N-Heterocyclic Carbene-Phosphinidene Complexes of the Coinage Metals

Article abstract of DOI:10.1002/chem.201502208

Coinage metal complexes of the N-heterocyclic carbene-phosphinidene adduct IPr·PPh (IPr=1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene) were prepared by its reaction with CuCl, AgCl, and [(Me₂S)AuCl], which afforded the monometallic complexes [(IPr·PPh)MCl] (M=Cu, Ag, Au). The reaction with two equivalents of the metal halides gave bimetallic [(IPr·PPh)(MCl)₂] (M=Cu, Au); the corresponding disilver complex could not be isolated. [(IPr·PPh)(CuOTf)₂] was prepared by reaction with copper(I) trifluoromethanesulfonate. Treatment of [(IPr·PPh)(MCl)₂] (M=Cu, Au) with Na(BAr^F) or AgSbF₆ afforded the tetranuclear complexes [(IPr·PPh)₂M₄Cl₂]X₂ (X=BAr^F or SbF₆), which contain unusual eight-membered M₄Cl₂P₂ rings with short cuprophilic or aurophilic contacts along the chlorine-bridged M...M axes. Complete chloride abstraction from [(IPr·PPh)(AuCl)₂] was achieved with two equivalents of AgSbF₆ in the presence of tetrahydrothiophene (THT) to form [(IPr·PPh){Au(THT)}₂][SbF₆]₂. The cationic tetra- and dinuclear complexes were used as catalysts for enyne cyclization and carbene transfer reactions.

Full text of DOI:10.1002/chem.201502208

DOI: 10.1002/chem.201502208
Full Paper
&
Gold
N-Heterocyclic Carbene–Phosphinidene Complexes of the Coinage
Metals
Adinarayana Doddi, Dirk Bockfeld, Alexandre Nasr, Thomas Bannenberg, Peter G. Jones, and
[a]
Matthias Tamm*
Dedicated to Professor Dr. Dr. h.c. Hubert Schmidbaur on the occasion of his 80th birthday
F
Abstract: Coinage metal complexes of the N-heterocyclic
carbene–phosphinidene adduct IPr·PPh (IPr=1,3-bis(2,6-dii-
sopropylphenyl)imidazolin-2-ylidene) were prepared by its
Na(BAr ) or AgSbF6 afforded the tetranuclear complexes
F
[(IPr·PPh) M Cl ]X (X=BAr or SbF ), which contain unusual
eight-membered M Cl P rings with short cuprophilic or au-
2
4
2
2
6
4
2 2
reaction with CuCl, AgCl, and [(Me S)AuCl], which afforded
rophilic contacts along the chlorine-bridged M···M axes.
2
the monometallic complexes [(IPr·PPh)MCl] (M=Cu, Ag, Au).
Complete chloride abstraction from [(IPr·PPh)(AuCl) ] was
2
The reaction with two equivalents of the metal halides gave
achieved with two equivalents of AgSbF in the presence of
6
bimetallic [(IPr·PPh)(MCl) ] (M=Cu, Au); the corresponding
tetrahydrothiophene (THT) to form [(IPr·PPh){Au(THT)}2]
2
disilver complex could not be isolated. [(IPr·PPh)(CuOTf)2]
[SbF ] . The cationic tetra- and dinuclear complexes were
6 2
was prepared by reaction with copper(I) trifluoromethane-
used as catalysts for enyne cyclization and carbene transfer
reactions.
sulfonate. Treatment of [(IPr·PPh)(MCl) ] (M=Cu, Au) with
2
Introduction
Soon after the advent of stable N-heterocyclic carbenes
[
1]
(
NHC), phosphinidene adducts of type 1 (Scheme 1) were
[
2]
among the first carbene complexes of the p-block elements
to be prepared directly from free carbenes and suitable main-
[
3]
Scheme 1. Resonance structures of N-heterocyclic carbene–phosphinidene
adducts; IMes·PPh (1, R=2,4,6-trimethylphenyl, R’=Ph), IPr·PPh (2, R=2,6-
group compounds. Hence, the reaction between IMes,
bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene, and pentaphe-
diisopropylphenyl, R’=Ph), IPr·PSiMe
R’=SiMe3).
3
(3, R=2,6-diisopropylphenyl,
[
4]
nylcyclopentaphosphane, (PPh) , afforded IMes·PPh (1). Alter-
5
natively, both this and a series of related NHC adducts, for ex-
ample IPr·PPh (2), can be prepared by reaction of the respec-
tive carbene with dichlorophenylphosphine followed by reduc-
[
10]
bilized diphosphorus”) upon reaction with BH ·THF or dioxy-
3
[5]
[11,12]
tion with two equivalents of KC8. As illustrated by the reso-
nance structures A–C (Scheme 1), carbene–phosphinidene
adducts can be regarded as inversely polarized phosphaal-
gen.
In view of the great, general interest in NHC–phosphorus
[
3]
compounds, it is surprising that N-heterocyclic carbene–
phosphinidene adducts, despite their ease of accessibility, have
found only little application in coordination chemistry
(Figure 1), whereas acyclic derivatives have been studied to
[
6–8]
kenes,
of which the mesomeric forms B and C are able to
act as strongly nucleophilic P-donor ligands with two poten-
tially available lone pairs of electrons. Indeed, this possibility
has been demonstrated by the isolation of the bis(borane)
[
6,13]
a somewhat larger extent.
Previous examples merely com-
[9]
adduct [IMes·PPh(BH ) ] (4, Figure 1). Similar reactivity was re-
prise the reaction of IMes·PPh with a Grubbs-type ruthenium–
benzylidene complex to afford 5, and, very recently, a series
3
2
[
14]
ported for the diphosphinidene system IPr·P ·IPr (“carbene-sta-
2
of bimetallic coinage metal complexes [(IMes·PPh)(MX) ] (M=
2
[
15]
CuCl, AgCl, AuCl, CuBr), for example the gold(I) complex 6.
In addition, related digold complexes, such as 7 and 8, have
been reported.
[
a] Dr. A. Doddi, D. Bockfeld, Dr. A. Nasr, Dr. T. Bannenberg,
Prof. Dr. P. G. Jones, Prof. Dr. M. Tamm
Institut für Anorganische und Analytische Chemie
Technische Universität Braunschweig
Hagenring 30, 38106 Braunschweig (Germany)
E-mail: m.tamm@tu-bs.de
Homepage: http://www.tu-braunschweig.de/iaac
[
16,17]
Our own contribution to this field is based on our long-
standing interest in the chemistry of imidazolin-2-iminato li-
gands and our quest for establishing synthetic access to their
[
18]
phosphorus analogues. As imidazolin-2-imines, such as IPr·N-
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/chem.201502208.
[
19]
SiMe3, have served as precursors for the formation of metal–
Chem. Eur. J. 2015, 21, 16178 – 16189
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Figure 2. ORTEP diagram of adduct 2 with thermal displacement parameters
drawn at the 50% probability level. Hydrogen atoms were omitted for clari-
ty. Selected bond lengths [Š] and angles [8]: PÀC1 1.7658(10), PÀC31
1
1
.8238(10), C2ÀC3 1.3408(14), N1ÀC1 1.3808(12), N1ÀC2 1.4027(12), N1ÀC11
.4443(12), N2ÀC21 1.4380(12) Š; C1-P-C31 104.61(4), N2-C1-N1 104.35(8),
N2-C1-P1 118.15(7), N1-C1-P1 137.01(7), C31-P-C1-N1 À24.58.
Figure 1. Examples of carbene–phosphinidene (4–8) and carbene–phosphi-
nidyne complexes (9–11); Mes=2,4,6-trimethylphenyl, Dipp=2,6-diisopro-
pylphenyl. We note that the representation of the complexes and the avoid-
ance of formal charges and arrows might appear arbitrary, but the reader
may refer to Scheme 1 for mesomeric forms and to ref. [26] for a revealing
discussion of the pros and cons of using arrows for the description of car-
bene–element adducts.
similar to those that have been established for other carbene–
phosphinidene systems: an acute C1-P-C31 angle of 104.61(4)8
and a PÀC1 bond length of 1.7658(10) Š correspond to a signif-
[
4,27]
icantly elongated double bond,
and a reduced degree of
PÀC p interaction might be indicated by a twist between the
PÀC31 bond and the imidazole plane, which afforded a C31-P-
C1-N1 torsion angle of À24.58.
[
20]
nitrogen bonds, we recently introduced the corresponding
carbene–phosphinidene IPr·PSiMe3 (3, Scheme 1), which was
used as a convenient starting material for the preparation of
the carbene–phosphinidyne transition-metal complexes 9–11.
To supplement the previously reported electronic structure
[
8]
calculations on NHC–phosphinidene adducts, the molecular
structure of 2 was optimized by applying the density function-
al theory (DFT) method B97-D, which was followed by natural
bond orbital (NBO) analysis. The two relevant NBOs that
belong to the exocyclic PÀC1 moiety are shown in Figure 3a.
The highest occupied NBO represents a PÀC p interaction and
a low-lying P-localized lone pair (NBO-13). The atomic orbital
(AO) contributions of both P and C atoms in the p(PÀC1) NBO
are unequal, with values of 60.7 and 39.3%, respectively. This
indicates a polarized PÀC bond with significant p back-dona-
tion into the empty p orbital of the C1 atom, as described by
the mesomeric forms in Scheme 1. In contrast to this p interac-
tion, the two PÀC s bonds to C1 and C31 atoms are largely C-
localized with carbon contributions of 66.5 and 63.6%, respec-
tively (Table 1).
Furthermore, treatment with [(Me S)AuCl] afforded bi- and tri-
2
[
21]
metallic RuAu, RhAu, and Rh Au complexes. Desilylation of
2
IPr·PSiMe3 furnished the parent phosphinidene IPr·PH, which
had previously been accessed by other routes, such as sily-
[
22]
[23]
lene-to-carbene phosphinidene transfer
or the use of
sodium phosphaethynolate, Na(OCP), as a phosphorus-transfer
[
24]
reagent. As a supplement to these studies and in continua-
tion of our general interest in strongly nucleophilic imidazole-
[18,25]
based ligand systems,
we aimed to develop the coordina-
tion chemistry of carbene–phosphinidene adducts and to in-
vestigate their use as ancillary ligands in homogeneous cataly-
sis. Herein, we report mono- and bimetallic copper(I), silver(I),
and gold(I) complexes, which contain the phosphinidene
ligand IPr·PPh (2), together with the use of the resulting digold
complexes for gold-catalyzed organic transformations.
Results and Discussion
Structural and electronic properties of the N-heterocyclic
carbene–phosphinidene adduct 2
The carbene–phosphinidene adduct IPr·PPh (2) was prepared,
as described previously, by reaction of the carbene IPr with di-
chlorophenylphosphine followed by reduction with potassium
[
5]
graphite (KC8). The spectroscopic data was similar to those al-
3
1
ready reported, for example the P NMR resonance in C D6
6
was found at À19.4 ppm. For comparison, the molecular struc-
ture of 2 was determined by X-ray diffraction analysis
Figure 3. a) NBO isosurfaces (isovalue=0.04) of the N-heterocyclic carbene–
phosphinidene adduct 2. b) Result of an electron localization function (ELF)
analysis at the P and C1 atoms in adduct 2 (isovalue=0.75).
(
Figure 2). The structural characteristics that we observed were
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Table 1. NBO analysis of the PÀC1 bond in adduct 2.
Bond
Occ.
E [a.u.] P [%] C [%] Hybridization
5
.01
1.46
s(PÀC1)
p(PÀC1)
1.961 À0.53
1.905 À0.20
33.5 66.5
60.7 39.3
36.4 63.6
0.579(sp )P+0.815(sp )C
0.779(p)P+0.627(p)C
4.70
2.58
s(PÀC31) 1.952 À0.47
0.603(sp )P+0.798(sp )C
0.50
LP(P)
1.930 À0.38
100
0
(sp )P
The availability of two P-localized NBOs (Figure 3a) suggests
that ligand 2 should be capable of forming up to two addition-
al P–element or P–metal bonds, as was already demonstrated
[
9,15]
by the isolation of complexes 4 and 6 (Figure 1).
To investi-
31
Figure 4. Variable temperature P NMR spectrum of [(IPr·PPh)(AgCl)] (13) in
[D ]THF, which shows Ag–P coupling at low temperatures; the singlet reso-
gate further the shape of the two phosphorus lone pairs, addi-
tional electron localization function (ELF) analysis was applied
on the calculated wave function of ligand 2, which revealed
a symmetrically distributed electron density around the phos-
phorus atom (Figure 3b, see the Supporting Information). The
resulting banana-shaped ELF isosurface, with maximum elec-
tron density in oblique directions, suggests that coordination
of Lewis acidic metal fragments can be expected to occur from
8
nances (marked with an asterisks in the bottom spectrum) at about À47
and À56 ppm are tentatively assigned to unknown impurities, possibly
[30]
n
(PPh) species.
31
ble-temperature P NMR study, and the resulting spectra that
were recorded between 26 and À1048C are shown in Figure 4.
At room temperature, a broad singlet with a full width at half
maximum (fwhm) of 23 Hz was observed, which gradually
broadened and split into two signals below about À408C. At
À948C, the spectrum shows two fully resolved doublets, as ex-
[8a]
below and/or above the C1ÀPÀC31 plane (see below).
Preparation and characterization of neutral copper(I),
silver(I), and gold(I) metal complexes
1
07
pected for the coupling of phosphorus with the Ag and
109
[29]
1
31
107
1
109
Ag nuclei, that is J( P, Ag)=327 Hz and J(P, Ag)=
Towards the preparation of both mono- and bimetallic coinage
3
77 Hz. These findings indicate that a monometallic complex
metal complexes, adduct 2 was initially treated with one
equivalent of CuCl, AgCl, or [(Me S)AuCl] in THF, which afford-
[
(IPr·PPh)AgCl] was present in solution at low temperature,
2
whereas phosphorus–silver coupling was not observed at
higher temperature, which indicates the existence of a dynamic
process that is likely to involve fast AgCl transfer via a phosphi-
nidene-bridged silver(I) species of the type [(IPr·PPh)AgCl]n.
The absence of such oligomeric or polymeric species in the
solid state has been reported for trinuclear complexes of the
ed the complexes [(IPr·PPh)MCl] (12, M=Cu; 13, M=Ag; 14,
M=Au) as pale yellow to white solids in 82, 30, and 73%
3
1
1
yields, respectively (Scheme 2). The P{ H} NMR spectra exhibit
singlets at d=À44.6, À45.6, and À16.5 ppm for the monome-
tallic copper, silver, and gold complexes, respectively, which is
comparable to the trend that has been established for com-
plexes of the type [(IMes·PPh)(MCl) ] and [(Mes P)M]BF (M=
[31]
type [{(Me N) C·PR}CuCl] (R=Ph, tBu). We proceeded to es-
tablish the molecular structure of the corresponding copper
2
2
3
2
3
4
[
15,28]
Cu, Ag, Au).
The absence of silver–phosphorus coupling in
complex 12, which showed a similarly broad signal in the
P NMR spectrum at room temperature (fwhm=32 Hz), by
the spectrum of complex 13 prompted us to perform a varia-
31
[32]
X-ray diffraction analysis of its toluene hemisolvate (Figure 5).
The copper atom exhibits a rarely observed two-coordinate PÀ
[
33]
CuÀCl environment
with structural characteristics that are
similar to those that have been established for the two termi-
[
15]
nal CuCl moieties in tetrameric [(IMes·PPh)(CuCl) ] , that is
2
4
PÀCu=2.1651(6) Š, CuÀCl=2.1138(6) Š, P-Cu-Cl=166.69(3)8.
Compared with adduct 2, copper coordination was associated
with a slightly elongated PÀC1 bond length of 1.8097(19) Š,
and the PÀC31 bond was significantly more twisted than the
imidazole plane, which afforded a large C31-P-C1-N2 torsion
angle of 47.98. The PÀCu bond was twisted in the opposite di-
rection, which resulted in a Cu-P-C1-N1 torsion angle of À34.28
and the copper atom lying 0.37 Š out of the imidazole plane.
Accordingly, the phosphorus atom resides at the apex of
a rather acute trigonal pyramid, as indicated by an angle sum
of 321.38, and this geometry is reminiscent of the structures
that have been established for “carbene–phosphenium” cat-
Scheme 2. Preparation of mono- and bimetallic carbene–phosphinidene
complexes 12–17.
+
[34]
ions [NHCÀPR2] (R=Ph).
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Figure 5. ORTEP diagram of complex 12 with thermal displacement parame-
ters drawn at the 50% probability level. Hydrogen atoms and the solvent
molecule were omitted for clarity. Selected bond lengths [Š] and angles [8]:
CuÀCl 2.1138(6), CuÀP 2.1651(6), PÀC1 1.8097(19), PÀC31 1.848(2), N1ÀC1
Figure 6. ORTEP diagram of complex 15 with thermal displacement parame-
ters drawn at the 50% probability level. For the molecular structure of iso-
typic complex 16, see the Supporting Information, Figure S1. Hydrogen
atoms were omitted for clarity. Selected bond lengths [Š] and angles [8] in
complex 15: Cu1ÀP 2.1660(7), Cu2ÀP 2.1702(8), Cu1ÀCl1 2.1117(7), Cu2ÀCl2
1
.364(2), C2ÀC3 1.346(3) Š; Cl-Cu-P 166.69(3), C1-P-C31 104.09(9), C1-P-Cu
110.39(7), C31-P-Cu 106.82(7), C1-N1-C2 110.04(16), Cu-P-C1-N1=À34.28.
2
1
.1163(7), PÀC31 1.825(3), PÀC1 1.835(3), C2ÀC3 1.355(4) Š; Cu1-P-Cu2
03.24(3), Cl1-Cu1-P 167.56(3), Cl2-Cu2-P 170.49(3), C31-P-C1 105.36(11), C31-
P-Cu1 112.25(9), C31-P-Cu2 111.74(9), C1-P-Cu1 111.47(8), C1-P-Cu2 112.99(8),
N1-C1-N2 106.3(2)8; in complex 16: Au1ÀP 2.2322(7), Au2ÀP 2.2366(8), Au1À
Cl1 2.2889(7), Au2ÀCl2 2.2962(7), PÀC31 1.824(3), PÀC1 1.843(3) Š; Au1-P-
Au2 104.39(3), P-Au1-Cl1 172.86(3), P-Au2-Cl2 171.01(3), C31-P-C1 105.19(12),
C31-P-Au1 112.33(9), C31-P-Au2 111.63(10), C1-P-Au1 111.84(9), C1-P-Au2
The presence of a stereochemically active lone pair in com-
plex 12 indicated the possibility of coordinating a second
metal atom. Accordingly, treatment of adduct 2 with two
equivalents of CuCl or (Me S)AuCl in THF at room temperature
2
111.65(9), N1-C1-N2 106.0(2)8.
furnished the bimetallic complexes [(IPr·PPh)(MCl) ] (15, M=
2
Cu; 16, M=Au) in good yield (ꢀ90%, Scheme 2). In contrast,
we were unable to isolate the corresponding disilver complex
[
36]
[37]
[
(IPr·PPh)(AgCl) ], and even the reaction of ligand 2 with
plexes, for example [Ph PNPPh ][R P(AuCl) ] (R=Cy, tBu),
3 3 2 2
2
a large excess of AgCl resulted in the formation of the mono-
which contain two AuCl moieties that are coordinated to a tet-
racoordinate phosphorus atom. The intramolecular Au1···Au2
distance in complex 16 is 3.5309(2) Š, which falls below the
sum of the van der Waals radii, but may be too long for con-
3
1
metallic complex [(IPr·PPh)(AgCl)] (13). The P chemical shifts
of complexes 15 and 16 showed opposite trends compared
with the values that were observed for the monometallic
copper and gold species 12 (d=À44.6 ppm) and 14 (d=
[
38,39]
sideration as a significant aurophilic interaction.
Intermo-
À16.5 ppm). Accordingly,
a
shift to higher field (d=
lecular, short gold–gold contacts were not observed, presuma-
bly for steric reasons.
À53.3 ppm) was observed for complex 15, whereas a low-field
shift (d=0.7 ppm) was observed for complex 16. These values
are in agreement with those that were reported for [(IMes
Another dicopper complex, [(IPr·PPh)(CuOTf) ] (17), was pre-
2
pared in 75% yield by the reaction of ligand 2 with copper(I)
31
·
PPh)(CuCl) ] (d=À54.8 ppm) and [(IMes·PPh)(AuCl)2] (d=
trifluoromethanesulfonate, Cu(OTf), in THF. The P NMR spec-
trum exhibited a broad singlet at À56.9 ppm, which is slightly
upfield from the chemical shift of complex 15 (d=À53.3 ppm).
X-ray diffraction analysis to establish the molecular structure
(Figure 7) revealed a tetrahedral coordination sphere around
the phosphorus atom, which resembles the geometry found
for complex 15 with similar CuÀP bond lengths: Cu1ÀP=
2.1793(8) Š and Cu2ÀP=2.1661(8) Š. The two copper atoms
display notably short copper–carbon contacts; for Cu1, an in-
termolecular arene–copper interaction was indicated by Cu···C
distances of 2.775 and 2.815 Š, which involve the phenyl
group that is attached to the P atom, whereas Cu2 showed
a particularly short Cu2···C11 distance of 2.726 Š, which in-
volves the ipso-carbon atom of one Dipp substituent (see the
2
[
15]
À4.0 ppm), in which the large discrepancy of the chemical
shifts was ascribed to the particular strength of the AuÀP
[
35]
bond.
Single crystals of complexes 15 and 16 were isolated from
n-hexane/CH Cl solutions for analysis by X-ray diffraction. The
2
2
two compounds are isotypic and crystallize in the monoclinic
space group Cc; the molecular structure of complex 15 is pre-
[
15]
sented in Figure 6. Unlike tetrameric [(IMes·PPh)(CuCl) ] , the
2
4
solid state structure of complex 15 consists of discrete mono-
meric [(IPr·PPh)(CuCl) ] complexes, in which the phosphorus
2
atom resides in a slightly distorted tetrahedral environment.
Coordination of a second CuCl moiety afforded a longer PÀC1
bond than in complex 12 (1.835(3) Š vs. 1.8097(19) Š), whereas
almost identical CuÀP and CuÀCl bond lengths (av. 2.168 Š
and 2.114 Š, respectively) were found within the almost linear
PÀCuÀCl units. The overall geometry in the isotypic digold
complex 16 is very similar; it contains AuÀP and AuÀCl bond
lengths (av. 2.234 Š and 2.293 Š, respectively) that are in excel-
lent agreement with those that have been established for
[
40]
Supporting Information, Figure S4 for a packing diagram).
The latter contact, albeit significantly elongated (3.013 Š), was
also found in the corresponding CuCl complex 12, and the
presence of shorter contacts in complex 15 can be ascribed to
the higher electronegativity of the OTf counterion, which en-
hances the electrophilicity and Lewis acid character of the cop-
[15–17]
[41]
complexes 6, 7, and 8 (Figure 1)
as well as other com-
per(I) ion.
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Scheme 3. Preparation of cationic copper(I) and gold(I) complexes 18–21
(THT=tetrahydrothiophene).
Figure 7. ORTEP view of complex 17 with thermal displacement parameters
drawn at the 50% probability level. Hydrogen atoms are omitted for clarity.
Selected bond lengths [Š] and angles [8]: Cu1ÀP 2.1793(8), Cu2ÀP 2.1661(8),
Cu1ÀO3 1.920(2), Cu2ÀO4 1.916(2), PÀC1 1.832(3), PÀC31 1.834(3) Š; Cu2-P-
Cu1 112.22(3), O3-Cu1-P 166.37(8), O4-Cu2-P 164.57(7), C1-P-C31 106.04(11),
C1-P-Cu1 105.11(9), C1-P-Cu2 104.40(8), C31-P-Cu1 116.70(9), C31-P-Cu2
111.21(9), N1-C1-N2 106.1(2)8.
Preparation and characterization of cationic copper(I) and
gold(I) complexes
[
42]
[43]
[44]
Dinuclear
or dual gold catalysis
(“Gold Catalysis 2.0”)
has recently added a new facet to the ever expanding field of
[45]
homogeneous gold catalysis, and several cationic gem-diau-
rated species have been isolated in the context of dual-activa-
Figure 8. ORTEP diagram of the dicationic moiety in 18 with thermal dis-
[
46]
placement parameters drawn at the 50% probability level. Hydrogen atoms
tion studies. As the phosphorus-bridged copper and gold
complexes 15 and 16 represent related geminally dicuprated
or diaurated species, respectively, we aimed to convert them
into cationic and potentially catalytically active complexes by
chloride abstraction. Treatment of complex 15 with one equiv-
alent of sodium tetrakis[(3,5-trifluoromethyl)phenyl]borate,
F
and counter anions (BAr ) are omitted for clarity. Selected bond lengths [Š]
and angles [8]: Cu1ÀCu2’ 2.6381(6), Cu1ÀP 2.1847(8), Cu2ÀP 2.1918(8), Cu1À
Cl 2.1678(7), Cu2ÀCl 2.1792(7), P1ÀC1 1.831(3), PÀC31 1.837(3) Š; Cu1-Cl-Cu2
74.73(3), C1-P-C31 105.98(12), C1-P-Cu1 106.49(9), C1-P-Cu2 105.09(9), C31-P-
Cu1 103.17(9), C31-P-Cu2 103.66(9), Cu1-P-Cu2 130.40(4), N1-C1-N2 105.9(2)8.
F
Na(BAr ), in dichloromethane at room temperature afforded
F
10
10
the tetranuclear complex [(IPr·PPh) Cu Cl ][BAr ] (18) as
can therefore be considered as a closed-shell d –d cuprophil-
2
4
2
2
31
[48,49]
a white solid in moderate yield (39%, Scheme 3). The P NMR
ic interaction.
In contrast, the phosphorus-bridged
[
32]
spectra revealed dynamic behavior on the NMR time scale,
Cu1···Cu2 distance of 3.9729 (5) Š revealed the absence of such
an interaction along this copper–copper axis.
and we observed a broad signal at À65.4 ppm, which is up-
F
field from the chemical shift that we had observed for complex
The tetranuclear gold complex [(IPr·PPh) Au Cl ][BAr ] (19)
2
4
2
2
1
5 (d=À53.3 ppm). The compound crystallized as a CH Cl sol-
was obtained from the reaction of [(IPr·PPh)(AuCl) ] (16) with
Na(BAr ), whereas treatment with Ag(SbF6) gave the
2
2
2
F
vate in the triclinic space group P 1¯ , and the asymmetric unit
+
F
consisted of a dinculear [(IPr·PPh)Cu Cl)] moiety, a BAr ion,
hexafluoroantimonate [(IPr·PPh) Au Cl ][SbF ] (20) (Scheme 3).
2
2
4
2
6 2
and one solvent molecule. Thus, complex 18 contained centro-
symmetric dications, in which the four copper atoms and the
geminally bridging phosphorus and chlorine atoms form an
eight-membered ring (Figure 8). Accordingly, the four Cu and
the two m-Cl atoms are coplanar, with the P atoms lying 0.60 Š
above and below this plane. The CuÀP bond lengths (Cu1ÀP=
Both complexes were isolated as white solids in good yield
31
(ꢀ80%). Their P NMR spectra exhibited signals at À27.0 (19)
and À28.2 ppm (20), which are significantly higher field than
the signal that we observed for complex 16 (d=0.7 ppm). The
crystal structures of both compounds were established by X-
ray diffraction analysis; complexes 19 and 20 crystallized as
a CH Cl hexasolvate in the monoclinic space group P2 /c and
2
.1847(8) Š, Cu2ÀP=2.1918(8) Š) are slightly longer than those
2
2
1
of the dicopper complex 15, whereas a significantly larger
Cu1-P-Cu2 bond angle was observed (130.40(4)8 vs. 103.24(3)8
in 15). An acute Cu1-Cl-Cu2 bond angle of 74.73(3)8 was
found, which afforded a Cu···Cu distance of 2.6381(6) Š, which
a CH Cl2 tetrasolvate in P2 /n, respectively. Similar to the
2 1
copper congener 18, the asymmetric units of both structures
contained one half of a centrosymmetric dication [(IPr·P-
2
+
Ph) Au Cl ] with similar structural parameters. Therefore, the
2
4
2
[
47]
is shorter than the sum of the van der Waals radii (1.4 Š) and
structural discussion is restricted to the cationic moiety in com-
Chem. Eur. J. 2015, 21, 16178 – 16189
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ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

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Figure 9. ORTEP diagram of the dicationic moiety in complex 20 with ther-
mal displacement parameters drawn at the 50% probability level. Hydrogen
atoms and counter anions (SbF ) are omitted for clarity. Selected bond
6
lengths [Š] and angles [8]: Au1ÀP 2.2397(10), Au1ÀCl 2.3487(9), Au1ÀAu2’
3
1
.0245(2), Au2ÀP 2.2471(10), Au2ÀCl 2.3503(9), PÀC31 1.811(4), PÀC1
.840(4) Š; Au1-P-Au2 109.32(4), P-Au1-Cl 173.83(3), C31-P-C1 107.67(17),
Figure 10. ORTEP view of dicationic moiety in complex 21 with thermal dis-
placement parameters drawn at the 50% probability level. Hydrogen atoms
C31-P-Au1 111.76(13), C1-P-Au1 109.05(12), N1-C1-N2 106.6(3)8.
6
and counter anions (SbF ) are omitted for clarity. Selected bond lengths [Š]
and angles [8]: Au1ÀAu2, 3.510, Au1ÀP 2.2681(7), Au2ÀP 2.2200(8), Au2AÀP
2.3529(9), Au1ÀS1 2.3350(8), Au2ÀS2 2.3313(16), Au2AÀS2A 2.341(2), PÀC31
1.813(3), PÀC1 1.835(3) Š; Au2-P-Au1 102.88(3), P-Au1-S1 170.23(3), P-Au2-S2
plex 20 (Figure 9, see the Supporting Information, Figure S6
for the structure of 19). Unlike the chair conformation found in
complex 18 (Figure 8), the eight-membered (Au1ÀPÀAu2ÀCl)2
ring in complex 20 was virtually planar, and the phosphorus
atoms were displaced by just 0.10 Š from the Au Cl plane.
1
73.30(6), C31-P-C1 106.25(14), C31-P-Au1 114.71(11), C31-P-Au2 104.38(12),
C1-P-Au1 110.60(9), C1-P-Au2 118.23(10), N1-C1-N2 106.2(2)8.
4
2
The rectangle that was formed by the four gold atoms con-
tained short chlorine- and long phosphorus-bridged Au···Au
edges, 3.0245(2) Š and 3.6600(2) Š, respectively, which indi-
cates that only the former should be regarded as a definite au-
Cationic phosphinidene–gold complexes as single-source
catalysts
With the cationic phosphinidene–gold complexes in hand, we
[
38]
rophilic interaction. It should be noted that complex 19 ex-
hibited an even shorter Au···Au distance of 2.9517(4) Š (see the
Supporting Information). We are unaware of similar structural
motifs, and related di[gold(I)]halonium cations usually feature
longer Au···Au distances between the halide-bridged gold
chose to study the catalytic performance of [(IPr·PPh) Au Cl ]
2
4
2
F
[BAr ] (19) and [(IPr·PPh){Au(THT)} ][SbF ] (21). Initially, the cy-
2
2
6 2
cloisomerization of the 1,6-enynes 22 (R=H) and 24 (R=Me)
was investigated, which should afford five- or six-membered
1,3-dienes as the result of exo- or endo-cyclic skeletal rear-
[
50]
[54]
atoms. These species might dimerize and self-assemble to
rangements, respectively (Table 2). The reactions were car-
give tetrameric structures, such as {[(Ph P)Au] (m-Cl)} [SbF ] ,
ried out in polar solvents (dichloromethane or 1,2-dichloro-
ethane) at room temperature with 1 mol% catalyst loading,
which corresponded to 4 and 2 mol% Au concentration for
catalysts 19 and 21, respectively. With the tetragold catalyst
19, full conversion of both enynes 22 and 24 into mixtures of
vinylcyclopentenes 23a/25a and methylenecyclohexenes 23b/
25b was achieved within one hour. Similar to previously stud-
ied catalysts, enyne 22 was predominantly converted into
the six-membered ring diene (23a/23b=1:4, entry 1), whereas
the formation of the five-membered ring diene was favored for
the enyne substrate 24 (25a/25b=3:1, entry 2). Catalyst 21
displayed similar chemoselectivity; however, complete conver-
sion was only accomplished with substrate 24 (entries 3 and
4).
3
2
2
6 2
which displays comparatively long Au···Au distances of
+
ꢀ
3.66 Š within the monomeric cation {[(Ph P)Au] (m-Cl)} , but
3 2
short unsupported Au···Au distances of ꢀ3.07 Š between the
monomeric units. Likewise, several short Au···Au distances
were also found in a decanuclear gold(I) cluster, which con-
[
51]
[
52]
tained the acyclic carbene–phosphinidene (Me N) C·PtBu.
2
2
[
54]
The abstraction of both chlorine atoms from complex 16
was achieved by treatment with two equivalents of Ag(SbF ) in
6
the presence of an excess of tetrahydrothiophene (THT), which
furnished [(IPr·PPh){Au(THT)} ][SbF ] (21) as a white crystalline
2
6 2
3
1
solid in 78% yield. The P NMR spectrum exhibited a sharp
signal at À6.2 ppm, which is slightly upfield from the chemical
shift that we observed for complex 16. The formation of a di-
cationic complex was confirmed by X-ray diffraction analysis
Additionally, we employed complexes 19 and 21 as catalysts
[
55]
(
Figure 10), and the structural parameters around the phos-
for carbene-transfer reactions from ethyl diazoacetate (EDA),
phorus atoms were similar to those of the chloro gold precur-
sor 16. One of the (THT)Au moieties was disordered over two
positions, so that the molecular dimensions should be inter-
preted with caution; however, AuÀS bond lengths of ꢀ2.33 Š
could be established, which fall within the range of bond
lengths that have been observed for other gold(I) THT com-
which is particularly well studied for NHC–Au complexes in the
activation and functionalization of OÀH bonds and aromatic
[
56]
and aliphatic CÀH bonds by insertion of the DCHCOOEt unit.
By using methanol as the substrate, we observed a clean and
rapid conversion (>90%) into ethyl 2-methoxyacetate at room
temperature with both catalysts (Table 3, entries 1 and 2). The
corresponding conversion versus time diagrams with catalyst
loadings of 1 mol%, that is 4 and 2 mol% Au concentration for
catalysts 19 and 21, respectively, are shown in Figure 11, and
[
53]
plexes.
Chem. Eur. J. 2015, 21, 16178 – 16189
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ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
+
into a monocationic gold species of the type [(IPr·PPh)Au Cl]
[
a]
2
Table 2. Cycloisomerization of the enynes 22 and 24.
with one “active” gold cation; we propose that both gold ions
in complex 21 may mediate carbene transfer via a catalytically
2
+
active dication [(IPr·PPh)Au2] . Similarly, carbene insertion into
the OÀH bond of ethanol was accomplished with catalyst 21
to give 96% yield of the isolated product (entry 3). It should
be noted that the formation of diethyl fumarates or maleates
was not observed, which might have formed as side products
by carbene dimerization.
[b]
Entry
Substrate
Cat.
Au [mol%]
t [min]
Yield [%] (a/b)
[
56]
As demonstrated for NHC–gold complexes, the functional-
ization of aromatic CÀH bonds was accompanied by cyclo-
propanation; hence, mixtures of ethyl 2-phenylacetate
1
2
3
4
22
24
22
24
19
19
21
21
4
4
2
2
60
60
420
90
>99 (1:4)
>99 (3:1)
68 (1:10)
[c]
>99 (3:1)
(
PhCH COOEt) and ethyl cyclohepta-2,4,6-trienecarboxylate
2
[
a] Conditions: room temperature in CH
2
Cl
2
(entries 1 and 2) or
(C H CO Et) in a ꢀ2:1 ratio were isolated with catalysts 19 and
7
6
2
CH ClCH Cl (entries 3 and 4). [b] Combined yield of isolated products,
2
2
2
1 (entries 4 and 5). However, for catalyst 21, a higher reaction
1
product ratios were determined by H NMR spectroscopy (see the Sup-
porting Information). [c] Full conversion was not achieved; the product
mixture contained 22, 23a, and 23b in ꢀ5:1:10 ratio.
temperature (658C) was required to achieve full EDA conver-
sion.
Conclusion
[a]
Table 3. Carbene transfer reactions with ethyl diazoacetate (EDA).
The carbene–phosphinidene adduct IPr·PPh (2) forms
mono- and bimetallic coinage metal complexes of
[
b]
Entry
Subst.
Product
Cat.
Au
mol%]
T
Yield
the type [(IPr·PPh)MCl] (M=Cu, Ag, Au) and
(IPr·PPh)(MCl) ] (M=Cu, Au). It seems that the steric
[
[min]
[%] (ratio)
[
2
1
2
3
4
5
MeOH
MeOH
EtOH
MeOCH
MeOCH
2
COOEt
COOEt
19
21
21
19
21
4
2
2
4
2
40
15
45
60
45
93
90
96
bulk provided by the IPr moiety prevents the forma-
2
EtOCH
2
COOEt
tion of oligomeric species through MÀPÀM or MÀClÀ
C
C
6
H
H
6
PhCH
PhCH
2
COOEt/C
COOEt/C
7
7
H
H
6
CO
CO
2
Et
Et
95 (2:1)
97 (5:3)
M bridges. Chlorine abstraction from [(IPr·PPh)-
6
6
2
6
2
(
MCl)2] afforded unusual tetranuclear complexes
F
[
a] Conditions: room temperature, except for entry 5 (T=658C). [b] Yield of isolated
product(s), product ratios were determined by H NMR spectroscopy (see the Support-
ing Information).
[(IPr·PPh) M Cl ]X (X=BAr , SbF6), which feature
2 4 2 2
1
almost planar eight-membered (MÀClÀMÀP)2 rings
with short Cu···Cu and Au···Au distances along the
chlorine-bridged metal–metal axes. These cuprophilic
and aurophilic interactions might be responsible for
the high stability of these complexes towards air and moisture,
which allows the corresponding digold complex to be used
as a robust single-source catalyst. Complete chloride abstrac-
tion to afford the tetrahydrothiophene complex [(IPr·PPh)-
{
Au(THT)} ][SbF ] was also achieved, which exhibits a slightly
2 6 2
inferior catalytic performance. To the best of our knowledge,
this is the first study that uses N-heterocyclic phosphinidene
adducts as ancillary ligands in homogeneous catalysis, and
their suitability has been demonstrated, but the catalytic activi-
ties reported herein not go beyond those of previously studied
systems. The role and the interplay of the two gold atoms in
the catalytically active species are yet to be investigated.
Experimental Section
Figure 11. Conversion versus time diagram for the reaction of ethyl diazo-
acetate (EDA) in neat methanol at room temperature with the catalysts 19
Materials and methods
(
*) and 21 (!); conversion was followed by gas chromatography with n-
All the manipulations were performed under a dry argon atmos-
phere by using standard Schlenk techniques and dry argon-filled
glove boxes. Solvents used were dried by using the MBraun sol-
vent purification system. The starting materials, carbene–phosphin-
decane as internal standard.
they reveal an almost identical catalytic performance. This
comparison indicates that the tetragold complex 19 is not sup-
plying a more catalytically active gold species than the digold
complex 21. In solution, we expect that catalyst 19 dissociates
[5]
[57]
[58]
dene adduct (2), [(Me S)AuCl], and enynes 22 and 24, were
2
1
13
prepared according to previously published procedures. H, C,
and P NMR spectra were measured on Bruker DPX200 (200 MHz),
Bruker AV 300 (300 MHz), and Bruker DRX400 (400 MHz) spectrome-
31
Chem. Eur. J. 2015, 21, 16178 – 16189
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16184
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
+
ters. The chemical shifts are given in parts per million (d; ppm) rel-
ative to residual solvent peaks (d=7.15 (C D ), 5.34 (CD Cl ), 7.24
[D ]THF): d=À44.62 ppm (s); MS (EI): m/z (%): 594 ([M] , <1), 496
8
+
+
+
([MÀCuCl] , 9), 453 ([MÀCuClÀiPr] , 64), 387 ([MÀCuClÀPPhÀH] ,
6
6
2
2
(
CDCl ), 3.58 ([D ]THF) ppm). Coupling constants (J) are reported in
100); elemental analysis calcd (%) for C H N PClCu (595.67): C
3
8
33 41
2
Hertz (Hz), and splitting patterns are indicated as s (singlet), d
doublet), t (triplet), m (multiplet), sept (septet) and br (broad). All
66.54, H 6.94, N 4.70; found: C 66.84, H 6.82, N 4.39.
(
Synthesis of [(IPr·PPh)(AgCl)] (13)
the spectra were measured at room temperature unless otherwise
stated. IR spectra were recorded on a PerkinElmer Spectrum 100
FT-IR as neat samples. Mass spectra were recorded on Finnigan
MAT95 (EI) and Finnigan MAT95XL (ESI) systems. Elemental analy-
ses were carried out on a Vario Micro Cube System.
Carbene–phosphinidene adduct 2 (0.050 g, 0.100 mmol) dissolved
in THF (3 mL) was added to a stirred suspension of silver chloride
(
0.015 g, 0.100 mmol) in THF (3 mL), and the resulting mixture was
stirred overnight at room temperature. All volatile components
were removed under vacuum, and the residue was washed with n-
hexane (3”1 mL) and extracted with THF (2 mL). Subsequent re-
moval of the solvent under vacuum gave the light sensitive com-
plex 13 (30%, based on 2) as a pale yellow solid. (Note: this reac-
X-ray structure determination
Crystallographic data are given in the Supporting Information, Ta-
bles S1, S2, and S3. Suitable single crystals were mounted on glass
fibres in perfluorinated inert oil. Intensity measurements were per-
formed at 100 K by using Oxford Diffraction diffractometers with
monochromated MoKa or mirror-focussed CuKa radiation. Absorp-
tion corrections were based on multi-scans. The structures were re-
1
tion was performed under exclusion of light). H NMR (400 MHz,
3
[
D ]THF): d=7.63 (s, 2H, HC N ), 7.44 (t, 2H, JH,H =7.8 Hz, p-
8
2
2
3
CH(Dipp)), 7.24 (d, 4H, JH,H =7.8 Hz, m-CH(Dipp)), 7.12–7.08 (m,
H, m-CH(Ph)), 6.95–6.91 (m, 1H, p-CH(Ph)), 6.82–6.78 (m, 2H, o-
CH(Ph)), 2.63 (sept, 4H, J =6.9 Hz, CH(CH ) ), 1.34 (d, 12H, J =
H,H
.9 Hz, CH(CH3)2), 1.13 ppm (d, 12H, JH,H =6.9 Hz, CH(CH3)2);
C{ H} NMR (75 MHz, [D ]THF): d=165.7 (d, J =82 Hz, PCcarbene),
46.2 (o-C(Dipp)), 140.2 (d, J =18.3 Hz, o-C(Ph)), 134.1 (NC(Dipp)),
33.4 (d, JP,C =17.2 Hz, PC ), 132.1 (p-C(Dipp)), 128.2 (m-C(Ph)),
28.1 (p-C(Ph)), 125.9 (C N ), 125.7 (m-C(Dipp)), 30.0 (CH(CH ) ), 25.6
CH(CH ) ), 23.2 ppm (CH(CH ) ); P{ H} NMR (161 MHz, [D ]THF,
2
3
3
2
[59]
fined anisotropically on F by using the program SHELXL-97. Hy-
drogen atoms were included by using a riding model or rigid
methyl groups. Exceptions and special features: The toluene mole-
cule of structure 12 was disordered over an inversion centre. Sev-
H,H
3 2
3
6
1
3
1
1
8
P,C
2
1
1
1
(
2
P,C
1
eral CF groups of structures 18 and 19 were rotationally disor-
ph
3
dered; appropriate restraints were employed to improve the stabil-
ity of refinement. In complex 19, one of the three independent di-
chloromethane molecules was severely disordered and had to be
2
2
3 2
31
1
3 2
3 2
1
8
31
68C): d=À46.4 ppm (s); P{ H} NMR (161 MHz, [D ]THF, À1048C):
8
1
107
31
1
109
31
[60]
d=À52.5 ppm (dd, J( Ag, P)=327 Hz, J( Ag, P)=377 Hz); el-
omitted by using SQUEEZE. Disorder was also observed for struc-
ture 20, in which Au2 and its THT ligand were disordered over two
positions. Although the refinement apparently proceeded well, the
AuÀP bond lengths were significantly different for the two Au2
sites. We are confident that the qualitative picture is correct, but
great caution is advisable when interpreting the dimensions of
these disordered groups.
emental analysis calcd (%) for C H N PClAg (640.00): C 61.93, H
33 41
2
6
.46, N 4.38; found: C 60.57, H 6.50, N 4.22. Note: The reaction
with two equivalents of AgCl also gave the complex 13, which was
isolated in 65% yield.
Synthesis of [(IPr·PPh)(AuCl)] (14)
Carbene–phosphinidene adduct 2 (0.07 g, 0.141 mmol) in THF
CCDC 1405071 (2), 1405078 (12), 1405073 (15), 1405072 (16),
(4 mL) was added to a stirred suspension of (Me S)AuCl (0.041 g,
2
1
1
405079 (17),
1405074 (18·2CH Cl ),
1405077 (19·6CH Cl ),
0.139 mmol) in THF (3 mL) at room temperature, And the resulting
clear mixture was stirred overnight. All volatiles were removed
under vacuum and, the residue was washed with n-hexane (5”
3 mL) and dried under vacuum to afford 14 (0.075 g, 73%, based
2
2
2
2
405075 (20·4CH Cl ), and 1405076 (21) contain the supplementary
2
2
crystallographic data for this paper. These data are provided free
of charge by The Cambridge Crystallographic Data Centre.
1
on 2) as a white solid. H NMR (300 MHz, C D ): d=7.31–7.22 (m,
6
6
Gas chromatography
3
4
H, CH(Ar)), 6.99 (d, 4H, J =7.4 Hz, CH(Ar)), 6.77–6.62 (m, 3H,
CH(Ar)), 6.34 (s, HC N ), 2.61 (sept, 4H, J =6.9 Hz, CH(CH ) ), 1.34
d, 12H, JH,H =6.7 Hz, CH(CH ) ), 0.91 ppm (d, 12H, JH,H =6.9 Hz,
H,H
GC analyses were performed on a SHIMADZU GC-2010 device. The
temperature program started at 408C and, after holding it for
2
then held for 5 min (split temperature: 2008C and FID tempera-
ture: 3108C).
3
2
2
H,H
3 2
3
3
(
À1
3 2
min, the temperature was raised by 158Cmin to 3008C, and
31
CH(CH ) );
P NMR (C D
6,
121 MHz): d=À16.64 ppm (s);
3
2
6
13
1
2
C{ H} NMR (75 MHz, C D ): d=147 (NC(Dipp)), 139.7 (d, JP,C
=
6
6
5
2
1 Hz), 137.7, 133.4, 132.0, 128.5, 125.3, 29.8 (d, JP,C =2.2 Hz,
Synthesis of [(IPr·PPh)(CuCl)] (12)
CH(CH) ), 25.9 (CH(CH ) ), 23.1 ppm (CH(CH ) ); MS (EI): m/z (%):
3
+
3 2
3 2
+
+
7
28([M] , <1), 712 ([MÀCH ] , 5), 685 ([MÀiPr] , 5), 496
Compound 2 (0.095 g, 0.191 mmol) in THF (3 mL) was added to
a stirred suspension of copper(I) chloride (0.019 g, 0.191 mmol) in
THF (3 mL) at room temperature. After its complete addition, con-
sumption of copper(I) chloride was observed as the suspension
turned clear pale yellow. The resulting mixture was stirred over-
night at ambient temperature, and then all volatiles were removed
in vacuo. The residue was washed with n-hexane (2”3 mL) and
3
+
+
(
[MÀAuCl] , 11), 453 ([MÀAuClÀiPr] , 100); elemental analysis
calcd (%) for C H N PClAu (728.24): C 54.36, H 5.67, N 3.84;
33 41
2
found: C 55.15, H 5.66, N 3.70.Synthesis of [(IPr·PPh)(CuCl) ] (15)
2
Carbene–phosphinidene adduct 2 (0.154 g, 0.310 mmol) in THF
(8 mL) was added slowly to a stirred suspension of two equivalents
of copper(I) chloride (0.061 g, 0.620 mmol) in THF (7 mL). The re-
sulting mixture was stirred overnight at room temperature, during
which a white precipitate formed. The product was fully precipitat-
ed by the addition of n-hexane (20 mL); the solids were isolated by
filtration and quickly washed with cold THF (2 mL). The residue
was extracted with CH Cl , and the solvent removed under
dried in vacuo to give analytically pure complex 12 (0.097 g, 82%
1
based on 2) as a pale yellow solid. H NMR (300 MHz, [D ]THF): d=
8
3
7
4
.55 (s, 2H, HC N ), 7.44 (t, 2H, J =7.6 Hz, p-CH(Dipp)), 7.24 (d,
2
2
H,H
3
H, J =7.4 Hz, m-CH(Dipp)), 7.08 (m, 2H, o-CH(Ph)), 6.92 (m, 1H,
H,H
3
p-CH(Ph)), 6.78 (m, 2H, m-CH(Ph)), 2.65 (sept, 4H, JH,H =6.7 Hz,
2
2
3
CH(CH ) ), 1.32 (d, 12H, J =6.8 Hz, CH(CH ) ), 1.13 ppm (d, 12H,
vacuum to afford complex 5 (87%, based on 2) as a pale yellow
3
2
H,H
13
3 2
3
1
1
3
JH,H =6.9 Hz, CH(CH ) ); C{ H} NMR (75 MHz, [D ]THF): d=146.3
solid. H NMR (300 MHz, CD Cl ): d=7.53 (t, 2H, JH,H =7.8 Hz, p-
2 2
3 2
8
3
4
3
(
1
1
NC(Dipp)), 140.7 (d, JP,C =17.4 Hz, C N ), 134.3 (o-C(Dipp)), 132.
(C(Ar)), 128.2 (d, JP,C =7.8 Hz, o-C(Ph)), 128.1 (C(Ar)), 125.8 (C(Ar)),
CH(Dipp)), 7.29 (d, 2H, JP,H =0.73 Hz, HC N ), 7.25 (d, 2H, JH,H =
2 2
2
2
2
7.9 Hz, m-CH(Dipp)), 7.12–7.03 (m, 3H, CH(Ph)), 6.92–6.86 (m, 2H,
4
3
25.6 (C(Ar)), 125.0 (C(Ar)), 30.1(d, JP,C =2.10 Hz, CH(CH ) ), 25.6
CH(Ph)), 2.48 (sept, 4H, J =6.8 Hz, CH(CH ) ), 1.27 (d, 12H, 12H,
3 2
H,H
3 2
3
5
31
3
(
CH(CH ) ), 23.2 ppm (d, J =2.5 Hz, CH(CH3)2); P NMR (121 MHz,
JH,H =6.9 Hz, CH(CH ) ), 1.05 ppm (d, 12H, J =6.7 Hz, CH(CH3)2);
3 2 H,H
3
2
P,C
Chem. Eur. J. 2015, 21, 16178 – 16189
www.chemeurj.org
16185
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
1
3
1
1
C{ H} NMR (75 MHz, CD Cl ): d=154.5 (d, JP,C =24 Hz, PCcarbene),
The resulting cloudy reaction mixture was stirred at room tempera-
ture for 15 h and filtered through a pad of Celite; the solvent was
removed under vacuum. The solid residue was washed with tolu-
2
2
1
1
1
1
3
45.5 (NC(Dipp)), 140.1 (d, J =16 Hz, PC(Ph)), 132.8 (o-C(Dipp)),
P,C
32.7 (m-C(Dipp)), 130.0 (d, JP,C =2 Hz, C N ), 128.7 (d, JP,C
0.2 Hz, o-C(Ph)), 126.7 (m-C(Ph)), 126.5 (p-C(Ph), 125.9 (p-C(Dipp)),
0.0 (CH(CH )), 26.0 (CH(CH ) ), 23.5 ppm (CH(CH ) ; P{ H} NMR
1
3
=
2
2
ene followed by n-hexane and dried under vacuum to afford 18
3
1
1
1
(0.103 g, 39%) as a pale yellow solid. H NMR (300 MHz, [D ]THF):
3
3 2
3 2
8
F
(
121 MHz, CD Cl ): d=À53.2 ppm. IR (neat): n˜ =2691 (w), 2925 (w),
d=8.08 (s, 2H, HC N ), 7.80–7.78 (br, 8H, H(BAr ) and 1H, H(Ph)),
7.58 (m, 6H, H(Ar)), 7.37–7.34 (m, 4H, H(BAr )), 6.83–6.78 (m, 4H,
H(Ph)), 2.43 (bsept, 4H, JH,H =6.7 Hz, CH(CH ) ), 1.19 (d, 12H, J
2
2
2
2
F
2
1
7
867 (vw), 1555 (s), 1461 (s), 1437 (s), 1386 (s), 1365 (w), 1324 (w),
257 (w), 1207 (w), 1181 (w), 1124 (w), 1060 (w), 935 (w), 798 (vs),
44 (vs), 697 cm
=
H,H
3 2
À1
(vs); elemental analysis calcd (%) for
6.3 Hz, CH(CH ) ), 1.09 ppm (d, 12H, J =6.5 Hz, CH(CH ) );
3
2
H,H
3 2
F
1
13
C H N PCl Cu · = CH Cl (722.98): C 55.38, H 5.81, N 3.87; found: C
5
C NMR (100 MHz, CD Cl ): d=162.4 (q, J =50.3 Hz, C(BAr )),
145.2 (s, NC(Dipp)), 138.7 (C(Ph)), 135.4 (m, C(BAr )), 134.0 (C N ),
3
3
41
2
2
2
3
2
2
2
2
B,C
F
5.29, H 5.80, N 3.51.
2
2
1
3
31.3 (o-C(Dipp)), 129.5 (m-C(Dipp)), 129.4 (qq, J =31.4 Hz, JB,C
.1 Hz, C(BAr )), 129.2 (p-C(Dipp),127.8 (C(Ph)), 126.9 (C(Ph)), 125.8
=
C,F
Synthesis of [(IPr·PPh)(AuCl)2] (16)
F
Carbene–phosphinidene adduct 2 (0.255 g, 0.514 mmol) in THF
(C(Ph)), 125.2 (q, J =272 Hz, CF (BArF)), 118.0 (sept, J =4.5 Hz,
C,F 3 F, C
(
(
8 mL) was slowly added to a stirred suspension of [(Me S)AuCl]
0.303 g, 1.03 mmol) in THF (7 mL). After its complete addition the
F
2
C(BAr )), 30.3 (CH(CH ) ), 25.8 (CH(CH ) ), 23.5 ppm (CH(CH ) );
3
2
3 2
3 2
31
11
P NMR (121 MHz, [D ]THF): d=À65.4 ppm; B NMR (96 MHz,
8
suspension became clear, and a white precipitate was observed
after 20 min. The reaction mixture was stirred overnight at room
temperature. The product was fully precipitated by the addition of
n-pentane (20 mL). The solids were isolated by filtration and quick-
ly washed with cold THF (3 mL) followed by n-hexane (4”3 mL)
19
[
D ]THF): d=À5.98 ppm;
F NMR (188 MHz, CD Cl ): d=
2 2
8
À62.68 ppm (s, CF ); elemental analysis calcd (%) for
3
C
H B Cl Cu F N P (3044.88): C 51.28, H 3.51, N 1.84; found: C
30 106 2 2 4 48 4 2
1
5
1.66, H 3.60, N 1.88.
F
Synthesis of [(IPr·PPh) Au Cl ][BAr ] (19)
2
4
2
2
and dried in vacuo to afford complex 16 (0.440 g, 89%, with re-
F
1
The solid Na(BAr ) (0.138 g, 0.156 mmol) was added to a stirred so-
lution of [IPr·PPh(AuCl) ] (0.150 g, 0.156 mmol) in CH Cl (20 mL).
spect to 2) as a white solid. m.p. 2188C; H NMR (300 MHz, CDCl ):
3
3
d=7.58 (t, 2H, JH,H =7.6 Hz, p-CH(Dipp)), 7.41–7.37 (m, 1H, o-
2
2
2
4
The resulting reaction mixture was stirred for 3 h at room tempera-
ture and filtered over a pad of Celite; the solvent was then re-
moved under reduced pressure. The residue was washed with tolu-
ene (10 mL”2), n-hexane (5”3 mL) and dried under vacuum, and
colorless crystals of complex 19 (0.220 g, 81%) were grown by the
CH(Ph)), 7.36 (d, 2H, JP,H =1 Hz, HC N ), 7.36–7.32 (m, 1H, o-
2
2
3
CH(Ph)), 7.27 (d, 4H, JH,H =7.8 Hz, m-CH(Dipp)), 7.22–7.15 (m, 1H,
3
p-CH(Ph)), 7.00–6.94 (m, 2H, m-CH(Ph)), 2.58 (sept, 4H, JH,H
=
3
6
(
1
(
.8 Hz, CH(CH ) ), 1.41 (d, 12H, JH,H =6.6 Hz, CH(CH ) ), 1.12 ppm
3 2 3 2
3
13
1
d, 12H, J =6.7 Hz, CH(CH ) ); C{ H} NMR (75 MHz, CDCl ): d=
H,H 3 2 3
1
3
cooling (À308C) of CH Cl solution layered with n-hexane. H NMR
45.3 (C(Ar)), 138.6 (d, JP,C =17.5 Hz, C N ), 132.8 (C(Ar)), 132.4
C(Ar)), 131.0 (d, J =2.4 Hz, PPh), 128.4 (C(Ar)), 128.2 (C(Ar)),127.0
2
2
2
2
4
(
200 MHz, CD Cl ): d=7.74–7.42 (br, 33H, CH(Ar)), 7.21–6.98 (br,
2 2
P,C
1
1
7H, CH(Ar)), 2.23 (sept, 8H, CH(CH ) ), 1.12 (d, 24H, CH(CH ) ),
3 2 3 2
(
2
C(Ar)), 126.3 (C(Ar)), 125.4 (C(Ar)), 29.9 (CH(CH ) ), 26.2 (CH(CH ) ),
3
2
3 2
13
3
1
.03 ppm (d, 24H, CH(CH3)2); C NMR (75 MHz, CD Cl ): d=162.2
3.4 ppm (CH(CH ) ); P NMR (121 MHz, CDCl ): d=0.73 ppm; IR
2
2
3
2
3
(
q, JB,C =49.3 Hz, BC), 145.5 (NC(Dipp)), 138.2 (d, J =18 HZ, C(Ph)),
(
(
(
6
7
9
1
4
neat): n˜ =3083 (w), 2960 (w), 2925 (w), 2902 (w), 1587 (w), 1456
s), 1434 (s), 1386 (w), 1366 (w), 1324 (w), 1259 (w), 1213 (w), 1180
w), 1094 (s), 1060 (w), 820 (s), 797 (vs), 750 (vs), 702 (s), 691 (s),
P,C
F
1
1
1
35.3 (m, C(BAr )), 133.9 (C N ), 131.8 (o-C(Dipp), 130.0 (m-C(Dipp),
2
2
F
29.8 ((p-C(Dipp), 129.4 (qq, JC,F =31.1 Hz, JB,C =3.0 Hz, C(BAr )),
À1
+
28.8 (C(Ph)), 128.7 (C(Ph)), 126.2 (C(Ph)), 125.7 (q, J =271 Hz,
41 cm (w); MS (EI): m/z (%): 960 ([M] , <1), 917 ([MÀiPr], <1),
28 ([MÀAuCl] , 1), 712 ([MÀAuClÀMe] , 3), 685 ([MÀAuClÀiPr] ,
), 496 ([MÀAu Cl ] , 6), 453 ([(IPr·PPh)ÀiPr] , 56), 387 [IPrÀH] ,
C,F
F
F
+
+
+
CF (BAr )), 118.0 (sept, J =3.8 Hz, C(BAr )), 30.5 (CH(CH ) ), 25.9
(
2
3
F,C
3 2
3
1
+
+
+
CH(CH ) ), 23.3 ppm (CH(CH ) ); P NMR (81 MHz, CD Cl ); d=
3 2 3 2 2 2
2
2
19
7.01 ppm (s); F NMR (188 MHz, CD Cl ): d=À2.74 ppm (s,
00); elemental analysis calcd (%) for C H N PCl Au (961.51): C
2
2
3
3
41
2
2
2
F
1
1
F
CF BAr ); B NMR (96 MHz, CD Cl ); d=À6.43 ppm (s, BAr ); MS
1.22, H 4.30, N 2.91; found: C 41.00, H 4.40, N 2.85.
3
2
2
+
(
(
(
ESI): m/z, [M] =cationic monomeric unit C H N ClPAu (%): 948
33 41 2 2
Synthesis of [(IPr·PPh)(CuOTf) ] (17)
2
+
+
+
[M+Na] , 48), 912 ([MÀCl] , 6), 838 ([MÀ2(iPr)] , 25), 713
+
The toluene adduct of copper(I) triflate (0.122 g, 0.47 mmol) and
adduct 2 (0.100 g, 0.2 mmol) were suspended in THF (12 mL) and
stirred overnight at room temperature. The resulting solution was
filtered through a syringe filter, and all volatiles were removed
under vacuum to afford complex 17 (75%, based on 2) as a pale
[MÀAuCl+Na] , 100); elemental analysis calcd (%) for
C
H Au B Cl F P N ·CH Cl (3660.49): C 42.94, H 2.97, N 1.53;
30 106 4 2 2 48 2 4 2 2
1
found: C 42.61, H 2.97, N 1.91.
Synthesis of [(IPr·PPh) Au Cl ][SbF ] (20)
2
4
2
6 2
1
Solid AgSbF (0.040 g, 0.117 mmol) was added to a stirred solution
of [IPr·PPh(AuCl) ] (0.113 g, 0.117 mmol) in CH Cl (20 mL). The re-
6
yellow solid. H NMR (300 MHz, CD Cl ): d=7.73–7.62 (m, 2H, p-
CH(Dipp)), 7.55 (s, 2H, HC N ), 7.44–7.36 (m, 4H, m-CH(Dipp)), 7.29–
2
2
2
2
2
2
2
sulting cloudy solution was stirred for 3.5 h at RT (under the exclu-
sion of light) and then filtered through a syringe filter, after which
the solvent was removed under reduced pressure. The residue was
washed with n-hexane (4”5 mL) and dried under vacuum to
7
.22 (m, 1H, p-CH(Ph)), 7.11–7.00 (m, 4H, o- and m-CH(Ph)), 2.34
3
3
(
brsept, 4H, JH,H =6.7 Hz, CH(CH ) ), 1.31 (d, 12H, JH,H =6.8 Hz,
3 2
3
13
CH(CH ) ), 1.14 ppm (d, 12H, JH,H =6.7 Hz, CH(CH ) ); C NMR
3
2
3 2
2
(
75 MHz, CD Cl ): d=145.0 (o-C(Dipp)), 139.2 (d, JP,C =17 Hz, o-
2 2
1
afford complex 20 (0.105 g, 77%) as a white powder. H NMR
C(Ph)), 133.6 (p-C(Dipp)), 131.6 (NC(Dipp), 131.1 (p-C(Ph)), 129.4 (d,
4
3
(300 MHz, CD Cl ): d=7.70 (d, 4H, J =1.5 Hz, HC N ), 7.62 (t, 4H,
2
2
P,H
2
2
JP,C =11.1 Hz, C N ), 127.4 (m-C(Ph)), 126.4 (m-C(Dipp)), 125.2 (d,
2
2
3
1
JP,H =1.5 Hz, p-CH(Dipp)), 7.51–7.48 (m, 2H, CH(Ar)), 7.34–7.08 (m,
16H, CH(Ar)), 2.24 (sept, 8H, J =6.8 Hz, CH(CH ) ), 1.10 (d, 24H,
=6.8 Hz, CH(CH ) ), 1.05 ppm (d, 24H, J =6.7 Hz, CH(CH ) );
H,H 3 2 H,H 3 2
C NMR (75 MHz, CD Cl ): d=145. 6 (NC(Dipp)), 138.2 (d, JP,C
0 Hz, PC(Ph)), 133.8 (o-C(Dipp)), 133.56 (d, JP,C =3.7 Hz, C N ),
2 2
32.0 (m-C(Dipp)), 130. 0 (C(Ph)), 129.8 (C(Ph)), 129.7 (C(Ph)), 126.1
JP,C =14.0 Hz, m-C(Ph)), 30.2 (CH(CH ) ), 25.8 (CH(CH ) ), 23.0 ppm
3 2
3 2
3
3
1
1
H,H
3 2
(
CH(CH ) );
P{ H} NMR (121 MHz, CD Cl ): d=À58.02 ppm;
3
2
2
2
3
3
1
9
J
F NMR (188 MHz. CD Cl ): d=À76.7 ppm (s, CuOSO CF ); elemen-
2
2
2
3
13
1
=
2
2
tal analysis calcd (%) for C H Cu F N O PS (921.90): C 45.60, H
4
3
5
41
2
6
2
6
2
3
2
1
.48, N 3.04; found: C 45.62, H 4.63, N 3.93.
F
Synthesis of [(IPr·PPh) Cu Cl ][BAr ] (18)
2
4
2
2
(
p-C(Dipp)), 30.4 (CH(CH ) ), 25.9 (CH(CH ) ), 23.4 ppm (CH(CH ) );
3 2 3 2 3 2
31
CH Cl (13 mL) was added to a mixture that contained [IPr·PPh-
P NMR (121 MHz, CD Cl ): d=À28.17 ppm (s); HRMS (ESI): m/z
2
2
2
2
F
(
CuCl) ] (0.060 g, 0.086 mmol) and Na(BAr ) (0.076 g, 0.086 mmol).
calcd for [(IPr·PPh) Au Cl ][SbF ]: 2087.29788, found: 2087.29917;
2 4 2 6
2
Chem. Eur. J. 2015, 21, 16178 – 16189
www.chemeurj.org
16186
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
1
calcd for [(IPr·PPh)Au Cl]: 925.20307, found: 925.20190; elemental
oil was obtained; H NMR analysis showed the presence of unreact-
ed 23a, 22, and 23b in the ratio of 1:5:10. For details see the Sup-
porting Information.
2
analysis calcd (%) for C H Au Cl F N P Sb ·5CH Cl (2748.26): C
6
6
82
4
2
12
4
2
2
2
2
3
1.03, H 3.37, N 2.04; found: C 31.09, H 3.07, N 2.16.
Synthesis of [(IPr·PPh){Au(THT)} ][SbF ] (21)
Cycloisomerization of enyne 24 by using catalyst 21: The solid
catalyst 21 (5.5 mg, 0.0035 mmol) was added to a stirred solution
of enyne 24 (0.080 g, 0.356 mmol) in 1,2-dichloroethane (5 mL).
The resulting clear mixture was stirred at room temperature for
2
6 2
A mixture of AgSbF6 (0.075 g, 0.218 mmol) and tetrahydrothio-
phene (THT) (0.091 g, 1.041 mmol) in CH Cl (10 mL) was added to
2
2
a stirred solution of 16 (0.100 g, 0.104 mmol) in CH Cl2 (10 mL).
2
9
0 min, and then passed through a short pad of silica gel. The sol-
The resulting mixture was stirred for 6 h at room temperature and
then filtered through a pad of Celite. The solvent was removed
under reduced pressure, and the residue was washed with toluene
vent was removed under reduced pressure to obtain a mixture of
1
2
5a and 25b (3:1 as confirmed by H NMR analysis, combined
yield= >99%) as a colourless oil. Analytical data are similar to
those obtained for the cyclization of 24 with the catalyst 19.
(
10”3 mL), n-hexane (10”3 mL), and dried under vacuum to
afford complex 21 as an off-white microcrystalline solid. Colorless
crystals of complex 21 (0.125 g, 78%, with respect to 16) were
Carbene transfer reactions with ethyl diazoacetate
1
grown by cooling a CH Cl /hexane solution to À308C. H NMR
Insertion reaction of CH OH and EDA by using catalysts 19 and
3
21: With catalyst 19: A solution containing methanol (0.578 g,
18.00 mmol) and EDA (0.103 g, 0.900 mmol) was added to a stirred
2
2
3
(
2
300 MHz, CD Cl ): d=7.78 (d, 2H,
H, JH,H =7.8 Hz, p-CH(Dipp)), 7.42 (d, 4H, JH,H =7.9 Hz, m-
J
=1.38 Hz, HC N ), 7.71 (t,
2
2
H,H
2
2
3
3
CH(Dipp)), 7.25–7.12 (m, 5H, PPhH), 3.28 (m, 8H, THT), 2.35 (sept,
solution of the catalyst 19 (0.032 g, 0.009 mmol) in CH Cl (4 mL).
2 2
It was stirred for 40 min at room temperature, then passed
through a short pad of silica gel, and the solvent was removed
3
3
4
6
H, J =6.2 Hz, CH(CH ) ), 2.09 (m, 8H, THT), 1.32 (d, 12H, J =
H,H
H,H
3 2
3
.7 Hz, CH(CH ) ), 1.18 ppm (d, 12H, JH,H =6.6 Hz, CH(CH3)2);
3
2
1
3
C NMR (75 Hz, CD Cl ): d=146 (NC(Dipp)), 137.9 (d, J =17.1 Hz,
under reduced pressure to give CH
3
OCH
): d=4.23 (q, JH,H =6.9 Hz, 2H, CH
), 3.45 (s, 3H, CH ), 1.29 ppm (t, 3H, JH,H =7.2,
); C NMR (75 MHz, CDCl ): d=170.0, 69.7, 59.1, 50.7,
2
COOCH
2
CH
3
(93%).
2
2
P,C
1
PC(Ph)), 133.7 (C(Ar)), 132.4 (C(Ar)), 130.2(C(Ar)) (d, JP,C =13.1 Hz),
H NMR (300 MHz, CDCl
4.02 (s, 2H, CH
3
2
CH ),
3
1
3
30.0 (C(Ar)), 129.5 (C(Ar)), 128.7 (C(Ar)), 126.2 (C(Ar)), 39.8 (THT),
1.4 (THT), 30.6 (CH(CH ) ), 26.1 (CH(CH ) , 23.6 ppm (CH(CH ) );
2
3
13
CH
CH
3
2
3 2
3 2
2
3
3
31
P NMR (121 MHz, CD Cl ): d=À6.20 ppm (s); MS (ESI): m/z (%):
14.0 ppm. With catalyst 21: 2 mol% of 21 in 15 min at RT yielded
ethyl methoxyacetate (90%) in a similar manner to that reported
for the catalyst 19.
2
+
2
+
7
11 ([(IPr·PPh)Au+H O] , 6), 693 ([(IPr·PPh)Au] , 100); elemental
2
1
analysis calcd (%) for C H Au F N PS Sb · = CH Cl (1566.76): C
4
1
57
2
12
2
2
2
3
2
2
3
1.69, H 3.71, N 1.79; found: C 31.61, H 3.80, N 1.91.
Insertion reaction of C H OH and EDA by using catalyst 21: A
2
5
mixture of ethanol (0.207 g, 4.501 mmol) and EDA (0.103 g,
.900 mmol) was added to a stirred solution of the catalyst 21
0.013 g, 0.009 mmol) in CH Cl (4 mL) at room temperature. After
Enyne cyclization reactions
0
(
Cycloisomerization of enyne 22 by using catalyst 19: The solid
catalyst 19 (0.012 g, 0.003 mmol) was added to a stirred solution of
enyne 22 (0.070 g, 0.332 mmol) in CH Cl2 (4 mL). The resulting
2
2
stirring for 45 min, the mixture was passed through a short pad of
silica gel and the solvent was removed under reduced pressure to
2
clear mixture was stirred at RT for 1 h, and then passed through
a short pad of silica gel. The solvent was removed under reduced
pressure to obtain a mixture of 23a and 23b (1:4 ratio as con-
1
isolate C H OCH CO C H (96%). H NMR (300 MHz, CDCl ): d=4.22
2
5
2
2
2
5
3
(
q, JH,H =7.2 Hz, 2H), 4.07 (s, 2H, CH ), 3.60 (q, J =7.1 Hz, 2H,
2 H,H
CH ), 1.21 (t, 3H, J =7.0, CH CH ), 1.25 ppm (t, 3H, J =6.8,
1
2
H,H
2
3
H,H
firmed by H NMR analysis, combined yield= >99%) as a colorless
13
CH CH ); C NMR (75 MHz, CDCl ): d=170.4, 68.0, 67.0, 60.6, 14.8,
1
20
2
3
3
oil. H NMR (300 MHz, CDCl ): d=6.47 (dd,
=
”1H, J =17.7,
3
100
H,
80
H
1
4.0 ppm.
8
0
1
5
3
3
2
1
5
0.5 Hz), 6.14 (dt,
=
1
”1H, JH, H =9.8, 1.3 Hz), 5.76 (m,
=
”1H),
”2H),
”2H),
00
100
2
0
20
80
Catalytic coupling of benzene and EDA by using catalysts 19
and 21: With catalyst 21: The catalyst (0.026 g, 1 mol%) was sus-
pended in benzene (8 mL) and heated to 658C. A solution of EDA
(0.200 g, 1.748 mmol) in benzene (2 mL) was added to this stirred,
hot solution. The resulting mixture was heated for 45 min, passed
through a pad of neutral Al O , and then purified by flash column
.57 (br,
.74 (s,
.11–3.09 (m,
.63 ppm (m,
=
”1H), 5.12–5.07 (m,
”6H), 3.71 (s,
=
”2H), 4.92 (m,
”6H), 3.14–3.12 (m,
= ”2H, JH, H =1.9 Hz), 2.71–
100
=
1
00
100
100
2
0
80
20
=
=
=
100
1
00
100
2
0
80
=
”2H), 2.87 (t,
1
00
8
0
13
=
”2H); C NMR (75 MHz, CDCl ): d=172.4, 171.3,
3
39.9, 138.8, 132.3, 128.8, 126.7, 126.3, 115.1, 113.5, 58.6, 53.9, 52.8,
2.7, 40.8, 39.1, 35.8, 31 ppm.
1
00
2
3
1
chromatography to obtain a colourless oil. H NMR analysis of the
Cycloisomerization of enyne 24 by using catalyst 19: The solid
catalyst 19 (12.7 mg, 0.0035 mmol, 1 mol%) was added to a stirred
solution of enyne 24 (0.080 g, 0.356 mmol) in CH Cl (4 mL). The
mixture showed that it contained both PhCH COOEt and
2
C H CO Et, approximately in the ratio of 5:3 (combined yield=
7
6
2
1
2
2
9
7%). H NMR (300 MHz, CDCl ): d=7.34–7.22 (m, 5H, ArH), 6.66–
3
mixture was stirred at RT for 1 h and worked up as reported for
6
.63 (m), 6.28–6.22 (m), 5.46–5.41 (m), 4.25 (q, JH,H =7.0 Hz), 4.14 (q,
the enyne 22 to give a mixture of 25a and 25b (3:1 as confirmed
JH,H =7.1 Hz; CH CH ), 3.60 (s, CH ), 2.53 (tt, J =5.5 Hz, 1.2 Hz),
2
3
2
H,H
1
1
by H NMR analysis, combined yield= >99%). H NMR (300 MHz,
1
.30 (t, JH H =7.3 Hz, CH CH ), 1.24 ppm (t, J =7.0 Hz, CH CH );
2 3 H,H 2 3
2
5
75
CDCl ): d=6.42 (dt,
=
”1H, JH,H =10.7, 2.2 Hz), 5.73 (m,
”1H), 5.39–5.37 (m,
= ”
100
13
3
100
C NMR (75 MHz, CDCl ); d=173.0, 171.5, 134.1, 130.8, 129.1,
3
2
5
75
1
H), 5.65–5.58 (m,
=
= ”1H), 3.74 (s,
100
1
00
1
28.4, 126.9, 125.5, 117.2, 60.9, 60.7, 44.0, 41.3, 14.2, 14.1 ppm (see
7
5
25
75
=
1
”6H), 3.70 (s, = ”6H), 3.27–3.18 (m, = ”2H), 3.05–3.03
100
00
7
100
25
the Supporting Information). With catalyst 19: EDA (0.040 g,
5
25
(
m, = ”2H), 2.84 (m, = ”2H), 2.68–2.64 (m, = ”2H), 1.82–
100 100 100
0
0
.349 mmol) was added to
.003 mmol) benzene (10 mL) and stirred at RT for 1 h. After purifi-
a solution of catalyst (0.012 g,
7
5
25
13
1
.78 (m,
=
1
”6H), 1.77–1.73 ppm (m,
= ”6H);
100
C NMR
00
(
75 MHz, CDCl ): d=172.5, 171.7, 8738.7, 135.5, 129.6, 125.6, 124.4,
3
cation of this mixture, it contained both PhCH COOEt and
2
1
2
23.7, 122.4, 120.6, 59.2, 54.0, 52.7, 52.5, 43.2, 40.2, 32.0, 31.0, 27.2,
0.4, 20.0, 19.7 ppm.
C H CO Et, approximately in 2:1 ratio (combined yield=95%).
7
6
2
Cycloisomerization of enyne 22 by using catalyst 21: The solid
catalyst 21 (5.8 mg, 0.003 mmol) was added to a stirred solution of
the enyne 22 (0.080 g, 0.380 mmol) in 1,2-dichloroethane (4 mL),
and the resulting solution was stirred at RT for 7 h. After the purifi-
cation of the product, as reported for the enyne 19, a colourless
Keywords: carbene ligands · coinage metals · copper · gold ·
phosphinidene
Chem. Eur. J. 2015, 21, 16178 – 16189
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16187
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Published online on September 14, 2015
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