction
occurred with P(tBu)3, whereas the use of the sterically less
demanding phosphine PCy3 readily afforded the correspond-
ing bis(silyl) gold(III) complex 4.[20] Interestingly, the PCy3
ligand was found to impart a somewhat higher stability to the
bis(silyl) gold(III) species. Indeed, complex 4 is stable up to
about ꢀ408C, but all our attempts to crystallize this species at
low temperatures have unfortunately remained unsuccessful
thus far.
¼
pathway was identified computationally (DH = 2.0 kcal
DFT calculations (B3PW91) were carried out to gain
more insight into the mechanism and reaction profile of the
molꢀ1; Figure S30).[20] Finally, the key NMR data of complex
IV was evaluated (gauge-including atomic orbital (GIAO)
calculations using both the relativistic effective core potential
(RECPs) and all-electron basis sets). The computed values
for the chemical shifts of 29Si (56.2 ppm) and 31P (66.6 ppm),
as well as for the JSi,P coupling constant (34.5 Hz), were in
good agreement with the experimental results.
In conclusion, phosphine gold chlorides have been shown
to readily react with disilanes at low temperature in the
presence of GaCl3. This joint experimental and computational
ꢀ
oxidative addition of s(Si Si) bonds. The reaction of the
neutral complex [(Ph3P)AuCl] (I) was examined first. Acti-
vation of the disilane was found to be endothermic (DH =
16.0 kcalmolꢀ1) and to have a rather high activation barrier
2
¼
(DH = 27.8 kcalmolꢀ1
;
Supporting Information, Fig-
ure S29).[20] This is consistent with the fact that no reaction
had occurred in the absence of the chloride abstractor. The
presence of GaCl3 was thus taken into account computation-
ally (Figure 3).
From complex I, the for-
mation of a close adduct II is
thermodynamically favored
by 17.6 kcalmolꢀ1 in DH
(6.4 kcalmolꢀ1 in DG).[23]
The chlorine atom that is
directly attached to the gold
center interacts tightly with
the gallium center (Cl–Ga
distance: 2.39 ꢀ), and the
ꢀ
Au Cl bond is noticeably
elongated (from 2.30 ꢀ in I
to 2.38 ꢀ in II). Dissociation
of GaCl4ꢀ from the ion pair II
is predicted to be endother-
mic by 19.6 kcalmolꢀ1, which
makes the formation of the
Figure 3. Computed reaction profile for the oxidative addition of the disilane (PhMe2Si)2 upon reaction with
bare cationic gold complex (Ph3P)AuCl/GaCl3.
Angew. Chem. Int. Ed. 2014, 53, 747 –751
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
749

.
Angewandte
Communications
De Buck Becker, M. Rudolph, C. Scholz, F. Rominger, Adv.
Synth. Catal. 2012, 354, 133 – 147; f) M. H. Pꢂrez-Temprano, J. A.
Casares, ꢃ. R. de Lera, R. ꢃlvarez, P. Espinet, Angew. Chem.
2012, 124, 5001 – 5004; Angew. Chem. Int. Ed. 2012, 51, 4917 –
4920; g) M. H. Pꢂrez-Temprano, J. A. Casares, P. Espinet, Chem.
Eur. J. 2012, 18, 1864 – 1884; h) T. P. Cornell, Y. Shi, S. A. Blum,
Organometallics 2012, 31, 5990 – 5993.
study provides evidence for a very elusive elementary step at
gold, namely oxidative addition. The feasibility of such
reactions at the intermolecular level was demonstrated,
which gave access to unusual cationic Y-shaped bis(silyl)
gold(III) complexes. These thermally unstable complexes are
closely related to the intermediate species that were proposed
by the groups of Klinkhammer and Stratakis to account for
disilane activation in gold-mediated processes.[27] Chelating
assistance is a common strategy in organometallic chemistry,
but it is always questionable as to which extent the anchoring
sites enforce the observed reactivity. The intermolecular
reactions described herein substantiate that oxidative addi-
tion can readily proceed at gold centers. These results provide
important insights into the intrinsic reactivity of gold com-
plexes and open promising perspectives for the development
of new gold-catalyzed redox transformations. Future work in
our group will seek to study the ability of gold to activate
other s bonds and to gain an improved knowledge of the
factors that govern the reactivity of gold complexes towards
oxidative addition.
[7] M. Joost, P. Gualco, S. Mallet-Ladeira, A. Amgoune, D.
Bourissou, Angew. Chem. 2013, 125, 7301 – 7304; Angew.
Chem. Int. Ed. 2013, 52, 7160 – 7163.
[8] a) A. Tamaki, S. A. Magennis, J. K. Kochi, J. Am. Chem. Soc.
1974, 96, 6140 – 6148; b) S. Komiya, T. A. Albright, R. Hoff-
mann, J. K. Kochi, J. Am. Chem. Soc. 1976, 98, 7255 – 7265.
[9] S. Komiya, A. Shibue, Organometallics 1985, 4, 684 – 687.
[10] S. Lavy, J. J. Miller, M. Pazicky, A. S. Rodrigues, F. Rominger, C.
Jꢄkel, D. Serra, N. Vinokurov, M. Limbach, Adv. Synth. Catal.
2010, 352, 2993 – 3000.
[11] V. J. Scott, J. A. Labinger, J. E. Bercaw, Organometallics 2010,
29, 4090 – 4096.
[12] N. P. Mankad, F. D. Toste, Chem. Sci. 2012, 3, 72 – 76.
[13] R. E. Bachman, S. A. Bodolosky-Bettis, C. J. Pyle, M. A. Gray, J.
Am. Chem. Soc. 2008, 130, 14303 – 14310.
ꢀ
[14] For early studies on the oxidative addition of Me I, see: a) A.
Tamaki, J. K. Kochi, J. Organomet. Chem. 1972, 40, C81 – C84;
b) A. Tamaki, J. K. Kochi, J. Chem. Soc. Dalton Trans. 1973,
2620 – 2626; c) A. Tamaki, J. K. Kochi, J. Organomet. Chem.
1974, 64, 411 – 425.
Received: August 29, 2013
Revised: October 23, 2013
Published online: December 4, 2013
ꢀ
[15] For recent studies on the activation of Ar X bonds at gold, see:
Keywords: density functional calculations · gold ·
NMR spectroscopy · oxidative additions · silicon
a) A. Corma, R. Juarez, M. Boronat, F. Sanchez, M. Iglesias, H.
Garcia, Chem. Commun. 2011, 47, 1446 – 1448; b) M. T. Johnson,
J. M. Janse van Rensburg, M. Axelsson, M. S. G. Ahlquist, O. F.
Wendt, Chem. Sci. 2011, 2, 2373 – 2377; c) P. S. D. Robinson,
G. N. Khairallah, G. da Silva, H. Lioe, R. A. J. OꢅHair, Angew.
Chem. 2012, 124, 3878 – 3883; Angew. Chem. Int. Ed. 2012, 51,
3812 – 3817.
.
[1] Modern Gold Catalyzed Synthesis (Eds.: A. S. K. Hashmi, F. D.
Toste), Wiley-VCH, Weinheim, 2012.
[2] For a recent review on gold-catalyzed C H bond functionaliza-
ꢀ
tion, see: T. C. Boorman, I. Larrosa, Chem. Soc. Rev. 2011, 40,
[16] a) P. Gualco, S. Ladeira, K. Miqueu, A. Amgoune, D. Bourissou,
Angew. Chem. 2011, 123, 8470 – 8474; Angew. Chem. Int. Ed.
2011, 50, 8320 – 8324; b) P. Gualco, S. Ladeira, K. Miqueu, A.
Amgoune, D. Bourissou, Organometallics 2012, 31, 6001 – 6004;
1910 – 1925.
[3] For
a recent review on gold-catalyzed oxidative coupling
reactions, see: M. N. Hopkinson, A. D. Gee, V. Gouverneur,
Chem. Eur. J. 2011, 17, 8248 – 8262.
[4] a) A. S. K. Hashmi, Angew. Chem. 2010, 122, 5360 – 5369;
Angew. Chem. Int. Ed. 2010, 49, 5232 – 5241; b) L. P. Liu, G. B.
Hammond, Chem. Soc. Rev. 2012, 41, 3129 – 3139.
ꢀ
for examples of s(Sn Sn) bond activation at gold, see: c) N.
Lassauque, P. Gualco, S. Mallet-Ladeira, K. Miqueu, A.
Amgoune, D. Bourissou, J. Am. Chem. Soc. 2013, 135, 13827 –
13834.
[5] For B-to-Au transmetalation, see: a) D. V. Partyka, M. Zeller,
A. D. Hunter, T. G. Gray, Angew. Chem. 2006, 118, 8368 – 8371;
Angew. Chem. Int. Ed. 2006, 45, 8188 – 8191; b) D. V. Partyka, M.
Zeller, A. D. Hunter, T. G. Gray, Inorg. Chem. 2012, 51, 8394 –
8401; c) H. K. Lenker, T. G. Gray, R. A. Stockland, Dalton
Trans. 2012, 41, 13274 – 13276; d) S. G. Weber, D. Zahner, F.
Rominger, B. F. Straub, Chem. Commun. 2012, 48, 11325 –
11327; e) S. Dupuy, L. Crawford, M. Bꢁhl, A. M. Z. Slawin,
S. P. Nolan, Adv. Synth. Catal. 2012, 354, 2380 – 2386; for Si-to-
Au transmetalation, see: f) S. Dupuy, A. M. Z. Slawin, S. P.
Nolan, Chem. Eur. J. 2012, 18, 14923 – 14928; for Sn-to-Au
transmetalation, see: g) Y. Chen, M. Chen, Y. Liu, Angew. Chem.
2012, 124, 6285 – 6290; Angew. Chem. Int. Ed. 2012, 51, 6181 –
6186; h) J. delPozo, D. Carrasco, M. H. Pꢂrez-Temprano, M.
Garcia-Melchor, R. Alvarez, J. A. Casares, P. Espinet, Angew.
Chem. 2013, 125, 2245 – 2249; Angew. Chem. Int. Ed. 2013, 52,
2189 – 2193.
[6] a) M. Contel, M. Stol, M. A. Casado, G. P. M. van Klink, D. D.
Ellis, A. L. Spek, G. Van Koten, Organometallics 2002, 21, 4556 –
4559; b) Y. Shi, S. M. Peterson, W. W. Haberaecker, S. A. Blum,
J. Am. Chem. Soc. 2008, 130, 2168 – 2169; c) J. J. Hirner, Y. Shi,
S. A. Blum, Acc. Chem. Res. 2011, 44, 603 – 613; d) D. Serra,
M. E. Moret, P. Chen, J. Am. Chem. Soc. 2011, 133, 8914 – 8926;
e) A. S. K. Hashmi, C. Lothschꢁtz, R. Dçpp, M. Ackermann, J.
[17] Previous contributions from our group include the coordination
of Group 13 and 14 Lewis acids; see: a) M. Sircoglou, S.
Bontemps, M. Mercy, N. Saffon, M. Takahashi, G. Bouhadir, L.
Maron, D. Bourissou, Angew. Chem. 2007, 119, 8737 – 8740;
Angew. Chem. Int. Ed. 2007, 46, 8583 – 8586; b) M. Sircoglou, M.
Mercy, N. Saffon, Y. Coppel, G. Bouhadir, L. Maron, D.
Bourissou, Angew. Chem. 2009, 121, 3506 – 3509; Angew.
Chem. Int. Ed. 2009, 48, 3454 – 3457; c) P. Gualco, T. P. Lin, M.
Sircoglou, M. Mercy, S. Ladeira, G. Bouhadir, L. M. Perez, A.
Amgoune, L. Maron, F. P. Gabbai, D. Bourissou, Angew. Chem.
2009, 121, 10076 – 10079; Angew. Chem. Int. Ed. 2009, 48, 9892 –
9895; d) A. Amgoune, D. Bourissou, Chem. Commun. 2011, 47,
ꢀ
ꢀ
859 – 871; for examples of the coordination of s(Si Si) and (Si
H) bonds, see: e) P. Gualco, A. Amgoune, K. Miqueu, S. Ladeira,
D. Bourissou, J. Am. Chem. Soc. 2011, 133, 4257 – 4259; f) M.
Joost, S. Mallet-Ladeira, K. Miqueu, A. Amgoune, D. Bourissou,
ꢀ
Organometallics 2013, 32, 898 – 902; for the activation of P C
ꢀ
and P H bonds, see: g) E. J. Derrah, S. Ladeira, G. Bouhadir, K.
Miqueu, D. Bourissou, Chem. Commun. 2011, 47, 8611 – 8613;
h) E. J. Derrah, C. Martin, S. Mallet-Ladeira, K. Miqueu, G.
Bouhadir, D. Bourissou, Organometallics 2013, 32, 1121 – 1128.
[18] Upon addition of GaCl3 (1 equiv), the 31P NMR resonance signal
of [(Ph3P)AuCl] shifted from d = 33 to 31 ppm. The resulting
750
www.angewandte.org
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2014, 53, 747 –751

Angewandte
Chemie
adduct is stable for hours at ꢀ808C, but rapidly decomposes at
higher temperatures.
is not correct, and therefore, the DG value will not be discussed
further in this manuscript.
[24] For comparison, the reaction profile for the bare complex,
denoted as VI, is given in the Supporting Information, Fig-
ure S32.
[19] According to 29Si NMR spectroscopy, the main decomposition
products are the chlorosilane PhMe2SiCl and the disiloxane
PhMe2SiOSiMe2Ph.
[20] See the Supporting Information for details.
[21] a) J. Meyer, J. Willnecker, U. Schubert, Chem. Ber. 1989, 122,
223 – 230; b) O. Monge, A. Schier, H. Schmidbaur, Z. Natur-
forsch. B 1999, 54, 26 – 29; c) M. Theil, P. Jutzi, B. Neumann, A.
Stammler, H. G. Stammler, J. Organomet. Chem. 2002, 662, 34 –
42.
[22] G. Berthon-Gelloz, B. de Bruin, B. Tinant, I. Marko, Angew.
Chem. 2009, 121, 3207 – 3210; Angew. Chem. Int. Ed. 2009, 48,
3161 – 3164.
[25] Calculations also suggested reductive elimination to form a
ꢀ
Si Cl bond as a possible decomposition pathway for the gold
bis(silyl) complexes; an activation barrier of 26.1 kcalmolꢀ1 was
predicted for the formation of the chlorosilane and the silyl
gold(I) complex (Figure S29).[20]
[26] N. Takagi, S. Sakaki, J. Am. Chem. Soc. 2012, 134, 11749 – 11759.
[27] a) M. Wilfling, K. Klinkhammer, Angew. Chem. 2010, 122, 3287 –
3291; Angew. Chem. Int. Ed. 2010, 49, 3219 – 3223; b) C.
Gryparis, M. Stratakis, Chem. Commun. 2012, 48, 10751 – 10753.
[23] As the reaction is accompanied by a decrease in molecularity
(three molecules giving a single ion pair), the computed entropy
Angew. Chem. Int. Ed. 2014, 53, 747 –751
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
751