Luminescent silver(I) and copper(I) systems containing pyridyl phosphine bridges

Article abstract of DOI:10.1515/znb-2009-11-1236

Luminescent silver(I) and copper(I) complexes containing pyridylphosphine ligands have been synthesized and structurally characterized by single crystal X-ray diffraction methods. The reaction of Ag(OTf) (OTf = trifluoromethanesulfonate) with 2-pyridyldip

Full text of DOI:10.1515/znb-2009-11-1236

Luminescent Silver(I) and Copper(I) Systems Containing
Pyridyl Phosphine Bridges
Olga Crespo, M. Concepcio´n Gimeno, Antonio Laguna, and Carmen Larraz
Departamento de Qu´ımica Inorga´nica, Instituto de Ciencia de Materiales de Arago´n,
Universidad de Zaragoza-CSIC E-50009 Zaragoza, Spain
Reprint requests to Prof. M. C. Gimeno. E-mail: gimeno@unizar.es
Z. Naturforsch. 2009, 64b, 1525 – 1534; received September 29, 2009
Dedicated to Professor Hubert Schmidbaur on the occasion of his 75th birthday
Luminescent silver(I) and copper(I) complexes containing pyridylphosphine ligands have been
synthesized and structurally characterized by single crystal X-ray diffraction methods. The reaction
of Ag(OTf) (OTf = trifluoromethanesulfonate) with 2-pyridyldiphenylphosphine in different molar
ratios gives the species [Ag2(OTf)2(µ-PPh2py)2] (1), [Ag(PPh2py)2]OTf (2), [Ag(PPh2py)3]OTf
(3), and [Ag2(PPh2py)3](OTf)2 (4) with several modes of coordination of the pyridylphosphine.
The oxidation of the phosphine in compound 4 gave [Ag2(OTf)(µ-PPh2py)2(OPPh2py)]OTf (5)
which has been structurally characterized. It shows two bridging phosphine ligands and one chelating
OPPh2py ligand. The reactions of the silver salt with bis(2-pyridyl)phenylphosphine in different mo-
lar ratios affords the complex [Ag2(OTf)2(µ-PPhpy2)2] (6), while the corresponding reactions with
[Cu(NCMe)4]PF6 lead to two different compounds, namely [Cu2(NCMe)2(µ-PPhpy2)2](PF6)2 (7)
and [Cu2(PPhpy2)2(µ-PPhpy2)2](PF6)2 (8). All complexes exhibit luminescence in the solid state at
room temperature and at 77 K.
Key words: Silver, Copper, Pyridylphosphines, Luminescence, Metallophilic Interactions
Introduction
unsymmetrical ligand, which forms a rigid bridge
between two metal ions, was first used by Balch and
coworkers for comparison with the symmetrical bridg-
ing ligand bis(diphenylphosphino)methane (dppm)
and for the construction of heterobimetallic systems
[19]. A similar ligand, which has been less explored
in coordination chemistry, is the bis(2-pyridyl)phenyl-
phosphine (PPhpy2) which has an additional pyridine
ring and thus can act as tridentate ligand.
Luminescent d10 compounds [1, 2] have received in-
creasing attention over the past decade because of their
interesting photophysical and photochemical proper-
ties, their possible applications in OLED display tech-
nology [3, 4], as dopant emitters [5 – 9] and in sen-
sor development for luminescence-based detection of
volatile organic compounds (VOCs) [10 – 14]. For
such applications, polynuclear d10 complexes that ex-
hibit intense, long-living luminescence in the solid
state at ambient temperatures with emission energies
spanning the visible spectrum appear particularly at-
tractive [1, 2]. In many of these compounds the inter-
esting luminescent properties are enhanced in the pres-
ence of the metallophilic interactions [15, 16], and this
is particularly true for gold complexes but also to a
lesser extend for the silver and copper derivatives.
Specific examples with two bridging ligands in
group 11 metal complexes include the dimeric Au(I)
complex [Au2(µ-PMe2py)2](BF4)2 with a remarkably
short gold-gold distance [20], the dimeric Cu(I)
complexes [Cu2(NCMe)2(µ-PPh2py)2](PF6)2 and
[Cu2(NCMe)(µ-PPh2py)3](BF4)2, [21], and the silver
complexes [Ag2(NO3)2(µ-PPh2py)2], [Ag4(NO3)2(µ-
NO3)(µ-PPh2py)4]+, [Ag2(µ-PPh2py)2(PPh2py)]2+
,
and [Ag2Cl2(µ-PPh2py)(PPh2py)2] [22], and a variety
Bridging ligands play a key role in the formation of adducts of the type [AgX(PPh2py)] [23] (X = Cl,
and properties of polynuclear d10 complexes by Br, NO3, SCN, ClO4, BF4, O2CCF3). With the PPhpy2
helping to facilitate intramolecular metallophilic ligand the gold compound [Au(C6F5)(PPhpy2)] [24],
interactions. One notable ligand in this regard is the silver complex [Ag2(NCMe)2(PPhpy2)2](ClO4)2
2-pyridyldiphenylphosphine (PPh2py) [17, 18]. This [25], the copper complexes [Cu2Cl2(µ-PPhpy2)2]
c
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O. Crespo et al. · Luminescent Silver(I) and Copper(I) Systems
Scheme 1.
[26] and [Cu2(NCMe)2(µ-PPhpy2)2](ClO4)2 [27],
and palladium-copper [28] derivatives have been
described.
Here we report on the synthesis of silver(I) and
copper(I) complexes with the PPh2py and PPhpy2
ligands. Depending on the molar ratio, several coordi-
nation types have been achieved, and in the dinuclear
derivatives metallophilic bonding has been observed
only for silver complexes. The luminescence behavior
of these complexes has been studied. Regardless of the
metal different emissions have been observed depend-
ing on the phosphine ligand. A mixed intraligand and
LMCT (pyridine-to-metal) transitions are possible as
the origin of these emissions.
Fig. 1. Molecular structure of complex 1 in the crystal. Hy-
drogen atoms have been omitted for clarity. Radii are arbi-
trary.
Results and Discussion
ment with bridging PPh2py ligands; it corresponds to
an AB system for the phosphorus atoms coupled to
both silver nuclei with different coupling constants.
Simulation of the spectrum agrees with the proposal.
The crystal structure determination of complex 1
We studied the reactions of silver trifluoromethane-
sulfonate with the 2-pyridyldiphenylphosphine ligand
in several molar ratios in order to investigate the struc-
tures of these complexes and their luminescence prop-
erties. The reaction of Ag(OTf) with one equivalent
of PPh2py in acetone leads to the dinuclear deriva- shows the presence of a dinuclear bridging P,N unit
tive [Ag2(OTf)2(µ-PPh2py)2] (1) (see Scheme 1). forming an eight-membered ring where the silver
1
The 31P{ H} NMR spectrum of 1 presents a broad atoms are also bonded to one oxygen atom of the
temperature-dependent resonance, which is indicative triflate ligand. The molecule is shown in Fig. 1,
of ligand exchange processes involving dissociation of and a selection of bond lengths and angles is given
the Ag–P bonds. At −90 ◦C a spectrum with 6 symmet- in Table 1. One of the silver atoms, Ag1, is also
ric lines centered at 22.83 ppm occurs that is in agree- bonded to one oxygen atom of another triflate, O5,
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˚
˚
Table 1. Selected bond lengths (A) and angles (deg) for com- Table 2. Selected bond lengths (A) and angles (deg) for com-
plex 1a.
plex 5.
Ag(1)–N(1)
Ag(1)–P(1)
Ag(1)–O(2)
Ag(1)–Ag(2)
2.236(2)
2.3857(6)
2.5045(18) Ag(2)–P(2)
3.0623(3)
Ag(2)–N(3)
Ag(2)–N(2)
2.282(2)
2.332(2)
2.3813(6)
2.5009(17)
Ag(1)–N(2)
Ag(1)–P(1)
Ag(1)–O(1)
Ag(1)–O(5)#1
2.259(3) Ag(1)–Ag(2)
2.3707(9) Ag(2)–N(1)
2.433(2) Ag(2)–P(2)
2.582(2) Ag(2)–O(4)
3.0438(5)
2.220(3)
2.3816(9)
2.570(2)
Ag(2)–O(1)
N(1)–Ag(1)–P(1) 160.80(6)
N(1)–Ag(1)–O(2) 90.44(7)
P(1)–Ag(1)–O(2) 108.12(5)
N(1)–Ag(1)–Ag(2) 83.40(5)
N(3)–Ag(2)–O(1)
N(2)–Ag(2)–O(1)
P(2)–Ag(2)–O(1) 116.40(4)
N(3)–Ag(2)–Ag(1) 93.58(5)
76.12(6)
90.93(7)
N(2)–Ag(1)–P(1)
N(2)–Ag(1)–O(1)
P(1)–Ag(1)–O(1)
N(2)–Ag(1)–O(5)#1
156.61(7) O(5)#1–Ag(1)–Ag(2)
87.95(9) N(1)–Ag(2)–P(2)
115.41(6) N(1)–Ag(2)–O(4)
79.48(8) P(2)–Ag(2)–O(4)
97.38(5)
160.92(7)
95.73(9)
103.29(6)
85.79(7)
75.46(2)
164.65(5)
P(1)–Ag(1)–O(5)#1 106.29(6) N(1)–Ag(2)–Ag(1)
P(1)–Ag(1)–Ag(2) 77.457(16) N(2)–Ag(2)–Ag(1) 87.56(5)
O(1)–Ag(1)–O(5)#1
N(2)–Ag(1)–Ag(2)
P(1)–Ag(1)–Ag(2)
75.53(8) P(2)–Ag(2)–Ag(1)
83.12(7) O(4)–Ag(2)–Ag(1)
73.72(2)
O(2)–Ag(1)–Ag(2) 168.17(5)
N(3)–Ag(2)–N(2) 115.94(7)
N(3)–Ag(2)–P(2) 132.43(5)
N(2)–Ag(2)–P(2) 109.77(5)
P(2)–Ag(2)–Ag(1) 75.492(16)
O(1)–Ag(2)–Ag(1) 167.70(4)
P(3)–O(1)–Ag(2) 113.49(9)
O(1)–Ag(1)–Ag(2) 169.53(6)
a
Symmetry transformation used to generate equivalent atoms: #1 x,
−y+1/2, z+1/2.
Fig. 3. Structure of the cation of complex 5 in the crystal.
Hydrogen atoms have been omitted for clarity. Radii are ar-
bitrary.
Fig. 2. One-dimensional zig-zag coordination polymer of
complex 1 in the crystal.
(bonded to two triflate ligands) can be regarded as trig-
onal pyramidal. The Ag–P and Ag–N distances are
˚
at a distance of 2.582(2) A. The bridging nature
˚
˚
2.3707(9), 2.3816(9) A and 2.259(3), 2.220(3) A, re-
spectively, and are in the same range as those found
in the [Ag2(NO3)2{µ-PPh2(Bzim)}2] [30], which also
contains a P,N bridging ligand. The Ag–O distances are
of these triflate ligands leads to the formation of
a one-dimensional zig-zag polymer (Fig. 2). The
˚
Ag–Ag distance of 3.044(1) A is similar to others
found in dinuclear complexes with bridging ligands
˚
very different, with 2.433(2) A for the terminal triflate
ligand and 2.582(2) and 2.570(2) A for the bridging
such as [Ag2(µ-PPh2CH2SPh)2](ClO4)2 (2.9501(8),
˚
˚
2.9732(9) A) [29], with a P,S ligand, [Ag2(NO3)2{µ-
˚
triflate.
PPh2(Bzim)}2] (3.970 A) [30], with a P,N ligand,
and [Ag2(µ-PP)2]2+ (2.890– 3.095 A) (PP = diphos-
The reaction of Ag(OTf) and PPh2py in a mo-
˚
phine) in which the existence of argentophilic inter- lar ratio of 1:2 gives a complex of stoichiometry
actions was suggested based on spectroscopic evi- [Ag(PPh2py)2]OTf (2). There are several possible
dence [31]. The geometry around the silver centers modes of coordination of two phosphine ligands to the
in 1 is very irregular. In both cases the angles N– silver center: the complex can be mononuclear with
Ag–P are very distorted from a linear geometry with two chelate pyridyl-phosphine ligands, dinuclear with
angles N2–Ag1–P1 of 156.61(7) and N1–Ag2–P2 of two P,N-bridging ligands and one terminal P-ligand
160.92(7)◦. Consequently the other angles are also ir- bonded to each silver center, or dinuclear with two
regular, but Ag2 can be considered to be in a tetrahe- bridging P,N- and two chelating P,N-ligands. Conse-
dral environment, whereas the geometry around Ag1 quently, although the analytical data correspond to the
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O. Crespo et al. · Luminescent Silver(I) and Copper(I) Systems
Scheme 2.
proposed stoichiometry, the NMR data at low temper-
ature show the presence of several complexes that may
corresponds to all the possible isomers.
Complexes [Ag(PPh2py)3]OTf (3) and [Ag2-
(PPh2py)3](OTf)2 (4) have also been prepared by
treatment of AgOTf with the phosphine in molar ratios
of 1:3 and 2:3. The proposed structures correspond
to a trigonal-planar geometry for complex 3 and a
dinuclear compound with bridging P,N ligands and
a terminal phosphine ligand for complex 4, similar
to the structure obtained for the perchlorate salt
(Scheme 1). The NMR data also agree with those of
the perchlorate salt [22c]. During crystallization of
compound 4 crystals of the oxidized product [Ag2(µ-
PPh2py)2(OPPh2py)](OTf)2 (5) were obtained. Its
molecular structure is shown in Fig. 3, and a selection
of bond lengths and angles are given in Table 2. The
complex consists of a dinuclear unit with two bridging
P,N ligands in which one of the silver atoms is bonded
to a chelating N,O-ligand and the other one to the
oxygen atoms of the triflate unit. There is a short
Fig. 4. Association into dimers of complex 5.
The reactivity of the bis(2-pyridyl)phenylphosphine
ligand towards silver(I) and copper(I) has also been
studied. Treatment of PPhpy2 with Ag(OTf) leads to
the formation of the dinuclear species [Ag2(OTf)2(µ-
PPh2py)2] (6) independently from the molar ratios
1
used (1:1 or 2:1, see Scheme 2). The H NMR spec-
trum shows the resonances of the pyridine and phenyl
1
˚
rings of the phosphines, and the 31P{ H} NMR spec-
Ag···Ag distance of 3.023(3) A which is similar to
trum displays a broad resonance at 22.0 ppm that
splits into two broad doublets at low temperature. The
((+)-LSI) mass spectrum shows the cation molecu-
lar peak at m/z = 893 ([Ag2(OTf)(PPhpy2)4]+, 15 %),
and the most intense peak appears at m/z = 371
([Ag(PPhpy2)]+, 100%).
that found in complex 1. The geometry around the
silver center Ag2 is strongly distorted tetrahedral with
an angle P2–Ag2–N2 of 132.43(5)◦, and Ag1 shows
a very irregular trigonal-planar geometry with a wide
N1–Ag1–P1 angle of 160.80(6)◦. Ag1 displays a long
˚
intermolecular contact of 2.689 A to one oxygen atom
of the triflate ligand leading to dimeric units, as shown
in Fig. 4. The Ag–N and Ag–P distances are also very X-ray diffraction, and the molecule is shown in Fig. 5.
The structure of complex 6 has been established by
similar to those in compound 1.
A selection of bond lengths and angles is collected in
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O. Crespo et al. · Luminescent Silver(I) and Copper(I) Systems
1529
˚
˚
Table 4. Selected bond lengths (A) and angles (deg) for com-
Table 3. Selected bond lengths (A) and angles (deg) for com-
plex 7a.
plex 6a.
Ag(1)–N(1)#1
Ag(1)–N(2)#1
Ag(1)–P(1)
2.339(4)
2.352(5)
2.3727(16)
Ag(1)–O(1)
2.497(4)
3.1953(9)
Cu(1)–N(3)
2.032(3)
2.062(3)
2.067(3)
Cu(1)–P(1)
2.1940(11)
3.5303(10)
Cu(1)–N(2)#1
Cu(1)–N(1)#1
Cu(1)–Cu(1)#1
Ag(1)–Ag(1)#1
N(3)-Cu(1)-N(2)#1
99.06(12) N(3)-Cu(1)-P(1)
116.38(9)
N(1)#1-Ag(1)-N(2)#1 82.53(15) P(1)-Ag(1)-O(1)
109.49(16)
N(3)-Cu(1)-N(1)#1
100.68(12) N(2)#1-Cu(1)-P(1) 122.47(8)
N(1)#1-Ag(1)-P(1) 134.85(13) N(1)#1-Ag(1)-Ag(1)#1 84.97(11)
N(2)#1-Ag(1)-P(1) 128.60(10) N(2)#1-Ag(1)-Ag(1)#1 81.40(9)
N(2)#1-Cu(1)-N(1)#1 92.33(11) N(1)#1-Cu(1)-P(1) 120.87(8)
a
N(1)#1-Ag(1)-O(1)
84.08(15) P(1)-Ag(1)-Ag(1)#1
71.33(3)
Symmetry transformation used to generate equivalent atoms:
−x+1, −y, −z+1.
#1
N(2)#1-Ag(1)-O(1) 107.99(19) O(1)-Ag(1)-Ag(1)#1 164.47(12)
a
Symmetry transformation used to generate equivalent atoms:
−x+2, −y+2, −z.
˚
#1
Table 5. Selected bond lengths (A) and angles (deg) for com-
plex 8a.
Cu(1)–N(1)#1
2.043(3)
2.064(3)
Cu(1)–P(1)
Cu(1)–P(2)
2.2385(14)
2.2485(11)
Cu(1)–N(2)#1
N(1)#1-Cu(1)-N(2)#1 101.96(13) N(1)#1-Cu(1)-P(2) 110.44(10)
N(1)#1-Cu(1)-P(1)
108.01(10) N(2)#1-Cu(1)-P(2) 103.30(9)
105.91(10) P(1)-Cu(1)-P(2) 124.67(4)
N(2)#1-Cu(1)-P(1)
a
Symmetry transformation used to generate equivalent atoms:
#1
−x, −y+1, −z.
Fig. 5. Molecular structure of complex 6 in the crystal. Hy-
drogen atoms have been omitted for clarity. Radii are arbi-
trary.
Table 3. The complex crystallizes as a dimer with a
˚
short Ag(I)···Ag(I) contact of 3.1953(9) A, slightly
longer than that of the corresponding PPh2py deriva-
tive. Contrary to the situation in complex 1 the triflate
units in 6 are acting as monodentate ligands, and the
geometry for both silver(I) atoms is distorted tetrahe-
dral (not taking into account the argentophilic inter-
action) with a narrow N–Ag–N angle of 82.53(15)◦
and a very regular P–Ag–O angle of 109.49(16)◦.
Fig. 6. Structure of the cation of complex 7 in the crystal.
Hydrogen atoms have been omitted for clarity. Radii are ar-
bitrary.
˚
The Ag–N distances are 2.339(4) and 2.352(5) A, and
˚
the Ag–P bond length is 2.3727(16) A which is in
same range as those found in the acetonitrile derivative
[Ag2(NCMe)2(µ-PPhpy2)2](ClO4)2 [25].
The corresponding reactions of bis(2-pyridyl)phen-
ylphosphine with [Cu(NCMe)4]PF6, in a 1:1 or
2:1 molar ratio, lead to two different compounds,
namely [Cu2(NCMe)2(µ-PPhpy2)2](PF6)2 (7) and
[Cu2(PPhpy2)2(µ-PPhpy2)2](PF6)2 (8) (Scheme 2).
1
The 31P{ H} NMR spectra show a singlet for complex
7 at −6.36 ppm, indicating the equivalence of the phos-
phorus atoms, whereas for compound 8 a very broad
resonance is observed at 3.2 ppm even at low tem-
perature, probably arising from a rapid exchange be-
Fig. 7. Structure of the cation of complex 8 in the crystal.
Hydrogen atoms have been omitted for clarity. Radii are ar-
bitrary.
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O. Crespo et al. · Luminescent Silver(I) and Copper(I) Systems
Table 6. DRUV and Luminescence studies.
a
b
b
Compound
RDUV
λemis (λex
)
λemis a (λex
77 K
)
τ (µs)
298 K
298 K
[Ag2(OTf)2(µ-PPh2py)2] (1)
310 – 360
450
497 (407)
479 (360)
53.7
[Ag(PPh2py)2]OTf (2)
[Ag(PPh2py)3]OTf (3)
310 – 360
491 (366)
494 (407)
455(325)
51.8
25.7
240
290 – 400
436 (322)
497 (407)
[Ag2(PPh2py)3](OTf)2 (4)
[Ag2(OTf)2(µ-PPhpy2)2] (6)
240
300 – 400
496 (400)
547 (388)
482 (400)
464 (310)
10.2
62
220
300 – 250
360 – 400
450 (308)
555 (360)
[Cu2(NCMe)2(µ-PPhpy2)2](PF6)2 (7)
210
300 – 350
360 – 400
543 (360)
550 (380)
514 (319)
13
18
[Cu2(PPhpy2)2(µ-PPhpy2)2](PF6)2 (8)
260
340 – 450
510 (315)
568 (360)
a
Emission maxima in nm; b excitation maxima in nm.
tween the phosphine sites on the NMR time scale. The
mass spectra for both complexes show similar peaks
with similar abundances arising from the fragments
[Cu(PPhpy2)]+ at m/z = 327 (100%), [Ag(PPhpy2)2]+
at m/z = 591 (16 %) and [Ag2(PPhpy2)2]2+ at m/z =
654 (6 %).
The crystal structures of complexes 7 and 8 have
been determined, and the cations are shown in Figs.
6 and 7, respectively. A selection of bond lengths and
angles are collected in Tables 4 and 5. The structure
of complex 7 is similar to that recently communicated
with the perchlorate anion [27] and consists of two
copper atoms bridged by two PPhpy2 ligands and addi-
tionally bonded to an acetonitrile molecule. The coor-
dination around the copper atoms is distorted tetrahe-
Fig. 8. Emission spectra of complexes 2 (straight line) and 7
(dashed line).
and one or two additional bands in the 300 – 450 nm
region (Table 6). Absorptions at higher energies than
310 nm are not observed in 1 and 2.
˚
dral, and the distance Cu···Cu is 3.5303(10) A, which
can be considered as a weak copper-copper bonding
interaction. The structure of complex 8 is similar, but
now the acetonitrile positions are occupied by a ter-
minal phosphine ligand bonded via the phosphorus
atoms. The Au–N distances are very similar, 2.043(3)
All the complexes are emissive in the solid state,
both at r. t. and at 77 K. They display one or two emis-
sions (Table 6) in the range from 436 to 568 nm. Life-
times measured at r. t. are in the microsecond range,
which points to a phosphorescence nature of the emis-
sions. The general trend is that the emission maxima
for complexes with the phosphine PPhpy2 appear at
lower energies than those containing PPh2py (Fig. 8 il-
lustrates this behavior for complexes 2 and 7), although
˚
and 2.064(3) A, whereas the Ag–P bond lengths
˚
are slightly different, 2.2385(14) and 2.2485(11) A,
the shortest corresponding to the bridging phosphine
ligand.
Luminescence studies
The diffuse reflectance ultraviolet visible spectra the metal (copper or silver) is another factor to be taken
(DRUV) were recorded for all the complexes. The into account. The emissions observed for complexes
spectra of 3, 4, 6 – 8 consist of one band with maxima 1 – 4 (which contain PPh2py) resemble in general the
between 220 and 260 nm, depending on the complex, energies of the free monophosphine and are probably
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O. Crespo et al. · Luminescent Silver(I) and Copper(I) Systems
1531
due to intraligand (IL, PPh2py) [32] transitions mod- has been structurally characterized. The silver(I) and
ified through the coordination to silver. Furthermore copper(I) complexes with the bis(2-pyridyl)phenyl-
compounds 3 and 4 display two bands at 77 K. Thus, a phosphine ligand are dinuclear species with a tridentate
contribution of pyridine-to-silver charge-transfer tran- P,N,N phosphine and an equatorial ligand that can be
sitions to the emissive behavior of this complex can be triflate for silver and acetonitrile or another phosphine
postulated.
ligand for copper. Metallophilic interactions are only
present for the silver derivatives. The complexes are
emissive in the solid state, both at 298 and 77 K. The
emission maxima appear at lower energies for com-
plexes with the PPhpy2 ligand. The origin of the emis-
sion is postulated as mixed IL (monophosphine) and
LMCT (py → Cu or Ag), although IL transitions prob-
ably dominate in complexes containing PPh2py, and
LMCT are postulated as more important for the lumi-
nescence of the compounds containing PPhpy2.
Complexes 6 – 8 (which contain PPhpy2) display
emissions at higher energies than 1 – 4. The lumi-
nescence of [Cu2(NCMe)2(µ-PPhpy2)2]SO4 and
polymeric [Cu2(µ-PPhpy2)2(µ-SO4)]∞ has been
studied in the solid state at r. t. Both complexes display
green emission [27] which is consistent with our
results obtained for 7. It is interesting to compare
the emission of [Cu2(NCMe)2(µ-PPhpy2)2](PF6)2
(7), [Cu2(NCMe)2(µ-PPhpy2)2]SO4 and [Cu2(µ-
PPhpy2)2(µ-SO4)]∞ with that of the analogous silver
complexes [Ag2(NCMe)2(µ-PPhpy2)2](ClO4)2 and
[Ag2(µ-PPhpy2)2{1,3,5-C6H3(CO2)2(CO2H)}]∞ [25].
The blue emission of the silver complexes around
440 nm indicates that metal-metal interactions
and the axial ligand do not have an important
effect on the energy of the emission which was
postulated to originate from intra-ligand transi-
tions and resembles those observed at 77 K for
[Ag2(OTf)2(µ-PPhpy2)2] (6). Intra-ligand (PPhpy2)
Experimental Section
General procedure
Infrared spectra were recorded in the range of 4000 –
200 cm−1 on a Perkin-Elmer 883 spectrophotometer using
Nujol mulls between polyethylene sheets. C, H, N and S
analyses were carried out with a Perkin-Elmer 2400 micro-
analyzer. Mass spectra were recorded on a VG Autospec
instrument, with the liquid secondary-ion mass spectrome-
try (MS ((+)-LSI)) technique, using nitrobenzyl alcohol as
transitions [27], modified by the presence of cop- matrix. NMR spectra were recorded on Varian Unity 300
and Bruker ARX 300 spectrometers in CDCl3. Chemical
per and silver, could thus be responsible for the
luminescence of 6 – 8, but such an origin would
not explain the different emissions of the analogous
complexes [Ag2(NCMe)2(µ-PPhpy2)2](ClO4)2, (blue
emissive) [27] and [Cu2(NCMe)2(µ-PPhpy2)2]SO4
or [Cu2(NCMe)2(µ-PPhpy2)2](PF6)2 (7) (green
emissive) [25]. Pyridine-to-ligand charge transfer
transitions (LMCT, py → Cu or Ag) could be respon-
sible for this luminescence, however, since a similar
red shift when going from silver to copper has been
described for acetylide complexes [33], although the
emission of [Ag2(OTf)2(µ-PPhpy2)2] (6) does not
follow this pattern. Two bands are observed for 6
shifts are cited relative to SiMe4 (1H, external), 85 % H3PO4
(
31P, external), or CFCl3 19F, external). The starting ma-
(
terials PPhpy2 [34] and [Cu(NCMe)4]PF6 [35] were pre-
pared by published procedures. Other compounds were com-
mercially available. DRUV spectra were recorded with a
UnicamUV-4 spectrophotometer equipped with a Spectralon
RSA-UC-40 Labsphere integrating sphere. The solid sam-
ples were mixed with dried KBr and placed in a home-made
cell equipped with a quartz window. The intensities were
recorded in Kubelka-Munk units. Steady-state photolumines-
cence spectra were recorded with a Jobin-Yvon Horiba Flu-
orolog FL-3-11 spectrometer using band pathways of 3 nm
for both excitation and emission. Phosphorescence lifetimes
and 8 at 77 K indicating that the situation may be 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 package DATAMAX 2.20 [36] and the ORIGIN 5.0
program [37].
more complicated. Thus, the origin of the emissions
probably is mixed IL and LMCT (py → Cu or Ag), but
predominantly LMCT.
Conclusions
Preparations
Silver(I) complexes with the ligand 2-pyridyldi-
phenylphosphine have been synthesized and present
several modes of coordination of the pyridylphos-
phine. The oxidation of [Ag2(PPh2py)3](OTf)2 (4)
Synthesis of [Ag2(OTf)2(µ-PPh2py)2] (1)
To a solution of Ag(OTf) (0.026 g, 0.1 mmol) in 20 mL of
acetone was added PPh2py (0.026 g, 0.1 mmol) and the solu-
gave [Ag2(OTf)(µ-PPh2py)2(OPPh2py)]OTf, which tion stirred for 30 min. Evaporation of the solvent to ca. 2 mL
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1532
O. Crespo et al. · Luminescent Silver(I) and Copper(I) Systems
Table 7. Crystal structure data for complexes 1, 5, 6, 7, and 8.
Compound
Formula
Mr
1
5
6
7
8
C36H26Ag2F6N2O6P2S2 C57H52Ag2F6N3O8P3S2 C17H13AgF3N2O3PS C40H38Cu2F12N8P4 C34H30Cl2CuF6N4P3
1040.40
pale-yellow prism
1393.79
521.19
pale-yellow plate
1109.76
colorless needle
835.97
colorless prism
Habit
pale-yellow prism
0.24 × 0.20 × 0.16
triclinic
Crystal size, mm3 0.28 × 0.20 × 0.16
0.22 × 0.16 × 0.10 0.22 × 0.07 × 0.07 0.25 × 0.20 × 0.18
Crystal system
Space group
monoclinic
P21/c
12.400(2)
27.660(5)
11.555(2)
90
109.462(3)
90
3736.6(11)
4
monoclinic
P21/n
12.733(3)
9.923(2)
15.140(3)
90
monoclinic
P21/c
8.9781(18)
28.264(6)
9.1630(18)
90
92.92(3)
90
2322.2(8)
2
triclinic
P1
¯
¯
P1
˚
a, A
13.5195(7)
14.6439(7)
15.6835(8)
99.4870(10)
107.1560(10)
100.6360(10)
2835.3(2)
2
10.154(2)
13.549(3)
14.963(3)
67.06(3)
79.20(3)
75.34(3)
1825.1(6)
2
˚
b, A
˚
c, A
α, deg
β, deg
98.84(3)
90
1890.3(7)
4
1.83
1.3
γ, deg
3
˚
V, A
Z
DX, g cm−3
µ, mm−1
F(000), e
T, ◦C
1.85
1.3
2064
1.63
0.9
1408
1.58
1.1
1120
1.52
0.9
848
1032
−173
−173
−173
−173
−173
2θmax, deg
Refl. measured
Refl. independent 6923
Rint 0.037
Min. / max. transm. 0.78 / 0.816
51
56.6
50
51
50
21017
26925
13207
0.017
0.808 / 0.866
717
0.092
0.033
1.032
1.71
11081
3292
0.029
0.761 / 0.880
271
0.105
0.048
1.108
0.79
15474
4287
0.032
0.487 / 0.924
451
0.123
0.052
1.084
1.26
11679
6269
0.021
0.799 / 0.849
451
0.162
0.058
1.076
1.79
Parameters
wR (F2, all refl.)
R [I ≥ 2σ(I)]
S
505
0.080
0.033
1.091
1.26
−3
˚
∆ρmax, e A
and addition of diethyl ether gave complex 1 as a white solid tion stirred for 30 min. Evaporation of the solvent to ca. 2 mL
(0.050 g, 97 %). Calcd. (found) for C18H14AgF3NO3PS and addition of diethyl ether gave complex 3 as a white solid
(520.21): C 41.55 (41.31), H 2.71 (2.37), N 2.69 (2.45), (0.091 g, 88 %). Calcd. (found) for C52H42AgF3N3O3P3S
S 6.16 (5.96). – 1H NMR ((CD3)2CO): δ = 7.2 – 7.5 (m, 40H, (1046.76): C 59.66 (59.85), H 4.04 (4.38), N 4.01 (3.91),
1
Ph), 7.11 (d, 4H, py, J(HH) = 8.0 Hz), 7.58 (m, 4H, py), 7.84 S 3.06 (3.59). – H NMR ((CD3)2CO): δ = 7.26 – 7.36 (m,
1
(t, 4H, py, J(HH) = 8.0 Hz), 9.21 (m, 4H, py). – 31P{ H} 30 + 3H, Ph + py), 7.11 (m, 3H, py), 7.69 (m, 3H, py), 8.45
1
NMR ((CD3)2CO, 183 K), δA ≈ δB = 22.83 (AB system, 2P, (m, 3H, py). – 31P{ H} NMR ((CD3)2CO): δ = 7.4 (s, 3P,
PPh2py, J(Ag109P) = 767.1, J(Ag107P) = 673, J(Ag109P) = PPh2py).
673, J(Ag107P) = 590.1 Hz).
Synthesis of [Ag2(OTf)(PPh2py)3]OTf (4)
Synthesis of [Ag(PPh2py)2]OTf (2)
To a solution of Ag(OTf) (0.052 g, 0.2 mmol) in 20 mL of
To a solution of Ag(OTf) (0.026 g, 0.1 mmol) in 20 mL of acetone was added PPh2py (0.079 g, 0.3 mmol) and the solu-
acetone was added PPh2py (0.053 g, 0.2 mmol) and the solu- tion stirred for 30 min. Evaporation of the solvent to ca. 2 mL
tion stirred for 30 min. Evaporation of the solvent to ca. 2 mL and addition of diethyl ether gave a white solid of complex 4
and addition of diethyl ether gave complex 2 as a white solid (0.106 g, 82 %). Calcd. (found) for C53H42Ag2F6N3O6P3S2
(0.072 g, 93 %). Calcd. (found) for C18H14AgF3NO3PS (1303.69): C 48.82 (48.56), H 3.24 (3.12), N 3.22 (3.04),
(783.48): C 53.65 (53.34), H 3.60 (3.18), N 3.57 (3.58), S 4.91 (4.75). – 1H NMR ((CD3)2CO): δ = 7.1 – 7.8 (m, 30 +
1
S 4.09 (3.99). – 1H NMR ((CD3)2CO): δ = 7.2 – 7.55 (m, 6H, Ph + py), 6.91 (m, 3H, py), 9.38 (m, 3H, py). – 31P{ H}
20 + 2H, Ph + py), 7.61 (m, 2H, py), 7.94 (m, 2H, py), 8.96 NMR ((CD3)2CO): δ = 10.6 (t, br, 3P, PPh2py).
(m, 2H, py). – 31P{ H} NMR (CD3)2CO): δ = 12.5 (s, br,
1
Synthesis of [Ag2(OTf)2(PPhpy2)2] (6)
2P, PPh2py).
To a solution of Ag(OTf) (0.025 g, 0.1 mmol) in 20 mL
of acetone was added PPhpy2 (0.026 g, 0.1 mmol), and
Synthesis of [Ag(PPh2py)3]OTf (3)
To a solution of Ag(OTf) (0.026 g, 0.1 mmol) in 20 mL of the mixture was stirred for 30 min. Evaporation of the
acetone was added PPh2py (0.079 g, 0.3 mmol) and the solu- solvent to ca. 5 mL and addition of n-hexane gave com-
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O. Crespo et al. · Luminescent Silver(I) and Copper(I) Systems
1533
plex 6 as a white solid (0.09 g, 87 %). Calcd. (found) for added under argon atmosphere, and the mixture was stirred
C34H26Ag2F6N4O6P2S2 (1042.38): C 39.17 (39.34), H 2.51 for 15 min, whereupon the color turned yellow. Evapora-
(2.56), N 5.37 (5.34), S 6.15 (6.35). – MS ((+)-LSI): m/z tion of the solvent to dryness and addition of n-hexane gave
(%) = 371 (100), [Ag(PPhpy2)]+). – 1H NMR ((CD3)2CO): complex 8 as a yellow solid (0.212 g, 72 %). Calcd. (found)
δ = 8.96 (d, 2H, py, 3J(HH) = 4.7 Hz), 8.22 (t, 2H, py, for C64H52Cu2F12N8P6 (1474.06): C 52.14 (52.31), H 3.55
3J(HH) = 7.8 Hz), 7.87 (d, br, 2H, py, 3J(HH) ∼ 7.0 Hz), (3.21), N 7.60 (7.49). – 1H NMR ((CD3)2CO): δ = 9.00 – 6.8
1
1
7.82 – 7.63 (m, 5 + 2H, Ph). – 31P{ H} NMR ((CD3)2CO): (m, 20 + 32H, Ph + py). – 31P{ H} NMR (CD3)2CO), δ =
δ = 22.07 (s, 2P, PPhpy2); ((CD3)2CO, 183 K): δ = 22.41 (d, 3.25, ((CD3)2CO, 183 K): δ = 4.44.
br, PPhpy2, J(AgP)av = 428 Hz).
X-Ray structure determination
Synthesis of [Cu2(NCMe)2(PPhpy2)2](PF6)2 (7)
Data were measured using MoKα radiation (λ
=
To a solution of [Cu(NCMe)4]PF6 (0.074 g, 0.2 mmol)
in 20 mL of dichloromethane was added PPhpy2 (0.052 g,
0.2 mmol) under argon atmosphere, and the mixture was
stirred for 15 min, whereupon the solution turned yellow.
Evaporation of the solvent to dryness and addition of n-
hexane afforded complex 7 as a yellow solid (0.167 g,
75 %). Calcd. (found) for C40H44Cu2F12N8P4 (1115.79):
C 43.29 (43.53), H 3.45 (3.31), N 10.09 (10.94). – 1H NMR
((CD3)2CO): δ = 8.72 (d, 4H, py, 3J(HH) = 4.6 Hz), 8.48 (dd,
4H, py, 3J(HH) = 11.1, Hz, 3J(HH) = 7.0 Hz), 8.01 – 7.42 (m,
˚
0.71073 A) on a Bruker SMART 1000 CCD (1, 5) or a Xcal-
ibur Oxford Diffraction diffractometer (6, 7, 8). Absorption
corrections were based on multiple scans (program SAD-
ABS [38]). The structures were solved by Direct Methods,
and refined by full-matrix least-squares on F2 (SHELXL-97
[39]). All non-hydrogen atoms were refined anisotropically.
H atoms were included using a riding model. Further details
are given in Table 7.
CCDC 749320 – 749324 contain the supplementary crys-
tallographic 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.
10 + 8H, Ph + py), 3.75 (s, 6H, NCMe). – 31P{ H} NMR
1
((CD3)2CO): δ = −6.36, ((CD3)2CO, 183 K): δ = −3.09.
Synthesis of [Cu2(µ-PPhpy2)2(PPhpy2)2](PF6)2 (8)
Acknowledgement
To a solution of [Cu(NCMe)4]PF6 (0.074 g, 0.2 mmol) in
We thank the Ministerio de Ciencia e Innovacio´n
20 mL of dichloromethane PPhpy2 (0.106 g, 0.4 mmol) was (CTQ2007-67273-C02-01) for financial support.
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