Heteropolynuclear gold complexes with metallophilic interactions: Modulation of the luminescent properties

Article abstract of DOI:10.1021/ic100413x

Metalloligands of stoichiometry [AuCl(P-N)] have been obtained by the reaction of the heterofunctional phosphines P-N = PPh₂py, PPh ₂CH₂CH₂py, or PPhpy₂ with [AuCl(tht)] (tht = tetrahydrothiophene). Reactions of these metalloligands with several metal compounds have afforded heteropolynuclear species which exhibit luminescent properties. The stoichiometries depend on the molar ratio and the heterometal. Thus, the reaction with [Cu(NCMe)₄]⁺ in a molar ratio 2:1 gives the trinuclear compounds [Au₂CuCl ₂(P-N)₂]⁺, in which the structure and Au...Cu interactions depend on the phosphine ligand. With rhodium and iridium derivatives the reactivity is different leading to complexes of the type [AuMCl₂(cod)(P-N)] for P-N = PPh₂py, PPhpy₂, and [Au₂M₂Cl(cod)₂(P-N)₂]Cl with PPh₂CH₂CH₂py. Using [MCl₂(NCPh) ₂] (M = Pd, Pt) in a 2:1 molar ratio yields [Au₂MCl ₄(P-N)₂] and in a 1:1 molar ratio [AuPdCl ₃(μ₃-PPhpy₂)]. Several compounds have been characterized by X-ray diffraction showing in many cases short Au...M distances. The luminescence of these derivatives has been studied. The metalloligands display bands assigned to intraligand (IL) transitions. For the bimetallic (Au/M) systems the luminescence depends on the heterometal present and on the metallophilic interactions. The most important excitations in the relevant energy range were assigned essentially a MMLCT character (from Rh/Ir and Au to ligands) based on density functional theory (DFT) calculations in selected complexes. The luminescence behavior in Rh/Ir [AuMCl ₂(cod)(PPh₂py)] complexes was interpreted on the basis of the different nature of the half occupied orbitals in the triplet state.

Full text of DOI:10.1021/ic100413x

Inorg. Chem. 2010, 49, 8255–8269 8255
DOI: 10.1021/ic100413x
Heteropolynuclear Gold Complexes with Metallophilic Interactions:
Modulation of the Luminescent Properties
‡
†
†
,†
†
ꢀ
ꢀ
Maria Jose Calhorda, Carmen Ceamanos, Olga Crespo, M. Concepcion Gimeno,* Antonio Laguna,
Carmen Larraz,† Pedro D. Vaz,‡ and M. Dolores Villacampa†
†
´
ꢀ
ꢀ
Departamento de Quımica Inorganica, Instituto de Ciencia de Materiales de Aragon, Universidad de
‡
´
´
Zaragoza-C.S.I.C., E-50009 Zaragoza, Spain, and Departamento de Quımica e Bioquımica, CQB,
^
Faculdade de Ciencias da Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal
Received March 2, 2010
Metalloligands of stoichiometry [AuCl(P-N)] have been obtained by the reaction of the heterofunctional phosphines
P-N = PPh2py, PPh2CH2CH2py, or PPhpy2 with [AuCl(tht)] (tht = tetrahydrothiophene). Reactions of these
metalloligands with several metal compounds have afforded heteropolynuclear species which exhibit luminescent
properties. The stoichiometries depend on the molar ratio and the heterometal. Thus, the reaction with [Cu(NCMe)4]þ
in a molar ratio 2:1 gives the trinuclear compounds [Au2CuCl2(P-N)2]þ, in which the structure and Au Cu
3 3 3
interactions depend on the phosphine ligand. With rhodium and iridium derivatives the reactivity is different leading to
complexes of the type [AuMCl2(cod)(P-N)] for P-N = PPh2py, PPhpy2, and [Au2M2Cl(cod)2(P-N)2]Cl with
PPh2CH2CH2py. Using [MCl2(NCPh)2] (M = Pd, Pt) in a 2:1 molar ratio yields [Au2MCl4(P-N)2] and in a 1:1 molar
ratio [AuPdCl3(μ3-PPhpy2)]. Several compounds have been characterized by X-ray diffraction showing in many cases
short Au M distances. The luminescence of these derivatives has been studied. The metalloligands display bands
3 3 3
assigned to intraligand (IL) transitions. For the bimetallic (Au/M) systems the luminescence depends on the
heterometal present and on the metallophilic interactions. The most important excitations in the relevant energy range
were assigned essentially a MMLCT character (from Rh/Ir and Au to ligands) based on density functional theory (DFT)
calculations in selected complexes. The luminescence behavior in Rh/Ir [AuMCl2(cod)(PPh2py)] complexes was
interpreted on the basis of the different nature of the half occupied orbitals in the triplet state.
Introduction
nates from these aurophilic interactions.3,4 Heterometallic
gold species are also receiving a great deal of attention
because the interaction between gold atoms and other metal
centers may give rise to unusual structural frameworks and
properties, as exemplified in mixed complexes with several
metals such as silver, copper, thallium, mercury, and so forth.
Many of them present interesting luminescent properties that
are enhanced by the presence of these metallophilic interactions.
Suchheterometallic complexes can beobtainedby reaction of
[AuR2]- salts with metal centers which lead to donor-acceptor
species,5 by the reaction of trinuclear gold species [Au3(L-L)3],6
from the metallocryptands [Au2(L-L)3]2þ,7 or by reaction of
[Au(CN)2]- salts with different metals.8 However, the origin
The chemistry of gold has received much attention in the
past years in view of the intriguing features presented by its
complexes as, for example, the tendency of gold complexes to
aggregate into oligomers or supramolecular assemblies through
metal-metal interactions.1,2 These secondary bonds often
result in the interesting photochemical and photophysical
properties of the gold-containing complexes. Indeed, it has
been shown in many examples that their luminescence origi-
*To whom correspondence should be addressed. E-mail: gimeno@unizar.es.
(1) (a) Gold, Progress in Chemistry, Biochemistry and Technology; Schmid-
baur, H., Ed.; John Wiley & Sons: New York, 1999. (b) Modern Supramolecular
Gold Chemistry: Gold-Metal Interactions and Applications; Laguna, A.; Ed.
Wiley-VCH: New York, 2008.
(2) Gimeno, M. C.; Laguna, A. Comprehensive Coordination Chemistry
II; McCleverty, J. A., Meyer, T. J., Eds.; Elsevier: New York, 2003; Vol. 5, pp
911-1145.
(3) (a) Forward, J. M.; Fackler, J. P. Jr.; Assefa, Z. Optoelectronic
Properties of Inorganic Compounds; Roundhill, D. M., Fackler, J. P. J., Eds.;
Plenum Press: New York, 1999; pp 195-230. (b) Balch, A. L. Gold Bull. 2004,
37, 1–2. (c) Yam, V. W. W.; Chan, C. L.; Li, C. K.; Wong, K. M. C. Coord. Chem.
Rev. 2001, 216-217, 173–194. (d) Yam, V. W. W. Chem. Soc. Rev. 2008, 37,
1806–1813.
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€
J. M.; Monge, M.; Pyykko, P.; Sundholm, D. J. Am. Chem. Soc. 2000, 122,
ꢀ
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7287–7293. (b) Fernandez, E. J.; Lopez de Luzuriaga, J. M.; Monge, M.; Olmos,
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M. E.; Perez, J.; Laguna, A.; Mohamed, A. A.; Fackler, J. P., Jr. J. Am. Chem.
Soc. 2003, 125, 2022–2033.
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R. J. Chem. Commun. 1998, 95–96. (b) Burini, A.; Fackler, J. P., Jr.; Galassi, R.;
Grant, T. A.; Omary, M. A.; Rawashdeh-Omary, M. A.; Pietroni, B. R.; Staples,
R. J. J. Am. Chem. Soc. 2000, 122, 11264–11265.
(4) (a) Lee, Y. A.; Eisenberg, R. J. Am. Chem. Soc. 2003, 125, 7778–7779.
(b) Mansour, M. A.; Connick, W. B.; Lachicotte, R. J.; Gysling, H. J.; Eisenberg,
R. J. Am. Chem. Soc. 1998, 120, 1329–1320.
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r
2010 American Chemical Society
Published on Web 08/19/2010
pubs.acs.org/IC

8256 Inorganic Chemistry, Vol. 49, No. 18, 2010
Calhorda et al.
of the luminescent properties may be associated with such
different factors as the nature of the ligand and the hetero-
metal, or the presence or absence of metalophilic interactions.
Not many systematic studies of the luminescence properties
of heterometallic entities with different ligands and metals
have been published. We have previously reported the reac-
tion of chalcogenide gold complexes of stoichiometry [E{Au-
(P-N)}3]þ, where P-N represents a heterofunctional ligand
with silver or copper derivatives, which led to highly lumi-
nescent derivatives.9 However, the study could not be ex-
tended to many metal centers owing to the specific coordina-
tion requirements of the metalloligands. Therefore, in this
work ouraim was tosynthesize heteropolynuclearderivatives
of gold with potential luminescence properties. To achieve
this goal, we have selected heterofunctional ligands, with a
soft and a hard donor functionality, such as phosphines
2-pyridyldiphenylphosphine, 2-pyridylethyldiphenylphosphine,
and bis(2-dipyridyl)phenylphosphine. These ligands coordi-
nate to gold through the phosphorus atom and leave one or
two free donor atoms for other metal centers. This kind of
ligands have played an important role in the construction of
homo and heterodinuclear complexes as exemplified by the
use of 2-pyridylphenylphosphine.10 The challenge here is to
prepare a variety of complexes starting from the gold species
[AuCl(P-N)] and different metal centers such as Cu(I),
Rh(I), Ir(I), Pd(II), or Pt(II) and observe the trends, not only
on the structural frameworks and coordination modes but
also on the associated luminescence properties. These may be
modified by the influence of the heterometallic ligand on the
electronic spectra transitions and the states leading to emis-
sion. Density functional theory (DFT) and time dependent
DFT (TD-DFT) studies have been carried out to comple-
ment the experimental studies and to interpret the results.
Figure 1. Structure of complex 3 showing the atom numbering scheme.
Displacement parameter ellipsoids represent 50% probability surfaces. H
atoms are omitted for clarity.
Table 1. Bond Lengths [A] and Angles [deg] for Complex 3
Au(1)-P(1)
Au(1)-Cl(1)
P(1)-C(21)
P(1)-C(1)
2.2316(8)
2.2853(8)
1.814(3)
1.817(3)
1.823(3)
C(1)-N(1)
C(5)-N(1)
C(11)-N(2)
C(15)-N(2)
1.366(4)
1.354(5)
1.352(4)
1.347(4)
P(1)-C(11)
P(1)-Au(1)-Cl(1)
C(21)-P(1)-C(1)
C(21)-P(1)-C(11)
C(1)-P(1)-C(11)
C(21)-P(1)-Au(1)
C(1)-P(1)-Au(1)
C(11)-P(1)-Au(1)
N(1)-C(1)-C(2)
N(1)-C(1)-P(1)
C(2)-C(1)-P(1)
178.40(3)
107.02(15)
106.98(15)
102.35(15)
111.92(11)
112.83(11)
114.99(11)
121.1(3)
N(1)-C(5)-C(4)
C(5)-N(1)-C(1)
N(2)-C(11)-C(12)
N(2)-C(11)-P(1)
C(12)-C(11)-P(1)
N(2)-C(15)-C(14)
C(15)-N(2)-C(11)
C(22)-C(21)-P(1)
C(26)-C(21)-P(1)
122.0(4)
118.7(3)
124.1(3)
111.5(2)
124.3(3)
123.3(4)
116.4(3)
120.9(3)
118.2(3)
118.2(3)
120.7(3)
1
In the H NMR spectra, the resonances of the phenyl and
pyridine protons are observed, as well as two multiplets for
the methylene groups. Complex 1 has been structurally
characterized previously by Alcock et al.11c The structure
of complex 3 has been established by X-ray diffraction and is
shown in Figure 1. A selection of bond lengths and angles are
collected in Table 1. The coordination around the gold center
is linear with a Cl-Au-P angle of 178.40(3)°, and bond
distances Au-P of 2.2316(8) A and Au-Cl of 2.2853(8) A.
There are no short intermolecular aurophilic contacts in
contrast to those found in complex 1. However, there are
several Au H and Cl H short contacts that can be
Results and Discussion
The reaction of the gold complex [AuCl(tht)] with hetero-
functional phosphine ligands such as PPh2py, PPh2CH2CH2py,
or PPhpy2 gives the gold-phosphine metalloligands [AuCl-
(P-N)] (P-N = PPh2py (1), PPh2CH2CH2py (2), PPhpy2
(3)) (eq 1).
3 3 3
3 3 3
Complexes 111a and 311b have been previously prepared.
For complex 2 the 31P{1H} NMR spectrum shows the
presence of only one phosphorus resonance at 29.52 ppm.
classified as hydrogen bonds.
In these complexes the heterofunctional phosphine ligands
have pyridine groups that can be used to coordinate to other
metal centers. Thus the reaction of complexes 1-3 with the
copper(I) species [Cu(NCMe)4]X in a molar ratio 2:1 gives
the trinuclear derivatives [Au2CuCl2(P-N)2]X (P-N =
PPh2py, X = BF4 (4); PPh2CH2CH2py, X = PF6 (5);
PPhpy2, X = BF4 (6)) according to the Scheme 1.
The crystal structure of complex 4 has been established by
X-ray diffraction and is shown in Figure 2. A selection of
bond lengths and angles are collected in Table 2. The struc-
ture is based on a triangular Au2Cu cluster with an aurophilic
(8) (a) Lefebvre, J.; Batchelor, R. J.; Leznoff, D. B. J. Am. Chem. Soc.
2004, 126, 16117–16125. (b) Katz, M. J.; Sakai, K.; Leznoff, D. B. Chem. Soc.
Rev. 2008, 37, 1884–1895.
(9) (a) Wang, Q. M.; Lee, Y. A.; Crespo, O.; Deaton, J.; Tang, C.;
Gysling, H. J.; Gimeno, M. C.; Larraz, C.; Villacampa, M. D.; Laguna, A.;
Eisenberg, R. J. Am. Chem. Soc. 2004, 126, 9488–9489. (b) Crespo, O.;
Gimeno, M. C.; Laguna, A.; Larraz, C.; Villacampa, M. D. Chem.—Eur. J. 2007,
13, 235–246.
(10) (a) Farr, J. P.; Olmstead, M. M.; Balch, A. L. J. Am. Chem. Soc. 1980,
21, 6654–6656. (b) Farr, J. P.; Olmstead, M. M.; Hunt, C. H.; Balch, A. L. Inorg.
Chem. 1981, 20, 1182–1187. (c) McNair, R. J.; Nilsson, P. V.; Pignolet, L. H.
Inorg. Chem. 1985, 24, 1935–1939. (d) Olmos, M. E.; Schier, A.; Schmidbaur, H.
Z. Naturforsch., B: Chem. Sci. 1997, 52, 203–208. (e) Farr, J. P.; Olmstead,
M. P.; Wood, F. E.; Balch, A. L. J. Am. Chem. Soc. 1983, 105, 792–798.
(11) (a) Ang, H. G.; Know, W. E.; Mok, K. F. Inorg. Nucl. Chem. Lett.
1972, 8, 829–832. (b) Inoguchi, Y.; Milewski-Mahrla, B.; Schmidbaur, H. Chem.
Ber. 1982, 115, 3085–3095. (c) Alcock, N. W.; Moore, P.; Lampe, P. A.; Mok,
K. F. J. Chem. Soc., Dalton Trans. 1982, 207–210.
Au(1)-Au(2) contact of 3.0658(5) A, and Au(1) Cu(1)
3 3 3
and Au(2) Cu(1) contacts of 2.9827(11) A and 3.0485(11) A,
3 3 3
respectively. The copper atom is also bonded to the nitrogen
atoms of the pyridine groups with distances Cu(1)-N(1) and
Cu(1)-N(2) of 1.892(8) A and 1.888(8) A. The gold centers
have a linear geometry slightly distorted because of the

Article
Inorganic Chemistry, Vol. 49, No. 18, 2010 8257
Scheme 1
Table 2. Bond Lengths [A] and Angles [deg] for Complex 4
Au(1)-P(1)
Au(1)-Cl(1)
Au(1)-Cu(1)
Au(1)-Au(2)
Au(2)-P(2)
2.226(2)
2.296(2)
2.9827(11) Cu(1)-N(2)
3.0658(5)
2.233(2)
Au(2)-Cl(2)
Au(2)-Cu(1)
2.297(2)
3.0485(11)
1.888(8)
1.892(8)
Figure 3. Structure of complex 7 showing the atom numbering scheme.
Displacement parameter ellipsoids represent 30% probability surfaces. H
atoms are omitted for clarity.
Cu(1)-N(1)
groups form four covalent Cu-N bonds, defining a tetra-
hedral coordination of Cu(I), different from the linear co-
ordination observed in complex 4, where only two pyridine
groups are present in the ligands. This coordination is corro-
borated by NMR spectroscopy in solution and thus the 1H
NMR spectrum shows equivalent pyridine protons for all the
complexes even at low temperature. The 31P{1H} NMR
spectra show in all the cases one unique resonance indicating
the equivalence of the phosphorus atoms.
P(1)-Au(1)-Cl(1)
P(1)-Au(1)-Cu(1)
Cl(1)-Au(1)-Cu(1) 113.98(6)
P(1)-Au(1)-Au(2) 100.60(6)
Cl(1)-Au(1)-Au(2) 83.76(5)
Cu(1)-Au(1)-Au(2) 60.51(2)
P(2)-Au(2)-Cl(2)
P(2)-Au(2)-Cu(1)
Cl(2)-Au(2)-Cu(1) 116.50(6)
174.10(8)
71.80(6)
P(2)-Au(2)-Au(1)
Cl(2)-Au(2)-Au(1) 82.64(6)
Cu(1)-Au(2)-Au(1) 58.39(2)
103.19(6)
N(2)-Cu(1)-N(1)
N(2)-Cu(1)-Au(1)
N(1)-Cu(1)-Au(1)
N(2)-Cu(1)-Au(2)
N(1)-Cu(1)-Au(2)
176.1(3)
84.0(2)
94.3(2)
91.7(2)
84.4(2)
172.97(8)
70.29(6)
Au(1)-Cu(1)-Au(2) 61.09(2)
We have also studied the reaction of complexes 1-3 with
[M(μ-Cl)(cod)]2 (M = Rh or Ir) in a 2:1 molar ratio. The
results depend on the phosphine used. When the phosphine
ligand is PPh2py, the dinuclear complexes with Au Rh or
3 3 3
Au Ir short contacts are obtained (eq 2).
3 3 3
The 1H NMR spectra show the protons corresponding to
the phosphine and cycloctadiene (cod); the olefinic protons
appear around 4 ppm whereas the alkyl ones appear around
2.5 and 1.7 ppm. The 31P{1H} NMR spectra show only one
resonance for the phosphorus atom. The structures of com-
plexes 7 and 8 have been established by X-ray diffraction and
are shown in Figures 3 and 4. A selection of bond lengths and
angles are presented in Tables 3 and 4. They have intermetallic
distances Au Rh of 3.0385(9) A or Au Ir of 3.0148(4) A.
Figure 2. Structure of complex 4 showing the atom numbering scheme.
Displacement parameter ellipsoids represent 50% probability surfaces. H
atoms are omitted for clarity.
presence of metal metal short contacts, with the P(2)-
3 3 3
3 3 3
3 3 3
Au(2)-Cl(2) angle being 172.97(8)°, and P(1)-Au(1)-Cl(1)
174.10(8)°. The N(2)-Cu(1)-N(1) angle is 176.1(3)°, which
defines a linear geometry for the Cu atom, distorted also by
the metal close proximity to the other metals.
The geometry of the gold atom is distorted from linear, with
P-Au-Cl angles of 169.59(8)° for the rhodium complex and
169.28(7)° for the iridium derivative, which may be a con-
sequence of the metal metal short contacts. The Rh and Ir
3 3 3
These complexes have different colors, namely, complex 4
is yellow, complex 5 is white, and complex 6 orange. The
copper center is probably bonded in all complexes to the
nitrogen atoms of the heterofunctional phosphine ligands,
centers have a square-planar geometry, the narrower angles
being N(1)-Rh(I)-Cl(2) of 86.12(19)° and N(1)-Ir(1)-
Cl(2) of 86.99(15)°. The Rh-N distances of 2.118(6) A and
Ir-N of 2.109(5) A are similar to other M-N bonds in Rh(I)
or Ir(I) complexes, respectively.10a,12
and the color can be indicative of the presence of Au Cu
3 3 3
interactions, which should be favored in complexes 4 and 6
but not in complex 5 because of the longer chain of the phos-
phine ligand. In complex 6 it is likely that the four pyridine
(12) Drury, W. J., III; Zimmermann, N.; Keenan, M.; Hayashi, M.;
Kaiser, S.; Goddard, R.; Pfaltz, A. Angew. Chem., Int. Ed. 2004, 43, 70–74.

8258 Inorganic Chemistry, Vol. 49, No. 18, 2010
Calhorda et al.
Figure 4. Structure of complex 8 showing the atom numbering scheme.
Displacement parameter ellipsoids represent 50% probability surfaces. H
atoms are omitted for clarity.
Figure 5. Structure of complex 9 showing the atom numbering scheme.
Displacement parameter ellipsoids represent 50% probability surfaces. H
atoms are omitted for clarity.
Table 3. Bond Lengths [A] and Angles [deg] for Complex 7
Au(1)-P(1)
Au(1)-Cl(1)
Au(1)-Rh(1)
Rh(1)-N(1)
Rh(1)-C(30)
Rh(1)-C(27)
Rh(1)-C(26)
2.223(2)
2.308(2)
3.0385(9) P(1)-C(1)
2.118(6)
2.135(7)
2.135(8)
2.140(8)
Rh(1)-C(31)
Rh(1)-Cl(2)
2.154(7)
2.374(2)
1.812(8)
1.823(8)
1.835(8)
1.358(9)
1.349(10)
Table 5. Selected Bond Lengths [A] and Angles [deg] for Complex 9
P(1)-C(11)
P(1)-C(21)
C(21)-N(1)
C(25)-N(1)
Au(1)-P(1)
Au(1)-Cl(1)
Rh(1)-N(1)
Rh(1)-C(28)
2.2393(16) Rh(1)-C(24)
2.2913(16) Rh(1)-C(29)
2.123(5)
2.138(5)
2.152(5)
2.3809(17)
2.108(4)
2.121(5)
Rh(1)-C(25)
Rh(1)-Cl(2)
P(1)-Au(1)-Cl(1)
P(1)-Au(1)-Rh(1)
Cl(1)-Au(1)-Rh(1)
N(1)-Rh(1)-C(30)
N(1)-Rh(1)-C(27)
C(30)-Rh(1)-C(27) 81.1(3)
N(1)-Rh(1)-C(26) 93.9(3)
C(30)-Rh(1)-C(26) 97.8(3)
C(27)-Rh(1)-C(26) 38.4(3)
N(1)-Rh(1)-C(31)
C(30)-Rh(1)-C(31) 37.8(3)
C(27)-Rh(1)-C(31) 88.8(3)
C(26)-Rh(1)-C(31) 81.4(3)
N(1)-Rh(1)-Cl(2)
C(30)-Rh(1)-Cl(2)
C(31)-C(30)-Rh(1) 71.8(4)
C(29)-C(30)-Rh(1) 109.2(5)
169.59(8) C(27)-Rh(1)-Cl(2)
81.95(6) C(26)-Rh(1)-Cl(2)
157.8(2)
163.8(2)
95.5(2)
P(1)-Au(1)-Cl(1)
N(1)-Rh(1)-C(28)
N(1)-Rh(1)-C(24)
178.37(5)
91.34(18)
156.0(2)
C(28)-Rh(1)-C(25) 82.2(2)
C(24)-Rh(1)-C(25) 37.8(2)
C(29)-Rh(1)-C(25) 89.8(2)
108.13(6) C(31)-Rh(1)-Cl(2)
153.3(3)
93.8(3)
N(1)-Rh(1)-Au(1)
86.49(17)
C(28)-Rh(1)-C(24) 98.9(2)
N(1)-Rh(1)-Cl(2)
88.31(12)
C(30)-Rh(1)-Au(1) 117.2(2)
C(27)-Rh(1)-Au(1) 128.4(2)
C(26)-Rh(1)-Au(1) 90.0(2)
C(31)-Rh(1)-Au(1) 83.4(2)
N(1)-Rh(1)-C(29)
92.67(19)
C(28)-Rh(1)-Cl(2) 157.10(15)
C(24)-Rh(1)-Cl(2) 90.41(18)
C(29)-Rh(1)-Cl(2) 164.44(15)
C(28)-Rh(1)-C(29) 38.4(2)
C(24)-Rh(1)-C(29) 82.4(2)
N(1)-Rh(1)-C(25)
166.19(19) C(25)-Rh(1)-Cl(2) 92.91(17)
Cl(2)-Rh(1)-Au(1)
C(25)-N(1)-Rh(1)
C(21)-N(1)-Rh(1)
C(27)-C(26)-Rh(1)
C(33)-C(26)-Rh(1)
73.75(6)
114.1(5)
128.4(5)
70.6(5)
111.1(6)
71.0(4)
113.8(6)
70.3(4)
111.7(5)
168.9(3)
The structure of complex 9 has been confirmed by X-ray
diffraction and shown to be a dinuclear molecule as depicted
in Figure 5. Selected bond lengths and angles are collected in
Table 5. The complex crystallizes with a water molecule.
Gold-rhodium interactions are prevented by the relative
orientation between the two metals, as might be expected
owing to the long chain of the functionalized phosphine.
The gold center has a linear coordination with a Cl-Au-P
angle of 178.37(5)°, whereas the rhodium center displays a
square planar geometry, distorted because of the bite angle of
the cycloctadiene ligand, C-Rh-C 82.4(2)° or 82.2(2)°. The
Rh-N distance is 2.108(4) A, which is of the same order than
86.12(19) C(26)-C(27)-Rh(1)
89.0(2)
C(28)-C(27)-Rh(1)
C(30)-C(31)-Rh(1)
C(32)-C(31)-Rh(1)
Table 4. Selected Bond Lengths [A] and Angles [deg] for Complex 8
Au(1)-P(1)
Au(1)-Cl(1)
Au(1)-Ir(1)
Ir(1)-C(31)
Ir(1)-N(1)
2.2213(16)
2.3063(17)
3.0148(4)
2.099(6)
Ir(1)-C(38)
Ir(1)-C(35)
Ir(1)-C(34)
Ir(1)-Cl(2)
2.129(7)
2.133(6)
2.136(6)
2.3561(17)
2.109(5)
that in complex 7. There are several Cl H short con-
3 3 3
tacts about 2.8 A, which can be classified as hydrogen bonds;
one of them involves the hydrogen from the water molecule
with a distance Cl2-H0 of 2.581 A.
This crystal structure of complex 9 confirms the same
structural pattern observed in compounds 7 and 8. However,
the NMR data of complexes 9 and 10 do not agree with this
structure as they show a structural pattern different from that
of complexes 7 and 8, with two inequivalent phosphine and
P(1)-Au(1)-Cl(1)
P(1)-Au(1)-Ir(1)
Cl(1)-Au(1)-Ir(1)
C(31)-Ir(1)-N(1)
C(31)-Ir(1)-C(38)
N(1)-Ir(1)-C(38)
C(31)-Ir(1)-C(35)
N(1)-Ir(1)-C(35)
C(38)-Ir(1)-C(35)
C(31)-Ir(1)-C(34)
N(1)-Ir(1)-C(34)
C(38)-Ir(1)-C(34)
169.28(7)
82.44(4)
108.14(5)
92.6(2)
39.0(2)
92.4(2)
98.4(3)
152.9(2)
81.2(3)
81.3(3)
167.8(2)
89.5(3)
C(35)-Ir(1)-C(34)
C(31)-Ir(1)-Cl(2)
N(1)-Ir(1)-Cl(2)
C(38)-Ir(1)-Cl(2)
C(35)-Ir(1)-Cl(2)
C(34)-Ir(1)-Cl(2)
C(31)-Ir(1)-Au(1)
N(1)-Ir(1)-Au(1)
C(38)-Ir(1)-Au(1)
C(35)-Ir(1)-Au(1)
C(34)-Ir(1)-Au(1)
Cl(2)-Ir(1)-Au(1)
39.2(3)
164.67(18)
86.99(15)
156.33(19)
88.65(19)
96.1(2)
89.74(18)
86.90(14)
128.69(18)
117.64(18)
82.55(19)
74.93(4)
1
cycloctadiene ligands. In the H NMR spectra, the reso-
nances corresponding to two different pyridine groups and
two cyclooctadiene ligands are observed; furthermore all the
protons of the cyclooctadiene ligands appear as inequivalent.
In the 31P{1H} NMR spectra two resonances are observed for
each complex, with a chemical shift characteristic of phos-
phorus bonded to gold, namely, 32.41 and 29.49 ppm for the
The reaction of [AuCl(PPh2CH2CH2py)] with [M(μ-Cl)-
(cod)]2 (M = Rh, Ir) in a 2:1 molar ratio gives yellow solids
of complexes 9 and 10. The conductivity measurements
indicate that the compounds are conductors.

Article
Inorganic Chemistry, Vol. 49, No. 18, 2010 8259
Scheme 2
Scheme 3
Figure 6. Structure of complex 12 showing the atom numberingscheme.
Displacement parameter ellipsoids represent 30% probability surfaces. H
atoms are omitted for clarity.
Table 6. Selected Bond Lengths [A] and Angles [deg] for Complex 12
Au(1)-P(1)
Au(1)-Cl(1)
Au(1)-Ir(1)
Ir(1)-N(1)
Ir(1)-C(34)
Ir(1)-C(30)
Ir(1)-C(33)
Ir(1)-C(37)
Ir(1)-Cl(2)
2.216(3)
2.307(3)
Au(2)-P(2)
Au(2)-Cl(3)
Au(2)-Ir(2)
Ir(2)-C(77)
Ir(2)-N(3)
Ir(2)-C(70)
Ir(2)-C(73)
Ir(2)-C(74)
Ir(2)-Cl(4)
2.221(3)
2.300(3)
3.0417(10)
2.088(10)
2.097(15)
2.108(14)
2.137(16)
2.150(14)
2.359(4)
3.0427(11)
2.096(13)
2.105(10)
2.127(13)
2.127(13)
2.162(13)
2.370(3)
Rh complex, and 32.38 and 29.69 ppm for the Ir one. No
coupling between rhodium and phosphorus is observed.
Furthermore, the coordination of the phosphine to rhodium
or iridium does not take place because the chemical shift is
not characteristic of these types of bonds, and no coupling
with the rhodium atom is observed. We thus propose that one
dinuclear unit loses a chloride ligand in solution. The un-
saturated Rh or Ir atoms will then bind the chloride of a
second unit, to give a tetranuclear arrangement with only one
bridging chloride (suchspecies are not new in the chemistry of
these metals).13 The other coordination positions around the
rhodium or iridium centers are occupied by the cod and the
pyridine ligands, while the dissociated chlorine acts as coun-
terion. The observation of signals from two phosphine and
two cyclooctadiene ligands in the NMR spectra could arise
from the equilibrium between both species (see Scheme 2).
The treatment of [AuCl(PPhpy2)] with [M(μ-Cl)(cod)]2
(M = Rh, Ir), in a molar ratio 2:1, leads to the dinuclear
derivatives 11 and 12 in which the rhodium or iridium centers
are coordinated to one of the pyridine units from the phos-
phine ligand (Scheme 3). In the 1H NMR spectrum of com-
plex 11 only one resonance for each type of protons of the
pyridine is observed, which can arise from a rapid inter-
change between the pyridines coordinated to the rhodium
center. At low temperature, two types of pyridine groups are
observed, and the protons of the cyclooctadiene ligand also
become nonequivalent. The 1H NMR spectrum of a solution
of a crystalline sample of complex 12 shows at room tem-
perature two types of pyridine groups. The 31P{1H} NMR
P(1)-Au(1)-Cl(1)
P(1)-Au(1)-Ir(1)
Cl(1)-Au(1)-Ir(1)
N(1)-Ir(1)-C(34)
N(1)-Ir(1)-C(30)
C(34)-Ir(1)-C(30)
N(1)-Ir(1)-C(33)
C(34)-Ir(1)-C(33)
C(30)-Ir(1)-C(33)
N(1)-Ir(1)-C(37)
C(34)-Ir(1)-C(37)
C(30)-Ir(1)-C(37)
C(33)-Ir(1)-C(37)
Cl(3)-Au(2)-Ir(2)
C(77)-Ir(2)-N(3)
C(77)-Ir(2)-C(70)
N(3)-Ir(2)-C(70)
C(77)-Ir(2)-C(73)
N(3)-Ir(2)-C(73)
C(70)-Ir(2)-C(73)
C(77)-Ir(2)-C(74)
N(3)-Ir(2)-C(74)
C(70)-Ir(2)-C(74)
C(73)-Ir(2)-C(74)
169.88(12)
81.92(8)
107.99(10)
90.7(6)
170.5(5)
90.5(7)
93.7(6)
37.3(6)
81.6(7)
153.7(5)
82.4(6)
35.7(6)
96.0(7)
110.77(9)
93.1(5)
39.1(5)
92.2(5)
97.9(5)
153.2(4)
81.4(5)
80.4(5)
167.9(5)
89.2(5)
38.8(5)
N(1)-Ir(1)-Cl(2)
C(34)-Ir(1)-Cl(2)
C(30)-Ir(1)-Cl(2)
C(33)-Ir(1)-Cl(2)
C(37)-Ir(1)-Cl(2)
N(1)-Ir(1)-Au(1)
C(34)-Ir(1)-Au(1)
C(30)-Ir(1)-Au(1)
C(33)-Ir(1)-Au(1)
C(37)-Ir(1)-Au(1)
Cl(2)-Ir(1)-Au(1)
P(2)-Au(2)-Cl(3)
P(2)-Au(2)-Ir(2)
C(77)-Ir(2)-Cl(4)
N(3)-Ir(2)-Cl(4)
C(70)-Ir(2)-Cl(4)
C(73)-Ir(2)-Cl(4)
C(74)-Ir(2)-Cl(4)
C(77)-Ir(2)-Au(2)
N(3)-Ir(2)-Au(2)
C(70)-Ir(2)-Au(2)
C(73)-Ir(2)-Au(2)
C(74)-Ir(2)-Au(2)
Cl(4)-Ir(2)-Au(2)
87.8(3)
160.8(5)
94.2(5)
161.9(4)
90.5(4)
88.6(3)
122.8(5)
82.9(4)
85.7(4)
116.5(4)
76.29(9)
168.59(12)
80.48(9)
162.4(4)
87.4(3)
158.5(4)
89.3(4)
95.7(4)
87.4(3)
89.4(3)
126.5(4)
115.3(3)
80.1(4)
75.01(8)
spectra show in both complexes a single resonance for the
phosphorus atom.
The crystal structure of complex 12 has been determinedby
X-ray diffraction and is shown in Figure 6. A selection of
bond lengths and anglesare collected in Table 6. The complex
crystallizes with two independent molecules per asymmetric
unit. There is an intermetallic Au Ir distance of 3.0417(10)
3 3 3
A, which is similar to that found in complex 8. The geometry
around the gold atom is slightly distorted from linearity, with
a P-Au-Cl angle of 169.88(12)°, probably to allow the
gold-iridium interaction. The iridium center is in a square
planar geometry with the angle N(1)-Ir(1)-Cl(2) being
(13) (a) Wachter, J.; Jeanneaux, F.; Le Borgne, G.; Riess, J. G. Organo-
metallics 1984, 3, 1034–1038. (b) Broussier, R.; Laly, M.; Perron, P.; Gautheron,
B.; Nifant'ev, I. E.; Howard, J. A. K.; Kuz'mina, L. G.; Kalck, P. J. Organomet.
Chem. 1999, 587, 104–112. (c) Cuervo, D.; Diez, J.; Gamasa, M. P.; Gimeno, J.
Organometallics 2005, 24, 2224–2232.

8260 Inorganic Chemistry, Vol. 49, No. 18, 2010
Calhorda et al.
Figure 7. Structure of complex13 showingthe atomnumberingscheme.
Displacement parameter ellipsoids represent 50% probability surfaces. H
atoms are omitted for clarity.
Table 7. Selected Bond Lengths [A] and Angles [deg] for Complex 13a
Au(1)-P(2)
Au(1)-Cl(1)
Pd(1)-N(1)
Pd(1)-N(1)#1
2.2233(10) Pd(1)-Cl(2)
2.2846(10) P(2)-C(11)
2.2942(10)
1.803(4)
1.808(4)
1.817(4)
2.027(3)
2.027(3)
P(2)-C(1)
P(2)-C(17)
Figure 8. Structure of complex 18 showing the atom numberingscheme.
Displacement parameter ellipsoids represent 50% probability surfaces. H
atoms are omitted for clarity.
P(2)-Au(1)-Cl(1)
N(1)-Pd(1)-N(1)#1
N(1)-Pd(1)-Cl(2)
N(1)#1-Pd(1)-Cl(2)
Cl(2)-Pd(1)-Cl(2)#1 180.00(6)
C(11)-P(2)-C(1)
C(11)-P(2)-C(17)
177.01(4)
180.0(3)
90.25(9)
89.75(9)
C(1)-P(2)-C(17)
107.73(18)
C(11)-P(2)-Au(1) 114.87(14)
C(1)-P(2)-Au(1)
C(17)-P(2)-Au(1) 111.84(13)
C(19)-N(1)-Pd(1) 123.6(3)
113.00(13)
Table 8. Selected Bond Lengths [A] and Angles [deg] for Complex 18
Au(1)-P(1)
Au(1)-Cl(1)
Au(1)-Pd(1)
Pd(1)-N(2)
2.2255(8)
2.2790(8)
3.2010(7)
2.035(2)
Pd(1)-N(1)
Pd(1)-Cl(2)
Pd(1)-Cl(3)
2.040(2)
2.2934(9)
2.2936(10)
106.20(18) C(23)-N(1)-Pd(1) 117.0(3)
102.42(18)
a Symmetry transformations used to generate equivalent atoms: #1,
-xþ1/2,-yþ1/2,-z; #2, -xþ2,y,-zþ1/2.
P(1)-Au(1)-Cl(1)
P(1)-Au(1)-Pd(1)
172.10(3)
67.256(19) Cl(2)-Pd(1)-Cl(3)
Cl(1)-Au(1)-Pd(1) 114.49(2)
N(1)-Pd(1)-Cl(3)
177.88(7)
91.80(4)
88.42(6)
83.65(7)
87.8(3)°. The Ir-N bond distance is 2.088(10) A, which is
slightly shorter than in the derivative with the PPh2py ligand.
We have also studied the reactivity of the complexes
[AuCl(P-N)] toward palladium or platinum derivatives such
as [MCl2(NCPh)2] (M = Pd, Pt), in a molar ratio 2:1. We
have obtained the expected trinuclear complexes as pale
yellow solids, with the exception of M = Pd and P-N =
PPh2py, for which a mixture of complexes has been obtained.
The preparation of the complexes is shown in eq 3, and the Pd
or Pt atoms are coordinated to pyridine groups with a trans
disposition (see X-ray structure of complex 13, Figure 7).
N(2)-Pd(1)-Au(1)
N(1)-Pd(1)-Au(1)
Cl(2)-Pd(1)-Au(1) 91.55(2)
Cl(3)-Pd(1)-Au(1) 97.81(2)
N(2)-Pd(1)-N(1)
N(2)-Pd(1)-Cl(2)
N(1)-Pd(1)-Cl(2)
N(2)-Pd(1)-Cl(3)
87.85(9)
177.53(7)
89.69(7)
90.65(7)
the asymmetric unit. The geometry around the gold centers is
linear with a Cl-Au-P angle of 177.01(4)°. There are no
Au Pd short contacts, probably because of the longer back-
3 3 3
bone chain of this heterofunctional phosphine. The palla-
dium center is found in a regular square planar geometry with
the angles very close to 90°.
Finally, wetried the reaction of [AuCl(PPhpy2)] with trans-
[PdCl2(NCPh)2)] in a molar ratio 1:1. Since the phosphine
ligand has two pyridine groups available for bonding, the
expected result should be the coordination of the two pyri-
dine moieties to the palladium center affording a dinuclear
derivative as shown in eq 4.
1
In the H spectra of complexes 13-17, only some of the
protons of the pyridine moieties are resolved because the rest
overlap with the phenyl protons. When the phosphine ligand
is PPh2CH2CH2py, the methylene protons show resonances
at 4.20 and 3.35 ppm, for the palladium complex 13, and at
3.26 and 3.15 ppm for the platinum derivative 16. The
31P{1H} NMR spectra of these complexes show only one
resonance for the equivalent phosphorus atoms.
The structure of complex 13 has been confirmed by X-ray
diffraction studies, and the molecule is shown in Figure 7. A
selection of bond lengths and angles are collected in Table 7.
The complex crystallizes as the trans isomer, as expected
because of its higher stability compared to the cis isomer. The
molecule has a symmetry center and only half corresponds to
Complex 18 is a yellow air- and moisture-stable solid. The
1H NMR spectrum shows the four broad resonances for the
two pyridine groups, whereas the 31P{1H} NMR spectrum
presents one unique resonance for the phosphorus atoms.
The structure of complex 18 has been established by X-ray
diffraction studies, and the molecule is shown in Figure 8. A
selection of bond lengths and angles are collected in Table 8.
In contrast with the structure of complex 13, which possesses
a long chain phosphine ligand, the structure of 18 presents a

Article
Inorganic Chemistry, Vol. 49, No. 18, 2010 8261
Table 9. Maxima Observed in the DRUV Spectra of Complexes 1-18 in the Solid
For the discussion of the possible origin of these emis-
sions we shall first analyze the metalloligands themselves
and then the heterobimetallic systems.
The energies of the emissions for metalloligands 1 and 3
resemble those obtained for the monophosphines. Thus,
IL transitions are probably responsible for the lumines-
cence (IL, phosphine) in 1 and 3.
State at 298 K
compound
[AuCl(PPh2py)] (1)
[AuCl(PPh2(CH2)2py2)] (2)
DRUV
<300
<300
<300
[AuCl(PPhpy2)] (3)
[Au2CuCl2(μ-PPh2py)2]BF4 (4)
[Au2CuCl2(μ-PPh2(CH2)2py2)2]PF6 (5)
[Au2CuCl2(μ-PPhpy2)2]BF4 (6)
[AuRhCl2(μ-PPh2py)(cod)] (7)
[AuIrCl2(μ-PPh2py)(cod)] (8)
[AuRhCl2(μ-PPh2(CH2)2py2)(cod)] (9)a
[AuIrCl2(μ-PPh2(CH2)2py2)(cod)] (10)a
[AuRhCl2(μ-PPhpy2)2(cod)] (11)
[AuIrCl2(μ-PPhpy2)2(cod)] (12)
[Au2PdCl4(μ-PPh2(CH2)2py2)2] (13)
[Au2PdCl4(μ-PPhpy2)2] (14)
270, 320, 405, 470-510
210, 260, 330-400
270, 320, 405-550
250, 325, 410-500
250, 350, 450, 500-550
250, 325, 410-500
250, 350, 450, 500-600
250, 325, 410-500
250, 350, 450,500-600
250, 350, 450, 500
250, 350, 450, 500
270, 310-500
The heterobimetallic systems exhibit different beha-
vior. The Au/Cu species 4-6 are luminescent both at
298 and 77 K, but very weakly emissive at room tempera-
ture. The emission maxima for complexes 4 (P-N =
PPh2py) and 5 (P-N = PPh2CH2CH2py) appear be-
tween 516 and 558 nm (excitation maxima between 320
and 410 nm). Broad bands are observed at room tem-
perature, whereas at 77 K a band and a not well-defined
shoulder are observed. Lifetime measurements for these
complexes at room temperature [4 29 μs; 5 13 μs] point to
a phosphorescent nature of these emissions. The bands
appear at energies similar to those described for the free
phosphine, suggesting that they are not related to the
presence of metallophilic interactions. IL transitions
modified by the coordination to the copper center or
MLCT (metal to ligand charge transfer)15,16 could be
responsible of these emissions. Complex 6 displays an
emission at about 700 nm upon excitation at about 460
nm, both at 298 and 77 K. This emission is observed at
much lower energy than in 4 and 5. In CuN4 systems with
a coordination sphere similar to the one proposed for 6,
luminescence has been attributed to MLCT transi-
tions.15,16 The same explanation might be applied to 6,
[Au2PtCl4(μ-PPh2py)2] (15)
[Au2PtCl4(μ-PPh2(CH2)2py2)2] (16)
[Au2PtCl4(μ-PPhpy2)2] (17)
270, 310-400
270, 310-400
270, 320, 405, 470-510
[AuPdCl3(μ-PPhpy2)] (18)
a This complex could be a mixture of both present in solution.
short Au Pd distance of 3.2010(7) A, which can indicate
3 3 3
a weak bonding interaction. The geometries around the gold
and palladium atoms are linear and square-planar, respec-
tively, only with slight deviations from the ideal geometries.
The chloride ligands around the palladium center are in a
mutually cis disposition.
Diffuse Reflectance UV Studies. The diffuse-reflectance
UV (DRUV) spectra of the metalloligands (1-3) inthesolid
state display bands with maxima at λ < 300 nm (see Table
9). Upon coordination of heterometallic atoms to 1-3,
broad bands appear at λ g 400 nm. For compounds 5, 16,
and 17 the lowest energy band reaches 400 nm, but in most
of the cases it reaches 500 nm and even 600 nm (complexes
10 and 12). Intense absorptions at about 266 nm (shoulder at
275 nm) have been attributed to PPh2py intraligand (IL)
transitions (π f π* or n f π)14 in mixed phosphine-thiolate
gold(I) complexes. The absorptions observed at lower en-
ergies in our complexes (which include those which lead to
the emissions) could correspond to charge transfer processes
between the metallic atom and the ligands, or to the presence
of metallic interactions, as absorptions at 326 nm have been
although Au Cu interactions are possible in this com-
3 3 3
plex. Thus, the luminescent emissions of the bimetallic
Cu/Au complexes 4-6 seem to be more influenced by the
geometry around the copper center than by the presence
or absence or Au Cu interactions. The lower emission
3 3 3
energy suggests the assignment of a tetrahedral environ-
ment copper atom in 6, by comparison with other copper
complexes with coordination CuN4,15,16 distinct from the
linear one observed for 4 and proposed for 5.
The Au/Ir derivatives 8 and 12 only emit at 77 K,
displaying emissions with λmax > 608 nm, while 10 does
not display luminescence. For compound 12, two maxima
are observed which undergo changes in relative intensity
when the emission excitation is modified. Upon excitation
at 500 nm, the maximum at 711 increases its intensity, and
excitation at 450 nm leads to a band, whose emission
maximum appears at 620 nm, and to a shoulder. For these
gold/iridium derivatives the luminescence properties are
attributed to gold copper interactions in the complex
3 3 3
[{AuCu(Spy)(PPh2py)}2](PF6)2.14
Luminescence Studies. Upon excitation between 314
and 375 nm the free phosphines display an emission maxi-
mum at 554 nm (PPh2py)14 and 443 nm (PPh2CH2CH2py)
at room temperature, and at 529 nm (PPh2py), 491 nm
(PPh2CH2CH2py), and 499 nm (PPhpy2) at 77 K. The
luminescent behavior of the complexes may be summar-
ized in the following points: (i) None of the metalloligands
1-3 show luminescence at room temperature. At 77 K
compounds 1 and 3 display an emission at 499 nm upon
excitation at about 300 nm (see Table 10). (ii) The maxima
of emission shown by the heterometallic Au/Cu com-
plexes depend on the phosphine. (iii) All heterometallic
Au/Ir complexes display luminescence except compound
10, which contains the monophosphine with the longer
chain (PPh2CH2CH2py). (iv) The Au/Rh, Au/Pd, and Au/
Pt complexes are not emissive.
associated with the presence of Au Ir interactions,
3 3 3
observed in 8 and 12 but not expected in 10. In other
Au(I)/Ir(I)17 systems the luminescence has been assigned
to metal centered (dσ* f pσ) transitions. Despite the
important role apparently played by the metallophilic
interactions in the luminescent origin, from these data it is
not possible to assign the nature of the transitions asso-
ciated, since they might be metal centered, or metal charge
transitions involving Au and/or Ir (MMLCT). On the
(15) McMillin, D. R.; McNett, K. M. Chem. Rev. 1998, 98, 1201–1219.
(16) Patra, G. K.; Goldberg, I. Eur. J. Inorg. Chem. 2003, 969–977.
(17) (a) Balch, A. L.; Catalano, V. J.; Noll, B. C.; Olmstead, M. M. J. Am.
Chem. Soc. 1990, 112, 7558–7566. (b) Balch, A. L.; Catalano, V. J.; Olmstead,
M. M. J. Am. Chem. Soc. 1990, 112, 2010–2011. (c) Balch, A. L.; Catalano, V. J.
Inorg. Chem. 1991, 30, 1302–1308.
(14) Hao, L.; Mansour, M. A.; Lachicotte, R.; Gysling, H. J.; Eisenberg,
R. Inorg. Chem. 2000, 39, 5520–5529.

8262 Inorganic Chemistry, Vol. 49, No. 18, 2010
Calhorda et al.
Table 10. Luminescent Spectral Data and Lifetime Measurements for the Compounds in the Solid State
compound
[AuCl(PPh2py)] (1)
[AuCl(PPhpy2)] (3)
λmax (298 K) emission [excitation]
λ
max (77 K) emission [excitation]
τa
499 [300]
499 [310]
[Au2CuCl2(μ-PPh2py)2]BF4 (4)
[Au2CuCl2(μ-PPh2(CH2)2py2)2]PF6 (5)
[Au2CuCl2(μ-PPhpy2)2]BF4 (6)
[AuIrCl2(μ-PPh2py)(cod)] (8)
[AuIrCl2(μ-PPhpy2)2(cod)] (12)
558 (þ sh) [320, 360]
516 (br) [360]
715 [460]
552 (þ sh) [410]
520 (þ br) [370]
708 [465]
29 μs
13 μs
608 (þ sh) [470]
620, 711 [405, 500 ]
a At 298 K.
Table 11. Energy and Composition of More Intense Electronic Transitions of Complex [Au2CuCl2(PPh2py)2](BF4) (4)
[Au2CuCl2(PPh2py)2](BF4) (4)
excitation
composition
HOMOfLUMO (99%)
energy (eV)
wavelength (nm)
λmaxa (nm)
f ( ꢀ 103)
4.97
4.08
17.26
4.43
1
2
3
4
2.281
2.397
2.443
2.942
544
517
508
421
HOMO-1fLUMO (93%), HOMOfLUMOþ1 (7%)
HOMOfLUMOþ1 (92%), HOMO-1fLUMO (7%)
HOMO-3fLUMOþ1 (80%) HOMOfLUMOþ2 (12%),
HOMO-5fLUMO (5%), HOMOfLUMOþ3 (3%)
HOMOfLUMOþ2 (85%), HOMO-3fLUMOþ1 (11%)
HOMO-6fLUMO (72%), HOMOfLUMOþ4 (13%)
HOMO-9fLUMOþ1 (68%), HOMO-8fLUMOþ1 (17%)
HOMO-13fLUMOþ1 (36%), HOMOfLUMOþ6 (16%),
HOMO-5fLUMOþ2 (12%), HOMO-6fLUMOþ1 (11%)
470-510
5
6
7
8
2.956
3.21
3.42
3.58
420
386
362
347
5.80
405
320
33.37
25.77
1.34
a Experimental value (DRUV).
other hand, the same dσ* f pσ transitions have been
proposed as the origin of the luminescence in other Au/
Rh compounds,18 but the Au/Rh complexes 7, 9, and 11
are nonemissive.
ones (2.9827(11), 3.0485(11) A). The Mayer indices22 are
0.244 (Rh Au in 7) and 0.212 (Ir Au in 8). Although
these numbers are not directly comparable, they indicate
a weak bond between Au and the second metal in both
complexes. The geometry of the two binuclear complexes
7 and 8 was also optimized considering spin orbit cou-
3 3 3
3 3 3
DFT Calculations. DFT calculations19 (Amsterdam
Density Functional (ADF) program)20 were performed
on the trinuclear complex 4 [Au2CuCl2(PPh2py)2](BF4),
and the two binuclear analogues [AuCl(PPh2py)M(cod)-
Cl] with M = Rh (7), Ir (8), to gain more knowledge
about the luminescent behavior of these complexes.
The geometries of the three complexes were fully
optimized without any symmetry constraints and con-
sidering all phenyl groups (see Computational Details), as
they are usually needed to reproduce the luminescent
behavior of complexes.21
pling, but there was no change in the calculated M Au
3 3 3
distances.
TD-DFT calculations23 were performed to interpret
the electronic spectra of the three complexes. The most
relevant results concerning the three complexes are col-
lected in Tables 11-13, while the calculated spectra can
be seen in Figure 9.
For the trinuclear [Au2CuCl2(PPh2py)2]BF4 4, the ob-
served maxima are found at 320, 405, and 470-510 nm.
As shown in Figure 9, the calculated bands are all a bit
shifted toward lower energies, with the most intense band
between 350 and 450 nm, a shoulder at ∼420 nm, and
other weaker absorptions in the range 480-550 nm. It
should be noticed, in all the calculated spectra plotted in
Figure 9, that the curves are obtained from a fit over
several bands taking into account the respective oscillator
strengths. This leads to observed maxima that may not
coincide with the discrete values present in Tables 11-13.
The calculated maximum at 372 nm has main contribu-
tions from two excitations at 386 and 362 nm, respec-
tively, which start from the highest occupied molecular
orbital (HOMO), HOMO-6, HOMO-8, and HOMO-9,
and end mostly in lowest occupied molecular orbital
(LUMO), and LUMOþ1. The occupied orbitals are
strongly localized in the copper atom (HOMO, 57%, and
A good agreement between experimental and calcu-
lated structural parameters is observed (tables with dis-
tances are given in the Supporting Information, Table
S1). The most difficult distances to reproduce are those
involving weak interactions, which in these complexes
refer to the metal-metal distances. The Rh Au dis-
tance in 7 was calculated as 3.068, and the experimental
3 3 3
value is 3.0385 A, while the Ir Au distances in complex
8 are 3.111 (calculated) and 3.0148 A (experimental). In
3 3 3
the trinuclear 4, the Au Au distance is overestimated
(3.279 vs 3.0658(5) A), while the two calculated Au Cu
distances are shorter (2.794, 2.810 A) than the experimental
3 3 3
3 3 3
(18) Yip, H. K.; Lin, H. M.; Wang, Y.; Che, C. M. Inorg. Chem. 1993, 32,
3402–3407.
(19) Parr, R. G.; Young, W. Density Functional Theory of Atoms and
Molecules; Oxford University Press: New York, 1989.
(20) (a) ADF2007; SCM, Theoretical Chemistry, Vrije Universiteit: Amsterdam,
The Netherlands; http://www.scm.com. (b) te Velde, G.; Bickelhaupt, F. M.;
van Gisbergen, S. J. A.; Guerra, C. F.; Baerends, E. J.; Snijders, J. G.; Ziegler, T.
J. Comput. Chem. 2001, 22, 931–967. (c) Guerra, C. F.; Snijders, J. G.; te Velde,
G.; Baerends, E. J. Theor. Chem. Acc. 1998, 99, 391–403.
(23) (a) van Gisbergen, S. J. A.; Snijders, J. G.; Baerends, E. J. Comput.
Phys. Commun. 1999, 118, 119–138. (b) Rosa, A.; Baerends, E. J.; van
Gisbergen, S. J. A.; van Lenthe, E.; Groeneveld, J. A.; Snijders, J. G. J. Am.
Chem. Soc. 1999, 121, 10356–10365. (c) Wang, F.; Ziegler, T. Mol. Phys. 2004,
102, 2585–2595.
(21) Costa, P. J.; Calhorda, M. J. Inorg. Chim. Acta 2006, 359, 3617–3624.
(22) Mayer, I. Int. J. Quantum Chem. 1986, 29, 73–84.

Article
Inorganic Chemistry, Vol. 49, No. 18, 2010 8263
Table 12. Energy and Composition of More Intense Electronic Transitions of Complex [AuCl(PPh2py)Rh(cod)Cl] (7)
[AuCl(PPh2py)Rh(cod)Cl] (7)
a
energy
(eV)
wavelength
(nm)
λmax
(nm)
f
excitation
composition
(ꢀ103)
7.86
1
2
3
4
5
6
HOMOfLUMOþ2 (96%), HOMO-1fLUMO (3%)
1.969
2.010
2.240
2.387
2.629
3.035
630
617
554
520
472
409
HOMO-1fLUMO (89%), HOMOfLUMOþ3 (5%)
15.50
21.32
16.60
8.14
HOMOfLUMOþ3 (88%), HOMOfLUMOþ4 (5%), HOMO-1fLUMOþ1 (4%)
HOMOfLUMOþ4 (93%), HOMOfLUMOþ3 (4%)
HOMOfLUMOþ5 (95%), HOMOfLUMOþ7 (3%)
HOMOfLUMOþ6 (28%), HOMO-6fLUMO (20%), HOMOfLUMOþ7 (18%),
HOMO-7fLUMO (13%), HOMO-2fLUMOþ3 (11%)
410-500
13.23
7
HOMO-6fLUMO (57%), HOMOfLUMOþ7 (16%), HOMOfLUMOþ6 (12%),
3.043
407
13.44
HOMO-7fLUMO (8%)
8
9
HOMO-8fLUMO (45%), HOMO-7fLUMO (23%), HOMO-6fLUMO (12%)
HOMO-6fLUMOþ1 (78%), HOMO-2fLUMOþ5 (8%)
HOMO-6fLUMOþ2 (62%), HOMO-10fLUMO (22%), HOMO-11fLUMO (8%)
HOMO-10fLUMO (34%), HOMO-11fLUMO (33%), HOMO-6fLUMOþ2 (29%)
HOMO-11fLUMO (57%), HOMO-10fLUMO (36%)
3.260
3.443
3.655
3.662
3.694
3.799
3.850
4.078
380
360
339
339
336
326
322
304
56.42
10.57
8.40
11.56
18.86
10.57
10.33
13.63
10
11
12
13
14
15
325
HOMO-8fLUMOþ2 (92%)
HOMO-2fLUMOþ7 (73%), HOMO-9fLUMOþ1 (5%), HOMO-3fLUMOþ7 (4%)
HOMO-6fLUMOþ4 (85%), HOMO-4fLUMOþ6 (4%)
a Experimental value (DRUV).
Table 13. Energy and Composition of More Intense Electronic Transitions of Complex [AuCl(PPh2py)Ir(cod)Cl] (8)
[AuCl(PPh2py)Ir(cod)Cl] (8)
a
energy
(eV)
wavelength
(nm)
λmax
(nm)
f
excitation
composition
(ꢀ103)
1
2
HOMO-1fLUMO (76%), HOMOfLUMOþ3 (12%), HOMO-1fLUMOþ1 (8%)
HOMOfLUMOþ3 (74%), HOMO-1fLUMOþ1 (12%), HOMOfLUMOþ4 (6%),
HOMO-1fLUMO (4%)
2.0720
2.2454
599
552
21.90
23.40
3
4
5
6
7
8
9
10
11
HOMO-1fLUMOþ1 (72%), HOMOfLUMOþ4 (11%), HOMO-1fLUMO (9%)
HOMOfLUMOþ4 (81%), HOMOfLUMOþ3 (7%), HOMO-1fLUMOþ1 (4%)
HOMOfLUMOþ5 (93%), HOMOfLUMOþ6 (5%)
HOMO-4fLUMOþ1 (84%), HOMOfLUMOþ6 (14%)
HOMOfLUMOþ6 (72%), HOMO-4fLUMOþ1 (15%)
HOMO-8fLUMO (59%), HOMO-1fLUMOþ6 (15%)
HOMO-6fLUMOþ1 (86%), HOMO-8fLUMO (4%)
HOMO-9fLUMO (78%), HOMOfLUMOþ7 (11%)
HOMO-11fLUMO (27%), HOMO-10fLUMO (23%), HOMO-8fLUMOþ1 (20%),
HOMOfLUMOþ8 (8%)
2.3331
2.3841
2.613
3.0261
3.0580
3.3958
3.516
531
520
474
410
405
365
353
343
330
18.80
25.52
7.09
11.63
41.40
30.59
13.41
14.38
28.17
350
3.6147
3.7600
12
13
HOMO-7fLUMOþ2 (93%)
3.8923
4.1416
318
299
13.49
11.88
HOMO-6fLUMOþ4 (68%), HOMO-3fLUMOþ6 (8%), HOMOfLUMOþ10 (7%),
HOMO-11fLUMOþ1 (6%)
a Experimental value (DRUV).
HOMO-6, 68%). The HOMO has a small contribution
(8%) from each gold atom and is Au-Cu antibonding;
HOMO-8 and HOMO-9 have some localization in cop-
per and two phenyl groups of the phosphines, while the
unoccupied orbitals (LUMO and LUMOþ1) are concen-
trated on the pyridine rings (LUMO and LUMOþ1). The
transition can therefore be assigned as a charge transfer
from Cu to the pyridine ligands (MLCT), with some
mixture of ILCT (from the phenyl to the pyridine). The
orbitals involved are shown in Figure 10 (the composi-
tions of the orbitals of the three complexes are given in
Supporting Information, Table S2). The three excitations
contributing to the lower energy maximum (1, 2, and 3 in
Table 11) start in HOMO and HOMO-1 and end in
LUMO and LUMOþ1. The HOMO-1 is strongly Au-Cl
antibonding and Au-Cu antibonding, being delocalized
between each metal (∼15%) and Cl (21 and 25%). This
absorption can thus be assigned as MMLCT, involving
orbitals localized on the Cu and Au d orbitals and Au-Cl
orbitals to orbitals localized on the pyridyl rings. There-
fore, excitation in these ranges involves not only IL states,
but also MMCT (MMLCT becoming more important at
low energies).
The calculated spectra of the binuclear Au-Rh (7) and
Au-Ir (8) in the 300-400 nm range are different (Figure 9,
Tables 12 and 13), since the Rh complex exhibits two
maxima with comparable intensity at 326 and 383 nm,
while in the Ir complex the maximum at 315 nm is much
more intense than the one at 403 nm. These probably
correspond to the maxima experimentally observed at 325
(7) and 350 nm (8). In the lower energy range (450-650),
there are broad bands for both complexes.
Five transitions (11 to 15 in Table 12) are responsible
for the peak at 326 nm (7). They start in HOMO-2,
HOMO-6, HOMO-8, HOMO-10, and HOMO-11 and
end in LUMO, LUMOþ2, and LUMOþ7, contributing
in similar amounts to the higher energy band. The occu-
pied orbitals have different compositions, namely, Rh-
Cl(HOMO-2), Au-Cl and Rh-Cl(HOMO-6), Rh-Cl and
COD (HOMO-8), Au-Cl, phenyl, and COD (HOMO-10),

8264 Inorganic Chemistry, Vol. 49, No. 18, 2010
Calhorda et al.
Figure 10. Relevant frontier orbitals of [Au2CuCl2(PPh2py)2](BF4) (4)
involved in the transitions around 372 nm.
Figure 9. Calculated (TD-DFT; dotted line) and experimental (DRUV;
solid line) spectra of complexes [Au2CuCl2(PPh2py)2](BF4) (4) and
[AuCl(PPh2py)M(cod)Cl] with M = Rh (7), Ir (8).
and Au-Cl in HOMO-11. The LUMO is localized in the
pyridine ring, LUMOþ2 in the phenyl groups, and
LUMOþ7 on COD and Ph, with a small contribution of
Rh. The main character of this band can be thus described
as MLCT. The orbitals involved in these transitions are
depicted in Figure 11. The peak at 383 nm consists of one
intense transition (8 in Table 12) from HOMO-8, HOMO-7,
and HOMO-6 to the LUMO. As HOMO-7 is similar to
HOMO-6, this transition is a MMLCT from Au and Rh
to the pyridine ring.
The band in the lower energy region results mainly
from the transitions 2-4 (Table 12), and differs signifi-
cantly from the others. These excitations start in the
HOMO (71% Rh) and HOMO-1 (antibonding Rh-Cl;
Rh 49%, Cl 41%), and end in LUMO (py ring),
LUMOþ3 and LUMOþ4 (phenyl rings). Therefore, this
band can be assigned essentially to a MLCT from Rh and
Rh-Cl to the pyridine and phenyl rings.
For the Au-Ir complex (8), the higher energy band,
calculated at 315 nm consists of several transitions. The
most important ones are 10-12 (Table 13), starting in
HOMO (Ir), HOMO-7 and HOMO-8 (Au, Ir-Cl, COD),
HOMO-9 (Au, Ir-Cl, COD), HOMO-10 (Au-Cl, Ph,
COD), and HOMO-11 (Au-Cl, Ir-Cl, COD), and ending
in LUMO and LUMOþ1 (pyridine), LUMOþ2 (PPh2),
LUMOþ7 (Ir-Cl, pyridine, COD), and LUMOþ8 (Au,
PPh2). This transition has essentially MMLCT character
(from Au and Ir to pyridine) with some mixed LLCT (Cl
and COD to pyridine), in contrast to the corresponding
Figure 11. Relevant frontier orbitals of complex [AuCl(PPh2py)Rh-
(cod)Cl] (7) involved in the transitions around 326 and 383 nm.

Article
Inorganic Chemistry, Vol. 49, No. 18, 2010 8265
in the open shell excited states leads to some inversion in
the order of orbitals with close energies in the ground
state, with consequences in the nature of the frontier
orbitals and the geometric details.
In complex 4, the most visible change in geometry
concerns the metal-metal bond lengths. The Cu-Au
distances decrease as a result of removing one electron
from the Cu-Au antibonding HOMO. The other bonds
experience only slight changes (less than 0.05 A). In the
Au-Rh binuclear 7, the Au-Rh bond decreases signifi-
cantly from 3.068 in the ground state to 2.887 A in the
triplet state, and in 8 the Au-Ir bond shrinks from 3.111
to 2.895 A, respectively.
The calculated emission energy for complex 4 is 509
nm, very close to the experimentally determined values in
the range 520-558 nm. For the Au-Ir complex 8, the
calculated emission is 807 nm, a bit shifted from the
experimental value (ca. 700 nm). Finally, for the Au-Rh
complex 7, an emission value of 921 nm could be calcu-
lated, although it was not observed experimentally.
The triplet state has a higher energy relative to the
ground state in the Au-Ir derivative, where the metal-
metal bond decreases by 0.220 A, more than in the Au-
Rh compound where the bond only shortens 0.178 A. On
the other hand, the nature of the highest singly occupied
molecular orbital is different in the two complexes
(SOMO in Figure 13). In the Au-Rh complex, the SOMO
is a π bonding orbital between Rh and the pyridine ring,
similar to the LUMO in the ground state (Figure 11),
while in the Ir analogue it is almost completely localized in
one π* orbital of the phenyl rings (the ground state
LUMOþ2, Figure 12). The other singly occupied MO
(SOMO-1 in Figure 13) is the M-Cl antibonding MO for
both complexes (ground state HOMO-1). These two
factors are probably associated with the emissive nature
of the Au-Ir complex 8 and the non emissive nature of
the Au-Rh complex 7.
Figure 12. Relevant frontier orbitals of complex [AuCl(PPh2py)Ir-
(cod)Cl] (8) involved in the transitions around 315 and 403 nm.
one in the Rh derivative 7. A shoulder can be assigned to
transition 8, from HOMO-8 (Ir-Cl, Au) and HOMO-1
(Ir-Cl) to LUMO (pyridine) and LUMOþ6 (Ir-COD
and Ph), and exhibits a MMLCT nature. The band calcu-
lated at 403 nm comes from transition 7 (Table 13) mostly
(72%), starting in HOMO (Ir) and ending in LUMOþ6
(Ir-COD and Ph), with MLCT character. The orbitals
involved in these transitions are depicted in Figure 12.
The lower energy band has contributions from excitations
1-4 (Table 13), starting in the HOMO and HOMO-1, and
ending in LUMO, LUMOþ1, LUMOþ3, and LUMOþ4.
Both LUMOþ3 and LUMOþ4 are located in the phenyl
rings. This transition can be assigned as MLCT.
The low energy bands of the Au-Ir (8) complex (transi-
tions 1-7) have a significant participation of the HOMO
and HOMO-1, which are orbitals heavily localized in Ir or
Ir-Cl, while the comparable transitions in Au-Rh (7)
have a negligible participation of HOMO and HOMO-1.
Since the calculated excitation energy is at 500 and 450
nm, and these bands fall in the range of experimental
excitation energy, the different emission behavior of the
two complexes might be related to this. The higher energy
orbitals that would contribute to higher energy excita-
tions (∼300-400 nm) are much more delocalized over the
whole molecule in the Au-Ir (8) complex (see Figures 11
and 12).
Conclusions
Several heterometallic complexes have been synthesized
starting from the metalloligands [AuCl(P-N)], in which
P-N represents a heterofunctional phosphine, by reaction
with other metal centers. The structure of the complexes
depends on the heterofunctional ligand and the heterometal.
Thus the phosphines PPh2py and PPhpy2 favor the gold-
heterometal interaction, whereas PPh2CH2CH2py with a
longer backbone precludes the metal-metal interaction.
There are also differences between the first two phosphines,
because PPh2py has only one pyridine group available for
bonding and PPhpy2 has two and can afford tetra-coordina-
tion to the heterometal. These changes are key in the
luminescence properties showed by these derivatives. The
influence of the monophosphine, the presence or absence of a
heterometal, and the selected heterometal in the emission
energies led us to propose an origin for the observed emis-
sions, which is supported by DFT theoretical studies carried
out on some of the heterometallic complexes. The data and
final assignments may be summarized as follows. (i) The
metalloligands show weak luminescence only at low tempera-
ture, but the coordination of a heterometal generally enhances
the luminescent properties. (ii) DFT calculations for the Au/
Cu complex 4 suggest a MLCT origin (mostly MMLCT and
mixed with some ILCT) for the observed emissions, which
The emission energy was estimated by the difference
between the energy of the first triplet state and the energy
of the singlet state with the same geometry. Therefore, the
geometry of the first triplet state was optimized for the
three molecules. The different electron-electron repulsion

8266 Inorganic Chemistry, Vol. 49, No. 18, 2010
Calhorda et al.
(cod)]2,30 [PdCl2(NCPh)2],31 [AuCl(tht)]32 were prepared accor-
ding to published procedures. All other reagents were commer-
cially available.
Synthesis of [AuCl(P-N)] (P-N = PPh2py (1), PPh2CH2-
CH2py (2), PPhpy2 (3)). To a solution of [AuCl(tht)] (0.032 g, 0.1
mmol) in20mL ofdichloromethanewas added PPh2py(0.0263g,
0.1 mmol) or PPh2CH2CH2py (0.0291 g, 0.1 mmol) or PPhpy2
(0.0262 g, 0.1 mmol), and the mixture was stirred for 20 min. The
solvent was evaporated until approximately 2 mL, and the
addition of diethyl ether gave white solids of 1 (0.048 g, 97%),
or 2 (0.043 g, 82%), or 3 (0.047 g, 95%). Complex 2: elemental
analysis calcd. (%) for C17H18AuClNP (MW = 524): C, 43.57;
H, 3.46; N, 2.67, found: C, 43.58; H, 3.48; N, 2.69. NMR data:
31P{1H} (CDCl3, δ) 29.52 (s, 1P, PPh2CH2CH2py). 1H (CDCl3,
δ), 8.48 (d, br, 1H, py, 3JH-H ∼ 4.5 Hz), 7.72-7.43 (m, 10H, Ph),
7.57 (td, 1H, py, 3JH-H = 7.6 Hz, 4JH-H = 1.7 Hz), 7.13 (m, 2H,
py), 3.10 (m, 2H, CH2), 2.98 (m, 2H, CH2).
Figure 13. SOMOs in the triplet state of complexes [AuCl(PPh2py)-
Rh(cod)Cl] (7, top) and [AuCl(PPh2py)Ir(cod)Cl] (8, bottom).
Synthesis of [Au2CuCl2(μ-P-N)2]X, (P-N = PPh2py, X =
BF4 (4); PPh2CH2CH2py, X = PF6 (5); PPhpy2, X = BF4 (6)).
To a solution of [AuCl(PPh2py)] (1) (0.099 g, 0.2 mmol), or
[AuCl(PPh2CH2CH2py)] (2) (0.104 g, 0.2 mmol) or [AuCl-
(PPhpy2)] (3) (0.096 g, 0.2 mmol) in 20 mL of dichloromethane
under argon atmosphere was added [Cu(NCMe)4]X (0.1 mmol),
and the mixture was stirred for 20 min. The solution was
concentrated to about 5 mL, and addition of OEt2 gave a yellow
solid of 4 (0.093 g, 82%), a white solid of 5 (0.106 g, 85%), or an
orange solid of 6 (0.096 g, 84%).
Complex 4: elemental analysis calcd (%) for C34H28Cl2Au2-
CuBF4N2P2 (MW = 1141.73): C, 35.76; H, 2.47; N, 2.45 (%);
found: C, 35.74; H, 2.47; N, 2.41. NMR data: 31P{1H} (CDCl3,
δ), 34.05 (s, 2P, PPh2py). 1H (CDCl3, δ), 8.53 (m, 2H, py), 7.84
(m, 2H, py), 7.60-7.49 (m, 20 þ 2H, Phþpy), 7.36 (m, 2H, py).
Complex 5: elemental analysis calcd (%) for C38H36Cl2Au2-
CuF6N2P3 (MW = 1257.5): C, 36.33; H, 2.88; N, 2.23; found: C,
36.12; H, 2.30; N, 2.23. NMR data, 31P{1H} (CD3)2CO, δ),
29.42 (s, 2P, PPh2CH2CH2py). 1H (CD2Cl2, δ), 8.63 (m, 2H, py),
7.80 (m, 2H, py), 7.67-7.36 (m, 20 þ 4H, Phþpy), 3.24 (m, 4H,
CH2), 3.04 (m, 4H, CH2). Complex 6: elemental analysis calcd
(%) for C32H26Cl2Au2CuBF4N4P2 (MW = 1143.71): C, 33.60;
H, 2.29; N, 4.89 (%); found: C, 33.40; H, 2.12; N, 4.53. NMR
data, 31P{1H} (CD3)2CO, δ), 23.06 (s, 2P, PPhpy2). 1H (CD3)2-
CO, δ), 8.56 (m, 4H, py), 8.20 (m, 8H, Ph), 7.98 (m, 4H, py), 7.86
(m, 2 þ 4H, Phþpy), 7.73 (m, 4H, py).
partly supports the empirical proposal of an IL assignment
basedon theemission energy for 4 and 5. Theemission energy
for compound 6 appears at much lower energy and is tenta-
tively assigned as based in MLCT. (iii) The Au/Rh complexes
are not emissive, and the luminescence in the Au/Ir deriva-
tives seems to be determined by the different nature of the
highest energy level in the triplet state leading to lumines-
cence, which is localized in one phenyl ring in the Ir complex,
but is a π bonding orbital between Rh and the pyridine ring in
the other complex.
Experimental Section
Instrumentation. Infrared spectra were recorded in the range
4000-200 cm-1 on a Perkin-Elmer 883 spectrophotometer
using Nujol mulls between polyethylene sheets. Conductivities
were measured in about 5 ꢀ 10-4 mol dm-3 acetone solutions
with a Philips 9509 conductimeter. C, H, N, and S analyses were
carried out with a Perkin-Elmer 2400 microanalyzer. Mass
spectra were recorded on a VG Autospec, with the liquid
secondary-ion mass spectra (LSIMS) technique, using nitroben-
zyl alcohol as matrix. NMR spectra were recorded on Bruker
ARX 400 spectrometers in CDCl3, unless otherwise stated.
Chemical shifts are cited relative to SiMe4 (1H, external), CFCl3
(19F, external), and 85% H3PO4 (31P, external). DRUV spectra
were recorded with a UnicamUV-4 spectrophotometer equipped
with a Spectralon RSA-UC-40 Labsphere integrating sphere.
The solid samples were mixed with dried KBr and placed in a
homemade cell equipped with a quartz window. The intensities
were recorded in Kubelka-Munk units: log[R/(1 - R)2], where
R = reflectance. Steady-state photoluminescence spectra were
recorded with a Jobin-Yvon Horiba Fluorolog FL-3-11 spectro-
meter using band pathways of 3 nm for both excitation and
emission. Phosphorescence lifetimes were recorded with a
Fluoromax phosphorimeter accessory containing a UV xenon
flash tube at a flash rate between 0.05 and 25 Hz. The lifetime
data were fit using the Jobin-Yvon software package24 and the
Origin 5.0 program.25
Synthesis of [AuMCl2(μ-PPh2py)(cod)] (M = Rh (7), Ir (8)).
To a solution of [AuCl(PPh2py)] 1 (0.049 g, 0.1 mmol) in 20 mL
of dichloromethane and under argon atmosphere was added
[RhCl(cod)]2 (0.024 g, 0.05 mmol) or [IrCl(cod)]2 (0.033 g, 0.05
mmol), and the mixture was stirred for 20 min. The solvent was
evaporated to about 5 mL, and the addition of diethyl ether gave
a yellow solid of 7 (0.061 g, 83%) or the addition of hexane
afforded an orange solid of 8 (0.059 g, 72%). Complex 7:
elemental analysis calcd (%) for C25H26Cl2AuNPRh (MW =
831.54): C, 40.45; H, 3.53; N, 1.89 (%); found: C, 40.30; H, 3.41;
N, 1.82. NMR data, 31P{1H} (CDCl3, δ), 32.59 (s, 1P, PPh2py).
1H (CDCl3, δ), 8.79 (m, 1H, py), 7.99 (t, 1H, py, 3JH-H = 7.8
3
Hz), 7.81 (tddd, 1H, p-Ph, JH-H = 7.7 Hz, 4JH-H = 3.9 Hz,
4JH-H = 1.8 Hz), 7.72-7.37 (m, 9 þ 2H, Phþpy), 4.22 (m, 4H,
CH(cod)), 2.49 (m, 4H, CH2(cod)), 1.74 (m, 4H, CH2(cod)).
Complex 8: elemental analysis calcd (%) for C25H26Cl2AuIrNP
(MW = 831.54): C, 36.10; H, 3.15; N, 1.68 (%); found: C, 35.95;
H, 3.15; N, 1.56. NMR data, 31P{1H} (CDCl3, δ), 32.35 (s, 1P,
Starting Materials. The starting materials PPh2CH2CH2py,26
PPhpy2,27 [Cu(NCMe)4]PF6,28 [Rh(μ-Cl)(cod)]2,29 [Ir(μ-Cl)-
(24) DATAMAX, 2.20; Jobin Yvon, Inc.: Edison, NJ, 2001.
(25) Origin 5.0; Microcal Software, Inc.: Northampton, MA, 1991.
(26) Casares, J. A.; Espinet, P.; Soulantica, K.; Pascual, I.; Orpen, A. G.
Inorg. Chem. 1997, 36, 5251–5256.
(27) Xie, Y.; Chung, L. L.; Yang, Y.; Retting, S. J.; James, B. R. Can. J.
Chem. 1992, 70, 751–762.
(28) Kubas, G. J. Inorg. Synth. 1979, 19, 90–92.
PPh2py). 1H(CDCl3, δ), 8.62(m, 1H, py), 8.05(t, 1H, py, 3JH-H
=
7.6 Hz), 7.79 (m, 1H, Ph), 7.70-7.30 (m, 9 þ 2H, Phþpy), 4.43
(m, 4H, CH(cod)), 2.91 (m, 4H, CH2(cod)), 2.02 (m, 4H, CH2-
(cod)).
Synthesis of [AuMCl2(μ-PPh2CH2CH2py)(cod)] (M = Rh (9),
Ir (10)). To a solution of [AuCl(PPh2CH2CH2py)] 2 (0.052 g,
(29) Giordano, G.; Crabtree, R. H. Inorg. Synth. 1979, 19, 218–220.
(30) Herde, J. L.; Lambert, J. C.; Senoff, C. V. Inorg. Synth. 1974, 15,
18–20.
ꢀ
(32) Uson, R.; Laguna, A.; Laguna, M. Inorg. Synth. 1989, 26, 85–91.
(31) Anderson, G. K.; Lin, M. Inorg. Synth. 1990, 28, 60–63.

Article
Inorganic Chemistry, Vol. 49, No. 18, 2010 8267
0.1 mmol) in 20 mL of dichloromethane was added [RhCl(cod)]2
(0.024 g, 0.05 mmol) or [IrCl(cod)]2 (0.033 g, 0.05 mmol), and
the mixture was stirred for 20 min. The solution was concen-
trated to about 5 mL, and the addition of OEt2 gave a yellow
solid of 9 (0.065 g, 85%) or a yellow solid of 10 (0.079 g, 92%).
Complex 9: elemental analysis calcd (%) for C54H60Cl4Au2-
N2P2Rh2 (MW = 1540.54): C, 42.10; H, 3.93; N, 1.82; found: C,
42.49; H, 3.53; N, 1.65. ΛM (Ω-1 cm2 mol-1): 135. NMR data,
31P{1H} (CD2Cl2, δ), 32.41 (s, 1P, PPh2CH2CH2py), 29.49 (s,
yellow solids of 15 (0.098 g, 83%), or 16 (0.082 g, 67%) or 17
(0.090 g, 72%). Complex 15: elemental analysis calcd (%) for
C34H28Cl2Au2N2P2Pt (MW = 1186.46): C, 34.42; H, 2.38; N,
2.36, found: C, 34.12; H, 2.17; N, 2.88. NMR data, 31P{1H}
(CDCl3, δ), 32.36 (s, 2P, PPh2py). 1H NMR (CDCl3, ppm), 8.79
3
(d, br, 2H, py, JH-H ∼ 4.7 Hz), 7.98 (t, 2H, py, 3JH-H = 7.8
Hz), 7.83-7.43 (m, 20 þ 2H, Phþpy), 7.39 (m, 2H, py). Complex
16: elemental analysis calcd (%) for C38H36Cl4Au2N2P2Pt
(MW = 1313.47): C, 34.75; H, 2.76; N, 2.13; found: C, 34.52;
H, 2.41; N, 2.42. NMR data, 31P{1H} ((CD3)2CO, δ), 35.62 (s,
1P, PPh2CH2CH2py). 1H(CD2Cl2, δ), 8.79 (d, br, 1H, py, 3JH-H
∼
1
3
2P, PPh2CH2CH2py). H (CD3)2CO, δ), 8.50 (d, br, 2H, py,
5.2 Hz), 8.47 (d, br, 1H, py’, JH-H ∼ 4.5 Hz), 8.06 (m, 2H,
3JH-H ∼ 4 Hz), 8.05-7.57 (m, 20 þ 2H, Phþpy), 7.40 (d, 2H, py,
3JH-H = 7.5 Hz), 7.28 (t, 2H, py, 3JH-H = 6.2 Hz), 3.26 (m, 4H,
CH2), 3.15 (m, 4H, CH2). Complex 17: Elemental analysis (%);
Found: C, 31.12; H, 2.47; N, 4.04. Calculated for C32H26Cl4-
Au2N4P2Pt (MW = 1259.34): C, 30.51; H, 2.08; N, 4.44. NMR
data, 31P{1H} NMR ((CD3)2CO, ppm), 32.79 (s, 2P, PPhpy2).
pyþpy0), 7.77-7.49 (m, 20H, PhþPh0), 7.34 (d, 1H, py, 3JH-H
=
7.9 Hz), 7.20 (t, 1H, py, 3JH-H = 7.0 Hz), 7.10 (m, 2H, pyþpy0),
4.62-3.2 (m, 4 þ 4H, CH(cod)þCH(cod)0), 2.95 (m, 8H
CH2CH2), 2.39-1.25 (m, 8 þ 8H, CH2(cod)þCH2(cod)0). Com-
plex 10: elemental analysis calcd (%) for C54H60Cl4Au2Ir2N2P2
(MW = 1719.16): C, 37.72; H, 3.52; N, 1.63; found: C, 37.22; H,
3.20; N, 1.40. ΛM (Ω-1 cm2 mol-1): 147. NMR data, 31P{1H}
(CD2Cl2, δ), 32.38 (s, 1P, PPh2CH2CH2py), 29.69 (s, 1P, PPh2-
CH2CH2py). 1H (CD2Cl2, δ), 8.66 (d, br, 1H, py, 3JH-H ∼ 5.7
Hz), 8.47 (d, br, 1H, py0, 3JH-H ∼ 4.7 Hz), 7.99 (m, 2H, pyþpy0),
3
1H NMR ((CD3)2CO, ppm), 8.78 (d, br, 4H, py, JH-H ∼ 4.7
Hz), 8.04 (d, br, 4H, py, 3JH-H ∼ 7.2 Hz), 8.07-7.90 y 7.67-7.55
(m, 10H, Ph), 7.85 (t, 4H, py, 3JH-H ∼ 6.6 Hz), 7.75 (t, 4H, py,
3JH-H ∼ 7.9 Hz).
7.63-7.41 (m, 20 þ 1H, PhþPh0þpy), 7.28 (t, 1H, py0, 3JH-H
=
Synthesis of [AuPdCl3(μ-PPhpy2)] (18). To a solution of
[AuCl(PPhpy2)] (3) (0.052 g, 0.1 mmol) in 20 mL of dichloro-
methane was added [PdCl2(NCPh)2] (0.047 g, 0.1 mmol), and
the mixture was stirred for 20 min. Then the solvent was evapo-
rated to about 5 mL, and the addition of OEt2 afforded a yellow
solid of 18 (0.047 g, 70%). Elemental analysis calculated for
C16H13Cl3AuN2PPd (MW = 674.006): C, 28.51; H, 1.94; N,
4.15; found: C, 28.19; H, 2.02; N, 3.99. NMR data, 31P{1H}
7.0 Hz), 7.13 (m, 2H, py), 4.43-3.10 (m, 4 þ 4H, CH(cod)þCH-
(cod)0), 3.01 (m, 8H, CH2CH2), 2.59-1.25 (m, 8 þ 8H, CH2-
(cod)þCH2(cod)0).
Synthesis of [AuMCl2(μ-PPhpy2)(cod)] (M = Rh (11), Ir (12)).
To a solution of [AuCl(PPhpy2)] (3) (0.052 g, 0.1 mmol) in 20 mL
of dichloromethane was added [RhCl(cod)]2 (0.024 g, 0.05 mmol)
or [IrCl(cod)]2 (0.033 g, 0.05 mmol), and the mixture was stirred
for 20 min. Then, the solvent was removed in vacuum to about
5 mL, and the addition of diethyl ether gave an orange solid of 11
(0.074 g, 77%) or a red solid of 12 (0.055 g, 67%). Complex 11:
elemental analysis calcd (%) for C24H25Cl2AuN2PRh (MW =
743.21): C, 38.78; H, 3.39; N, 3.76; found: C, 38.52; H, 3.19; N,
3.50. NMR data, 31P{1H} (CD2Cl2, δ), 32.20 (s, 1P, PPhpy2). 1H
(CD2Cl2, δ), 8.74 (d, br, 2H, py, 3JH-H ∼ 4.6 Hz), 7.92 (dd, br,
2H, py, 3JH-H ∼ 13.1 Hz, 3JH-H ∼ 7.1 Hz), 7.84-7.55 (m, 5H,
Ph), 7.50 (m, 2H, py), 7.39 (m, 2H, py), 4.22 (m, 4H, CH(cod)),
2.48 (m, 4H, CH2 (cod)), 1.77 (m, 4H, CH2 (cod)). Complex 12:
elemental analysis calcd (%) for C24H25Cl2AuIrN2P (MW =
832.53): C, 34.62; H, 3.02; N, 3.36.; found: C, 34.30; H, 2.76; N,
3.02. NMR data, 31P{1H} (CD2Cl2, δ), 32.46. 1H (CD2Cl2, δ),
9.21 (d, br, 1H, py, 3JH-H ∼ 4.9 Hz), 8.75 (d, 1H, py, 3JH-H ∼ 5.6
Hz), 7.97-7.41 (m, 5 þ 6H, Phþpy), 3.66 (m, 4H, CH (cod)),
2.57 (m, 4H, CH2 (cod)), 2.35 (m, 4H, CH2 (cod)).
1
(CDCl3, δ), 30.34 (s, P, PPhpy2). H (CDCl3, δ), 9.20 (m, 2H,
py), 8.24 (m, 2H, py), 8.0 (m, 2H, py), 7.91-7.6 (m, 5H, Ph), 7.34
(m, 2H, py).
Crystallography. Crystals were mounted in inert oil on glass
fibers and transferred to the cold gas stream of a Smart Apex
CCD (3, 4, 7, 8, 13) or Xcalibur Oxford Diffraction (9, 12, 18)
diffractometer equipped with a low-temperature attachment.
Data were collected using monochromated Mo KR radiation
(λ = 0.71073 A). Scan type ω. Absorption correction based on
multiple scans were applied with the program SADABS.33 The
structures were refined on F2 using the program SHELXL-97.34
All non-hydrogen atoms were refined anisotropically. Hydro-
gen atoms were included using a riding model. Further details of
the data collection and refinement are given in Tables 14 and 15.
Computational Details. All DFT calculations19 were per-
formed using the ADF program package (ADF).20 Gradient
corrected geometry optimizations,35 without symmetry con-
straints, were performed using the Local Density Approximation
of the correlation energy (Vosko-Wilk-Nusair),36 and the Gene-
ralized Gradient Approximation (Perdew-Wang37 exchange
and correlation corrections). Relativistic effects were treated
with the ZORA approximation.38 Unrestricted calculations
were performed for open shell species. The triplet state was
obtained by promoting one electron from the HOMO to the
LUMO. The core orbitals were frozen for Au, Ir ([1-4]s, [2-4]p,
[3-4]d); Rh ([1-3]s, [2-3]p, 3d); Cu ([1-2]s, 2p); P, Cl ([1-2]s,
2p); and C and N (1s). Triple ζ Slater-type orbitals (STO) were
used to describe the valence shells C, N (2s and 2p), P, Cl (3s, 3p),
Au, and Ir (4f, 5d, 6s), Rh (4d, 5s), and Cu (3d, 4s). A set of two
polarization functions was added to C, N (single ζ, 3d, 4f), P, Cl
Synthesis of [Au2PdCl4(μ-P-N)2] (P-N = PPh2CH2CH2py
(13), PPhpy2 (14)). To a solution of [AuCl(PPh2CH2CH2py)] (2)
(0.052 g, 0.2 mmol) or [AuCl(PPhpy2)] (3) (0.104 g, 0.2 mmol) in
20 mL of dichloromethane was added [PdCl2(NCPh)2] (0.038 g,
0.1 mmol), and the mixture stirred for 20 min. The solution was
concentrated to about 5 mL, and the addition of OEt2 gave a
yellow solid of 13 (0.105 g, 86%) or 14 (0.066 g, 57%). Complex
13: elemental analysis calcd (%) for C38H36Cl4Au2N2P2Pd
(MW = 1224.81): C, 37.26; H, 2.96; N, 2.28; found: C, 37.45;
1
H, 3.18; N, 2.42. NMR data, 31P{1H} (CDCl3, δ), 29.90. H
(CDCl3, δ), 8.86 (d, br, 2H, py, 3JH-H ∼ 5.1 Hz), 7.81-7.15 (m,
20 þ 6H, Phþpy), 4.20 (m, 4H, CH2), 3.35 (m, 4H, CH2).
Complex 14: elemental analysis calcd (%) for C32H26Cl4Au2-
N4P2Pd (MW = 1170.68): C, 32.83; H, 2.23; N, 4.78; found: C,
32.40; H, 1.98; N, 4.32. NMR data, 31P{1H} (DMSO, δ), 30.19.
1H (DMSO, δ), 9.17 (d, br, 4H, py, 3JH-H ∼ 5.2 Hz), 8.24-7.59
(m, 10 þ 8H, Phþpy), 7.33 (m, 4H, py).
(33) SADABS, Version 2.03; Bruker AXS, Inc: Madison, WI, 2000.
(34) Sheldrick, G. M. SHELXL-97, A program for Crystal Structure
Synthesis of [Au2PtCl4(μ-P-N)2] (P-N = PPh2py (15), PPh2-
CH2CH2py (16), PPhpy2 (17)). To a solution of [AuCl(PPh2py)]
(1) (0.099 g, 0.2 mmol), or [AuCl(PPh2CH2CH2py)] (2) (0.052 g,
0.2 mmol) or [AuCl(PPhpy2)] (3) (0.104 g, 0.2 mmol) in 20 mL of
dichloromethane was added [PtCl2(NCPh)2] (0.047 g, 0.1 mmol),
and the mixture was stirred for 20 min. Then the solvent was
evaporated to about 5 mL, and the addition of OEt2 afforded
€
€
Refinement; University of Gottingen: Gottingen, Germany, 1997.
(35) (a) Versluis, L.; Ziegler, T. J. Chem. Phys. 1988, 88, 322–328. (b) Fan,
L.; Ziegler, T. J. Chem. Phys. 1991, 95, 7401–7408.
(36) Vosko, S. H.; Wilk, L.; Nusair, M. Can. J. Phys. 1980, 58, 1200–1211.
(37) Perdew, J. P.; Chevary, J. A.; Vosko, S. H.; Jackson, K. A.; Pederson,
M. R.; Singh, D. J.; Fiolhais, C. Phys. Rev. 1992, B46, 6671–6678.
(38) van Lenthe, E.; Ehlers, A.; Baerends, E. J. J. Chem. Phys. 1999, 110,
8943–8953.

8268 Inorganic Chemistry, Vol. 49, No. 18, 2010
Calhorda et al.
Table 14. X-ray Data for Complexes 3, 4, 7, and 8
3
4
7
8
formula
Mr
habit
crystal size (mm)
crystal system
space group
cell constants:
a (A)
C16H13AuClN2P
496.67
colorless prism
0.18 ꢀ 0.16 ꢀ 0.12
monoclinic
C36H30Au2BCl8CuF4N2P2
1380.44
yellow plate
C25H26AuCl2NPRh
742.21
yellow prism
0.18 ꢀ 0.15 ꢀ 0.12
monoclinic
C25H26AuCl2IrNP
831.50
orange plate
0.24 ꢀ 0.14 ꢀ 0.08
monoclinic
P21/c
0.16 ꢀ 0.10 ꢀ 0.06
monoclinic
P21/c
P21/c
P21/c
7.9930(6)
11.0534(8)
17.7914(13)
99.0940(10)
1552.1(2)
4
2.125
9.747
936
13.1758(9)
15.0406(10)
22.4936(15)
101.6840(10)
4365.2(5)
4
2.100
7.799
2616
13.630(3)
10.027(2)
18.563(4)
103.98(3)
2461.7(8)
4
2.003
6.919
1424
13.5661(15)
10.0284(12)
18.574(2)
104.311(2)
2448.5(5)
4
2.256
11.712
1552
b (A)
c (A)
β (deg)
V (A3)
Z
Dx (Mg m-3
)
μ (mm-1
F(000)
T (°C)
2θmax
)
-173
56.6
-173
56
-173
56
-173
56.6
no. of refl.:
measured
independent
transmissions
Rint
18572
3777
0.2729-0.3876
0.028
190
25547
8596
0.368-0.652
0.0422
505
18623
4824
0.3113-0.4234
0.0876
280
15862
5803
0.1654-0.4543
0.0432
280
parameters
restraints
0
27
0
0
wR(F2, all Refl.)
R(I, >2σ(I))
0.0591
0.0234
1.914
0.1028
0.0461
3.263
0.1049
0.0468
1.011
0.0855
0.0366
1.026
max. ΔF (e A-3
)
Table 15. X-ray Data for Complexes 9, 12, 13, and 18
9 H2O
3
12 1/2CH2Cl2
3
13
18
formula
Mr
habit
crystal size (mm)
crystal system
space group
cell constants:
a (A)
b (A)
c (A)
R (deg)
β (deg)
C27H32AuCl2NOPRh
788.28
yellow prism
0.22 ꢀ 0.20 ꢀ 0.12
triclinic
C24.5H25.5AuCl3IrN2P
870.46
yellow plate
0.24 ꢀ 0.22 ꢀ 0.08
monoclinic
C43H48Au2Cl6N2OP2Pd
1383.81
paleyellow prism
0.25 ꢀ 0.20 ꢀ 0.18
monoclinic
C20H19AuCl3N4PPd
756.08
yellow plate
0.20 ꢀ 0.10 ꢀ 0.08
monoclinic
C2/c
P1
P21/c
C2/c
9.2224(18)
10.251(2)
15.128(3)
101.71(3)
90.65(3)
108.63(3)
2
1.979
6.448
764
18.090(4)
17.031(3)
17.584(4)
22.3635(12)
8.9788(5)
24.3721(13)
21.195(4)
12.250(3)
18.531(4)
114.23(3)
97.9210(10)
96.50(3)
γ (deg)
Z
8
4
8
Dx (Mg m-3
)
2.351
11.721
3268
-173
50
1.896
6.837
2656
-173
57
2.101
7.301
2864
-173
51
μ (mm-1
F(000)
T (°C)
2θmax
)
-173
51
no. of refl.:
measured
independent
transmissions
Rint
8583
4772
0.3312-0.5117
0.0126
307
56190
8624
0.165-0.454
0.083
586
15643
5722
0.279-0.372
0.021
265
34557
4427
0.323-0.592
0.024
272
parameters
restraints
0
0
0
0
wR(F2, all Refl.)
R(I, >2σ(I))
S
0.066
0.027
1.066
1.29
0.139
0.051
1.059
2.88
0.073
0.0279
1.038
2.24
0.037
0.017
1.141
0.95
max. ΔF (e A-3
)
(single ζ, 3d, 4p), Au, and Ir (single ζ, 6p, 5f), Rh (single ζ, 5p,
4f), and Cu (single ζ, 4p, 4f). Triple ζ Slater-type orbitals (STO)
were used to describe the valence shells of H (1s) with two
polarization functions (single ζ, 2s, 2p). Time dependent DFT
calculations (TD-DFT)23 in the ADF implementation were used
to determine the excitation energies. The seventy lowest single-
t-singlet excitation energies were calculated for the three com-
plexes, using the optimized geometries. Mayer bond orders22
and spin orbit coupling were calculated as implemented in ADF.
Three-dimensional representations of the orbitals were obtained
with Molekel,39 and structures and electronic spectra with
Chemcraft.40
ꢀ
Acknowledgment. We thank the Direccion General de Investi-
ꢀ
gacion Cientıfica y Tecnica (CTQ2007-67273-C02-01) for financial
ꢀ
´
€
(39) Portmann, S.; Luthi, H. P. Chimia 2000, 54, 766–770.
(40) http://www.chemcraftprog.com/index.html.

Article
Inorganic Chemistry, Vol. 49, No. 18, 2010 8269
support. M.J.C. and P.D.V. acknowledge FCT, POCI, and FEDER
(project PTDC/QUI/58925/2004) for financial support.
13, 18 (CCDC reference numbers 730877-730884). Tables S1
and S2, with results from DFT calculations (calculated
distances and composition of frontier orbitals). This material
is available free of charge via the Internet at http://pubs.
acs.org.
Supporting Information Available: Eight X-ray crystallo-
graphic files, in CIF format, for compounds 3, 4, 7, 8, 9, 12,