Syntheses and luminescence studies of mixed-metal gold(I)-copper(I) and -silver(I) alkynyl complexes. the turning-on of emission upon d 10 metal ion encapsulation

Article abstract of DOI:10.1039/b211909a

Reaction of the gold(I) alkynyl precursor complexes, [(R ₃P)Au{CξCC(=CH₂)Me}] (R = Ph 1,p-Tol 2) and [(μ-dppf)-Au₂{CξCC(=CH₂)Me}₂] 3, with copper(I) or silver(I) ions led to the formation of a series of luminescent η²-alkynyl mixed-metal complexes, [{η²- (R ₃P)Au{CξCC(=CH₂)Me}}₂Cu]PF₆ (R = Ph 4, p-Tol 5) and [(μ-dppf)Au₂{η²-CξCC-(= CH₂)Me}₂M]X (M = Cu, X = PF₆6; M = Ag, X = OTf 7). The X-ray crystal structures of 1 and 3 have been determined. The photophysical properties of the complexes have been investigated. Coordination of 1-3 as metalloligands to copper(I) and silver(I) ions to afford the respective complexes 4-7 has been demonstrated to be a versatile means to perturb the emission properties. The luminescence behaviour of 3 has been turned on upon copper(I) or silver(I) encapsulation in 6 and 7. The Royal Society of Chemistry 2003.

Full text of DOI:10.1039/b211909a

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Syntheses and luminescence studies of mixed-metal gold(I)–
copper(I) and –silver(I) alkynyl complexes. The “turning-on” of
emission upon d10 metal ion encapsulation
Vivian Wing-Wah Yam,* Kai-Leung Cheung, Eddie Chung-Chin Cheng, Nianyong Zhu and
Kung-Kai Cheung
Department of Chemistry, Centre for Carbon-Rich Molecular and Nano-Scale Metal-Based
Materials Research, and the HKU-CAS Joint Laboratory on New Materials,
The University of Hong Kong, Pokfulam Road, Hong Kong, People’s Republic of China.
E-mail: wwyam@hku.hk; Fax: (852) 2857-1586; Tel: (852) 2859-2153
Received 5th December 2002, Accepted 10th March 2003
First published as an Advance Article on the web 19th March 2003
᎐
Reaction of the gold() alkynyl precursor complexes, [(R P)Au{C᎐CC(᎐CH )Me}] (R = Ph 1, p-Tol 2) and [(µ-dppf )-
᎐
᎐
3
2
2
᎐
Au {C᎐CC(᎐CH )Me} ] 3, with copper() or silver() ions led to the formation of a series of luminescent η -alkynyl
mixed-metal complexes, [{η - (R P)Au{C᎐CC(᎐CH )Me}} Cu]PF (R = Ph 4, p-Tol 5) and [(µ-dppf )Au {η -C᎐CC-
᎐
᎐
2
2
2
2
2
᎐
᎐
᎐
᎐
᎐
3
2
2
6
2
(᎐CH )Me} M]X (M = Cu, X = PF 6; M = Ag, X = OTf 7). The X-ray crystal structures of 1 and 3 have been
᎐
2
2
6
determined. The photophysical properties of the complexes have been investigated. Coordination of 1–3 as
metalloligands to copper() and silver() ions to afford the respective complexes 4–7 has been demonstrated to be a
versatile means to perturb the emission properties. The luminescence behaviour of 3 has been “turned on” upon
copper() or silver() encapsulation in 6 and 7.
Experimental
Introduction
Since the first report on the X-ray crystal structural character-
ization of η2-alkynyl-coordinated complexes by Abu Salah
and Bruce in 1974,1 in which dimeric complexes were formed
from iron alkynyls that are π-bonded to copper via copper–
halide bridges, the field has blossomed due to the potential
application of such complexes in the deposition of thin
copper films for electronic devices and extensive series of
η2-alkynyl-coordinated complexes have been reported.2–5
Materials and reagents
Potassium tetrachloroaurate() (98ϩ%, Strem), triphenyl-
phosphine (Merck), tri(p-tolyl)phosphine (Strem), 2-methyl-
but-1-en-3-yne (Lancaster) and silver() trifluoromethane-
sulfonate (Aldrich) were used as received. [Cu(MeCN)4]PF6,12
[(R3P)AuCl]13,14 and [(µ-dppf )Au2Cl2]15 were prepared accord-
ing to the published procedure. All solvents were purified and
distilled using standard procedures before use.16 All other
reagents were of analytical grade and were used as received.
2
᎐
In particular, the reports on [{η -(CO) ReC᎐CRe(CO) -
᎐
5
5
Cu(µ-Cl)}2 by Beck and co-workers,6 and a series of poly-
heteronuclear coinage metal alkynyl complexes by Abu-Salah
and coworkers7 have demonstrated the presence and
importance of both σ- and π-bonding modes in the metal
alkynyl systems. Recently, we reported the syntheses and
Physical measurements and instrumentation
UV-visible spectra were obtained on a Hewlett-Packard 8452A
diode array spectrophotometer, IR spectra as KBr discs on a
Bio-Rad FTS-7 Fourier-transform infrared spectrophotometer
(4000–400 cmϪ1), and steady state excitation and emission
spectra on a Spex Fluorolog-2 Model F111 fluorescence
2
᎐
photophysical properties of [{η -Re(bpy)(CO) (C᎐CPh)} M]X,
᎐
3
2
᎐
᎐
[Pt Cu (C᎐CPh) ] and [Pt (dppm) (C᎐CPh) {M(MeCN)} ]X
᎐
᎐
2
4
8 2
2
2
4
2
2
(M = Cu, Ag; X = PF6, OTf ), which demonstrated the possi-
bility and feasibility of tuning the luminescence behaviour
through the perturbation of the electron richness of the alkynyl
ligands via π-coordination to different metal ions.8–10 As
an extension of our previous work on luminescent gold()
alkynyls,11 attempts have been made to probe the use of
gold() alkynyl complexes as π-donor metalloligands to
coordinate to metal centres. Here we report the syntheses and
spectrophotometer equipped with
a Hamamatsu R-928
photomultiplier tube. Low-temperature (77 K) spectra were
recorded by using a quartz sample tube in a quartz optical
Dewar flask. 1H NMR spectra were recorded on a Bruker
DPX-300 (300 MHz) Fourier transform NMR spectrometer in
CDCl3 at 298 K, with chemical shift values (δ, ppm) recorded
relative to tetramethylsilane (Me4Si). Positive-ion FAB and
positive ESI mass spectra were recorded on a Finnigan MAT95
mass spectrometer and a Finnigan LCQ mass spectrometer,
respectively. Elemental analyses of the newly synthesized com-
plexes were performed on a Carlo Erba 1106 or a Flash 1112
elemental analyser at the Institute of Chemistry, Chinese
Academy of Sciences. Emission lifetime measurements were per-
formed using a conventional laser system. The excitation source
was the 355-nm output (third harmonic) of a Spectra-Physics
Quanta-Ray Q-switched GCR-150-10 pulsed Nd-YAG laser.
Luminescence decay signals detected by a Hamamatsu R928
photomultiplier tube were converted to voltage changes by
connecting to a 50 Ω load resistor and were then recorded on a
Tektronix model TDS 620A digital oscilloscope. The emission
photophysical properties of a series of gold() enynyl complexes
᎐
with ancillary tertiary phosphine ligands, [(R P)Au{C᎐C-
᎐
3
᎐
C(᎐CH )Me}] (R = Ph, 1; p-Tol, 2) and [(µ-dppf )Au {C᎐C-
᎐
᎐
2
2
C(᎐CH )Me} ] 3 (Scheme 1). These complexes have been
᎐
2
2
shown to be capable of acting as metalloligands to coordinate
to copper() and silver() to form the mixed-metal gold()–
copper() and –silver() alkynyl complexes, [{η2-(PPh3)-
2
᎐
᎐
Au{C᎐CC(᎐CH )Me}} Cu]PF
4,
[{η -(Ptol )Au{C᎐C-
᎐
᎐
᎐
2
2
6
3
2
᎐
C(᎐CH )Me}} Cu]PF 5, [(dppf )Au {η -C᎐CC(᎐CH )Me} -
᎐
᎐
᎐
2
2
6
2
2
2
2
᎐
Cu]PF 6 and [(dppf )Au {η -C᎐CC(᎐CH )Me} Ag]OTf 7. The
᎐
᎐
6
2
2
2
luminescence properties of these complexes have been found to
be significantly perturbed through the coordination to copper()
and silver() metal centres.
D a l t o n T r a n s . , 2 0 0 3 , 1 8 3 0 – 1 8 3 5
T h i s j o u r n a l i s © T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 3
1830

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Scheme 1
lifetime, τ, was determined by a single exponential fitting of the
᎐CH ), 5.29 (d, 1H, J = 2.1 Hz, ᎐CH ), 7.29 (d, 6H, J = 7.8 Hz,
᎐ ᎐
2 2
luminescence decay trace with the relationship I = Ioexp(Ϫt/τ),
where I and Io are the luminescence intensity at time = t and 0,
respectively.
–C6H4–), 7.45 (d, 6H, J = 7.8 Hz, –C6H4–). IR (KBr, ν/cmϪ1):
ϩ
᎐
2101 (w) ν(C᎐C). Positive-ion FAB-MS: m/z 567 {M} . Found:
᎐
C, 54.91; H, 4.82%. C26H26AuP requires C, 55.13; H, 4.63%.
All solutions for photophysical studies were degassed on
a high vacuum line in a two-compartment cell consisting of a
10 ml Pyrex bulb and a 1-cm path length quartz cuvette, and
sealed from the atmosphere by a Bibby Rotaflo HP6 Teflon
stopper. The solutions were subject to at least four freeze–
pump–thaw cycles.
᎐
[(ꢀ-dppf)Au {C᎐CC(᎐CH )Me} ] (3). An ethanolic solution
᎐
᎐
2
2
2
of 2-methylbut-1-en-3-yne (14 mg, 0.21 mmol) and sodium
ethoxide (prepared in situ by addition of Na (7 mg, 0.30 mmol)
to EtOH (5 ml)) was added to a solution of [(µ-dppf )Au2Cl2]
(100 mg, 0.10 mmol) in EtOH–THF (10 ml; 1 : 1 v/v), and the
reaction mixture was stirred at room temperature. The solution
turned to clear orange after 30 min. After stirring for 5 h, the
solvent was evaporated to dryness and the resulting solid was
crystallized from dichloromethane–n-hexane to give 3 as orange
Synthesis of gold complexes
All reactions were performed under anaerobic and anhydrous
conditions using standard Schlenk techniques under an inert
atmosphere of nitrogen.
1
crystals (73 mg, 68%). H NMR (300 MHz, CDCl3): δ 1.97
(s, 6H, –CH3), 4.23 (m, 4H, –Cp), 4.69 (m, 4H, –Cp), 5.15 (d,
2H, J = 1.9 Hz, ᎐CH ), 5.31 (d, 2H, J = 1.9 Hz, ᎐CH ), 7.38–
᎐
᎐
2
2
7.53 (m, 20H, –PPh2). IR (KBr, ν/cmϪ1), 2105 (w) ν(C᎐C). Posi-
᎐
᎐
[(R P)Au{C᎐CC(᎐CH )Me}] (R ؍ Ph, 1; R ؍ p-Tol, 2). 1 and
᎐
᎐
᎐
3
2
2 were synthesized in a similar manner, and a typical prepar-
ation of 1 is described as follows. An ethanolic solution of
2-methylbut-1-en-3-yne (14 mg, 0.21 mmol) and sodium
ethoxide (prepared in situ by addition of Na (7 mg, 0.30 mmol)
to EtOH (5 ml)) was added to a solution of [(Ph3P)AuCl]
(100 mg, 0.20 mmol) in EtOH/THF (10 ml; 1 : 1 v/v) at room
temperature. The colourless solution turned to pale yellow
upon stirring for 30 min. After stirring for 5 h, the solvent was
evaporated to dryness and the residue was crystallized from
dichloromethane–n-hexane to give 1 as pale yellow crystals
tive-ion FAB-MS: m/z 1078 {M}ϩ. Found: C, 48.28; H, 3.33%.
C44H38Au2FeP2ؒ¼CH2Cl2 requires C, 48.33; H, 3.53%.
2
᎐
[ꢁ -{(R P)Au{C᎐CC(᎐CH )Me}} Cu]PF (R ؍ Ph, 4; R ؍
᎐
᎐
3
2
2
6
p-Tol, 5). A typical preparation of 4 is described as follows:
᎐
[(Ph P)Au{C᎐CC(᎐CH )Me}] (105 mg, 0.20 mmol) was dis-
᎐
᎐
3
2
solved in THF (20 ml) and a solid sample of [Cu(MeCN)4]PF6
(40 mg, 0.11 mmol) was added. The resulting solution was
stirred at room temperature for 30 min, and was then evacuated
to dryness. The residue was recrystallized from CH2Cl2–n-
hexane to give 4 as yellow crystals (43 mg, 34%). 1H NMR (300
MHz, CDCl3): δ 1.59 (s, 6H, –CH3), 5.31 (d, 2H, J = 2.0 Hz,
᎐CH ), 5.48 (d, 2H, J = 2.0 Hz, ᎐CH ), 7.46–7.65 (m, 30H,
1
(73 mg, 70%). 1: H NMR (300 MHz, CDCl3): δ 1.96 (s, 3H,
–CH ), 5.14 (d, 1H, J = 2.1 Hz, ᎐CH ), 5.31 (d, 1H, J = 2.1 Hz,
᎐
3
2
᎐CH ), 7.43–7.56 (m, 15H, PPh ). IR (KBr, ν/cmϪ1): 2112 (w)
᎐
᎐
᎐
2
3
2
2
ϩ
᎐
᎐
ν(C᎐C). Positive-ion FAB-MS: m/z 525 {M ϩ H} . Found: C,
PPh3). IR (KBr, ν/cmϪ1): 1968 (w) ν(C᎐C), 837 (s) ν(PF Ϫ).
᎐
᎐
6
52.59; H, 3.49%. C23H20AuP requires C, 52.68; H, 3.84%.
2: Yield: 78 mg, 69%. 1H NMR (300 MHz, CDCl3): δ 1.95 (s,
3H, –CH3), 2.43 (s, 9H, –C6H4CH3), 5.12 (d, 1H, J = 2.1 Hz,
Positive-ion FAB-MS: m/z 1112 {M Ϫ PF6}ϩ. Positive ESI-MS:
m/z 1112 {M Ϫ PF6}ϩ. Found: C, 42.88; H, 3.32%. C46H40Au2-
CuF6P3ؒ½CH2Cl2 requires: C, 42.97; H, 3.18%.
D a l t o n T r a n s . , 2 0 0 3 , 1 8 3 0 – 1 8 3 5
1831

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5: Yield, 46 mg, 37%. 1H NMR (300 MHz, CDCl3): δ 1.43 (s,
6H, –CH3), 2.41 (s, 18H, –C6H4CH3), 5.26 (d, 2H, J = 1.9 Hz,
expanded by Fourier methods and refined by full-matrix least
squares using the software package TeXsan20 on a Silicon
Graphics Indy computer. In the least-squares refinement, all 25
non-H atoms of the complex molecule were refined aniso-
tropically, and 19 other H atoms at calculated positions with
thermal parameters equal to 1.3 times that of the attached C
atoms, were not refined. CCDC-198509.
᎐CH ), 5.75 (d, 2H, J = 1.9 Hz, ᎐CH ), 7.21–7.40 (m, 24H,
᎐
᎐
2
2
–C6H4–). IR (KBr, ν/cmϪ1): 1973 (w) ν(C᎐C), 838 (s) ν(PF Ϫ).
᎐
᎐
6
Positive-ion FAB-MS: m/z 1196 {M Ϫ PF6}ϩ. Positive ESI-MS:
m/z 1196 {M Ϫ PF6}ϩ. Found: C, 45.39; H, 3.97%. C52H52Au2-
CuF6P3 requires: C, 45.57; H, 3.86%.
The crystal and structure determination data for 1 and 3 are
given in Table 1. Selected bond distances and angles are sum-
marized in Table 2.
CCDC reference numbers 198508 (1) and 198509 (3).
See http://www.rsc.org/suppdata/dt/b2/b211909a/ for crystal-
lographic data in CIF or other electronic format.
2
᎐
[(ꢀ-dppf)Au {ꢁ -C᎐CC(᎐CH )Me} Cu]PF (6). [(µ-dppf )Au -
᎐
᎐
2
2
2
6
2
᎐
{C᎐CC(᎐CH )Me} ] (110 mg, 0.10 mmol) was dissolved in
᎐
᎐
2
2
CH2Cl2 (20 ml) and a solid sample of [Cu(MeCN)4]PF6 (40 mg,
0.11 mmol) was added. The resulting solution was stirred at
room temperature for 30 min, and was then evacuated to dry-
ness. Orange crystals of 6 were obtained by recrystallization
from CH2Cl2–n-hexane. Yield, 57 mg, 43%. 1H NMR (300
MHz, CDCl3): δ 2.01 (s, 6H, –CH3), 4.24 (m, 4H, –Cp), 4.72 (m,
Results and discussion
All the gold() alkynyl complexes 1–3 were prepared by modifi-
cation of literature procedures,11,14,21 in which a mixed EtOH–
THF (1 : 1 v/v) solvent system was employed to render the
starting materials soluble in the reaction mixture. The use of a
homogeneous solution medium may have the advantage of
reducing the reaction time and leading to a more well-defined
reaction product.
4H, –Cp), 5.10 (d, 2H, J = 1.8 Hz, ᎐CH ), 5.25 (d, 2H, J = 1.8
᎐
2
Hz, ᎐CH ), 7.37–7.52 (m, 20H, –PPh ). IR (KBr, ν/cmϪ1): 2089
᎐
2
2
(w) ν(C᎐C), 838 (s) ν(PF Ϫ). Positive-ion FAB-MS: m/z 1142
᎐
᎐
6
{M Ϫ PF6 ϩ H}ϩ. Positive ESI-MS: m/z 1141 {M Ϫ PF6}ϩ.
Found: C, 40.20; H, 3.00%. C44H38Au2CuF6FeP3ؒ½CH2Cl2
requires: C, 40.20; H, 2.96%.
2
All the newly synthesized gold() complexes have been char-
᎐
[(ꢀ-dppf)Au {ꢁ -C᎐CC(᎐CH )Me} Ag]OTf (7). [(µ-dppf )-
᎐
᎐
2
2
2
1
acterized by positive-ion FAB-MS, IR and H NMR spectro-
᎐
Au {C᎐CC(᎐CH )Me} ] (110 mg, 0.10 mmol) was dissolved in
᎐
᎐
2
2
2
scopy, and all of them gave satisfactory elemental analyses.
Positive electrospray-ionization mass spectra were also
obtained for all the charged gold() complexes 4–7. The X-ray
crystal structures of 1 and 3 have also been determined.
Attempts to prepare the silver() analogues of 4 and 5 starting
from 1 and 2, respectively, have been made but only dark
intractable materials have been obtained, indicative of the
instability and rapid decomposition of the products.
CH2Cl2 (20 ml) and a solid sample of AgOTf (38 mg, 0.11
mmol) was added. The resulting solution was stirred at room
temperature for 30 min, and was then evacuated to dryness.
Orange crystals of 7 were obtained by recrystallization from
CH2Cl2–n-hexane. Yield: 53 mg, 40%. H NMR (300 MHz,
CDCl3): δ 1.93 (s, 6H, –CH3), 4.20 (m, 4H, –Cp), 4.65 (m, 4H,
1
–Cp), 5.13 (d, 2H, J = 1.9 Hz, ᎐CH ), 5.23 (s, 2H, J = 1.9 Hz,
᎐
2
᎐CH ), 7.37–7.52 (m, 20H, –PPh ). IR (KBr, ν/cmϪ1): 2089 (w)
᎐
2
2
Ϫ
From the IR spectral data, the relatively large perturbation
᎐
ν(C᎐C), 1436 (w) ν(OTf ). Positive-ion FAB-MS: m/z 1185
᎐
Ϫ1
᎐
{M Ϫ OTf}ϩ. Positive ESI-MS: m/z 1186 {M Ϫ OTf ϩ H}ϩ.
and shift of the ν(C᎐C) stretch from 2112, 2101 and 2105 cm
᎐
in 1, 2 and 3, respectively, to 1968, 1973, 2089 and 2089 cmϪ1
in 4–7 are consistent with the π-coordination of the alkynyl
2
–
Found: C, 43.49; H, 3.23%. C45H38AgAu2F3FeO3P2Sؒ3 C6H14
requires: C, 43.26; H, 3.51%.
moieties to the copper() or silver() centre that resulted in a
᎐
weakening of the C᎐C bond.
᎐
Crystal structure determination
Figs. 1 and 2 depict the perspective drawings of 1 and 3,
respectively, with atomic numbering scheme. The Fe atom was
found to lie on an inversion centre in 3. The observed Au–P
Crystals of 1 were obtained by slow diffusion of n-hexane into a
concentrated dichloromethane solution of the complex. The
X-ray diffraction data was collected on a MAR diffractometer
with a 300 mm image plate detector using graphite-monochro-
matized Mo-Kα radiation (λ = 0.71073 Å). 43 images were col-
lected. The images were interpreted and intensities integrated
using the program DENZO.17 The gold and most non-hydrogen
atoms were located according to the direct method. The posi-
tions of the other non-hydrogen atoms were found after suc-
cessful refinement by full-matrix least-squares using program
SHELXL-9718 on PC. The terminal methylene and methyl
groups should not be distinguishable due to disorder but the
C–C bond lengths provide a reference to locate them. The C(22)
atom was temporarily assigned as the C atom of the methylene
group and C(33) the methyl group, according to the C–C bond
lengths of C(21)-C(22) 1.36(2) Å and C(21)–C(23) 1.44(2) Å.
One crystallographic asymmetric unit consists of one formula
unit. In the final stage of least-squares refinement, all non-
hydrogen atoms were refined anisotropically. H atoms were
generated by program SHELXL-97.18 The positions of H
atoms were calculated based on riding mode with thermal
parameters equal to 1.2 times that of the associated C atoms,
and participated in the calculation of final R-indices.
bond distances of 2.2810(18) and 2.279(2) Å, Au–C bond dis-
᎐
tances of 2.029(82) and 2.005(10) Å and C᎐C bond distances of
᎐
1.21(1) and 1.169(10) Å for 1 and 3, respectively, are compar-
able to those observed in other alkynylgold() phosphine sys-
tems.11c,22 The observation of the Au–P bond distances being
longer than those in the chlorogold phosphine complexes23 is in
line with the higher trans influence of the alkynyl group. The
Crystals of 3 were obtained by slow diffusion of n-hexane
into a concentrated dichloromethane solution of the complex.
The X-ray diffraction data was collected on a MAR diffract-
ometer with a 300 mm image plate detector using graphite-
monochromatized Mo-Kα radiation (λ = 0.71073 Å). The space
group was uniquely determined based on systematic absences
and the structure was solved by direct method (SIR92)19 and
Fig. 1 Perspective drawing of 1 with atomic numbering. Hydrogen
atoms have been omitted for clarity. Thermal ellipsoids were shown at
the 30% probability level.
D a l t o n T r a n s . , 2 0 0 3 , 1 8 3 0 – 1 8 3 5
1832

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Table 1 Crystal and structure determination data for 1 and 3
Complex
1
3
Molecular formula
Mw
Crystal colour
Crystal size/mm
Collection range
C23H20AuP
524.33
C44H38Au2FeP2
1078.51
Yellow
0.35 × 0.15 × 0.10
h: 0 to 12;
k: 0 to 10;
l: Ϫ23 to 23
50.9
Pale yellow
0.30 × 0.25 × 0.20
h: Ϫ16 to 12;
k: Ϫ12 to 12;
l: Ϫ15 to 15
51.0
2θmax/Њ
Crystal system
Space group
a/Å
b/Å
c/Å
α/Њ
Monoclinic
P21/c (no. 14)
14.100(3)
10.423(2)
13.900(3)
90
Monoclinic
P1 (no. 2)
10.464(2)
9.378(2)
19.868(3)
90
¯
β/Њ
97.41(3)
90
2025.7(7)
4
104.14(2)
90
1890.6(6)
2
γ/Њ
V/Å3
Z
F(000)
1008
73.43
1.719
1032
82.61
1.894
µ/cmϪ1
Dc/g cmϪ3
T /K
R
wR
Max shift (∆/σ)max
Goodness-of-fit
301(2)
301(2)
0.058b
0.071b
0.02
0.0456a
0.1150a
0.001
1.016
1.78
No. of data collected
No. of unique data
Rint
No. of data used in refinement
No. of parameters refined
Residual extrema in final diff. map/eAϪ3
9094
3509
15800
3483
0.0464
0.066
2713c
2782d
223
226
ϩ1.471, Ϫ2.103
ϩ1.20, Ϫ2.45
2
2
2
2
2
2
a w = 1/[σ2(Fo ) ϩ (0.0721P)2], where P is [2(Fc2) ϩ Max(Fo ,0)]/3. b w = 4Fo /σ2(Fo ), where σ2(Fo ) = [σ2(I ) ϩ (0.040Fo )2] with I > 3σ(I ). c I > 4σ(I ).
d I > 3σ(I ).
Table 2 Selected bond distances (Å) and bond angles (Њ) for 1 and 3
1
Au(1)–C(19)
Au(1)–P(1)
C(19)–C(20)
C(20)–C(21)
C(21)–C(22)
C(21)–C(23)
2.029(8)
C(19)–Au(1)–P(1)
C(20)–C(19)–Au(1)
C(19)–C(20)–C(21)
178.3(2)
179.4(7)
179.6(11)
2.2810(18)
1.169(10)
1.455(11)
1.365(17)
1.443(17)
3
Au(1)–C(1)
Au(1)–P(1)
C(1)–C(2)
C(3)–C(4)
C(3)–C(5)
C(21)–C(23)
2.005(10)
2.279(2)
1.21(1)
1.43(2)
1.37(2)
P(1)–Au(1)–C(1)
Au(1)–C(1)–C(2)
C(1)–C(2)–C(3)
Fe(1)–C(6)–C(7)
172.3(3)
166.3(9)
174(1)
69.4(5)
1.443(17)
P–Au–C angles of 178.3(2) and 172.3(3)Њ and Au–C–C angles
of 179.4(7) and 166.3(9)Њ in 1 and 3, respectively, are slightly
deviated from the ideal 180Њ geometry. Such deviations are
commonly observed in other gold() phosphine and alkynyl
complexes.11,21,22 All other bond lengths and angles are normal.
The electronic absorption spectra of 4 and 5 (Table 3) show
Fig. 2 Perspective drawing of 3 with atomic numbering. Hydrogen
atoms have been omitted for clarity. Thermal ellipsoids were shown at
the 40% probability level. Starred atoms have coordinates at [Ϫx, 1 Ϫ y,
1 Ϫ z].
absorption bands at ca. 282–328 nm, which are red-shifted with
᎐
respect to their respective [(PR )Au{C᎐CC(᎐CH )Me}] pre-
᎐
᎐
3
2
cursors, 1 and 2 (Fig. 3). In addition, a new band appears at ca.
440–450 nm. With reference to our previous studies on the d10
metal–alkynyl systems,11 the high-energy bands at ca. 282–328
450 nm, which is absent in the gold() precursors may originate
from transitions characteristic of the copper()–π-alkynyl core.
On the other hand, the electronic absorption spectra of 6 and 7
showed intense absorption bands at 268–306 nm and a weak
shoulder at ca. 440–450 nm, with patterns very similar to that
nm are assigned as metal-perturbed intraligand (IL) [π
᎐
π*(C᎐C)] transitions with some metal-to-ligand charge transfer
᎐
(MLCT) character. The red shift in absorption energy is in
line with the lower π* orbital energy of the alkynyl unit upon
π-coordination to copper(). The low-energy band at ca. 440–
of their precursor complex 3. The high-energy bands are simi-
᎐
larly assigned to IL [π
π*(C᎐C)] and [σ
π*(Ar)] transi-
᎐
tions, while the band at ca. 440–450 nm, which is also present in
D a l t o n T r a n s . , 2 0 0 3 , 1 8 3 0 – 1 8 3 5
1833

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Table 3 Photophysical data for 1–7
Absorption in CH2Cl2
Emission
λem/nm (τo/µs)
Complex
λabs/nm (ε/dm3 molϪ1 cmϪ1
)
Medium (T /K)
1
2
3
4
5
6
7
258 (14770), 270 (14150),
294 sh (1530)
Solid (298)
Solid (77)
CH2Cl2 (298)
Solid (298)
Solid (77)
CH2Cl2 (298)
Solid (298)
Solid (77)
CH2Cl2 (298)
Solid (298)
Solid (77)
CH2Cl2 (298)
Solid (298)
Solid (77)
CH2Cl2 (298)
Solid (298)
Solid (77)
CH2Cl2 (298)
Solid (298)
Solid (77)
454 (1.5)
488, 522
423 (0.7)
463 (2.4)
496, 522
439 (<0.1)
256 (13090), 270 (7230),
290 sh (1620)
a
262 (46920), 272 (43270),
284 (32490), 310 (2400),
440 (210)
282 (14710), 328 sh (4850),
444 (960)
–
–
–
a
a
653 (0.14)
606
639 (0.22)
664 (0.27)
613
660 (0.39)
583 (<0.1)
572
585 (<0.1)
565 (<0.1)
542
282 (15020), 328 sh (3020),
448 (870)
272 (26,800), 306 sh (8,210),
452 (360)
268 (32,540), 306 sh (6,470),
444 (180)
CH2Cl2 (298)
553 (<0.1)
a Not emissive.
Fig. 3 Electronic absorption spectra of 1 (—) and 4 (---) in CH2Cl2 at
298 K.
Fig. 4 Normalized solid-state emission spectra of 1 (—) and 4 (---) at
298 K; *denotes an artifact from the spectrofluorometer.
[Au2(dppf )Cl2] and 3, is characteristic of ferrocene-containing
compounds.
Photo-excitation of 1 and 2 in the solid state at λ = 350 nm
gave rise to an intense long-lived blue luminescence at 454
and 463 nm, respectively. With reference to the findings for
24
᎐
[(Ph P)Au(C᎐CPh)],
it is possible to assign the emission
᎐
3
origin of 1 and 2 as derived from an admixture of metal-per-
3
3
᎐
᎐
turbed [π
π*(C᎐C)] IL and [σ(Au–P)
π*(C᎐C)] MLCT
᎐
᎐
states. The slight red shift in emission energy on going from 1 to
2 is in line with the fact that PTol3, being a better electron donor
than PPh3, would render the gold() centre more electron rich
and the σ(Au–P) orbital higher-lying in energy, giving rise to a
3
᎐
slightly lower [σ(Au–P)
π*(C᎐C)] emission energy. On the
᎐
other hand, excitation of the mixed-metal η2-alkynyl coordin-
ated complexes 4 and 5 at λ = 350 nm gave rise to an intense
long-lived orange–red luminescence at ca. 606–664 nm, which is
red-shifted relative to the respective precursor complexes 1 and
Fig. 5 Normalized emission spectra of 4 (—) and 5 (---) in CH2Cl2 at
298 K.
2 (Fig. 4). Such emission is likely assigned to originate from
a metal-perturbed 3[π
π*(C᎐C)] IL or a 3[σ(Au–P)
state, probably due to the efficient quenching effect of the
ferrocenyl moiety. By contrast, the solid-state emission spectra
of 6 and 7 at room temperature showed emission maxima at
ca. 565–583 nm. This band, which is absent in the gold() pre-
cursor 3, may originate from emissive states characteristic of
the copper()/silver() π-alkynyl core. With reference to our pre-
vious investigation on copper() and silver() alkynyl systems
and the fact that 6 has a lower emission energy than 7, such an
emission is tentatively ascribed to be derived from states of a
᎐
᎐
᎐
π*(C᎐C)] MLCT origin. Upon π-coordination to the copper()
metal centre, the π*(C᎐C) orbital energy is lowered, giving rise
᎐
᎐
᎐
to a lower energy emission. The lower emission energy of 5 than
4 is again in line with the better electron-donating ability of
PTol3 over PPh3 (Fig. 5). However, one cannot exclude the
possible assignment of the emission as derived from states
associated with the copper()–π-alkynyl core. For the dppf-
containing complex 3, no emission was observed in the solid
D a l t o n T r a n s . , 2 0 0 3 , 1 8 3 0 – 1 8 3 5
1834

View Article Online
LMCT parentage mixed with a metal-centred nd9(n ϩ 1)s1 state,
9 V. W. W. Yam, K. L. Yu and K. K. Cheung, J. Chem. Soc.,
Dalton Trans., 1999, 2913.
᎐
with some [π
π*(C᎐C)] IL character. Similar assignments
᎐
10 (a) V. W. W. Yam, K. L. Yu, K. M. C. Wong and K. K. Cheung,
Organometallics, 2001, 20, 721; (b) K. M. C. Wong, C. K. Hui,
K. L. Yu and V. W. W. Yam, Coord. Chem. Rev., 2002, 229,
123.
11 (a) V. W. W. Yam and S. W. K. Choi, J. Chem. Soc., Dalton Trans.,
1996, 4227; (b) V. W. W. Yam, S. W. K. Choi and K. K. Cheung,
J. Chem. Soc., Dalton Trans., 1996, 3411; (c) V. W. W. Yam, S. W. K.
Choi and K. K. Cheung, Organometallics, 1996, 15, 1734.
12 G. J. Kubas, Inorg. Synth., 1990, 28, 68.
13 C. A. McAuliffe, R. V. Parish and P. D. Randall, J. Chem. Soc.,
Dalton Trans., 1979, 1730.
14 R. J. Cross and M. F. Davidson, J. Chem. Soc., Dalton Trans., 1986,
411.
have been reported previously.25
Acknowledgements
V. W.-W. Y. acknowledges support from The University of
Hong Kong Foundation for Educational Development and
Research Limited and The University of Hong Kong. The work
described in this paper has been supported by the Research
Grants Council of the Hong Kong Special Administration
Region, China (Project No. HKU7120/02P). K.-L. C. acknow-
ledges the receipt of a postgraduate studentship, and E. C.-C.
C. and N. Z. the receipt of University Postdoctoral Fellowships,
all administered by The University of Hong Kong.
15 D. T. Hill, G. R. Girard, F. L. McCabe, R. K. Johnson, P. D. Stupik,
J. H. Zhang, W. M. Reiff and D. S. Eggleston, Inorg. Chem., 1989,
28, 3529.
16 D. D. Perrin and W. L. F. Armarego, Purification of Laboratory
Chemicals, Pergamon, Oxford, UK, 3rd edn., 1988.
17 DENZO: D. Gewirth, Z. Otwinowski and W. Minor, The HKL
Manual–A description of programs DENZO, XDISPLAYF, and
SCALEPACK, Yale University, New Haven, USA, 1995.
18 G. M. Sheldrick, SHELXL97, in SHELX97: Programs for Crystal
Structure Analysis (Release 97–2), 1997, University of Göttingen,
Germany.
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1835