Diphosphines and pyrazole/pyrazolate-type ligands as building blocks in luminescent Au(I) complexes

Article abstract of DOI:10.1016/j.jorganchem.2011.04.022

A series of gold(I) complexes containing diphenylphosphine bridging ligands, dppm, dppe, dpephos, dbfphos and biphep and co-ligands of the type pyrazole have been synthesized. The X-ray crystal structures of [Au ₂(μ-dpephos)(μ-pz^2CH3)][PF₆], [Au ₂(μ-dbfphos)(μ-pz^2CH3)][PF₆], and of the starting compound [Au₂Cl₂(μ-biphep)] indicate that the structural and stoichiometric characteristics of the new complexes depend on the diphosphine ligand. The three complexes show Au?Au contacts between 3.27 and 3.30 , with that of the biphep compound being the shortest. Digold (I)-diphosphine derivatives with a bridging pyrazolate ligand are obtained in all cases, except when [Au₂Cl₂(μ-biphep)] is used as starting material. Surprisingly, in this case, two monodentate neutral pyrazole ligands are attached to the gold atoms. The new complexes are luminescent in the solid state at 77 K and in solution both at room temperature and 77 K. Low energy emission bands related to the presence of Au?Au interactions have been identified in some of the compounds in the solid state and/or in solution.

Full text of DOI:10.1016/j.jorganchem.2011.04.022

Journal of Organometallic Chemistry 696 (2011) 2789e2796
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Diphosphines and pyrazole/pyrazolate-type ligands as building blocks
in luminescent Au(I) complexes
,
,
,
,2
María José Mayoral a 1, Paloma Ovejero a 1, Rosario Criado a 1, M. Cristina Lagunas b
,
Aranzazu Pintado-Alba b 2, M. Rosario Torres c 3, Mercedes Cano a
,
,
,
*
a Departamento de Química Inorgánica I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
b School of Chemistry and Chemical Engineering, Queen’s University Belfast, Belfast BT9 5AG, UK
c Laboratorio de Rayos-X, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of gold(I) complexes containing diphenylphosphine bridging ligands, dppm, dppe, dpephos,
dbfphos and biphep and co-ligands of the type pyrazole have been synthesized. The X-ray crystal
Received 8 February 2011
Received in revised form
19 April 2011
structures of [Au2(
compound [Au2Cl2(
m
-dpephos)(
m m-dbfphos)(m
-pz2CH3)][PF6], [Au2( -pz2CH3)][PF6], and of the starting
m
-biphep)] indicate that the structural and stoichiometric characteristics of the new
Accepted 21 April 2011
complexes depend on the diphosphine ligand. The three complexes show Au/Au contacts between
3.27 Å and 3.30 Å, with that of the biphep compound being the shortest. Digold (I)-diphosphine
derivatives with a bridging pyrazolate ligand are obtained in all cases, except when [Au2Cl2(m-biphep)] is
Keywords:
Pyrazole-type ligands
Pyrazolate-type ligands
Gold complexes
Luminescent materials
Aurophilic interactions
used as starting material. Surprisingly, in this case, two monodentate neutral pyrazole ligands are
attached to the gold atoms. The new complexes are luminescent in the solid state at 77 K and in solution
both at room temperature and 77 K. Low energy emission bands related to the presence of Au/Au
interactions have been identified in some of the compounds in the solid state and/or in solution.
Ó 2011 Elsevier B.V. All rights reserved.
1. Introduction
[(AuCl)2(m-diphos)] have been investigated [11e14]. Dinuclear Au(I)
complexes with non-rigid bridging diphosphines of the type
[dpp(CH2)n] (bis(diphenylphosphine)alkane) with variable length
have also been extensively studied [15e17]. In addition, most of the
Au(I) complexes containing tertiary phosphines are also stabilized
with N-donor co-ligands [18]. Therefore, in previous works we
were involved in the study of gold(I) complexes containing
pyrazolate and triphenylphosphine ligands. Those of the type
[Au(pz2R(n))(PPh3)] (pz2R(n) ¼ 3,5 alkyloxyphenyl substituted pyr-
Over the last years there has been much interest in the design,
synthesis and photochemical characterization of gold(I) complexes
with potential applications in molecular electronics and photonics
[1e3]. In addition, diphosphines are able to act as bridging ligands
between closed-shell Au(I) centers thus contributing to the stabi-
lization of complexes with attractive AueAu interactions which in
turn, are often responsible for the luminescent properties of the
compounds. Consequently, previous studies have focused in
establishing the relationship between optical properties and
structural characteristics in this type of complexes, particularly in
relation to the presence of Au/Au interactions [4e13]. In partic-
ular, the effects of the flexibility and bite angle of diphosphine
ligands like dpephos, xantphos and dbfphos on the structural and
azolate), and [(PPh3)Au(
m
-pzR(n))Au(PPh3)]þ (pzR(n) ¼ 3 alkyloxy-
phenyl substituted pyrazolate) (R(n) ¼ C6H4OCnH2nþ1) exhibit
luminescent properties, but only the latter contain Au/Au inter-
actions [19].
Herein, the properties of new binuclear Au(I) complexes are
studied, including compounds with heterobridged ligands (i.e.,
diphenylphosphine and pyrazolate), as well as with Au-pyrazole
moities bridged by a diphosphine ligand. In particular the diphe-
nylphosphines biphep (20-bis(diphenylphosphino)-1,10-biphenyl),
dpephos (bis(2-diphenylphosphino)phenyl ether) and dbfphos (6-
bis(diphenylphosphino)dibenzofuran) or dppm (1,2-bis(diphenyl
phosphino)methane) and dppe (1,2-bis(diphenylphosphino)
ethane) were selected as rigid or flexible bridging ligands
(Scheme 1). The influence on the luminescent properties of the
compounds of the flexibility and bite angle of the diphosphines,
optical properties of the Au(I) complexes [Au(m-diphos)2][SbF6] and
* Corresponding author. Tel.: þ34 91394 4340; fax: þ34 91394 4352.
E-mail addresses: c.lagunas@qub.ac.uk (M. Cristina Lagunas), mrtorres@quim.
ucm.es (M. Rosario Torres), mmcano@quim.ucm.es (M. Cano).
1
Tel.: þ34 91394 4340; fax: þ34 91394 4352.
2
Tel.: þ44 (0) 289097 4336; fax: þ44 (0) 2890976524.
3
Tel.: þ34 91394 4340; fax: þ34 91394 4352.
0022-328X/$ e see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2011.04.022

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M.J. Mayoral et al. / Journal of Organometallic Chemistry 696 (2011) 2789e2796
a
b
Diphosphine ligands
Pyrazole ligands
Ph
Ph
Ph
1
Ph
CH3
H3C
P
P
P
Ph
P
Ph
Ph
Ph
N
N
dppm
H
dppe
Hpz2(CH3)
5
6
5
3
9
2
3
8
OCnH2n+1
6
4
3
H2n+1CnO
7
1
4
1
4
6
2
O
2
O
5
N
N
P(Ph)2 P(Ph)2
P(Ph)2
P(Ph)2
P(Ph)2
P(Ph)2
H
Hpz2R(n)
dpephos
biphep
dbfphos
Scheme 1. Diphosphine (a) and pyrazole (b) ligands used in this work.
and of the different steric and electronic characteristics of the
pyrazole/pyrazolate ligands (Scheme 1b), is analyzed in order to
gain an insight into the relationships between these features and
the structures of the new Au(I) complexes. In particular, in the
show a multiplet at ca. 3.9 ppm corresponding to the dppm
methylene protons and the OCH2 protons of the R(n) groups. In the
case of 1, a broad signal at 3.4 ppm is related to the dppm methy-
lene group. The spectrum of 9 shows a ddd at 6.77 ppm and two
apparent triplets at 7.17 and 7.06 ppm assigned to the H(3), H(4)
and H(5) of the organic backbone, respectively. The signal at ca.
5.8 ppm (dd) is assigned to the dpephos H(6). This unusual lower
frequency is attributed to the paramagnetic shielding effect of
neighboring aromatic rings. For 10, a signal at ca. 8.3 ppm is related
to H(1) and H(9) of the dbfphos backbone.
present paper, the synthesis of new complexes of the types [Au2(
diphos)(
-pz2R)][A] (I) and [Au2( -diphos)(Hpz2R)2][A]2 (II)
(Scheme 2) is reported and their spectroscopic and luminescence
m-
m
m
properties studied. The crystal structures of two of them, [Au2(
m-
dpephos)( -dbfphos)(
m
-pz2(CH3))][PF6] (9) and [Au2(
m
m
-pz2(CH3))]
[PF6] (10), and that of one of the starting compound [Au2Cl2(
m-
biphep)] are comparatively discussed.
The 1H NMR spectra of the type II complexes (12 and 13) exhibit
singular features. In all cases the signals corresponding to the
diphosphine aromatic protons and the H(40) of the pyrazole ligand
appear between 6.2 and 7.9 ppm, whereas the pyrazole Hm and Ho,
unequivocally identified, are clearly separated from the aromatic
protons of the diphosphine ligands. In addition, two triplets at ca.
4.0 ppm corresponding to the OCH2 protons of the alkyloxyphenyl
groups suggest the presence of two inequivalent lateral chains in
the pyrazole ligands [20]. Analogous observations are made for
complex 11, with two singlets at ca. 1.9 and 2.3 ppm for the two
methyl groups of the coordinated pyrazole ligands in accordance
with the proposed formulation. Unfortunately, the signals for the
NH protons of the N-coordinated pyrazole ligands are not observed,
possibly due to the presence of intermolecular H-bonding inter-
actions with the counterions [21].
2. Results and discussion
All the new compounds described in this work with their cor-
responding numbering are recovered in Table 1.
2.1. Spectroscopic and structural characterization
The reaction of the sodium salt of the corresponding disubsti-
tuted pyrazole Napz2R (R ¼ CH3 or C6H4OCnH2nþ1; n ¼ 12, 14, or 16)
with [Au2Cl2(
m
-diphos)] (diphos ¼ dppe, dppm, dpephos and
dbfphos) in a 1:1 M ratio and in the presence of two equivalents of
AgA (A ¼ OTf or PF6) gave rise to the cationic binuclear compounds
of type I [Au2(m-diphos)(m
-pz2R)][A] (1e10) containing diphosphine
The 31P NMR spectra show in all cases one singlet at ca.
20e36 ppm. The values found are in the same range than those
observed in other complexes with aromatic phosphines bonded to
Auepz or AueHpz moieties (ca. 20e30 ppm) [19,22].
and pyrazolate as bridging PP and NN-ligands between the two
gold(I) centers (Scheme 2a, Table 1). However, similar reactions
using biphep yielded a new type of bimetallic complexes, II [Au2(m-
biphep)(Hpz2R)2][A]2 (11e13), exhibiting two Hpz2R ligands, each of
them N-coordinated in a monodentate fashion with the diphos-
phine ligand bridging both metals (Scheme 2b, Table 1).
The complexes are colorless and light sensitive solids. All the
compounds (1e13) were soluble in chloroform and dichloro-
methane, and were characterized by C, H, N elemental analysis, and
by 1H and 31P NMR spectroscopy. ESI-MS studies were carried out
for representative examples. Selected spectroscopic and structural
features are discussed below.
a
Type I
b
Type II
[Au2( -diphos)( -pz2R)][A] ( 1-10)
[Au2( -diphos)(Hpz2R)2][A]2 (11-13)
(Ph)2P
Au
P(Ph)2
Au
(Ph)2P
Au
P(Ph)2
Au
The 1H NMR spectra of the complexes are consistent with the
proposed formulations, exhibiting the characteristic signals of the
diphosphine ligand as well as those of the disubstituted pyrazolate
(type I) or the monocoordinated pyrazole (type II).
[A]2
[A]
N
N
H
H
N
N
N
N
R
R
(n)R
R(n)
R
R
For example, the dppe ethylene group in 5e8 appears at ca.
3.1 ppm as a doublet or a broad signal, whereas complexes 2e4
Scheme 2. Molecular structure of the Au(I) complexes of the type I and II.

M.J. Mayoral et al. / Journal of Organometallic Chemistry 696 (2011) 2789e2796
2791
Table 1
Formulation and numbering of the new compounds of the type I and II.
Type of compounds
Type I [Au2( -diphos)(
Diphosphine ligands (diphos)
dppm
Substituents at the pyrazole (R)
Counteranion [A]
OTf
Numbering of compounds
m
m
-pz2R)][A]
CH3
1
2
3
4
5
C6H4OC12H25
C6H4OC14H29
C6H4OC16H33
CH3
dppe
C6H4OC12H25
C6H4OC14H29
C6H4OC16H33
CH3
CH3
CH3
OTf
6
7
8
9
10
11
12
13
dpephos
dbfphos
biphep
PF6
PF6
OTf
Type II [Au2(
m
-biphep)(Hpz2R)2][A]2
C6H4OC14H29
C6H4OC16H33
The ESI-MS spectra of complexes 2, 7 and 8e10 show the peaks
corresponding to the fragments [Au2( -dppm)(
-pz2R(14))]þ,
[Au2( -dppe)( -dppe)(
-pz2R(14))]þ, [Au2( -pz2R(16))]þ, [Au2(
dpephos)( -dbfphos)(
-pz2(CH3))]þ and [Au2( -pz2(CH3))]þ, at m/z
1422.9, 1436.5, 1492.2, 1027.0 and 1025.0, respectively, as the most
intense signal. This agrees with the proposed 2:1:1 metal:-
diphosphine:pyrazolate ratio. The corresponding peaks for 12
could not be observed, probably due to the instability of the frag-
ments under the registration conditions.
forming a non-planar eleven-membered ring. The AueN bond
lengths are comparable to those found in other pyrazole or pyr-
azolate Au(I) complexes like [(Ph3P)Au(Hpz2R(4))][NO3], AueN:
m
m
m
m
m
m
m
m-
m
m
2.005 Å) [23] or [Au(
distance is comparable with that of dinuclear diphosphine
complexes [Au2Cl2( -dpephos)] (AueP: 2.234 Å) [11], [Au2Cl2(m-
m-pz)]3 (AueN: 2.00(2) Å) [17]. The AueP
m
dppe)] (AueP: 2.237 Å) [24] or mono-gold or digold pyrazole
complexes (e.g. [(Ph3P)Au(Hpz2R(4))][NO3], AueP: 2.234 Å [23],
[(
m
-dppe)Au2(3,5-HpzMe2)]2þ, AueP: 2.232(3) Å) [15].
The PeP distance in the dpephos ligand is 5.54 Å and the torsion
angle between the backbone phenyl rings is 77.5ꢀ, so indicating
some distortion of the diphosphine ligand. This feature allows to
maintain the two gold(I) centers in enough proximity to be bridged
by a pyrazolate ligand, which shows a AueNeNeAu torsion angle of
ca. 19.83ꢀ. The coordination geometries around the gold(I) atoms
are also slightly distorted from the linearity (PeAueN ¼ 176.5(3)ꢀ,
Table S2), probably as a consequence of the aurophilic interaction
and the bridging pyrazolate ligand.
2.2. Crystal structure of complexes [Au2(
[PF6] (9), [Au2( -dbfphos)(
-pz2(CH3))][PF6] (10) and of the starting
compound [Au2Cl2( -biphep)]
m-dpephos)(m
-pz2(CH3))]
m
m
m
Adequate crystals for X-ray diffraction studies of complexes 9,10
and of the starting compound [Au2Cl2( -biphep)] were obtained by
m
slow vapor diffusion of hexane into dichloromethane solutions of
the compounds. Selected bond lengths and angles, and crystal data
are included as Supplementary Information (Tables S1-S4).
The AueNeNeAu metallocycle trapezoidal structure is compa-
rable to that of trinuclear species, such as [Au(3,5-(CF3)2pz)]3 [10],
or [Au(m
-pzpp2)]3 [20] with Au/Au distances of 3.351 Å and ca.
2.2.1. [Au2(m-dpephos)(m
-pz2(CH3))][PF6] (9)
3.347 Å respectively. However, the NeNeAu angle of 117.3ꢀ, is
smaller than that found in the mentioned trinuclear species of
118.19ꢀ and 122.89ꢀ respectively being this fact probably caused by
the bridging dpephos ligand, which maintains the gold(I) atoms
into close proximity. Analogous behavior was observed in the
The molecular structure of the cation in 9 is shown in Fig. 1. The
complex crystallizes with 2.5 molecules of dichloromethane in the
monoclinic system, space group P2/c (Table S1). The cationic unit
consists of two gold(I) atoms exhibiting a weak Au/Au interaction
of 3.3010(10) Å (Table S1) which are bridged by one dpephos group
(AueP ¼ 2.247 Å) and by one pyrazolate ligand (AueN ¼ 2.030 Å)
complex [(
m-dppp)Au2(m
-3,5-pzPh2)], which has an NeNeAu angle
of 112e117ꢀ and a Au/Au distance of 3.109 Å [16].
2.2.2. [Au2(m-dbfphos)(m
-pz2(CH3))][PF6] (10)
Complex 10 crystallizes in the monoclinic system, space group
P21/n with 1.5 molecules of chloroform (Table S1). The molecular
structure of the cation (Fig. 2) exhibits similar structural features to
those of 9, with a non-planar eleven-membered ring formed by the
diphosphine and the pyrazolate ligand bridging between the two
gold(I) metal centers. The AueNeNeAu torsion angle is of ca.12.22ꢀ
and the AueP and AueN distances are of ca. 2.24 Å and 2.04 Å,
respectively (Table S3). The two gold atoms form a Au/Au inter-
action (3.3728(9) Å) weaker than that of 9, although it is the
shortest found in digold complexes with
a
dbfphos ligand:
[{Au(CCPh)}2(
3.457 Å [13].
m
-dbfphos)] 3.401 Å, [Au2(SC6HCl-4)2(( -dbfphos)]
m
The coordination geometry about the gold atoms (PeAueN: ca.
178ꢀ, Table S3) is less distorted from the linearity than in complex 9,
possibly as a consequence of the higher rigidity and larger bite
angle of dbfphos compared to dpephos. As shown in Fig. 2, the
dbfphos backbone forms a torsion angle of ca. 111ꢀ (Au1eP1eC8:
110.0(5)ꢀ, Au2eP2eC18: 112.4(5)ꢀ; Table S3), which is analogous to
Fig. 1. ORTEP plot of the cation in [Au2(
probability. Hydrogen atoms have been omitted for clarity.
m-dpephos)(m
-pz2(CH3))][PF6] (9) with 35%

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M.J. Mayoral et al. / Journal of Organometallic Chemistry 696 (2011) 2789e2796
P
P
9
d(P-P) = 5.54 Å
d(Au-Au) = 3.30 Å
Au
Au
N
N
10
d(P-P) = 5.51 Å
d(Au-Au) = 3.37 Å
(n)R
R(n)
Fig. 4. Schematic representation of the NeAuePePeAueN metallocycle for 9 and 10.
2.3. Comparative structural results
The nature of the diphosphine ligand appears to be responsible
for the overall structure and type (pyrazolate or pyrazole) of the
digold(I) complex.
Fig. 2. ORTEP plot of the cation in [Au2(m-dbfphos)(m
-pz2(CH3))][PF6] (10) with 35%
probability. Hydrogen atoms have been omitted for clarity.
The structures of [Au2(
m-dpephos)(m
-pz2(CH3))][PF6] (9) and
[Au2( -dbfphos)(
m
m
-pz2(CH3))][PF6] (10) exhibit similar features
showing an NeAuePePeAueN metallocycle with AueAu interac-
tions of 3.30 Å (dpephos) and 3.37 Å (dbfphos), and PeP distances
of 5.54 Å (dpephos) and 5.51 Å (dbfphos) (Fig. 4). The latter values
are close to those found in the free dbfphos (5.74 Å) as well as in its
chlorinated derivative (5.83 Å), but are significantly larger than that
of the free dpephos (4.04 Å) or its chlorinated derivative (4.85 Å)
[11]. These results are consistent with the higher flexibility of the
dpephos, allowing a larger variation of the PeP distance, than the
more rigid dbfphos, which maintains the same inter-phosphorus
distance in all compounds.
that found in the related complex [Co2(CO)6(m-dbfphos)] (angle
CoePeC of ca. 115ꢀ) [25]. The N2eN1eAu1 and N1eN2eAu2 angles
are 117.9(9) and 119.2(9)ꢀ, respectively (Table S3), similar to those
of the trinuclear pyrazolate gold species mentioned above [10,20].
The AueO distances, 3.390 Å and 3.426 Å, are analogous to those in
9 and [Co2(CO)6(m-dbfphos)] (CoeO: 3.302 Å) [25].
2.2.3. [Au2Cl2( -biphep)]
m
The X-ray crystal structure is depicted in Fig. 3. The complex
crystallizes in the monoclinic system, space group C2/c (Table S1).
The torsion angle in the biphenyl moiety of the biphep ligand is
of ca. 78ꢀ, this fact favoring the proximity of the gold (I) centers.
Thus, the compound shows a Au/Au interaction of 3.2766(5) Å
which forces the Au coordination environments to deviate slightly
from linearity with PeAueCl angles of 176.09(7)ꢀ (Table S4). The
PeAueCl fragments are almost perpendicular to each other, being
the torsion angle Cl(1)eAu(1)eAu(2)eCl(2) of 91.8(2)ꢀ which gives
rise to a CleCl distance of 4.97 Å. The distance between the P atoms
(4.707 Å) is shorter than that observed in related compounds
In the case of the related digold(I) complexes with biphep, two
pyrazole ligands unexpectedly coordinate to the metal centers
forming complexes [Au2(
the PeP distance of the starting compound [Au2Cl2(
(4.70 Å) is similar to that of [Au2Cl2( -dpephos)] (4.85 Å) (Fig. 5),
m
-biphep)(Hpz2R)2][OTf]2 (11e13). Since
m-biphep)]
m
a pyrazolate complex like 9 or 10 should be possible for 11e13.
However, even a relatively rigid diphosphine such as dbfphos has
been found to favor different structural arrangements in complexes
otherwise analogous. For example, two types of structures have
been described for [Au2X2(m-dbfphos)] depending on the nature of
X (Br or I) [22] (Fig. 6). It appears than in the case of the biphep
derivatives described herein, 11e13, a disposition in which the two
gold(I) centers are situated further apart, favors the coordination of
two pyrazole ligands (Fig. 7). Although all attempts to obtain single
crystals of 11e13 adequate for X-ray diffraction studies have been
unsuccessful, the proposed formulations are supported by NMR
spectroscopic evidence and C, H, N analysis.
[Au2Cl2(
[Au2Br2(
[22], which show aurophilic interactions of 3.0038(6), 2.9764(13),
2.9857(7), 3.1528(3) Å respectively, and in [Au2Cl2( -dbfphos)]
-dbfphos)] (5.897 Å) [22], without
m-dpephos)] (4.858 Å) [11], [Au2I2(m-dpephos)] (4.927 Å),
m-dpephos)] (4.913 Å), and [Au2I2(
m-dbfphos)] (5.365 Å)
m
(5.834 Å) [11] and [Au2Br2(
m
aurophilic contacts.
2.4. Optical properties
The absorption and emission spectra of representative
complexes of type I (1e3, 5e7, 9, 10) and II (11 and 12) have been
O
P(Ph)2
P(Ph)2
Au
(Ph)2P
(Ph)2
P
Au
Cl
Au
Cl
Au
Cl
Cl
d(P-P) = 4.85 Å
d(Au-Au) = 3.00 Å
d(Cl-Cl) = 3.96 Å
d(P-P) = 4.70 Å
d(Au-Au) = 3.27 Å
d(Cl-Cl) = 4.77 Å
Fig. 3. ORTEP plot of [Au2Cl2(m-biphep)] with 35% probability. Hydrogen atoms have
been omitted for clarity.
Fig. 5. Schematic representation of the compounds of the type [Au2Cl2(m-diphos)].

M.J. Mayoral et al. / Journal of Organometallic Chemistry 696 (2011) 2789e2796
2793
dbfphos and biphep) is also included in Table 2. All the compounds
are luminescent in the solid state at 298 K, in contrast to the general
absence of emission of compounds 1e12 in the same conditions.
O
O
Complexes [Au2Cl2(
one broad band at ca. 580 nm and [Au2Cl2(
a similar one at 620 nm with a shoulder at 450 nm. In the
complexes [Au2Cl2( -dppe)] and [Au2Cl2( -dbfphos)] [11] a band at
m-dppm)] [26] and [Au2Cl2(m-biphep)] exhibit
X
X
(Ph)2
P
(Ph)2P
m-dpephos)] [11] shows
Au
(Ph)2
P
P(Ph)2
Au
Au
Au
X
m
m
ca. 375 nm and a structured band in the 430e500 nm range,
respectively, are observed.
All the starting compounds, except the dpephos derivatives, also
show emission in solution at room temperature, exhibiting a band
X
X = Br
d(P-P) = 5.90 Å
d(Au-Au) > 7.2 Å
X = I
d(P-P) = 5.37 Å
d(Au-Au) = 3.15 Å
at 585 nm ([Au2Cl2(m-dppm)]) [26], 375 nm ([Au2Cl2(m-dppe)]) and
Fig. 6. Schematic representation of the complexes [Au2X2(
m-dbfphos)] [22].
600 nm ([Au2Cl2( -biphep)]). It should be noted that the latter had
m
been previously reported as non-emissive [14]; however clear
evidence of its luminescent behavior has been found herein. A
structured band centered at 450 nm for [Au2Cl2(m-dbfphos)] is
studied and compared with those of the corresponding starting
compounds. The photophysical data are summarised in Table 2.
With the exception of complexes 9 and 11, none of the
compounds showed emission at room temperature in the solid
state. However, except for complexes 10 and 12, they all are lumi-
nescent at 77 K. In particular, complexes 1 and 5, containing the
bridging 3,5-dimethyl pyrazolate ligand, and 11, with two 3,5-
dimethyl pyrazole ligands, display emission bands at 450, 350
and 500 nm, respectively. The related pyrazolate complex 9 shows
a vibronic structured band with a maximum at 367 nm, while
complex 10 is not luminescent. The emission of complexes 2, 3, 6
and 7, with alkyloxyphenyl substituents at the 3,5 positions of the
pyrazolate ring, differs from that of methyl-substituted analogs (1, 5
and 11), with the former exhibiting well-resolved vibrational
features in the 440e500 nm range, when excited at ca. 320 nm.
Luminescence measurements were also performed in
dichloromethane solution at 298 and 77 K for all complexes
(Table 2). The room temperature emission spectra of 1e3, 5e7, and
11 show a band in 390e440 nm range when excited at ca. 400 nm
independently of the type of ligand, pyrazolate or pyrazole, present
in the complexes and the nature of the substituents. Complexes 9
and 10 display a band bathochromically shifted at 620 and 650 nm,
respectively. By contrast, the spectrum of 12 exhibits a structured
band between 350 and 500 nm with a maximum at 380 nm when
excited at 350 nm.
observed [11]. The low energy emissions at ca. 600 nm in the dppm
and biphep derivatives, which are not observed in the free
diphosphine ligands [12,27], have been previously related to the
aurophilic interaction present in these complexes [11,28], and is
attributed to metalemetal to ligand charge transfers (MMLCT) [11].
Similarly, the low energy emission observed in type I complexes 9
and 10 in solution at r.t. (i.e., a broad band at 620 and 650 nm,
respectively) is likely to be related to the aurophilic contact and
could be assigned to an MC or MMLCT transition [11]. At 77 K,
however, only higher energy emission bands, related to ligand
centered
Analogous thermochromic behavior has previously been observed
in the related compound [Au2Cl2(
-xantphos)] (xantphos ¼ 9,9-
dimethyl-4,5-bis(diphenylphosphino)xanthene) [11], and in some
samples of [Au2Cl2( -dpephos)] [12].
p /
p* transitions [11], are observed for both complexes.
m
m
Although complexes 9 and 10 show analogous features in their
crystal structures with Au/Au contacts of 3.3003(11) and
3.3724(10) Å, respectively, they exhibit different emission profiles
in the solid state. Complex 9 shows similar behavior as in solution,
with an emission at 612 nm at room temperature, and a structured
band at higher energy at 77 K, corresponding to MC/MMLCT and
ligand centered
p /
p* transitions, respectively. Complex 10,
however, is non-emissive in the solid state at room temperature or
77 K. This may be due to quenching of the emission by traces of one
or more impurities present in the sample, undetectable by the
characterization techniques used, or by a small percentage of
solvent of crystallization [12,29]. Similar considerations can be
made in the case of complex 12, also non-emissive in the solid state.
On the other hand, the emission of complexes 1e3 (type I) and
11e12 (type II), containing dppm and biphep diphosphines, display
emission at ca. 440 nm in solution at room temperature. This is
140e200 nm blue-shifted with respect to that of the corresponding
At 77 K, the solution spectra are analogous to the spectra in the
solid state at 77 K of the complexes with 3,5-dimethyl pyrazolate/
pyrazole ligands described above. So, complexes 1, 5, 9, 10 and 11
exhibit a band in the 430e470 nm range when excited at ca.
325 nm, and complexes 2e3, 6e7 and 12 gave emission profiles
characterized by a vibronic structure in the 400e500 nm range
when excited ca. 325 nm.
For comparison purposes the photoluminescence of the starting
complexes [(AuCl)2(
m
-diphos)] (diphos ¼ dppm, dppe, dpephos,
starting compounds, [Au2Cl2(m-dppm)] [20] and [Au2Cl2(m-
biphep)], which emit at ca. 600 nm and exhibit Au/Au contacts in
their crystal structures. This could be explained by the lack of intra-
molecular aurophilic contacts in solution in 1e3, 11 and 12, and
their emission therefore attributed to ligand centered
p /
p*
transitions, as shown on several other gold complexes [12,13].
However, the solid state emission of complex 11 (500, 515 nm)
occurs at significantly lower energy than in solution, indicating that
a Au/Au contact may be present in the solid. None of the other
compounds show clear low energy MC/MMLCT bands that could be
related to the presence of Au/Au interactions in the solid state or
in solution at 77 K. The lack of metallophilic contacts, however, is
surprising in the case of the dppm derivatives 1e3, given the
relative rigidity of the metallocyclic structures and the small bite
angle of the bridging pyrazolate ligands. Since the compounds only
emit at 77 K in the solid state, it is possible that the MC/MMLCT
band is not seen due to a thermochromic effect analogous to that
P(Ph)2
Au
P(Ph)2
H
R
N
N
R
Au
N
H
N
R
R
Fig. 7. Schematic representation of the complexes 11e13.

2794
M.J. Mayoral et al. / Journal of Organometallic Chemistry 696 (2011) 2789e2796
Table 2
Absorption (labsmax) and emission (lemmax) maxima in nm, molar absorption coefficients (
3
) in Lmolꢂ1 cmꢂ1 of 1e3, 5e7, 9, 10 (type I), 11 and 12 (type II) in aerated 1 ꢃ10ꢂ4
M
dichloromethane solution and in the solid state at 298 K. Data of the starting compounds are also included for comparative purpose.
solutiona
3
lemmax solutionb
lem
solid
d(Au/Au) Å
max
max
labs
77 K
298 K
77 K
298 K
d
d
[Au2Cl2(
1
2
3
[Au2Cl2(
5
6
7
[Au2Cl2(
9
[Au2Cl2(
10
[Au2Cl2(
11
12
m
m
-dppm)]c
-dppe)]
268
297
400
400
266
280
400
400
269
276
298
298
268
340
350
28100
10384
56700
52340
4642
10110
41500
42100
7912
56050
43802
80100
14737
15600
55400
585
390
440
440
375, 574
375
439
585
3.351(2)
k
440
450e
k
k
442, 468, 496sh
443, 466, 500sh
440
445, 470, 500she
442, 469, 500she
383, 405, 423
350f
l
385
k
415
k
k
442, 469, 502sh
400
431, 654
348sh, 360, 376
430, 454, 486sh
430
550
470
435, 460, 493
441, 467, 500shg
443, 469, 501shg
628
439
k
m
m
m
-dpephos)]h
-dbfphos)]h
-biphep)]
450sh, 620
3.0038(6)
620
331, 350, 367, 384f
612f
3.3010(10)
l
430, 450, 489sh
650
600
400
427, 456, 488sh
429, 458, 488sh
k
k
3.3728(9)
3.2766(5)
k
580f
500i
515j
k
k
380, 397, 425sh
In bold means the most intense band.
a
Estimated error: ꢁ1 nm.
b
c
d
e
f
max
lex
¼
labs
solution; estimated error ꢁ1 nm.
Ref. [26].
No study has been performed.
lex ¼ 330 nm; estimated error: ꢁ1 nm.
lex ¼ 280 nm; estimated error: ꢁ1 nm.
lex ¼ 312 nm; estimated error: ꢁ1 nm.
Ref. [8].
lex ¼ 395 nm; estimated error: ꢁ1 nm.
lex ¼ 353 nm; estimated error : ꢁ1 nm.
Emission is not observed.
g
h
i
j
k
l
Aurophilic interaction is not present.
mentioned above. In addition, whereas broad low-energy emission
bands are often related to the presence of metallophilic contacts,
the fact that the luminescence spectrum is dominated by intra-
ligand bands does not necessarily imply that Au/Au contacts are
absent [30].
For the dppe type I derivatives (5e7), the emission maximum is
observed either at the same position that in the starting compound
or slightly red shifted (ca. 60 nm). This indicates that Au/Au
interactions are not present in the pyrazolate-complexes. However,
as in the case of the dppm derivatives, the lack of low energy
emission may be due to other factors.
contacts of ca. 3.3 Å. The luminescent behavior of the three
complexes is consistent with the presence of interactions also in
solution (i.e., emission bands at 600e650 nm, attributed to MC/
MMLCT, are seen in the solution spectra at r.t.). With the exception of
the biphep complex 11, spectroscopic evidence of metallophilic
contacts has not been obtained for any of the other complexes.
However, these are likely to occur, in particular in the case of the
dppm (type I) derivatives. The fact that MC/MMLCT emission bands
have not been identified in the luminescence spectra of these
compoundsmaybe due tothermochromic and/orquenching effects.
Some spectral features appear to be related to the nature of the
pyrazole ligand coordinated to the Au center. Thus, the presence of
methyl groups in the heterocyclic ring gives rise to one band,
whereas those with alkyloxyphenyl substituents show emissions
with well-resolved vibrational structures typical of the aromatic
groups [31]. Finally, as expected, the chain length of the alkyl group
of the alkyloxyphenyl substituents has virtually no effect on the
spectroscopic properties of the compounds [19].
4. Experimental
4.1. Materials and physical measurements
All commercial reagents were used as supplied. The starting Au-
complexes [Au2Cl2(
m
-dppm)] [32], [Au2Cl2(
m-dppe)] [33],
[Au2Cl2( -biphep)] [14,34], [Au2Cl2(
m
m-dbfphos)] [11], [Au2Cl2(m-
dpephos)] [11] and the 3,5-bis(4-alkyloxyphenyl)-1H-pyrazoles
(Hpz2R(n)) (R ¼ C6H4OCnH2nþ1; n ¼ 12, 14, 16) [35], were prepared
by procedures analogous to those previously described.
Elemental analyses (C, H, N) were carried out by the Microan-
alytical Service of Complutense University.
3. Conclusions
The systematic study of the structural and luminescent prop-
erties of a series of diphosphine Au(I) complexes with pyrazole/
pyrazolate ligands offers an insight in the factors that affect such
properties, and how these could therefore be tuned for future
applications of the compounds.
1H and 31P{1H} NMR spectra were performed in CDCl3 at room
temperature on a Bruker DPX-300 spectrometer (NMR Service of
Complutense University). Chemical shifts, d, are listed relative to
TMS using the signal of the deuterated solvent as reference
(7.26 ppm), and coupling constants J are in hertz. Multiplicities are
indicated as s (singlet), d (doublet), dd(doublet of doublets), ddd
(doublet of doublets of doublets), t (triplet), m (multiplet), br
(broad signal). The 1H chemical shifts and coupling constants are
accurate to ꢁ0.01 ppm and ꢁ0.3 Hz, respectively.
A series of pyrazolate-bridged digold(I) complexes (type I) have
been obtained from the reactions of [Au2Cl2(m-diphos)]
(diphos ¼ dppm, dppe, dpephos, dbfphos) with Napz2R. Unex-
pectedly, the same synthetic procedure using [Au2Cl2(m-biphep)]
yielded compounds with two Au-pyrazole moieties attached to the
diphosphine (type II).
The ESI-MS spectra of complexes 2, 7 and 8e10 were acquired
on an LC Squire spectrometer (ESI), using dry MeCN, CHCl3 or
MeOH as solvent.
The crystal structures of [Au2Cl2(m-biphep)] and of the pyrazolate
derivatives with dpephos (9) and dbfphos (10) show weak Au/Au

M.J. Mayoral et al. / Journal of Organometallic Chemistry 696 (2011) 2789e2796
2795
3
The photophysical properties were determined in the solid state
and in solution at 298 and 77 K. UVevis absorption spectra were
recorded on a Perkin Elmer UV/Vis spectrometer Lambda800 and
the emission spectra were recorded on a Perkin Elmer LS55 lumi-
nescence spectrometer equipped with an R928 photomultiplier
and a low temperature accessory.
3JH,H 8.5, Hm), 7.63 (4 H, d, JH,H 8.5, Ho), 6.45e7.94 (20 H, m,
Ph(dppm)). dP(H) (121.49 MHz; CDCl3) 30.6.
4.3.4. [Au2(m
-dppm)(pz2R(16))][OTf] (4)
Yield: 50%. Elemental analyses: found: C, 53.0; H, 5.8; N, 1.6.
C73H97N2O5 F3P2SAu2 requires C, 53.9; H, 6.0; N, 1.7%. dH (300 MHz;
CDCl3; Me4Si) 0.89 (6 H, t, 3JH,H 6.8, CH3), 1.26e1.83 (56 H, m, CH2),
4.2. Crystallographic structure determination
4.04 (6 H, m, OCH2
þ
PCH2P), 6.64e7.94 (29 H, m,
H(40)(pz)) þ Hm þ Ho þ Ph(dppm)). dP(H) (121.49 MHz; CDCl3) 30.6.
Data collection for all compounds was carried out at room
temperature on a Bruker Smart CCD diffractometer using graphite-
4.4. Preparation of complexes of the type [Au2(m-dppe)(m
-pz2R)]
monochromated Mo-K
50 kV and 25 mA for [Au2Cl2(
a
radiation (
l
¼ 0.71073 Å) operating at
[OTf] (R ¼ CH3 (5); R ¼ C6H4OCnH2nþ1, n ¼ 12 (6), n ¼ 14 (7), n ¼ 16
m-biphep)], 50 kV and 20 mA for 9 and
(8))
10. In all cases, data were collected over a hemisphere of the
reciprocal space by combination of three exposure sets. Each
To a solution of [Au2Cl2(m-dppe)] (0.092 mmol) in dry THF was
exposure was of 20 s and covered 0.3ꢀ in
u
. The cell parameter were
added AgOTf (0.184 mmol) and Napz2R (prepared in situ by treating
Hpz2R (0.092 mmol) with an excess of NaH (60% wt in mineral oil)
in dry THF). The reaction mixture was stirred for 24 h in absence of
light, and filtered through celite. The filtrate was concentrated in
vacuum. The addition of hexane/ether afforded the precipitation of
the new complex as a white solid.
determined and refined by a least-squares fit of all reflections. The
first 100 frames were recollected at the end of the data collection to
monitor crystal decay, and no appreciable decay was observed. A
semi-empirical adsorption correction was applied for all cases.
A summary of the fundamental crystal and refinement data are
given in Table S1.
The structures were solved by direct methods and conventional
Fourier techniques and refined by applying full-matrix least-
squares on F2 [36]. All non-hydrogen atoms were refined aniso-
tropically, with the exceptions of the fluorine atoms from the
hexafluorophosphate groups and the crystallization solvent mole-
4.4.1. [Au2(m-dppe)(m
-pz2(CH3))][OTf] (5)
Yield: 48%. Elemental analyses: found: C, 36.6; H, 3.2; N, 3.1.
C32H31N2O3 F3P2SAu2 requires C, 37.1; H, 3.0; N, 2.7%. dH (300 MHz;
CDCl3; Me4Si) 2.42 (6H, s, CH3), 3.11 (4H, br, PCH2CH2P), 6.46 (1H, s,
H(40)(pz)), 7.32e7.97 (20H, m, Ph). dP(H) (121.49 MHz; CDCl3) 32.0.
cules (THF for [Au2Cl2(m-biphep)], CH2Cl2 for 9 and CHCl3 for 10)
which were refined isotropically. In addition, the hexa-
fluorophosphate group in 9 and the crystallization solvent mole-
cules in the three described compounds were refined using
geometric restraints and variable common PeF or CeC, CeO and
CeCl distances respectively. All hydrogen atoms were included in
their calculated positions and refined riding on the respective
carbon atoms.
4.4.2. [Au2(m-dppe)(m
-pz2R(12))][OTf] (6)
Yield: 40%. Elemental analyses: found: C 51.5, H 5.5, N 1.9%;
C66H83N2O5 F3P2SAu2 requires C 51.8, H 5.5, N 1.8. dH (300 MHz;
CDCl3; Me4Si) 0.88 (6H, m, CH3), 1.48e1.82 (40H, m, CH2), 3.17 (4H,
1
3
d, JH,H 8.6, PCH2CH2P), 4.00 (4H, t, JH,H 6.9, OCH2), 6.84 (1H, s,
3
3
H(40)(pz)), 7.04 (4H, d, JH,H 8.3, Hm), 7.76 (4H, d, JH,H 8.3, Ho),
6.90e7.99 (20H, m, Ph(dppe)). dP(H) (121.49 MHz; CDCl3) 32.3.
4.3. Preparation of complexes of the type [Au2(
m
-dppm)(
m
-pz2R)][OTf]
4.4.3. [Au2(m-dppe)(m
-pz2R(14))][OTf] (7)
(R ¼ CH3 (1); R ¼ C6H4OCnH2nþ1, n ¼ 12 (2), n ¼ 14 (3), n ¼ 16 (4))
Yield: 45%. Elemental analyses: found: C, 53.0; H, 5.7; N, 1.7.
C70H91N2O5 F3P2SAu2 requires C, 53.0; H, 5.8; N, 1.7%. dH (300 MHz;
3
To a solution of [Au2Cl2( -dppm)] (0.094 mmol) in dry THF was
m
CDCl3; Me4Si) 0.89 (6H, t, JH,H 6.1, CH3), 1.47e1.82 (48H, m, CH2),
added AgOTf (0.188 mmol) and Napz2R (prepared in situ by treating
Hpz2R (0.094 mmol) with an excess of NaH (60% wt in mineral oil)
in dry THF). The reaction mixture was stirred for 24 h in the absence
of light, and filtered through celite. The filtrate was concentrated in
vacuum. The addition of hexane/ether afforded the precipitation of
the new complex as a white solid.
3.09 (4H, br, PCH2CH2P), 3.99 (4H, t, JH,H 6.2, OCH2), 6.95 (5H, m,
3
H(40)(pz) þ Hm), 7.19e7.67 (20H, m, Ph(dppe)), 7.84 (4 H, m, Ho).
dP(H) (121.49 MHz; CDCl3) 32.2.
4.4.4. [Au2 (m-dppe)(m
-pz2R(16))][OTf] (8)
Yield: 50%. Elemental analyses: found: C, 54.3; H, 6.2; N, 1.7.
C74H99N2O5 F3P2SAu2 requires C, 54.1; H, 6.1; N, 1.7%. dH (300 MHz;
3
4.3.1. [Au2(
m
-dppm)(
m
-pz2(CH3))][OTf] (1)
CDCl3; Me4Si) 0.87 (6H, t, JH,H 6.6, CH3), 1.48e1.84 (56H, m, CH2),
3
Yield: 55%. Elemental analyses: found: C, 36.7; H, 3.2; N, 2.7.
C31H29N2O3 F3P2SAu2 requires C, 36.4; H, 2.9; N, 2.7%. dH (300 MHz;
CDCl3; Me4Si) 2.17 (6 H, s, CH3), 3.44 (2 H, br, PCH2P), 6.24 (1 H, s,
H(40)(pz)), 6.96e8.22 (20 H, m, Ph). dP(H) (121.49 MHz; CDCl3) 36.6.
3.17 (4H, d, 1JH,H 7.1, PCH2CH2P), 4.03 (4H, t, JH,H 6.5, OCH2), 6.99
3
(1H, s, H(40)(pz)), 7.04 (4H, d, JH,H 8.5, Hm), 6.90e7.99 (24H, m,
Ph(dppe) þ Ho). dP(H) (121.49 MHz; CDCl3) 32.2.
4.5. Preparation of compound [Au2(
m-dpephos)(m
-pz2(CH3))][PF6] (9)
4.3.2. [Au2(m-dppm)(m
-pz2R(12))][OTf] (2)
Yield: 42%. Elemental analyses: found: C, 52.2; H, 5.7; N, 2.0.
C65H81N2O5 F3P2SAu2 requires C, 52.1; H, 5.5; N, 1.8%. dH (300 MHz;
CDCl3; Me4Si) 0.88 (6 H, t, 3JH,H 6.11, CH3), 1.27e1.83 (40 H, m, CH2),
To a solution of [Au2Cl2( -dpephos)] (80 mg, 0.079 mmol) in dry
m
THF was added AgPF6 (40.20 mg, 0.159 mmol) and Napz2R(Me),-
prepared in situ by treating Hpz2(CH3) (7.59 mg, 0.079 mmol) with
an excess of NaH in dry THF. The reaction mixture was stirred for
24 h in absence of light, and filtered through celite. The filtrate was
concentrated in vacuum. The addition of hexane/ether afforded the
precipitation of the new complex as a white solid.
3.94 (6 H, m, OCH2
þ
PCH2P), 6.62e7.94 (29 H, m,
H(40)(pz) þ Hm þ Ho þ Ph(dppm)). dP(H) (121.49 MHz; CDCl3) 30.7.
4.3.3. [Au2(m-dppm)(m
-pz2R(14))][OTf] (3)
Yield: 40%. Elemental analyses: found: C, 53.6; H, 5.8; N, 1.8.
C69H89N2O5 F3P2SAu2 requires C, 53.3; H, 5.9; N, 1.7%. dH (300 MHz;
CDCl3; Me4Si) 0.87 (6 H, t, 3JH,H 6.8, CH3), 1.27e1.87 (48 H, m, CH2),
3.95 (6 H, m, OCH2 þ PCH2P), 6.45 (1 H, s, H(40)(pz)), 6.82 (4 H, d,
Yield: 55%. Elemental analyses: found: C, 42.0; H, 3.0; N, 2.2.
C41H35N2OF6P3Au2 requires C, 42.0; H, 3.0; N, 2.4%. dH (300 MHz;
CDCl3; Me4Si) 2.34 (6H, s, CH3), 6.37 (1 H, s, H(40)(pz)), 5.79 (2H,
apparent dd, 3JH,H 5.5, 4JH,H 8.3, H(6)), 6.60 (2H, m, H(3)), 6.77 (2H,

2796
M.J. Mayoral et al. / Journal of Organometallic Chemistry 696 (2011) 2789e2796
ddd, 3JH,H 6.9, 4JH,H 2.5, H(3)), 7.06 (2 H, t, 3JH,H 7.4, H(5)), 7.16 (2H, t,
3JH,H 7.6, H(4)), 7.76e7.46 (20H, m, Ph). dP(H) (121.49 MHz; CDCl3)
22.1.
Appendix A. Supplementary material
CCDC 808500, 808501 and 808502 contain the supplementary
crystallographic data for this paper. These data can be obtained free
of charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
4.6. Preparationof compound[Au2(
m-dbfphos)(m
-pz2(CH3))][PF6] (10)
To a solution of [Au2Cl2( -dbfphos)] (80 mg, 0.080 mmol) in dry
m
THF was added AgPF6 (40.45 mg, 0.160 mmol) and Napz2R(Me),-
prepared in situ by treating Hpz2(CH3) (7.70 mg, 0.080 mmol) with
an excess of 60% NaH (60% wt in mineral oil) in dry THF. The
reaction mixture was stirred for 24 h in absence of light, and filtered
through celite. The filtrate was concentrated in vacuum. The addi-
tion of hexane/ether afforded the precipitation of the new complex
as a white solid.
Appendix. Supplementary material
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.jorganchem.2011.04.022.
References
Yield: 65%. Elemental analyses: found: C, 41.3; H, 2.8; N, 2.1.
C41H33N2OF6P3Au2 requires C, 41.6; H 2.9; N, 2.2. dH (300 MHz;
CDCl3; Me4Si) 2.41 (6H, s, CH3), 6.37 (1H, s, H(40)(pz)), 6.86 (2H, dd,
3JH,H 7.3, H(3) þ H(7)), 7.62e7.40 (22 H, m, Ph), 8.35 (2H, d, 3JH,H 7.8,
H(1) þ H(9)). dP(H) (121.49 MHz; CDCl3) 18.2.
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(2004) 1761.
4.7. Preparation of compounds of the type [Au2(
[OTf]2 (R ¼ CH3 (11); R ¼ C6H4OCnH2nþ1, n ¼ 14 (12), n ¼ 16 (13))
m
-biphep)(Hpz2R))2]
To a solution of [Au2Cl2( -biphep)] (0.092 mmol) in dry THF was
m
added AgOTf (0.185 mmol) and Napz2R, prepared by treating Hpz2R
(0.092 mmol) with an excess of NaH (60% wt in mineral oil) in dry
THF. The reaction mixture was stirred for 24 h in absence of light,
and filtered through celite. The filtrate was concentrated in
vacuum. The addition of hexane/ether afforded the precipitation of
the new complex as a white solid.
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4.7.1. [Au2(m
-biphep)(Hpz2R(CH3))2][OTf]2 (11)
Yield: 54%. Elemental analyses: found: C, 41.1; H, 3.1; N, 3.8.
C48H44N4O6 F6P2S2Au2 requires C, 41.0; H, 3.1; N, 4.0%. dH (300 MHz;
CDCl3; Me4Si) 1.98 (6H, s, CH3), 2.39 (6H, s, CH3), 6.27 (2H, s,
H(40)(pz)), 6.43e7.64 (28H, m, Ph þ H(3), H(4), H(5) and H(6)
biphep). dP(H) (121.49 MHz; CDCl3) 25.7.
4.7.2. [Au2(m
-biphep)(Hpz2R(14))2][OTf]2 (12)
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Yield: 55%. Elemental analyses: found: C, 59.3; H, 6.3; N, 2.1.
C124H164N4O10 F6P2S2Au2 requires C, 59.5; H, 6.5; N, 2.2%. dH
3
(300 MHz; CDCl3; Me4Si) 0.88 (12H, t, JH,H 6.3, CH3), 1.27e1.92
3
3
(96H, m, CH2), 3.99 (4H, t, JH,H 6.6, OCH2), 4.05 (4H, t, JH,H 6.5,
OCH2), 6.84 (8H, d, 3JH,H 8.7, Hm), 7.80 (8H, d, 3JH,H 8.7, Ho), 6.20e7.93
(30H, m, Ph þ H(3), H(4), H(5) and H(6) biphep þ H(40)(pz)). dP(H)
(121.49 MHz; CDCl3) 24.7.
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4.7.3. [Au2(m
-biphep)(Hpz2R(16))2][OTf]2 (13)
Yield: 56%. Elemental analyses: found: C, 60.4; H, 7.1; N, 2.2.
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C132H180N4O10 F6P2S2Au2 requires C, 60.1; H, 7.0; N, 2.1%. dH
3
(300 MHz; CDCl3; Me4Si) 0.88 (12H, t, JH,H 6.8, CH3), 1.22e1.88
3
3
(112H, m, CH2), 3.99 (4H, t, JH,H 6.6, OCH2), 4.05 (4H, t, JH,H 6.2,
3
3
OCH2), 6.84 (8H, d, JH,H 8.6, Hm), 7.79 (8H, d, JH,H 8.6, Ho),
6.20e7.81 (30H, m, Ph
þ
H(3), H(4), H(5) and H(6)
biphep þ H(40)(pz)). dP(H) (121.49 MHz; CDCl3) 24.7.
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Acknowledgments
We thank the Secretaría de Estado de Investigación (DGU) del
Ministerio de Ciencia e Investigación of Spain, projects CTQ2009-
11880 and CTQ2010-19470, and Universidad Complutense de
Madrid (Spain), project UCM2009-910300. A. P.-A. acknowledges
the McClay Trust for financial support. We also thank Claudio
Mendicute-Fierro for his help with the luminescent measurements.