Synthesis and properties of gold alkene complexes. Crystal structure of [Au(bipyoXyl)(η2-CH2CHPh)](PF6) and DFT calculations on the model cation [Au(bipy)(η2-CH 2CH2)]+

Article abstract of DOI:10.1039/b610657a

Unprecedented 16-electron gold(i) olefin complexes of general formula [Au(bipy^R,R′)(η²-olefin)](PF₆) and [Au₂(bipy^R,R′)₂(-η²: η²-diolefin)](PF₆)₂ (bipy ^R,R′ = 6-substituted-2,2′-bipyridine) have been prepared by reaction of dinuclear gold(iii) oxo complexes [Au₂(bipy ^R,R′)₂(-O)₂](PF₆)₂ with the appropriate olefin. The X-ray crystal structures of two mononuclear complexes (olefin = styrene) show in-plane coordination of the olefin and a CC bond distance considerably lengthened with respect to the free olefin. The spectroscopic properties of the complexes are discussed and compared with those of analogous d¹⁰ metal derivatives. Both structural and spectroscopic information indicate a substantial contribution of π-back-donation to the Au-olefin bond in the three-coordinate species. Theoretical calculations carried out at the hybrid-DFT level on the model compound [Au(bipy)(η²- CH₂CH₂)]⁺ show excellent agreement with the experimental findings giving in addition an estimate of a π-back-bonding contribution higher than that of the σ-bonding. The Royal Society of Chemistry.

Full text of DOI:10.1039/b610657a

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PAPER
www.rsc.org/dalton | Dalton Transactions
Synthesis and properties of gold alkene complexes. Crystal structure of
2
[Au(bipyoXyl)(g -CH2 CHPh)](PF6) and DFT calculations on the model
=
2
+
=
cation [Au(bipy)(g -CH2 CH2)] †
Maria A. Cinellu,*a Giovanni Minghetti,a Fabio Cocco,a Sergio Stoccoro,a Antonio Zucca,a Mario Manasserob
and Massimiliano Arcac
Received 25th July 2006, Accepted 18th September 2006
First published as an Advance Article on the web 2nd October 2006
DOI: 10.1039/b610657a
ꢀ
Unprecedented 16-electron gold(I) olefin complexes of general formula [Au(bipyR,R )(g -olefin)](PF6)
2
ꢀ
ꢀ
2
2
and [Au2(bipyR,R )2(l-g :g -diolefin)](PF6)2 (bipyR,R = 6-substituted-2,2ꢀ-bipyridine) have been prepared
ꢀ
by reaction of dinuclear gold(III) oxo complexes [Au2(bipyR,R )2(l-O)2](PF6)2 with the appropriate olefin.
The X-ray crystal structures of two mononuclear complexes (olefin = styrene) show in-plane
=
coordination of the olefin and a C C bond distance considerably lengthened with respect to the free
olefin. The spectroscopic properties of the complexes are discussed and compared with those of
analogous d10 metal derivatives. Both structural and spectroscopic information indicate a substantial
contribution of p-back-donation to the Au–olefin bond in the three-coordinate species. Theoretical
2
+
=
calculations carried out at the hybrid-DFT level on the model compound [Au(bipy)(g -CH2 CH2)]
show excellent agreement with the experimental findings giving in addition an estimate of a
p-back-bonding contribution higher than that of the r-bonding.
Recently we preliminarily communicated the synthesis of
the first cationic olefin complexes supported by 6-sub-
stituted-bipyridines and the structural characterization of the
Introduction
The binding of unsaturated hydrocarbons to transition metals is
a topic of paramount importance in organometallic chemistry
for various reasons.1 A great number of studies have concerned
p-coordination complexes of Group 9–11 elements due to their
involvement in a number of chemical, industrial and natural
processes.1,2 As for Group 11 metal–olefin p-complexes, the
wide variety of copper(I) and silver(I) derivatives has not been
matched by analogous gold(I) species.3 Indeed, only few gold(I)
olefin complexes have been reported: mostly they are monomers
(olefin)AuCl,4 synthesized many years ago, which tend to have
poor thermal and solution stabilities. Evidence for these species
mainly rests on spectroscopic information. Only in a few cases
could X-ray diffraction analysis be performed and their structure
established:5 they are typical linear 14-electron derivatives where
AuCl is coordinated to the mid-point of the olefin. A different
environment around a gold atom was first observed in a complex
tetranuclear species where an S2Au fragment is coordinated to a
iPr
2
iPr
=
styrene derivative [Au(bipy )(g -CH2 CHPh)](PF6) (bipy
=
6-isopropyl-2,2ꢀ-bipyridine).8 This and other olefin complexes
were obtained by reactions of a series of dinuclear gold(III)
ꢀ
oxo complexes9 [Au2(bipyR,R )2(l-O)2](PF6)2. In the course of our
studies we isolated also the unprecedented oxaauracyclobutane
[Au(bipyMe)(j2-O,C-2-oxynorbornyl)](PF6)10 and established that
the alkene complexes are formed, together with oxygenated
organic products, by reaction of the auraoxetane species with
excess olefin. Indeed, in the case of norbornene, exo-2,3-
epoxynorbornane and the norbornene complex were obtained
from the isolated auraoxetane.
Herein we describe
a
series of new alkene com-
ꢀ
ꢀ
2
2
2
plexes, [Au(bipyR,R )(g -olefin)](PF6) and [Au2(bipyR,R )2(l-g :g -
diolefin)](PF6)2, obtained by reaction of gold(III) oxo species. Their
synthesis, analytical and spectroscopic characterization is reported
2
in detail. The structure of [Au(bipyoXyl)(g -CH2 CHPh)](PF6)
=
=
[bipyoXyl = 6-(2,6-dimethylphenyl)-2,2ꢀ-bipyridine] as obtained by
means of X-ray diffraction analysis is also described. The nature
of the olefin–gold(I) bond will be discussed on the basis of
spectroscopic and structural information as well as on theoretical
calculations carried out at the hybrid-DFT level on the model
C C bond inside the backbone of a diphosphine ligand: an X-ray
study6 demonstrated that in-plane coordination of the olefin is
preferred as in the case of analogous d10 L2M(olefin).7
2
+ 11
=
compound [Au(bipy)(g -CH2 CH2)] .
aDipartimento di Chimica, Universita` di Sassari, via Vienna 2, 07100,
Sassari, Italy. E-mail: cinellu@uniss.it; Fax: +39 079229559; Tel: +39
079229499
Further insight into the structural features and electronic
properties of these still rare gold olefin derivatives can be of
interest, for example, in the design of new catalysts. In the
last two decades, the activation of C–C multiple bonds by
gold catalysts has received considerable attention.12 Most of the
applications have concerned the addition of carbon-, nitrogen- and
bDipartimento di Chimica Strutturale e Stereochimica Inorganica, Universita´
di Milano, Centro CNR, via Venezian 21, 20133, Milano, Italy
cDipartimento di Chimica Inorganica ed Analitica, Universita` di Cagliari,
S.S. 554 bivio per Sestu, 09042, Monserrato (CA), Italy
† The HTML version of this article has been enhanced with colour images.
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©

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oxygen-nucleophiles to the multiple bond of alkynes12b,c,f ,13 while
theactivationof theallene14 and the alkene bonds15 for the addition
of these nucleophiles has been far less undertaken. In most
cases, gold-unsaturated molecule adducts and cyclic organogold
species have been suggested to be key intermediates in C–E bond
formation (E = C, N, O). Alkene–gold intermediates have also
been proposed in the gold(I) catalyzed oxidative cleavage of C–C
double bonds in water.16
Dinuclear species, featuring a bridging dialkene, have been
obtained with nbd10 and cod, while with dcpd a mixture of the
dinuclear 11 and mononuclear 8 species is formed, from which
only the mononuclear complex 8 could be isolated in a pure form.
The alkene adducts 2–10 have good thermal stability and are
stable in various solvents and in the presence of water. They can be
dried at 10−1 mbar at ambient temp◦erature without decomposition.
Melting points are well above 100 C, the bipyMe derivatives being
the most stable in each series; cf. for example: 7a, mp 206–207 ◦C,
and 7d, mp 114–115 ◦C. Satisfactory elemental analyses have
been obtained in all cases and the molecular ions of most of the
complexes detected by FAB mass spectrometry. The mononuclear
Results and discussion
ꢀ
derivatives 2–8 give the molecular ions [Au(bipyR,R )(olefin)]+;
Synthesis of the complexes
very low intensity peaks (≤5%) corresponding to [Au(olefin)]+
and low to medium intensity peaks at [M + 16], due to au-
raoxetanes, have been detected in most of the spectra. Peaks
corresponding to the mononuclear species are also present in
the spectra of the dinuclear derivatives 9 and 10. The molecular
Novel cationic gold(I) alkene complexes, stabilized by 6-
substituted-bipyridines, have been obtained by reaction of a series
ꢀ
of dinuclear gꢀold(III) oxo complexes [Au2(bipyR,R )2(l-O)2](PF6)2,9
1a–1f (bipyR,R = 6-R- or 6,6ꢀ-R2-2,2ꢀ-bipyridine; see Scheme 1 for
ꢀ
ions [Au2(bipyR,R )2(diolefin)(PF6)]+ have been observed in the case
R). The reaction has been carried out with various linear and
ꢀ
2
cyclic mono- and diolefins to give mononuclear [Au(bipyR,R )(g -
alkene)](PF6), 2–8, {alkene = ethylene (et), 2; styrene (sty),
3; 4-methoxystyrene (van), 4; a-methylstyrene (Mesty), 5; cis-
of 10c and 11a (mixture of 8a and 11a); low intensity peaks
corresponding to M/2 have been found for all the dinuclear
species.
stilbene (stil), 6; norbornene (nb), 7; dicyclopentadiene (dcpd),
ꢀ
8} and dinuclear [Au2(bipyR,R )2(l-g :g -dialkene)](PF6)2, 9–11
{diolefin = 2,5-norbornadiene (nbd), 9; 1,5-cyclooctadiene (cod),
10; dicyclopentadiene (dcpd), 11} alkene complexes, respectively
(Scheme 1). The oxo complexes 1 treated with an excess of the ap-
propriate olefin in Me2CO or MeCN give the olefin complexes 2–11
in low to moderate yields—e.g. the yield for the styrene derivatives
3a–3f is in the range 15–55% (see Experimental section). Metallic
gold and organic products arising from oxidation of alkenes are
also formed in all cases.17 In the case of a-methylꢀstyrene and
norbornene, unprecedented auraoxetanes [Au(bipyR,R )(j2-O,C-2-
oxyalkyl)](PF6) (alkyl = a-methylstyryl 4O, norbornyl 7O) are
also formed in variable amounts depending on the olefin, the
bipyridine ligand and the preparative conditions; e.g. significant
amounts of 7O are obtained by reaction of nb with 1a in MeCN–
H2O.10 Evidence was also provided for the formation of the
olefin complex 7a and 2,3-epoxynorbornane from the isolated
auraoxetane 7Oa and excess nb.10 An analogous reaction pathway
is thus assumed for the formation of the other olefin complexes
and of the oxygenated olefin derivatives.
2
2
Spectroscopic characterization
Compounds 2–11 have been characterized by standard 1D multi-
nuclear NMR spectroscopy (Table 1). Dissociation of the olefin is
not observed even in coordinating solvents such as CD3CN. Nev-
ertheless, addition of one equivalent of the corresponding olefin
causes broadening of the signals of the coordinated olefin,
indicating fast intermolecular exchange at room temperature: a
dynamic process, involving free rotation of the coordinated olefin
around the metal–olefin bond, gives rise to a single set of signals in
all complexes; e.g. the four ethylene protons give a singlet. Variable
1
temperature H NMR spectroscopy carried out on complex 3c
shows that the process is frozen at low temperature as shown by
the spectrum at 193 K, where, owing to the unsymmetrical nature
of ligand c, two well-separate sets of signals (molar ratio 1.3 : 1)
are observed for the olefin protons as well as for the CH and the
‡
diastereotopic CH3 of the isopropyl group. The calculated DGrot
value (50.3 kJ mol−1 at 243 K) is in the range previously reported
for d10 olefin complexes with a-diimine ligands.18
Scheme 1 Oxo complexes 1a–1g (1a, 1b and 1c are mixtures of the cis and trans isomer) and olefin complexes 2–8 and 9–11.
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©

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With few exceptions—which will be discussed later—the signals
of the olefin protons are sharp and show a typical pattern;
in all cases they are significantly shifted to high field with
Alkene adducts 2–11 are unprecedented in the chemistry of gold:
they are the first 16-electron gold olefin complexes and the first
isolated cationic species.26
respect to those of the free alkenes, with Dd(H) [Dd = d(H)free
−
It is widely acknowledged that the NMR parameters give useful
insight into the nature of the metal–olefin bond: in particular
the extent of the shift featured by the coordinated olefin carbons
gives an estimate of the electronic density around the olefinic
carbon nuclei.18b,27 According to the model originally proposed
by Chatt, Dewar and Duncanson, both r-donation from the
olefin to the metal and p-back-donation from the metal to the
olefin contribute to the metal–olefin bond.28 Several studies have
been addressed to evaluate the magnitude of these contributions;
most have concerned platinum compounds, due to their chemical
inertness and to the wide variety of olefins and coordination
environments. A number of theoretical11 and experimental (in the
gas phase)26 studies have also been performed on the ethylene
adducts of Group 11 metals; it was established that in the cationic
d(H)coord] in the range 0.8–2.2 ppm: the low value corresponds
to the cod adducts 10, the high to the nbd adducts 9. The
chemical shifts of the olefin protons show some dependence on
the solvent (see Experimental section and Table 1). At variance, in
a given solvent the chemical shift is independent of the bipyridine
ligand, with the exception of the e and f derivatives (Table 1).19
Compounds 9 and 10 display only one set of signals for the
protons of the bridging diolefin: these are sharp singlets in 9
while in 10 they are broad; in both cases upfield shifts are
observed.
The resonances of the olefin carbon atoms of 2–11 are likewise
shifted upfield with coordination-induced shift Dd(C) [Dd(C) =
d(C)free − d(C)coord] in the range 47.5–61.7 ppm (Table 1); the follow-
ing general trend is observed: Dd(CRRꢀ) < Dd(CHR) < Dd(CH2)
with differences Ddd = Dd(CH2) − Dd(CHR) and Dd(CHR) −
Dd(CRRꢀ) of ca. 5 ppm. As observed for the proton resonances,
the corresponding methynic carbons of the coordinated cod and
nbd are less and more shielded respectively compared to those of
the other olefins.
2
+
=
species [M(g -CH2 CH2)] r-donation is by far more important
than p-back-donation.11a–d Structural data in the case of copper(I)
compounds support this trend; on the other hand, on the basis
of thermodynamic and spectroscopic data, p-back-donation is
suggested to be a weak but important factor in stabilizing these
olefin complexes.20c,3a–c
1
The H and 13C NMR data of 2–11, in particular the extent
According to the acknowledged trend that the high-field
coordination shift of the olefin protons and carbons increases
on increasing p-back-donation contribution,18b,27 a remarkable
p-contribution to the olefin–gold bond in compounds 2–11 is
suggested on the basis of the NMR parameters, notwithstanding
the positive charge expected to considerably decrease the p-back-
donation.27a The spectral features on which this statement is based
can be summarized as follows:
(i) High-field coordination shift of the olefin protons Dd(H) and
carbons Dd(C) in the range 0.8–2.2 and 48–62 ppm, respectively.
The high-field shift of the olefin protons, although less meaningful
than that of the carbons, has been used as a probe of the extent of
p-back-donation also in palladium and platinum complexes.29
(ii) In the styrene complexes 3 and 4, small differences in the
upfield shift Dd(C) are observed between the olefinic carbons
(DDd = 4.0 ppm in 3 and 4.9 ppm in 4); a small difference (DDd =
7.0 ppm) is also found in the a-methylstyrene derivatives 5 between
the methylenic and quaternary carbon. These data indicate a low
of the upfield shift of the olefinic protons and carbons, can be
compared with those of various d10 olefin complexes. Comparison
with the 14-electron (olefin)AuCl4 complexes, for which, inter alia,
only the proton spectra have been reported,4c–g,i underlines the
different bonding mode of the coordinated alkene; indeed, in these
complexes the olefin protons feature small (either low- or upfield)
=
shifts: e.g. in {CH2 CH(CH2)nMe}AuCl the methylenic protons
are shifted 0.1 ppm upfield and the methynic proton 0.1 ppm
downfield.4d More meaningful is the comparison with other
tricoordinate d10 metal ion complexes. A number of comparable
copper(I) derivatives [(NˆN)Cu(olefin)]n+, both cationic (n = 1;
20
=
NˆN = bipy, phen and their derivatives, HN(2-py)2, O C(2-py)2)
and neutral (n = 0; NˆN = H2B[3,5-(CF3)2pz]2),3a,d have been
reported which exhibit Dd(H) values in the range 0.1 to 0.8 ppm.
Larger Dd(H) (0.9–2.3 ppm) are found for Cu(I) olefin complexes
supported by diamines20d,21 or electron-rich anionic ligands, such
as b-diketiminato18a and iminophosphanamide.22 Carbon spec-
tra have also been reported for the compounds supported by
diamines21 and anionic ligands:3a,d,18a,22 these feature upfield shift of
the olefinic carbons with the same trend observed for the proton
resonances. For example, the ethylene complexes supported by
the diamines or the electron-rich anionic ligands exhibit Dd(C)
of 42 and 50 ppm, respectively; lower values have been found
in the other cases. Silver(I) mainly forms isoleptic complexes
=
polarization of the C C double bond and, as a consequence, a
high degree of p-back-donation.27
(iii) A small value for d(CHR) − d(CH2) of coordinated styrene
is also considered diagnostic of high p-back-donation.27b,30 For
complexes 3 and 4 this difference is small, 27.5 and 29.7 ppm,
respectively; in the free olefins it is 23.2 (sty) and 24.8 ppm (van).
+
23
=
such as the trigonal planar ethylene complex [Ag(CH2 CH2)3] ,
Structural characterization
this shows downfield shift of the olefin protons and a very
2
small upfield shift (Dd 6.9 ppm) of the carbons; a slightly larger
shift (Dd 20.1 ppm) of the ethylene carbons was exhibited by
The structure of 3e consists of the packing of [Au(bipyoXyl)(g -
+
−
styrene)] cations, 3eꢀ, PF6 anions and CH2Cl2 molecules in
the molar ratio 1 : 1 : 1 with normal van der Waals contacts.
Fig. 1 shows an ORTEP view of the cation 3eꢀ; principal bond
parameters are reported in Table 2, together with corresponding
distances and angles in cation 3cꢀ. The orientation of the olefin
is coplanar with the pyridine backbone, which chelates the gold
centre with a bite angle of 75.1(1)◦. The gold atom is in a square
planar environment with a slight tetrahedral distortion, maximum
+
=
the trigonal complex [Ag(NˆN)(CH2 CH2)] supported by a
chelating diamine.3e Substantially larger high-field shift [Dd(H)
3.0–3.5 ppm, Dd(C) 90–120 ppm] of both olefin protons and
carbons was observed for several palladium(0) and platinum(0)
complexes of the type [(NˆN)M(olefin)] (NˆN = diamine, diimine)
with electron accepting olefins,18b,c,24 as well as for some five-
coordinate Pt(II)25 complexes of electron-rich olefins.
5706 | Dalton Trans., 2006, 5703–5716
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2
+
=
level on the model cationic complex [Au(bipy)(g -CH2 CH2)]
(2gꢀ), differing from 3cꢀ 8 and 3eꢀ in having unsubstituted bipyridine
(bipy) and ethylene as ligands at the gold(I) metal centre. With
the aim of evaluating a proper computational set-up, calculations
2
+
=
have been carried out on the complex [Au(g -CH2 CH2)] with
different functionals and basis sets (BS’s). In particular, we have
focussed on hybrid-DFT calculations (with both Becke3LYP32 and
mPW1PW33 functionals) considering the 6-31+G*34 and Ahlrichs
pVDZ35 BS’s for the organic framework and three different BS’s
with relativistic effective core potentials (RECP) for the metal ion
(LanL2DZ,36 Stuttgart RSC,37 CRENBL38).39 An examination
of the results of our calculations (Table 3) allows us to deduce
that: 1) the two BS’s used for C and H yield very similar
results, which are comparable to those reported previously on
the same system11a,c and can be considered reliable based on
the calculation on free ethylene (for example, the C–C distance
˚
˚
dC–C is calculated in the range 1.330–1.335 A, to be compared to
40
the solid-state experimental value of 1.339 A) ; 2) in agreement
with the results reported previously,41 the Becke3LYP functional
Fig. 1 ORTEP view of cation 3eꢀ. Ellipsoids are drawn at the 30%
probability level.
yields slightly overestimated dAu–C lengths (in the range 2.214–
2.253 A), reflected in lower bond dissociation energy (BDE) values
(55.9–61.1 kcal mol−1), as compared to those obtained with the
˚
◦
ꢀ
8
Table 2 Selected bond lengths (A) and angles ( ) in 3c and 3eꢀ, with
˚
˚
mPW1PW functional (dAu–C in the range 2.176–2.213 A; BDE
estimated standard deviations (e.s.d.s) on the last figure in parentheses
56.8–63.3 kcal mol−1);11a,c,26a,42,43 3) within each series, the Stuttgart
BS gives the poorest estimates of the BDE values,42 corresponding
to the highest dAu–C and the lowest dC–C distances. In all cases,
as expected on the basis of the Dewar–Chatt–Duncanson bond
model,28 the interaction between Au+ and ethylene results in
3cꢀ
3eꢀ
Au–N(1)
Au–N(2)
Au–C(14)
Au–C(15)
C(14)–C(15)
C(14)–C(16)
2.150(3)
2.217(5)
2.114(6)
2.098(5)
1.384(8)
1.488(6)
2.176(2)
2.204(2)
2.118(2)
2.105(3)
1.409(4)
1.484(4)
a lengthening DdC–C of the C–C ethylene bond distance dC–C
,
corresponding to a lowering in the C–C bond order. This can
be evaluated through the Wiberg bond index WBIC–C, whose
variation DWBIC–C with respect to free ethylene is not sensibly
affected by the level of theory (0.442–0.487). As pointed out by
Lee and co-workers,11a the degree of r-donation (from the filled
p-bonding orbital of ethylene to an empty orbital centred on the
metal) and p-back-donation (from a filled d orbital of the metal
to the unoccupied antibonding p* orbital of ethylene) can be
separately evaluated by the electron populations Pp and Pp* of
the involved natural bonding orbitals (NBO’s)44 localised on the
N(1)–Au–N(2)
N(1)–Au–C(14)
N(1)–Au–C(15)
N(2)–Au–C(14)
N(2)–Au–C(15)
C(14)–Au–C(15)
C(15)–C(14)–C(16)
75.1(2)
119.6(2)
157.8(2)
165.4(2)
127.0(2)
38.4(2)
75.1(1)
119.7(1)
158.6(1)
165.2(1)
126.2(1)
39.0(1)
126.3(5)
125.5(2)
˚
distances from the best plane being +0.030(3) and −0.031(3) A for
C(14) and C(15), respectively. The dihedral angle between the Au–
N(1)–N(2) and Au–C(14)–C(15) planes is 3.2(1.1)◦, that between
the metal coordination plane and the C(14)–C(15)–C(16) plane
is 78.6(2)◦, which means that there is a bending back angle of
11.4(2)◦ of the phenyl ring with respect to an ideal orthogonal
coordination. As can be seen in Table 2 all bond lengths and angles
in 3eꢀ are in good agreement with those found in 3cꢀ and previously
2
+
=
olefin in the complex [Au(g -CH2 CH2)] . In agreement with the
values reported previously for the same complex,11a the variation
in the electron population on the p-bonding orbital of ethylene is
higher than that on the p*-antibonding orbital, confirming that
the extent of donation is higher than that of back-donation.
2
+
=
Based on the results obtained for [Au(g -CH2 CH2)] , we
have performed DFT calculations on 2gꢀ with the Becke3LYP
and mPW1PW functionals, using the Ahlrichs pVDZ BS’s for
the ligands, and the LanL2DZ and CRENBL basis sets with
RECP’s for the central metal ion. In concordance with the
discussed.8 In particular, the C(14)–C(15) distance in 3eꢀ is even
ꢀ
˚
slightly longer than that found in 3c (1.409(4) vs. 1.384(8) A). The
distances of H2 and H3 from the centroid of the xylyl ring are
2
+
=
calculations on the [Au(g -CH2 CH2)] moiety, a comparison
of the optimised bond lengths and angles with the average
structural values collected for 3cꢀ8 and 3eꢀ clearly indicates that
the mPW1PW functional yields more reliable results (Table 4). In
fact, geometry optimisations performed with Barone’s functional
perfectly reproduce the experimental bond lengths, especially
when the CRENBL BS is used for the gold centre. The C–C
distance of the ethylene ligand is only slightly overestimated in
all the explored combinations of functionals and BS’s (1.404–
˚
3.12(4) and 3.09(4) A, respectively, suggesting some kind of non-
covalent interaction with the aromatic ring. It is worth noting that,
1
in agreement, in the H NMR the same protons are remarkably
upfield shifted as previously commented.19
Theoretical calculations
In order to verify the actual relationship between the spectroscopic
and structural features and the extent of p-back-donation, an
investigation was undertaken at density functional theory (DFT)31
˚
1.412 A), the C–C elongation with respect to free ethylene resulting
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©

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˚
˚
˚
Table 3 Optimised Au–C (dAu–C , A) bond distance, C–C (dC–C, A) bond distance and variation with respect to free ethylene (DdC–C, A), C–C Wiberg
bond index (WBIC–C) and variation with respect to free ethylene (DWBIC–C), population of the p natural bond orbital (Pp, e) and variation with respect to
free ethylene (DPp, e), population of the p* natural bond orbital (Pp*, e), and bond dissociation energies (BDE, kcal mol−1) calculated at DFT level with
different hybrid functionals and basis sets (BS’s) on the [Au(CH2 CH2)] model complex
+
=
m
Functional C,H BS
Au BS
dAu–C
dC–C
DdC–C
WBIC–C
DWBIC–C
Pp
DPp
Pp
BDEn
B3LYP
Ahlrichs pVDZ LanL2DZ
CRENBL
2.242
2.214
1.400 0.067a
1.402 0.069a
1.397 0.064a
1.403 0.068b
1.403 0.068b
1.399 0.064b
1.397 0.067c
1.399 0.069c
1.394 0.064c
1.400 0.068d
1.400 0.068d
1.396 0.064d
1.600
1.559
1.594
1.586
1.557
1.587
1.602
1.560
1.600
1.560
1.555
1.588
0.443e
0.484e
0.449e
0.455f
0.484f
0.454f
0.442g
0.484g
0.444g
0.482h
0.487h
0.454h
1.631 0.368i
1.587 0.412i
1.611 0.388i
1.619 0.381j
1.585 0.415j
1.605 0.395j
1.647 0.352k
1.599 0.400k
1.628 0.371k
1.628 0.372l
1.594 0.406l
1.619 0.381l
0.131 58.2
0.142 61.1
0.119 55.9
0.137 59.9
0.142 60.9
0.123 56.4
0.145 59.6
0.154 62.9
0.130 56.8
0.130 62.1
0.154 63.3
0.135 58.0
Stuttgart RSC 1997 2.253
LanL2DZ
CRENBL
6-31 + G*
2.239
2.219
Stuttgart RSC 1997 2.249
Ahlrichs pVDZ LanL2DZ
CRENBL
mPW1PW
2.201
2.176
Stuttgart RSC 1997 2.213
LanL2DZ
CRENBL
6-31 + G*
2.199
2.180
Stuttgart RSC 1997 2.209
a
b
c
d
˚
˚
˚
˚
dC–C = 1.333 A for free ethylene. dC–C = 1.335 (b) A for free ethylene. dC–C = 1.330 (c) A for free ethylene. dC–C = 1.332 (d) A for free ethylene.
e WBIC–C = 2.043 for free ethylene. f WBIC–C = 2.041 for free ethylene. g WBIC–C = 2.044 for free ethylene. h WBIC–C = 2.042 for free ethylene. i Pp = 1.999
e for free ethylene. j Pp = 2.000 e for free ethylene. k Pp = 1.999 e for free ethylene. l Pp = 2.000 e for free ethylene. m The NBO p* is unoccupied in free
ethylene. n Calculated with unscaled ZPE corrections.
˚
˚
˚
˚
Table 4 Au–N (dAu–N , A) and Au–C (dAu–C , A) bond distances, C–C (dC–C, A) bond distances and variation with respect to free ethylene (DdC–C, A),
N–Au–N (aN–Au–N
◦) and C–Au–C (aC–Au–C ◦) angles optimized at DFT level for the model complex 2gꢀ, as compared to the corresponding experimental
average values derived from the XRD data collected for 3c and 3e
,
,
Functional
B3LYP
Au BS
dAu–N
dAu–C
dC–C
DdC–C
aN–Au–N
aC–Au–C
DFTa
LanL2DZ
CRENBL
LanL2DZ
CRENBL
2.276
2.245
2.237
2.210
2.186
2.181
2.142
2.141
2.109
2.109
1.404
1.411
1.405
1.412
1.396
0.071b
0.078b
0.075c
0.082c
0.057d
73.09
73.94
73.81
71.59
75.09
37.55
38.47
38.30
39.10
38.67
mPW1PW
Experimental
c
d
a Ahlrichs pVDZ BS’s for C, H, and N. b dC–C = 1.333 A calculated for free ethylene. dC–C = 1.330 A calculated for free ethylene. dC–C = 1.339 A for free
˚
˚
˚
ethylene (ref. 40).
˚
orbital on ethylene with the highest occupied molecular orbital
of [Au(bipy)]+, which features a very large contribution from the
5dxy Au atomic orbital, to give HOMO−1 and LUMO+3 in the 2gꢀ
cation. Interestingly enough, all calculations agree in evaluating a
anyway in an agreement within 0.02 A with the experimental
average value. The nature of the bonding between the closed-
shell fragments [Au(bipy)]+ and ethylene in 2gꢀ, for which a BDE
value of 64.5 kcal mol−1 was calculated {BDE = 62.9 kcal mol−1
2
+
slight but significant negative NBO charge QC (of about −0.1 e)
=
H
for [Au(g -CH2 CH2)] at the same level of theory, Table 3},
can be rationalised in terms of a fragment molecular orbital
(FMO)45 approach (Fig. 2). In agreement with the Dewar–Chatt–
Duncanson bond model,28 the ethylene filled p orbital is symmetry
allowed to r-interact with the lowest unoccupied orbital of the
[Au(bipy)]+ moiety, which is centred on the metal ion and is
mainly 6py in nature, resulting in the HOMO−2 and LUMO+5
of 2gꢀ. The back-bonding occurs between the unoccupied p*
2
4
2
on the g -coordinating ethylene, the positive charge of the cationic
complex being entirely concentrated on the [Au(bipy)]+ fragment
(Table 5). This suggests that, contrary to what was calculated
2
+
=
for the [Au(g -CH2 CH2)] model complex, the extent of p-back-
bonding would be higher than that of the r-bonding, as previously
2
=
observed for complexes of the type [L2M(g -CH2 CH2)] (M = Ni,
Pd, Pt; L = PH3, PMe3).43 Accordingly, the electron population
Table 5 Calculated NBO charges (QAu , Qbipy, and QC , e) on the Au centre and on the bipy and ethylene ligands, respectively, population of the p
2 H4
natural bond orbital (Pp, e) and variation with respect to free ethylene (DPp, e), population of the p* natural bond orbital (Pp*, e), C–C Wiberg bond
a
index (WBIC–C) and variation with respect to free ethylene (DWBIC–C), calculated at DFT level on model complex 2gꢀ
c
Functional
B3LYP
Au BS
QAu
Qbipy
QC
Pp
DPp
Pp*
WBIC–C
DWBIC–C
2 H4
LanL2DZ
CRENBL
LanL2DZ
CRENBL
0.797
0.778
0.839
0.803
0.258
0.298
0.256
0.303
−0.073
−0.076
−0.110
−0.098
1.741
1.699
1.743
1.697
0.258b
0.300b
0.256b
0.303b
0.312
0.352
0.341
0.375
1.547
1.487
1.405
1.412
0.496d
0.556d
0.639e
0.632e
mPW1PW
a Ahlrichs pVDZ BSs for C, H, and N. b Pp = 1.999 e for free ethylene. c The NBO p* is unoccupied in free ethylene. d WBIC–C = 2.043 for free ethylene.
e WBIC–C = 2.044 for free ethylene.
5708 | Dalton Trans., 2006, 5703–5716
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2
+
Fig. 2 MO diagram showing the interaction between the [Au(bipy)]+ and g -CH2 CH2 moieties in the model complex [Au(bipy)(CH2 CH2)] (2gꢀ),
calculated at DFT level (mPW1PW functional, Ahlrichs pVDZ BS’s for C and H, LanL2DZ BS with RECP for Au). The MOs HOMO, LUMO+1,
LUMO+2, and LUMO+4 are centred on the bipy ligand.
=
=
Pp* on the p* natural orbital of the coordinated olefin is slightly
higher than the variation of the population DPp on the p orbital
(0.375 and 0.303 e, respectively, at mPW1PW/CRENBL level).
and explained by the pyramidalization effect occurring in strained
cyclic alkenes, which results in a stronger metal–olefin bond.46 In
agreement, addition of excess dicyclopentadiene to the dinuclear
dcpd complex 11a (the major component of the mixture obtained
by reaction of 1a with dcpd) results in the ready displacement of
2
+
=
The increased back-bonding on passing from [Au(g -CH2 CH2)]
to 2gꢀ is reflected not only in the optimised C–C bond distances,
but also in the Wiberg bond indexes, lower for the latter model
complex (1.560 and 1.412, respectively, at mPW1PW/CRENBL
level).
=
the less strong p-bond, i.e. that to the C C of the cyclopentene
ring, with formation of the mononuclear species 8a, where the
=
gold atom is bonded to the C C bond of the norbornene ring.
The coordinated styrene in complex 3a is not displaced by
CO, at least at one atmosphere pressure. It is worth noting that
addition of excess olefin to a gold carbonyl complex has been
used to synthesize alkene complexes of type (olefin)AuCl (olefin =
norbornene, cis-cyclooctene, dcpd).5 As a consequence of the
greater Cu→CO back donation, the opposite behaviour has been
observed for most of the copper(I) olefin complexes supported by
chelating anionic O- and N-donor ligands, for which the olefin/CO
exchange reaction has been thoroughly studied.3a–c
Exchange reactions of the alkene complexes. Some aspects of
the reactivity of the new gold alkene complexes have been explored.
As discussed before, the intermolecular exchange between the
coordinated and the free styrene was found to be very fast for
complexes 3 on the NMR time scale at room temperature, as shown
by broadening of the signals of the coordinated styrene on addition
of an equimolar amount of styrene to a solution of the complex;
the exchange reaction between coordinated and free norbornene is
fast also for complexes 7. At variance, no broadening was observed
for the coordinated ethylene protons when a solution of complex
2a in (CD3)2CO was saturated with ethylene. From complex 3a the
coordinated styrene was readily displaced by excess ethylene and
norbornene to give 2a and 7a, respectively; the reverse reaction
in the case of complex 2a affords an equilibrium mixture of 2a
and 3a (2a : 3a = 1 : 1), free styrene and ethylene. Addition of
ethylene to a dichloromethane solution of 3e resulted in the partial
displacement of the coordinated styrene to give a 2 : 1 mixture of
3e and 2e. Norbornene was not displaced by other olefins; the
relatively higher stability of the norbornene complexes 7, com-
pared to 3, is consistent with the larger values of Dd which suggest
a stronger p-bond of this strained alkene to gold. An analogous
behaviour has been observed in a cationic platinum(II) complex,27c
Conclusion
Unprecedented 16-electron gold(I) cationic olefin complexes have
been successfully obtained by reaction of dinuclear gold(III) oxo
complexes, through auraoxetane intermediates.10 Owing to their
novelty, they have been thoroughly studied both in solution,
1
mainly by H and 13C NMR spectroscopy, and in the solid state,
by X-ray diffraction analysis. Excellent correlation has been found
between spectroscopic and structural parameters which point to
a significant contribution of p-donation from the metal to the
alkene. These findings have also been corroborated by theoretical
calculations carried out at hybrid-DFT level on the model
2
+
=
cation [Au(bipy)(g -CH2 CH2)] ; these give an estimate of a
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=
p-back-bonding contribution higher than that of the r-bonding. A
few analogies, such as the upfield shift of the 1H and 13C resonances
of the coordinated olefin, have been observed with analogous
complexes of other d10 metal ions of Groups 10 and 11. In
contrast, it is worth underlining the differences with the copper(I)
derivatives, for which a weak p-back-donation was suggested
on the basis of thermodynamic and spectroscopic data and by
theoretical calculations as well. A different behaviour between
the gold and copper derivatives was also found in the CO/olefin
exchange reaction; indeed, the coordinated olefin, e.g. styrene, is
not displaced by CO, at least at atmospheric pressure.
CH2 CHC6H4OMe-4 (van). (CD2Cl2): dH 5.15 (dd, J = 0.9,
11.0 Hz, 1H, Ha), 5.64 (dd, J = 0.9, 17.6 Hz, 1H, Hb), 6.70 (dd,
=
=
J = 11.0, 17.6 Hz, 1H, Hc); dC 111.6 ( CH2), 136.5 ( CH);
{(CD3)2CO}: dH 5.08 (dd, J = 1.1, 10.9 Hz, 1H, Ha), 5.64 (dd,
J = 1.1, 17.6 Hz, 1H, Hb), 6.68 (dd, J = 10.9, 17.6 Hz, 1H, Hc);
=
=
dC 111.6 ( CH2), 137.3 ( CH).
=
CH2 C(Me)Ph (Mesty). (CD2Cl2) dH 5.12 (quint, J = 1.6 Hz,
=
1H, Ha), 5.41 (m, J = 1.6 Hz, 1H, Hb); dC 112.4 ( CH2), 143.7
=
( C); {(CD3)2CO}: dH 5.09 (quint, J = 1.5 Hz, 1H, Ha), 5.39 (m,
=
=
=
J = 1.5 Hz, 1H, Hb); dC 112.6 ( CH2), 141.9 ( C). PhCH CHPh
=
=
(stil) (CD2Cl2): dH 6.65 (s, CH); dC 130.6 ( CH).
Norbornene (nb). (CD2Cl2): dH 6.02; dC 135.6; {(CD3)2CO}: dH
5.97; dC 135.9.
Experimental
General experimental details
=
Dicyclopentadiene (dcpd). (CD2Cl2): dH 5.51 (m, CH2,3), 5.95
=
(m, JAB = 5.8 Hz, JAX = 3.0 Hz, CH6), 6.01 (m, JBA = 5.8 Hz,
Compounds 1a–1f were synthesized according to ref. 9. Ethylene
(et) was purchased from SAPIO, styrene (sty), 4-vinylanysole
(van), a-methylstyrene (Mesty), cis-stilbene (stil), norbornene
(nb), 2,5-norbornadiene (nbd), 1,5-cyclooctadiene (cod) and di-
cyclopentadiene (dcpd) were obtained from Aldrich Chimica.
Solvents were purchased from Carlo Erba Reagents and dis-
tilled prior to use, while anhydrous MeCN (H2O ≤ 0.001%;
acidity ≤0.002%) was used as received. Elemental analyses were
performed with a Perkin-Elmer Elemental Analyzer 240B by
Mr A. Canu (Dipartimento di Chimica, Universita` di Sassari).
Conductivity measurements were performed with a Philips PW
9505 conductivity meter. Infrared spectra were recorded with a
=
=
=
JBY = 3.0 Hz, CH5); dC 132.3 ( CH5,6), 132.7 ( CH3), 136.3
=
( CH(2)).
2,5-Norbornadiene (nbd). (CD2Cl2): dH 6.78; dC 143.6;
(CD3CN): dH 6.77; dC 144.2; {(CD3)2CO}: dH 6.85; dC 144.0.
1,5-Cyclooctadiene (cod). (CD2Cl2): dH 5.59; dC 128.9;
(CD3CN): dH 5.55; dC 129.5; {(CD3)2CO}: dH 5.51; dC 129.2.
Synthesis and characterisation
ꢀ
ꢀ
[Au(bipyR,R )(olefin)](PF6)
(2–8)
and
[Au2(bipyR,R )2(l-
diolefin)](PF6)2 (9–11). Reactions of compounds 1a–1d with
sty and of compounds 1a–1e with nb and nbd to give 3a–3d,
7a–7e and 9a–9d have been reported in detail in ref. 8 and in ref.
10, respectively. 2a, 2c–2e, 3f, 4a, 4c–4e, 5a, 8a, 10a, 10c, 11a
were synthesized according to the following general procedure:
to 25–30 mL of a MeCN solution of 1 (0.2 mmol), 4 mmol (10
equiv.) of the respective alkene and 3–5 mL of water were added;
in the case of ethylene the solution was saturated with the gas.
The resulting mixture was stirred for 10–15 d at 10–15 ◦C, filtered
through Celite, evaporated to dryness and the residue extracted
with CH2Cl2 (3 × 15 mL). The combined chloroform extracts
were filtered and concentrated to a small volume; addition of Et2O
gave a whitish solid product which was recovered by filtration
under vacuum. In most cases the analytical sample was obtained
by recrystallization from dichloromethane–diethyl ether. A pure
sample of 7a as a white solid was obtained by adding MeOH to a
CH2Cl2 solution of a mixture of 7a and 7Oa cooled to −20 ◦C. At
variance, after an analogous workup of the mixture (7c + 7Oc) a
pure sample of 7c could not be separated. Some 8a was extracted
with CHCl3 from the mixture containing 11a; the residue was still
a mixture (11a : 8a = 2 : 1; NMR criterion) from which more 8a
was obtained on addition of dcpd to a CH2Cl2 solution.
1
Jasco FTIR-480 Plus spectrophotometer using Nujol mulls. H
1
and 13C{ H} NMR spectra were recorded with a Varian VXR
300 spectrometer operating at 300.0 and 75.4 MHz, respectively,
at 293 K or at a different temperature (specified in the text); the
1H NMR shifts were referenced to the resonance of the residual
protons of the solvents (d = 7.27, CDCl3; 5.35, CD2Cl2; 2.05,
(CD3)2CO; 1.95, CD3CN), the 13C NMR shifts to the solvent
resonance (d = 77.0, CDCl3; 53.8, CD2Cl2; 29.8, (CD3)2CO; 1.3,
CD3CN). Mass spectra were recorded with a VG 7070 instrument
operating under FAB conditions, with 3-nitrobenzyl alcohol as
supporting matrix.
1H and 13C NMR shifts of the free olefins in various solvents
=
CH2 CH2 (et). (CD2Cl2): dH 5.43; dC 116.8; (CD3CN): dH 5.42;
dC 117.4.
Molar conductivity, KM, of compounds 2–8 (5 × 10−4 mol dm−3,
Me2CO) is in the range 115–120 X−1 cm2 mol−1; that of compounds
9–10 (5 × 10−4 mol dm−3, Me2CO) 170–180 X−1 cm2 mol−1.
[Au(bipyMe)(et)](PF6) (2a). Yield: 15%; mp 143–144 ◦C
(decomp.). Anal. Calcd. for C13H14AuF6N2P: C, 28.90; H, 2.61;
N, 5.19%. Found C, 28.85; H, 2.56; N, 5.18%. Selected IR bands:
=
CH2 CHPh (sty). (CDCl3): dH 5.24 (dd, J = 1.0, 11.0 Hz,
1H, Ha), 5.75 (dd, J = 1.0, 17.6 Hz, 1H, Hb), 6.72 (dd, J = 11.0,
=
=
17.6 Hz, 1H, Hc); dC 113.7 ( CH2), 137.0 ( CH); (CD2Cl2): dH
5.28 (dd, J = 1.0, 10.9 Hz, 1H, Ha), 5.79 (dd, J = 1.0, 17.6 Hz, 1H,
=
Hb), 6.76 (dd, J = 10.9, 17.6 Hz, 1H, Hc); dC 113.9 ( CH2), 137.2
=
( CH); (CD3CN): dH 5.26 (dd, J = 1.0, 11.2 Hz, 1H, Ha), 5.81 (dd,
J = 1.0, 17.6 Hz, 1H, Hb), 6.77 (dd, J = 11.2, 17.6 Hz, 1H, Hc); dC
(m/cm−1, Nujol mull): 1597s, 1569m, 1030m, 842vs(br), 780s,
1
=
=
=
114.5 ( CH2), 137.8 ( CH); {(CD3)2CO}: dH 5.23 (dd, J = 1.0,
725m. H NMR (CD3CN): d 2.91 (s, 3H; Me), 3.81 (s, 4H; CH2),
ꢀ
11.0 Hz, 1H, Ha), 5.81 (dd, J = 1.0, 17.7 Hz, 1H, Hb), 6.76 (dd,
7.80–8.52 (m, 6H; ArH), 8.88 (d, J = 5.1 Hz, 1H; H6 bipyMe);
13
1
=
=
=
C{ H} NMR (CD3CN): d 28.6 (Me), 61.7 ( CH2), 122.0, 125.0,
J = 11.0, 17.7 Hz, 1H, Hc); dC 113.4 ( CH2), 137.2 ( CH).
5710 | Dalton Trans., 2006, 5703–5716
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127.6, 128.6, 128.7, 128.9, 142.7, 152.7, 152.9, 153.7, 161.1. MS
4.35%. Found C, 39.01; H, 3.38; N, 4.24%. Selected IR bands:
+
data (FAB+): m/z 395 (55%) (M ), 367 (37%) (M − CH2 CH2),
(m/cm−1, Nujol mull): 1595s, 1567m, 1226m, 1028m, 842vs(br),
=
171 (100%) (bipyMe + H).
778s, 701m. H NMR {(CD3)2CO}: d 1.18 (d, J = 6.8 Hz, 3H;
1
3
[Au(bipyiPr)(et)](PF6) (2c). Yield: 18%; mp 131–132 ◦C
(decomp.). Anal. Calcd. for C15H18AuF6N2P: C, 31.70; H, 3.19;
N, 4.93%. Found C, 31.41; H, 2.98; N, 4.85%. Selected IR bands:
(m/cm−1, Nujol mull): 1597vs, 1574s, 1491vs, 1308m, 1262m,
CH3), 1.51 (d, 3J = 6.8 Hz, 3H; CH3), 3.55 (sept, 3J = 6.8 Hz, 1H;
CH), 4.24 (dd, Jab = 2.0, Jac = 9.0 Hz, 1H; Ha), 4.41 (dd, Jba
=
2.0, Jbc = 13.6 Hz, 1H; Hb), 5.64 (dd, Jca = 9.0, Jcb = 13.6 Hz,
3
1H; Hc), 7.31–8.82 (m, 11H, ArH), 8.89 (d, J = 4.6 Hz, 1H;
1
1
H6 bipyiPr); 13C{ H} NMR {(CD3)2CO}: d 22.4 (Me), 23.0 (Me),
ꢀ
1169m, 1031s, 1006m, 842vs(br), 641m. H NMR (CD3CN): d
=
=
1.45 (d, J = 7.0 Hz, 6H; Me), 3.58 (sept, J = 7.0 Hz, 1H; CH),
41.8 (CHMe2), 55.6, ( CH2), 83.1 ( CH), 122.6, 124.9, 125.3,
=
3.83 (s, 4H; CH2), 7.74–8.59 (m, 6H; ArH), 8.88 (d, J = 5.2 Hz,
127.5, 128.6, 129.4, 129.9, 137.9, 142.8, 143.2, 152.2, 153.7, 169.0.
MS data (FAB+): m/z 515 (5%) (M + O), 499 (100%) (M+), 395
(90%) (M − PhCH CH2), 301 (<5%) (M − bipy ), 154 (90%)
1H; H6 bipyiPr).
ꢀ
[Au(bipynP)(et)](PF6) (2d). Yield: 25%; mp 134–135 ◦C.
Anal. Calcd. for C17H22AuF6N2P: C, 34.24; H, 3.72; N, 4.70%.
Found C, 34.09; H, 3.65; N, 4.62%. Selected IR bands:
(m/cm−1, Nujol mull): 1605s, 1573s, 1497s, 1310m, 1225m, 1025m,
iPr
=
(bipyiPr). Crystals suitable for X-ray diffraction were obtained by
slow diffusion of diethyl ether into an acetonitrile solution.
The activation barrier for styrene rotation in 2c was calculated
using the following 1H NMR data {(CD3)2CO, 193 K}: d 0.73 [d,
3J = 6.7 Hz, 3H; CH3(A)], 1.42 [d, 3J = 7.0 Hz, 3H; CH3(B)], 1.46
[d, 3J = 6.7 Hz, 3H; CH3(A)], 1.51 [d, 3J = 6.7 Hz, 3H, CH3(B)],
3.10 (m, broad, 1H, CH(A)], 3.65 (m, broad, 1H; CH(B)], 4.03 [d,
Jac = 8.3 Hz, 1H; Ha(B)], 4.19 [d, Jac = 8.8 Hz, 1H; Ha(A)], 4.35
[d, Jbc = 13.4 Hz, 1H; Hb(A)], 4.49 [d, Jbc = 13.3 Hz, 1H; Hb(B)],
5.48 (dd, Jca = 8.8, Jcb = 13.4 Hz, 1H; Hc(A)], 5.60 (dd, Jca = 8.3,
Jcb = 13.3 Hz, 1H; Hc(B)], 7.27–9.03 (m, 24H; ArH(A) + ArH(B)]
(A : B = 1 : 1.3). Coalescence of the styrene CH peaks at d 5.48
and 5.60 (Dm = 36 Hz, Tc = 243 K) corresponds to an activation
barrier DG‡ = 50.3 kJ mol−1 at 243 K.
1
840vs(br), 781vs, 740m. H NMR (CD2Cl2): d 1.06 (s, 9H; Me),
=
3.26 (s, 2H; CH2), 3.87 (s, 4H; CH2), 7.85–8.57 (m, 6H; ArH),
8.83 (d, J = 5.2 Hz, 1H; H6 bipynP).
ꢀ
[Au(bipyoXyl)(et)](PF6) (2e). Yield: 20%; mp 134–135 ◦C
(decomp.). Anal. Calcd. for C20H20AuF6N2P: C, 38.11; H, 3.20;
N, 4.44%. Found C, 38.01; H, 3.05; N, 4.36%. Selected IR
bands: (m/cm−1, Nujol mull): 1601s, 1574s, 1238m, 1029m, 996m,
1
842vs(br), 780s. H NMR (CD2Cl2): d 2.07 (s, 6H; Me), 3.09 (s,
=
4H; CH2), 7.26–8.61 (m, 9H; ArH), 8.81 (ddd, J = 5.2; 1.7;
1
0.9 Hz, 1H; H6 bipyoXyl); 13C{ H} NMR (CD2Cl2): d 20.3 (Me),
ꢀ
=
61.6 ( CH2), 122.4, 124.4, 128.2, 128.5, 128.8, 130.4, 136.2, 141.3,
142.1, 142.9, 152.1, 152.4, 152.8, 161.3.
[Au(bipynP)(sty)](PF6) (3d). Yield: 45%; mp 158–
159 ◦C. Calcd for C23H26AuF6N2P: C, 41.08; H, 3.90; N,
4.17%. Found C, 40.96; H, 3.87; N, 4.14%. Selected IR bands:
(m/cm−1, Nujol mull): 1604s, 1567m, 1226s, 1023m, 846vs(br),
[Au(bipyMe)(sty)](PF6) (3a). Yield: 15%; mp 136 ◦C (de-
comp.). Anal. Calcd. for C19H18AuF6N2P: C, 37.02; H, 2.94; N,
4.55%. Found C, 37.39; H, 2.74; N, 4.64%. Selected IR bands:
(m/cm−1, Nujol mull): 1600s, 1565m, 1223m, 1030m, 848vs(br),
778s, 696m. 1H NMR (CDCl3): d 1.03 (s, 9H; Me), 3.13 (d, JAB
=
785s, 700m. 1H NMR (CD2Cl2): d 2.85 (s, 3H; Me), 4.09 (dd, Jab
=
12.8 Hz, 1H; CHAHB), 3.24 [d, JAB = 12.8 Hz, 1H; CHAHB),
4.03 (dd, Jab = 2.0, Jac = 9.0 Hz, 1H; Ha), 4.08 (dd, Jba = 2.0,
Jbc = 13.4 Hz, 1H; Hb), 5.43 (dd, Jca = 9.0, Jcb = 13.4 Hz, 1H;
Hc), 7.29–8.49 (m, 12H; ArH); (CD2Cl2): d 1.08 (s, 9H; Me), 3.21
(d, JAB = 12.9 Hz, 1H, CHAHB), 3.29 (d, JAB = 12.9 Hz, 1H,
2.1, Jac = 9.0 Hz, 1H; Ha), 4.16 (dd, Jba = 2.1, Jbc = 13.5 Hz, 1H;
Hb), 5.41 (dd, Jca = 9.0, Jcb = 13.5 Hz, 1H; Hc), 7.33–8.44 (m,
11H; ArH), 8.57 (d, broad, 1 H; H6 bipyMe); (CD3CN): d 2.80 (s,
ꢀ
3H; Me), 4.06 (dd, Jab = 2.0, Jac = 9.1 Hz, 1H; Ha), 4.20 (dd, Jba
=
2.0, Jbc = 13.5 Hz, 1H; Hb), 5.44 (dd, Jca = 9.1, Jcb = 13.5 Hz, 1H;
CHAHB), 4.09 (dd, Jab = 2.0, Jac = 9.0 Hz, 1H; Ha), 4.15 (dd, Jba =
Hc), 7.32–8.46 (m, 11H; ArH), 8.60 (d, broad, 1H; H6ꢀ bipyMe);
2.0, Jbc = 13.6 Hz, 1H; Hb), 5.46 (dd, Jca = 9.0, Jcb = 13.6 Hz,
1H; Hc), 7.37–8.48 (m, 12H; ArH); (CD3CN): d 1.02 (s, 9H; Me),
3.22 (s, 2H; CH2), 4.06 (dd, Jab = 1.9, Jac = 9.1 Hz, 1H; Ha), 4.20
13
1
=
=
C{ H} NMR (CD3CN): d 27.5 (Me), 54.7 ( CH2), 80.9 ( CH),
121.5, 123.9, 125.1, 127.46, 128.4, 129.4, 130.0, 138.0, 142.7, 143.2,
152.0, 153.7, 169.2. MS data (FAB+): m/z 487 (<5%) (M + O),
(dd, Jba = 1.9, Jbc = 13.6 Hz, 1H; Hb), 5.44 (dd, Jca = 9.1, Jcb =
+
=
471 (100%) (M ), 367 (92%) (M − PhCH CH2), 301 (5%) (M −
13.6 Hz, 1H; Hc), 7.30–8.53 (m, 12H; ArH); {(CD3)2CO}: d 1.06
(s, 9H; Me), 3.34 (s, 2H; CH2), 4.25 (dd, Jab = 1.8, Jac = 9.0 Hz,
1H; Ha), 4.41 (dd, Jba = 1.8, Jbc = 13.6 Hz, 1H; Hb), 5.71 (dd,
bipyMe), 171 (57%) (bipyMe + H).
[Au(bipyEt)(sty)](PF6) (3b). Yield: 20%; mp 130–
131 ◦C. Calcd for C20H20AuF6N2P: C, 38.11; H, 3.20; N,
4.45%. Found C, 37.95; H, 3.08; N, 4.48%. Selected IR bands:
(m/cm−1, Nujol mull): 1595s, 1568m, 1227m, 1027m, 842vs(br),
Jca = 9.0, Jcb = 13.6 Hz, 1H; Hc), 7.34–8.70 (m, 11H; ArH) 8.77
1
(d, J = 7.8 Hz, 1H; H6 bipynP); 13C{ H} NMR {(CD3)2CO}: d
ꢀ
=
=
26.9 (Me), 33.4 (CMe3), 55.6 ( CH2), 56.3 (CH2), 82.8 ( CH),
122.8, 125.0, 127.5, 128.5, 129.2, 129.5, 129.9, 137.5, 141.9, 142.8,
1
3
777s, 698m. H NMR {(CD3)2CO}: d 1.36 (t, J = 7.7 Hz, 3H;
Me), 3.20 (dq, 2J = 11.2, 3J = 7.7 Hz, 2H; CH2), 4.23 (dd, Jab
=
151.9, 152.4, 154.0, 162.0. MS data (FAB+): m/z 543 (5%) (M +
+
=
2.0, Jac = 9.1 Hz, 1H; Ha), 4.40 (dd, Jba = 2.0, Jbc = 13.7 Hz, 1H;
Hb), 5.64 (dd, Jca = 9.1, Jcb = 13.7 Hz, 1H; Hc), 7.33–8.79 (m,
11H; ArH), 8.85 (d, 3J = 3.6 Hz, 1H; H6ꢀ bipyEt); (CD2Cl2): d 1.37
O), 527 (85%) (M ), 423 (100%%) (M − PhCH CH2), 301 (10%)
(M − bipynP), 227 (95%) (bipynP + H).
[Au(bipyoXyl)(sty)](PF6) (3e). Yield: 55%; 118–119 ◦C. Calcd
for C26H24AuF6N2P: C, 44.21; H, 3.42; N, 3.97%. Found C, 43.98;
H, 3.18; N, 3.67%. Selected IR bands: (m/cm−1, Nujol mull): 1601s,
2
3
(t, J = 7.7 Hz, 3H; Me), 3.11 (dq, J = 11.2, J = 7.7 Hz, 2H;
CH2), 4.09 (dd, Jab = 2.1, Jac = 9.1 Hz, 1H; Ha), 4.16 (dd, Jba
=
1
2.1, Jbc = 13.6 Hz, 1H; Hb), 5.42 (dd, Jca = 9.1, Jcb = 13.6 Hz,
1573m, 1226s, 1028m, 996m, 842vs(br), 780vs, 697m. H NMR
3
ꢀ
1H; Hc), 7.34–8.45 (m, 11H; ArH), 8.58 (d, J = 5.4 Hz, 1H; H6
(CD2Cl2): d 2.06 (s, 3H; Me), 2.13 (s, 3H; Me), 2.97 (m, 2H;
bipyEt).
CH2), 5.11 (dd, Jca = 9.5, Jcb = 13.0 Hz, 1H; CH), 7.27–
=
=
[Au(bipyiPr)(sty)](PF6) (3c). Yield: 25%; mp 140–
141 ◦C. Calcd for C21H22AuF6N2P: C, 39.14; H, 3.44; N,
8.45 (m, 15H; ArH), 8.53 (ddd, J = 8.1; 2.4; 0.9 Hz, 1H; H6
ꢀ
bipyoXyl);{(CD3)2CO}: d 2.07 (s, 3H; Me), 2.17 (s, 3H; Me), 3.02
This journal is
The Royal Society of Chemistry 2006
Dalton Trans., 2006, 5703–5716 | 5711
©

View Online
=
=
=
(d, J = 12.1 Hz, 2H; CH2), 5,29 (pseudot, J = 8.0, 11.2 Hz, 1H;
57.6 ( CH2), 95.0 ( CMePh), 121.7, 123.5, 124.2, 124.5, 125.8,
127.7, 128.3, 128.6, 129.1, 141.9, 142.1, 151.0, 151.1, 152.9, 168.5.
MS data (FAB+): m/z 529 (24%) (M + 16), 513 (100%) (M+), 395
(90%) (M − Mesty), 315 (5%) (M − bipyiPr), 197 (32%) (bipyiPr–H).
=
ꢀ
CH), 7.25–8.66 (m, 15H; ArH), 8.85 (d, J = 8.06 Hz, 1H; H6
bipyoXyl); 13C{ H} NMR (CD2Cl2): d 20.3 (Me), 20.4 (Me), 81.9
1
=
( CH), 122.4, 124.4, 126.4, 128.2, 128.5, 128.8, 129.1, 129.5, 136.2,
[Au(bipynP)(Mesty)](PF6) (5d). Yield: 40%; mp 131–133 ◦C
(decomp.). Calcd for C24H28AuF6N2P: C, 41.99; H, 4.11; N,
4.08%. Found C, 41.48; H, 3.95; N, 3.96%. Selected IR bands:
(m/cm−1, Nujol mull): 1598s, 1572s, 1310m, 1265m, 1168m, 1028m,
136.4, 141.3, 142.2, 142.9, 151.2, 151.9, 152.6, 161.5; {(CD3)2CO}:
=
=
d 20.2 (Me), 20.3 (Me), 53.6 ( CH2), 81.6 ( CH), 123.2, 125.1,
127.06, 128.7, 128.8, 129.2, 129.3, 129.8, 130.7, 136.8, 136.9, 137.6,
142.2, 142.8, 143.6, 152.0, 152.8, 153.5, 161.6. MS data (FAB+):
m/z 561 (30%) (M ), 457 (15%) (M − PhCH CH2), 261 (100%)
+
=
1
842vs(br), 780vs, 697m. H NMR (CD2Cl2): d 1.07 (s, 9H; Me),
(bipyoXyl + H).
2.44 (s, 3H; Me Mesty), 3.29 (s, 2H; CH2), 3.92 (d, J = 1.7 Hz,
1H; Ha), 4.21 (d, J = 1.7 Hz, 1H; Hb), 7.39–8.44 (m, 12H; ArH).
MS data (FAB+): m/z 557 (10%) (M + 16), 541 (85%) (M+), 423
[Au(bipyMe,Me)(sty)](PF6) (3f). Yield: 35%; mp 166–
◦
167 C. Calcd for C20H20AuF6N2P: C, 38.11; H, 3.20; N, 4.44%.
Found C, 38.23; H, 3.31; N, 4.30%. Selected IR bands: (m/cm−1,
Nujol mull): 1601s, 1571m, 1245m, 1182m, 1022m, 841vs(br),
793vs, 714m, 698m. 1H NMR (CD2Cl2): d 2.81 (s, 6H; Me), 4.10
(95%) (M − Mesty), 315 (5%) (M − bipynP), 227 (100%) (bipynP
+
H).
[Au(bipyoXyl)(Mesty)](PF6) (5e). Yield: 35%; mp 140–141 ◦C
(decomp.). Calcd for C27H26AuF6N2P: C, 45.01; H, 3.64; N,
3.87%. Found C, 44.81; H, 3.48; N, 3.66%. Selected IR bands:
(m/cm−1, Nujol mull): 1600s, 1573m, 1312m, 1268m, 1170m,
1028m, 840vs(br), 788vs, 700s. 1H NMR (CD2Cl2): d 2.09 (s, 6H;
Me), 2.20 (s, 3H; Me Mesty), 2.79 (d, J = 2.4 Hz, 1H; Ha), 3.00
(d, J = 2.4 Hz, 1H; Hb), 7.29–8.55 (m, 15H; ArH); {(CD3)2CO}:
d 2.11 (s, 6H; Me), 2.24 (s, 3H; Me Mesty), 2.87 (d, J = 2.2 Hz,
1H; Ha), 3.03 (d, J = 2.2 Hz, 1H; Hb), 7.30–8.87 (m, 15H; Ar–
(dd, Jba = 2.0, Jbc = 13.4 Hz, 1H; Hb), 4.20 (dd, Jab = 2.0, Jac
=
9.0 Hz, 1H; Ha), 5.31 (dd, Jca = 9.0, Jcb = 13.4 Hz, 1H; Hc), 7.35–
8.27 (m, 11H, ArH). MS data (FAB+): m/z 501 (<5%) (M + 16),
+
=
485 (75%) (M ), 381 (70%) (M − PhCH CH2), 301 (<5%) (M −
bipyMe,Me), 185 (100%) (bipyMe,Me + H).
[Au(bipyMe)(van)(PF6) (4a). Yield: 59%; mp 144–145 ◦C
(decomp.). Calcd for C20H20AuF6N2OP: C, 37.17; H, 3.12; N,
4.33%. Found C, 37.23; H, 3.31; N, 4.28%. Selected IR bands:
(m/cm−1, Nujol mull): 1596s(br), 1530m, 1301m, 1254m, 1028m,
H); 13C{ H} NMR {(CD3)2CO}: d 20.3 (Me bipyoXyl), 23.7 (Me
1
1
841vs(br), 775vs, 699m. H NMR (CD2Cl2): d 2.85 (s, 3H; Me),
=
=
Mesty), 55.9 ( CH2), 95.2 ( CMePh), 123.1, 125.2, 126.2, 128.7,
128.8, 129.1, 129.4, 129.7, 130.7, 136.9, 140.6, 142.1, 142.8, 143.4,
147.8, 152.0, 152.6, 153.5, 161.5. MS data (FAB+): m/z 591 (5%)
(M + 16), 575 (100%) (M+), 457 (55%) (M − Mesty), 315 (<5%)
(M − bipyoXyl), 259 (50%) (bipyoXyl–H).
3.83 (s, 3H; MeO), 4.01 (dd, Jab = 2.1, Jac = 9.0 Hz, 1H; Ha),
4.08 (dd, Jba = 2.1, Jbc = 13.7 Hz, 1H, Hb), 5.43 (dd, Jca = 9.0,
Jcb = 13.7 Hz, 1H, Hc), 6.94 (d, J = 8.8 Hz, 2H; Ho van), 7.45 (d,
J = 8.8 Hz, 2H; Hm van), 7.70–8.42 (m, 6H; ArH), 8.58 (d, J =
4.8 Hz, 1H: H6 bipyMe); {(CD3)2CO}: d 2.94 (s, 3H; Me), 3.80 (s,
ꢀ
[Au(bipyMe)(stil)](PF6) (6a). Yield: 30%; mp 139–
140 ◦C. Calcd for C25H22AuF6N2P: C, 43.37; H, 3.20; N,
4.05%. Found C, 43.09; H, 3.11; N, 3.89%. Selected IR bands:
(m/cm−1, Nujol mull): 1600s, 1573m, 1530w, 1252m, 1167m,
1029m, 842vs(br), 776vs, 703m. 1H NMR (CD2Cl2): d 2.58 (s, 3H;
3H; MeO), 4.16 (dd, Jab = 2.0, Jac = 9.0 Hz, 1H; Ha), 4.33 (dd,
Jba = 2.0, Jbc = 13.6 Hz, 1H; Hb), 5.66 (dd, Jca = 9.0, Jcb = 13.6 Hz,
1H; Hc), 6.95 (d, J = 8.9 Hz, 2H; Ho van), 7.62 (d, J = 8.9 Hz, 2H;
ꢀ
Hm van), 7.91–8.78 (m, 6H; ArH), 8.84 (d, J = 4.7 Hz, 1H; H6
bipyMe); 13C{ H} NMR {(CD3)2CO}: d 53.3 ( CH2), 55.7 (MeO),
1
=
=
Me), 5.77 (s, 2H; CH), 7.25–7.33 (m, 5H; ArH stil), 7.38–7.44
=
83.0 ( CH), 114.9, 121.2, 124.1, 128.0, 128.1, 128.2, 128.5, 142.0,
(m, 5H; ArH stil), 7.66–8.63 (m, 7H; ArH bipyMe); 13C{ H} NMR
1
151.3, 151.6, 152.7, 160.3, 160.6.
=
[Au(bipyMe)(Mesty)](PF6) (5a). Yield: 31%; mp 93–94 ◦C
(decomp.). Calcd for C20H20AuF6N2P: C, 38.11; H, 3.20; N, 4.44%.
Found C, 37.98; H, 3.02; N, 4.32%. Selected IR bands: (m/cm−1,
Nujol mull): 1601s, 1573m, 1306m, 1260m, 1028m, 842vs(br),
780vs, 697m. 1H NMR (CD2Cl2): d 2.44 (s, 3H; Me Mesty), 3.86
(CD2Cl2): d 27.5 (Me), 79.2 ( CH), 121.5, 124.4, 127.4, 128.6,
129.0, 129.1, 130.1, 135.3, 142.2, 142.3, 151.1, 151.8, 153.1, 160.6.
[Au(bipyMe)(nb)](PF6) (7a). Yield: it depends on the prepar-
ative conditions;10 mp 206–207 ◦C. Calcd for C18H20AuF6N2P: C,
35.65; H, 3.32; N, 4.62%. Found C, 35.71; H, 3.31; N, 4.55%.
Selected IR bands: (m/cm−1, Nujol mull): 1597s, 1575m, 1561m,
1125m, 1027m, 1011m, 839vs(br), 780s, 741m. 1H NMR (CD2Cl2):
d 0.81 (dt, J = 9.7, 1.5 Hz, 1H; CHH-7), 1.21 (2d overlapped, 3H;
CHH5,6 + CHH7), 1.78 (dm, 2H; CHH5,6), 3.04 (s, 3H; Me), 3.22
(s, 3H; Me bipyMe), 3.97 (d, Jab = 1.8 Hz, 1H; Ha), 4.23 (d, Jab
=
1.8 Hz, 1H; Hb), 7.34–8.44 (m, 11H; ArH), 8.55 (ddd, J = 5.2,
1.6, 0.8 Hz, 1H; H6 bipyMe); 13C{ H} NMR (CD2Cl2): d 24.1 (Me
1
ꢀ
Mesty), 28.0 (Me bipyMe), 57.8 ( CH2), 95.8 ( CMePh), 121.3,
124.3, 125.8, 128.1, 128.4, 129.2, 129.5, 139.7, 142.0, 142.2, 150.9,
151.5, 152.8, 160.3. MS data (FAB+): m/z 501 (20%) (M + O),
=
=
=
(s, 2H; CH1,4), 4.22 (s, 2H; CH CH), 7.75–8.45 (m, 6H, ArH),
8.86 (dd, J = 5.2, 1.7 Hz, 1H; H6 bipyMe); {(CD3)2CO}: d 0.77
ꢀ
485 (30%) (M+), 367 (50%) (M − Mesty), 171 (100%) (bipyMe
+
(dt, J = 9.8 Hz, 1H; CHH7), 1.18 (dm, J = 7.8, 2.4 Hz, 2H;
CHH5,6), 1.30 (dt, J = 9.5 Hz, 1H; CHH7), 1.74 (dm, J = 7.4 Hz,
2H; CHH5,6), 3.11 (s, 3H; Me), 3.25 (s, 2H; CH1,4), 4.36 (s, 2H;
H).
[Au(bipyiPr)(Mesty)](PF6) (5c). Yield: 38%; mp 104–106 ◦C
(decomp.). Calcd for C22H24AuF6N2P: C, 40.13; H, 3.67; N,
4.25%. Found C, 39.98; H, 3.38; N, 4.02%. Selected IR bands:
(m/cm−1, Nujol mull): 1599s, 1574s, 1308m, 1261m, 1170m, 1027m,
841vs(br), 778vs, 698m. 1H NMR (CD2Cl2): d 1.23 (d, J = 6.9 Hz,
3H; Me), 1.48 (d, J = 6.9 Hz, 3H; Me), 2.42 (s, 3H; Me Mesty),
3.45 (sept, J = 6.9 Hz, 1H; CHMe2), 3.97 (d, J = 1.8 Hz, 1H; Ha),
=
ꢀ
CH CH), 7.95–8.79 (m, 6H; ArH), 9.12 (d, J = 4.4 Hz, 1H; H6
bipyMe). 13C{ H} NMR (CD2Cl2): d 25.4 [2C, CH2(5,6)], 28.41 (1C,
1
=
Me), 42.8 (2C, CH1,4), 43.6 [1C, CH2(7)], 83.3 (2C, CH), 121.3
(1C, CH), 124.2 (1C, CH), 128.0 (1C, CH), 128.3 (1C, CH), 141.9
(1C, CH), 142.0 (1C, CH), 151.7 (1C, CH), 152.1 (1C, qC), 153.0
(1C, qC) 160.1 (1C, qC). MS data (FAB+) m/z: 461 (100%) (M+),
4.22 (d, J = 1.8 Hz, 1H; Hb), 7.35–8.57 (m, 12H; ArH); 13C{ H}
367 (68%) (M − nb), 291 (5%) (M − bipyMe), 171 (60%) (bipyMe
+
1
NMR (CD3CN): d 22.0 (Me), 22.2 (Me), 23.1 (Me), 41.0 (CH),
H).
5712 | Dalton Trans., 2006, 5703–5716
This journal is
The Royal Society of Chemistry 2006
©

View Online
[Au(bipynP)(nb)](PF6) (7d). Yield: 40%; mp 142–
143 ◦C. Calcd for C22H28AuF6N2P: C, 39.89; H, 4.26; N,
4.23%. Found C, 39.71; H, 4.16; N, 4.21%. Selected IR bands:
(m/cm−1, Nujol mull): 1597vs, 1573s, 1307s, 1227s, 1167m, 1128m,
1025s, 1009s, 838vs(br), 789s, 765s, 741m, 723m, 654m, 639m. 1H
NMR (CD2Cl2): d 0.81 (d, J = 9.7 Hz, 1H; CHH7anti), 1.09 (s, 9H,
Me), 1.18–1.23 (m, 3H; CHH5,6 + CHH7syn), 1.79 (d, J = 9.0 Hz,
2H; CHH5,6), 3.26 (s, 2H; CH1,4), 3.38 (s, 2H, CH2CMe3), 4.23 (s,
Found C, 33.45; H, 3.11; N, 4.65%. Selected IR bands: (m/cm−1,
Nujol mull): 1585s, 1560m, 1020m, 840vs(br), 780s. 1H NMR
{(CD3)2CO}: d 1.52 (d, J = 6.8 Hz, 12H; CH3), 1,55 [s, 2H; CH2(7)],
=
3.96 (sept, J = 6.8 Hz, 2H; CHMe2), 4.84 (s, 4H; CH CH), 8.03–
iPr
ꢀ
8.90 (m, 12H; ArH), 9.17 (d, J = 5.2 Hz, 2H; H6 bipy ). MS data
(FAB+) m/z: 487 (70%) [Au(bipyip)(nbd)], 395 (50%) [Au(bipyip)].
[Au2(bipynP)2(l-nbd)](PF6)2 (9d). Yield: 41%; mp 147–
148 ◦C (decomp.). Calcd for C37H44Au2F12N4P2: C, 36.17; H, 3.61;
N, 4.56%. Found C, 35.98; H, 3.33; N, 4.48%. Selected IR bands:
(m/cm−1, Nujol mull): 1600s, 1573m, 1228m, 1026m, 842vs(br),
782s, 740m. 1H NMR (CD2Cl2): d 1.18 (s, 18H; Me), 1.43 [s, 2H;
CH2(7)], 3.36 (s, 4H; CH2CMe3), 4.16 (br, 2H; CH1,4), 4.68 (br, 4H;
=
2H; CH CH), 7.73–8.47 (m, 6H, ArH), 8.86 (d, J = 4.8 Hz, 1H;
1
H6 bipynP). 13C{ H} NMR (CD2Cl2): d 25.2 [2C, CH2(5,6)], 29.7
ꢀ
(3C, Me), 33.2 (1C, CH2CMe3), 42.7 (2C, CH1,4), 43.4 [1C, CH2(7)],
=
55.9 (1C, CH2CMe3), 84.1 (2C, CH), 122.0, 124.2, 127.9, 129.1,
141.0, 141.9, and 151.4 (ArCH), 152.1, 153.5, and 161.5 (ArC).
MS data (FAB+) m/z: 553 (12%) (M + 16), 517 (100%) (M+), 423
(42%) (M − nb), 291 (5%) (M − bipynP), 227 (15%) (bipynP + H).
[Au(bipyoXyl)(nb)](PF6) (7e). Yield: 19%; mp 114–
115 ◦C. Calcd for C25H26AuF6N2P: C, 43.12; H, 3.76; N,
4.02%. Found C, 42.91; H, 3.78; N, 4.09%. Selected IR bands:
(m/cm−1, Nujol mull): 1600s, 1574m, 1167m, 1126m, 1026m,
=
ꢀ
CH CH), 7.75–8.41 (m, 12H, ArH), 8.98 (d, J = 4.7 Hz, 2H; H6
bipynP).
[Au2(bipyMe)2(l-cod)](PF6)2 (10a). Yield: 30%; mp 115–
116 ◦C (decomp.). Calcd for C30H32Au2F12N4P2: C, 31.82; H,
1
2.85; N, 4.95%. Found C, 31.75; H, 2.90; N, 4.87%. H NMR
{(CD3)2CO}: d 2.39 (broad m, 4H; CH2), 2.70 (broad m, 4H; CH2),
=
3.04 (s, 6H; Me), 4.94 (broad m, 4H; CH CH), 7.92–8.81 (m, 12H;
1
ArH), 9.03 (dd, J = 5.2, 0.9 Hz, 2H, H6 bipyMe); (CD3CN): d 2.56
1005m, 842vs(br), 778s, 739m, 722m. H NMR (CD2Cl2): d 0.56
ꢀ
(d, J = 9.5 Hz, 1H; CHH7), 0.86–0.89 (m, 3H; CHH5,6 + CHH7),
(broad m, 4H; CH2), 2.84 (broad m, 4H; CH2), 2.97 (s, 6H; Me),
4.72 (broad m, 4H; CH CH), 7.72–8.78 (m, 14H; H6 bipyMe).
1.54 (d, J = 8.7 Hz, 2H; CHH5,6), 2.08 (s, 6H; Me), 2.67 (s, 2H;
=
ꢀ
=
[Au2(bipyiPr)2(l-cod)](PF6)2 (10c). Yield: 44%; mp 109–
110 ◦C (decomp.). Calcd for C34H40Au2F12N4P2: C, 34.36; H, 3.39;
N, 4.71%. Found C, 34.08; H, 3.01; N, 4.58%. 1H NMR (CD2Cl2):
d 1.49 (d, J = 7.0 Hz, 6H; Me), 1.52 (d, J = 7.0 Hz, 6H; Me),
2.27 (broad m, 2H; CH2), 2.52–2.83 (m, 4H; CH2), 2.93 (broad d,
J = 12.5 Hz, 2H; CH2), 3.55 and 3.56 (2 sept, J = 7.0 Hz, 2H,
CH1,4), 3.46 (s, 2H; CH CH), 7.32–8.58 (m, 9H; ArH), 8.82 (dd,
1
J = 5.2, 1.7 Hz, 1H; H6 bipyoXyl); 13C{ H} NMR (CD2Cl2): d 20.4
ꢀ
(2C, Me), 24.7 [2C, CH2(5,6)], 42.6(2C, CH1,4), 43.5 [1C, CH2(7)],
=
83.9 (2C, CH), 122.4, 124.2, 128.2, 128.4, 128.9, 130.2, 136.2,
140.9, 141.9, 142.6, 151.6, 152.5, 152.6, 161.4. MS data (FAB+)
m/z: 567 (5%) (M + O), 551 (100%) (M+), 457 (30%) (M − nb),
291 (5%) (M − bipyoXyl), 259 (15%) (bipyoXyl–H).
=
CH), 4.79 (broad m, 4H; CH CH), 7.75–8.82 (m, 14H; ArH);
[Au(bipyMe)(dcpd)](PF6) (8a). Yield: 32%; mp 146–147 ◦C
(decomp.). Calcd for C21H22AuF6N2P: C, 39.14; H, 3.44; N, 4.35%.
Found C, 38.85; H, 3.36; N, 4.30%. Selected IR bands: (m/cm−1,
Nujol mull): 1606s, 1518s, 1488s, 1255s, 1175s, 1027s, 842vs(br),
776s, 727m. 1H NMR (CD2Cl2): d 1.05 (dt, J = 9.9, 1.5 Hz, 1H;
CH,H8), 1.44 (dt, J = 9.9, 1.5 Hz, 1H; CH,H8), 2.15–2.40 [m, 2H;
CH2(1)], 2.60–2.94 (m, 1H, CH7a), 3.01 (s, 3H; Me), 3.22 (broad s,
1
13C{ H} NMR (CD2Cl2): d 23.0 (2C, Me), 29.9 (2C, CH2), 30.4
=
(2C, CH2), 42.0 (2C, CH), 80.5 (4C, CH), 121.7 (2C, CH), 124.0
(2C, CH), 124.6 (2C, CH), 128.1 (2C, CH), 141.9 (2C, CH), 142.3
2C, CH), 151.5 (2C, CH), 151.7 82C, qC), 152.9 (2C, qC), 168.7
(2C, qC). MS data (FAB+) m/z: 1043 (15%) (M + PF6), 503 (65%)
[M − Au(bipyiPr)], 449 (5%) (M/2), 395 (100%) [Au(bipyiPr)], 197
(bipyiPr–H).
=
2H; CH4,7), 3.37 (m, 1H; CH3a), 4.18 (d, JAB = 4.3 Hz, 1H; CH5),
Spectroscopic data of [Au2(bipyMe)2(l-dcpd)](PF6)2 (11a).
1H NMR (CD2Cl2): d 1.04 (d, J = 10.0 Hz, 1.5H; CHH-8 8a
+ 11a), 2.00 (d, J = 10.0 Hz, 1H; CHH-8), 2.22–2.47 (m, 6H;
CH2 8a + 11a), 2.68–2.95 (m, 3H; CH-7a 8a + 11a), 3.01 (s, 3H;
Me), 3.05 (s, 3H; Me), 3.27 [broad s, 1H; CH4(7)], 3.61 (broad s,
=
=
4.38 (d, JBA = 4.3 Hz, 1H; CH6), 5.71 (s, 2H; CH2,3), 7.72–
8.45 (m, 6H; ArH), 8.84 (d, J = 5.1 Hz; H6 bipyMe); 13C{ H}
1
ꢀ
NMR (CD2Cl2): d 28.4 (1C, Me), 33.0 [1C, CH2(1)], 41.5 (1C), 45.2
=
=
(1C), 46.6 (1C), 80.6 (1C, CH5), 84.9 (1C, CH6), 121.2 (1C,
CH), 124.1 (1C, CH), 128.0 (1C, CH), 128.3 (1C, CH), 131.3 (1C,
=
2H; CH7(4) + CH7a), 4.54 (d, JAB = 4.3 Hz 1H; CH5), 4.60 (d,
=
=
CH2), 132.7 (1C, CH3), 141.9 (2C, CH), 151.7 (1C, CH), 152.0
(1C, qC), 152.9 (1C, qC), 160.0 (1C, qC).
=
=
JBA = 4.3 Hz 1H; CH6), 4.84 (t, J = 4.2 Hz 1H; CH2), 5.02
=
(d, J = 4.2 Hz 1H; CH3), 7.36–8.97 (m, 35 H; ArH 8a + 11a);
[Au2(bipyMe)2(l-nbd)](PF6)2 (9a). Yield: 15%; mp 130 ◦C
(decomp.). Anal. Calcd for C29H28Au2F12N4P2: C, 31.19; H, 2.53;
N, 5.02%. Found C, 31.08; H, 2.54; N, 5.14%. Selected IR bands:
(m/cm−1, Nujol mull): 1590s, 1565m, 1030m, 850vs(br), 785s,
13C{ H} NMR (CD2Cl2): d 27.9 (Me), 28.6 (Me), 33.7, 43.6, 45.6,
1
=
=
=
=
46.3, 46.7, 81.2 ( CH), 82.6 ( CH), 83.8 ( CH), 85.8 ( CH),
121.1, 123.9, 128.3, 141.9, 151.7, 152.0, 152.2, 152.7, 160.2. MS
data (FAB+) m/z: 1043 (M + PF6 + 32), 1027 (M + PF6 + 16),
1011 (M + PF6), 882 (M + 16), 499 [M − Au(bipyMe)], 433 (M/2),
367 [Au(bipyMe)], 171 (bipyMe + H).
1
735m. H NMR (CD3CN): d 1.38 [s, 2H; CH2(7)], 2.99 (s, 6H;
=
Me), 4.03 (s, 2H; CH1,4), 4.59 (s, 4H; CH CH), 7.80–8.49 (m,
1
12H; ArH), 8.91 (d, J = 4.5 Hz, 2H; H6 bipyMe). 13C{ H} NMR
ꢀ
(CD3CN): d = 28.6 (2C, Me), 49.6 (2C, CH1,4), 55.6 [1C, CH2(7)],
X-Ray data collection and structure determination
=
85.2 (4C, CH), 122.1 (2C, CH), 125.0 (2C, CH), 128.7 (2C,
CH), 129.0 (2C, CH), 142.8 (4C, CH) 152.8 (2C, CH), 153.0
(2C, qC), 153.8 (2C, qC), 161.0 (2C, qC). MS data (FAB+) m/z:
551 (50%) [Au(bipyMe)(nbd)2], 457–461 ≈ [Au(bipyMe)(nbd)], 367
(100%) [Au(bipyMe)].
[Au2(bipyiPr)2(l-nbd)](PF6)2 (9c). Yield: 10%; mp 141–
142 ◦C. Calcd for C33H36Au2F12N4P2: C, 33.80; H, 3.09; N, 4.78%.
Crystal data are summarised in Table 6. The diffraction experi-
ment was carried out on a Bruker SMART CCD area-detector
diffractometer at 150 K. No crystal decay was observed, so that
no time–decay correction was needed. The collected frames were
processed with the software SAINT,47 and an empirical absorption
correction was applied (SADABS)48 to the collected reflections.
This journal is
The Royal Society of Chemistry 2006
Dalton Trans., 2006, 5703–5716 | 5713
©

View Online
Ahlrichs35 and the 6-31+G*34 all-electron basis sets (BS’s) were
used for C, H, and N, while the LanL2DZ,36 Stuttgart RSC 1997
(ECP60MDF)37 and CRENBL38 BS’s with relativistic effective
core potentials (RECP’s) were tested for Au.39 For all compounds
NBO populations and Wiberg bond indexes were calculated at
the optimised geometries.44,53 Bond dissociation energies (BDE)54
were computed using the fully relaxed equilibrium structures and
corrected for zero point energy (ZPE), evaluated from vibrational
frequency calculations. Calculations were performed on a IBM
SP5/512 equipped with 512 IBM Power5 1.9 GHz processors
with 1.2 TB RAM running AIX 5.2, and on an Intel PIV 2.8 GHz
workstation running Linux Mandriva One 2006. The programs
GaussView 3.0,55 Molekel 4.3,56 and Molden 4.457 were used to
investigate the NBO charge distributions and MO compositions.
Table 6 Crystallographic data
Compound
Formula
M
3e·CH2Cl2
C27H26AuCl2F6N2P
791.36
Colourless
Monoclinic
P21/c
15.011(1)
13.445(1)
14.603(1)
108.48(1)
2795.3(3)
4
Colour
Crystal system
Space group
˚
a/A
˚
b/A
˚
c/A
b/◦
U/A
Z
3
˚
F(000)
1536
1.880
150
Dc/g cm−3
T/K
Crystal dimensions/mm
0.22 × 0.34 × 0.43
l (Mo–Ka)/cm−1
55.62
Min. and max. transmiss. factors
Scan mode
0.793–1.000
x
0.30
Acknowledgements
Frame width/◦
Support from the University of Sassari is gratefully acknowl-
edged. M.A. gratefully acknowledges CINECA (Consorzio In-
teruniversitario del Nord-Est per il Calcolo Automatico) and
INSTM (Istituto Nazionale per la Scienza e Tecnologia dei
Materiali) for computational resources.
Time per frame/s
No. of frames
h-range
15
2770
3–27
Full sphere
42473, 6102
0.0293
0.032, 0.056
0.019
5373
379
Reciprocal space explored
No. of reflections (total; independent)
Rint
Final R2 and R2w indicesa (F2, all reflections)
Conventional R1 index [I > 2r(I)]
Reflections with I > 2r(I)
No. of variables
References and notes
1 F. R. Hartley, Angew. Chem., Int. Ed. Engl., 1972, 11, 596; J. P. Collman,
L. S. Hegedus, J. R. Norton and R. G. Finke, Principles and Applications
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Valley, CA, 1987; R. H. Crabtree, The Organometallic Chemistry of
the Transition Metals, Wiley Interscience, Hoboken, New Jersey, IVth
Edition, 2005.
2 R. F. Heck, Palladium Reagents in Organic Synthesis, Academic Press,
New York, 1985; J. Tsuji, Palladium Reagents and Catalysts: Innovation
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hensive Organometallic Chemistry II, ed. E. W. Abel, F. G. A. Stone and
G. Wilkinson, Pergamon Press, London, 1995, vol. 9, pp. 533–588; B.
de Bruin, P. H. M. Budzelaar and A. W. Gal, Angew. Chem., Int. Ed.,
2004, 43, 4142; S. D. Ittel, L. K. Johnson and M. Brookhart, Chem.
Rev., 2000, 100, 1169; F. I. Rodr´ıguez, J. J. Esch, A. E. Hall, B. M.
Binder, G. E. Schaller and A. B. Bleecker, Science, 1999, 283, 996; J. R.
Ecker, Science, 1995, 268, 667; S. Linic, H. Piao, K. Abid and M. A.
Barteau, Angew. Chem., Int. Ed., 2004, 43, 2918.
3 Very recent examples of Cu(I) and Ag(I) alkene complexes: (a) G.
Pampaloni, R. Peloso, C. Graiff and A. Tiripicchio, Dalton Trans.,
2006, 3576; (b) G. Pampaloni, R. Peloso, C. Graiff and A. Tiripicchio,
Organometallics, 2005, 24, 4475; (c) G. Pampaloni, R. Peloso, C. Graiff
and A. Tiripicchio, Organometallics, 2005, 24, 819; (d) H. V. R. Dias,
S. A. Richey, H. V. K. Diyabalanage and J. Thankamani, J. Organomet.
Chem., 2005, 690, 1913; (e) E. Kieken, O. Wiest, P. Helquist, M. E.
Cucciolito, G. Flores, A. Vitagliano and P.-O. Norrby, Organometallics,
2005, 24, 3737; (f) H. V. R. Dias and X. Wang, Dalton Trans., 2005,
2985.
Goodness of fitb
0.984
ꢀ
ꢀ
ꢀ
ꢀ
a R2 = [ (|Fo − kFc2|/ Fo2], R2w = [ w/(Fo − kFc2)2/ w(Fo2)2]1/2
.
2
2
ꢀ
[
w(Fo − kFc2)2/(No − Nm)]1/2, where w = 4Fo2/r(Fo2)2, r(Fo2) =
b
2
[r2(Fo2) + (pFo2)2]1/2, No is the number of observations, Nm the number of
variables, and p, the ignorance factor, = 0.04.
The calculations were performed using the Personal Structure
Determination Package49 and the physical constants tabulated
therein.50 The structure was solved by direct methods (SHELXS)51
and refined by full-matrix least-squares using all reflections and
ꢀ
minimising the function w(Fo − kFc )2 (refinement on F2). All
the non-hydrogen atoms were refined with anisotropic thermal
factors. Hydrogen atoms H1–H3 and those of the two CH3 groups
were refined with a fixed isotropic thermal parameter. All the
other hydrogen atoms were placed in their ideal positions (C–H =
2
2
˚
0.97 A), with the thermal parameter U 1.10 times that of the
carbon atom to which they are attached, and not refined. In the
final Fourier map the maximum residual was 0.93(14) e A at
−3
˚
˚
0.91 A from Cl(1).
CCDC reference number 615695.
For crystallographic data in CIF or other electronic format see
DOI: 10.1039/b610657a
4 (a) A. J. Chalk, J. Am. Chem. Soc., 1964, 86, 4733 (first isolated
complex); (b) R. Huttel and H. Dietl, Angew. Chem., Int. Ed. Engl.,
1965, 4, 438; (c) R. Hu¨ttel, H. Reinheimer and H. Dietl, Chem. Ber.,
1966, 99, 462; (d) R. Hu¨ttel and H. Reinheimer, Chem. Ber., 1966, 99,
2778; (e) R. Hu¨ttel, H. Reinheimer and K. Nowak, Chem. Ber., 1968,
101, 3761; (f) R. Hu¨ttel, P. Tauchner and H. Forkl, Chem. Ber., 1972,
105, 1; (g) P. Tauchner and R. Hu¨ttel, Chem. Ber., 1974, 107, 3761;
(h) A. Johnson and R. J. Puddephatt, J. Chem. Soc., Dalton Trans.,
1977, 1384; (i) S. Komiya and J. K. Kochi, J. Organomet. Chem., 1977,
135, 65; (j) H. Coutelle and R. Hu¨ttel, J. Organomet. Chem., 1978, 153,
359.
¨
Calculations
Quantum-chemical DFT31 calculations were carried out on
2
+
2
+
=
=
the compounds [Au(g -CH2 CH2)] , [Au(bipy)(g -CH2 CH2)]
+
=
(2g), [Au(bipy)] , and CH2 CH2 with the well-known three-
parameters Becke3LYP32 and Barone’s mPW1PW33 functionals
using the commercially available suite of programs Gaussian03.52
Although the use of all-electron basis sets provides better accuracy,
pseudopotential techniques are useful when relativistic effects
have to be taken into account. Thus, the Schafer, Horn, and
5 (a) D. Belli Dell’Amico, F. Calderazzo, R. Dantona, J. Stra¨hle and H.
Weiss, Organometallics, 1987, 6, 1207; (b) M. Ha˚kansson, H. Eriksson
and S. Jagner, J. Organomet. Chem., 2000, 602, 133.
6 R. M. Da´vila, R. J. Staples and J. P. Fackler, Jr., Organometallics, 1994,
13, 418.
5714 | Dalton Trans., 2006, 5703–5716
This journal is
The Royal Society of Chemistry 2006
©

View Online
7 T. A. Albright, R. Hoffmann, J. C. Thibeault and D. L. Thorn, J. Am.
Chem. Soc., 1979, 101, 3801.
8 M. A. Cinellu, G. Minghetti, S. Stoccoro, A. Zucca and M. Manassero,
Chem. Commun., 2004, 1618.
3-methylene-cyclopentane carbaldehyde and 3-methyl-2-cyclopentane
carbaldehyde, reaction in MeCN; cis-endo-2,3-norbornanediol and
trans-2,3-norbonanediol in MeCN–H2O.
18 (Cu) (a) X. Dai and T. H. Warren, Chem. Commun., 2001, 1998 (Pd,
Pt); (b) R. van Asselt, C. J. Elsevier, W. J. J. Smeets and A. L. Spek,
Inorg. Chem., 1994, 33, 1521 (Pd); (c) K. J. Cavell, D. J. Stufken and K.
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Uguagliati and B. Crociani, J. Chem. Soc., Dalton Trans., 1996, 1921
and references cited in these papers.
19 For example, in the styrene complex 3f the signals of the methylene
protons are inverted with respect to 3a–3d: in CD2Cl2 dHa 4.20 (Jac
9.0; Jab 2.0 Hz), dHb 4.10 (Jbc 13.4; Jab 2.0 Hz), moreover Hb and Hc
are further shifted upfield of 0.05 and 0.15 ppm, respectively, while
Ha is shifted downfield of 0.11 ppm; while in 3e these protons give a
different pattern and different chemical shift as shown by its spectra in
CD2Cl2 and in (CD3)2CO. In, CD2Cl2 the olefin protons give second
order multiplets centred at 2.95 (Ha + Hb; DdHa 2.3, DdHb 2.8 ppm) and
5.10 (Hc; Dd 1.6 ppm) ppm, in acetone the methylenic protons resonate
as a doublet at 3.00 ppm (3JHH 11.7 Hz; DdHa 2.2, DdHb 2.8 ppm) and
the methynic proton as a pseudo-triplet at 5.29 ppm (DdHc 1.5 ppm).
Higher upfield shifts of the olefin protons are also observed for 2e, 5e
and 7e, likely due to the shielding of the aryl ring of bipyoXyl, e, which
face the olefin protons.
20 (a) H. Masuda, K. Machida, M. Munakata, S. Kitagawa and H.
Shimono, J. Chem. Soc., Dalton Trans., 1988, 1907; (b) H. Masuda,
N. Yamamoto, T. Taga, K. Machida, S. Kitagava and M. Munakata,
J. Organomet. Chem., 1987, 322, 121; (c) M. Munakata, S. Kitagawa,
S. Kosome and A. Asahara, Inorg. Chem., 1986, 25, 2622; (d) J. S.
Thompson and R. M. Swiatek, Inorg. Chem., 1985, 24, 110; (e) J. S.
Thompson and J. F. Whitney, Inorg. Chem., 1984, 23, 2813.
21 L. Cavallo, M. E. Cucciolito, A. De Martino, F. Giordano, I. Orabona
and A. Vitagliano, Chem. Eur. J., 2000, 6, 1127.
9 M. A. Cinellu, G. Minghetti, M. V. Pinna, S. Stoccoro, A. Zucca, M.
Manassero and M. Sansoni, J. Chem. Soc., Dalton Trans., 1998, 1735.
10 M. A. Cinellu, G. Minghetti, F. Cocco, S. Stoccoro, A. Zucca and M.
Manassero, Angew. Chem., Int. Ed., 2005, 44, 6892.
11 For theoretical studies on Group 11 ethylene complexes see for
example: M+ derivatives, (a) C. K. Kim, K. A. Lee, C. K. Kim,
B.-S. Lee and H. W. Lee, Chem. Phys. Lett., 2004, 391, 321; (b) H.-C.
Tai, I. Krossing, M. Seth and D. V. Deubel, Organometallics, 2004,
23, 2343; (c) R. H. Hertwig, W. Koch, D. Schro¨der, H. Schwarz, J.
Hrusa´k and P. Schwerdtfeger, J. Phys. Chem., 1996, 100, 12253; (d) T.
Ziegler and A. Rauk, Inorg. Chem., 1979, 18, 1558. M(0) derivatives,;
(e) G. Nicolas and F. Spiegelmann, J. Am. Chem. Soc., 1990, 112, 5410;
(f) D. F. McIntosh, G. A. Ozin and R. P. Messmer, Inorg. Chem., 1980,
19, 3321.
12 For recent reviews on gold catalysis, see: (a) A. S. K. Hashmi, Angew.
Chem., Int. Ed., 2005, 44, 6990; (b) C. Bruneau, Angew. Chem., Int. Ed.,
2005, 44, 2328; (c) A. Hoffmann-Ro¨der and N. Krause, Org. Biomol.
Chem., 2005, 3, 387; (d) A. Arcadi and S. Di Giuseppe, Curr. Org.
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(f) A. S. K. Hashmi, Gold Bull., 2003, 36, 3; (g) G. Dyker, Angew.
Chem., Int. Ed., 2000, 39, 4237.
13 Selected recent examples of alkyne activations: (a) R. Casado, M.
Contel, M. Laguna, P. Romero and S. Sanz, J. Am. Chem. Soc.,
2003, 125, 11925; (b) P. Roembke, H. Schmidbaur, S. Cronje and H.
Raubenheimer, J. Mol. Catal. A: Chem., 2004, 212, 35; (c) T. Yao,
X. Zhang and R. C. Larock, J. Am. Chem. Soc., 2004, 126, 11164;
(d) A. S. K. Hashmi, J. P. Weyrauch, W. Frey and J. W. Bats, Org. Lett.,
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(h) C. Nevado and A. M. Echavarren, Chem. Eur. J., 2005, 11, 3155;
(i) A. S. K. Hashmi, M. Rudolf, J. P. Weyrauch, M. Wo¨lfle, W. Frey
and J. W. Bats, Angew. Chem., Int. Ed., 2005, 44, 2798; (j) L. Zhang
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9976; (l) H. Kusama, Y. Miyashita, J. Tanaka and N. Iwasawa, Org.
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14 Selected examples of allene activations: (a) J. H. Teles, and M. Schulz
(BASF AG), WO-AI 9721648, 1997 (Chem. Abstr., 1997, 127, 121499);
(b) A. S. K. Hashmi, L. Schwarz, J.-H. Choi and T. M. Frost, Angew.
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(g) C.-Y. Zhou, P. W. H. Chan and C.-M. Che, Org. Lett., 2006, 8, 325;
(h) See also ref. 13c.
15 Selected examples of alkene activations: (a) S. Kobayashi, K. Kaku-
moto and M. Sugiura, Org. Lett., 2002, 4, 1319; (b) X. Yao and
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