Synthesis, characterization, structure and luminescence studies of mono-, di- and trinuclear gold(I) phosphine alkynyl complexes

Article abstract of DOI:10.1016/S0022-328X(03)00606-5

A series of luminescent gold(I) phosphine mono- and diynyl complexes with nuclearity ranging from one to three has been synthesized and characterized; one of them have its crystal structure determined. Their photophysical properties have been studied and emission origin elucidated.

Full text of DOI:10.1016/S0022-328X(03)00606-5

Journal of Organometallic Chemistry 681 (2003) 196ꢀ209
/
www.elsevier.com/locate/jorganchem
Synthesis, characterization, structure and luminescence studies of
mono-, di- and trinuclear gold(I) phosphine alkynyl complexes
Vivian Wing-Wah Yam *, Kai-Leung Cheung, Sung-Kong Yip, Kung-Kai Cheung
Centre for Carbon-Rich Molecular and Nano-Scale Metal-Based Materials Research, Department of Chemistry and HKU-CAS Joint Laboratory on
New Materials, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China
Received 16 May 2003; received in revised form 27 June 2003; accepted 27 June 2003
Abstract
A series of luminescent gold(I) phosphine mono- and diynyl complexes with nuclearity ranging from one to three has been
synthesized and characterized; one of them have its crystal structure determined. Their photophysical properties have been studied
and emission origin elucidated.
# 2003 Elsevier B.V. All rights reserved.
Keywords: Gold(I); Alkynyl ligands; Luminescence; Phosphine ligands
1. Introduction
dinuclear and trinuclear gold(I) phosphine complexes of
mono- and diynyl ligands.
Acetylenic compounds, especially terminal alkynes,
are valuable synthetic intermediates and there have been
enormous interests in the development of methods for
introducing an ethynyl group into both organic and
inorganic structures [1,2]. The linear geometry of the
alkynyl unit together with its p-unsaturated nature have
made the rigid metal alkynyl moieties ideal building
blocks for the construction of molecular wires and
organometallic oligomeric and polymeric materials
that may possess unique properties such as optical
nonlinearity, electrical conductivity, and liquid crystal-
2. Experimental
2.1. Materials
Phenylacetylene (Aldrich), 2-methylbut-1-en-3-yne
(Lancaster), pent-1-yne (Maybridge) and oct-1-yne
(Maybridge) were used as-received. Bis[di(4-methylphe-
nyl)phosphino]methane (dtpm) [8], 1,3-heptadiyne [9],
1,3-decadiyne [10], phenylbutadiyne [11], 2-ethynylthio-
phene [12], 5-ethynyl-2,2?-bithienyl [13] and the chlor-
ogold(I) phosphine precursor complexes [14] were
prepared according to literature procedures.
Dichloromethane (Lab Scan, AR) and tetrahydro-
furan (Lab Scan, AR) were purified and distilled using
standard procedures before use [15]. All other solvents
and reagents were of analytical grade and were used as
received.
linity [1ꢀ4].
/
During the last decade, the synthesis, molecular
structures and chemistry of gold(I) phosphine alkynyl
complexes have attracted growing attention, in part due
to the reports on their rich luminescence properties [5,6]
and their ability to build supramolecular structures [7]
based on the aurophilic nature of gold. Herein are
reported the synthesis, structure, electronic absorption,
and luminescence properties of a series of mononuclear,
2.2. Physical measurements and instrumentation
1H-NMR spectra were recorded on a 300 MHz
Bruker DPX300 FT-NMR spectrometer. Chemical
shifts (d ppm) were reported relative to tetramethylsi-
lane (Me4Si). Positive ion FAB mass spectra were
* Corresponding author. Tel.: ꢁ
1586.
E-mail address: wwyam@hku.hk (V.W.-W. Yam).
/
852-2859-2153; Fax: ꢁ852-2857-
/
0022-328X/03/$ - see front matter # 2003 Elsevier B.V. All rights reserved.
doi:10.1016/S0022-328X(03)00606-5

V.W.-W. Yam et al. / Journal of Organometallic Chemistry 681 (2003) 196ꢀ
/209
197
collected on a Finnigan MAT95 mass spectrometer.
Positive ion and negative ion ESI mass spectra were
collected on a Finnigan LCQ mass spectrometer. IR
spectra were obtained as KBr pellets on a Bio-Rad FTS-
atoms were refined anisotropically. Hydrogen atoms
were included but not refined. Convergence for 703
variable parameters by least-squares refinement
on
(0:040Fo2)2]; for 7169 reflections with I ꢀ
reached at Rꢃ0.066 and wRꢃ0.084 with a goodness-
of-fit 1.85. The maximum and minimum peaks on the
F
with wꢃ4Fo2=s2(Fo2); where s2(Fo2)ꢃ[s2(I)ꢁ
3s(I) was
7 Fourier-transform infrared spectrophotometer (4000ꢀ
/
/
400 cmꢂ1). UVꢀ
/
Vis spectra were obtained on a Hewlett
/
/
Packard 8452A diode array spectrophotometer. Steady-
state excitation and emission spectra were obtained on a
Spex Fluorolog 111 spectrofluorometer equipped with a
Hamamatsu R-928 photomultiplier tube. Low-tempera-
ture (77 K) spectra were recorded by using an optical
Dewar sample holder. Elemental analyses of the new
complexes were performed on a Carlo Erba 1106
elemental analyzer at the Institute of Chemistry, Chinese
Academy of Sciences.
final difference Fourier map corresponded to ꢂ
/
3.95 and
2.19 e Aꢂ3, respectively.
˚
2.4. Syntheses
All reactions were carried out under anhydrous and
anaerobic conditions under an inert atmosphere of
nitrogen using standard Schlenk technique.
Emission lifetime measurements were performed
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 pulsed Nd-
YAG laser (10 Hz). Luminescence decay signals were
recorded on a Tektronix model TDS-620A (500 MHz, 2
GS/s) digital oscilloscope, and analyzed using a program
for exponential fits. All solutions for photophysical
studies were prepared under vacuum in a 10 cm3
round-bottom flask equipped with a side-arm 1 cm
fluorescence cuvette and sealed from the atmosphere by
a Bibby Rotaflo HP6 Teflon stopper. Solutions were
rigorously degassed with no fewer than four freeze-
pump-thaw cycles.
2.4.1. Synthesis of mononuclear gold(I) phosphine
alkynyl complexes
2.4.1.1. [(Ph3P)Au(Cꢀ
/
CCꢀ
/
CC3H7)] (1). An ethano-
lic solution (5 ml) of 1,3-heptadiyne (20 mg, 0.21 mmol)
and sodium ethoxide (0.30 mmol, prepared in situ from
Na in EtOH) was added to a solution of [(Ph3P)AuCl]
(100 mg, 0.2 mmol) in EtOHꢀTHF (10 ml; 1:1, v/v) and
/
stirred at room temperature. The colourless solution
Table 1
Crystal and structure determination data for complex 14
2.3. Crystal structure determination
Empirical formula
Formula weight
Crystal size (mm3)
Crystal system
Space group
[C70H64P4Au4]
1817.04
X-ray quality crystals of [(dppm)2Au3{Cꢀ
/
CC(ꢁ
/
0.40ꢄ
/
0.15ꢄ0.10
/
CH2)Me}2][Au{CꢀCC(ꢁCH2)Me}2] (14) were obtained
/
/
Monoclinic
P21/n
14.299(2)
22.501(3)
19.906(3)
90
by recrystallization from dichloromethane-n-hexane. All
the experimental details are given in Table 1. Crystal
data for complex 14: empirical formula, [C70H64P4Au4];
˚
a (A)
˚
b (A)
˚
c (A)
formula weightꢃ
/
1817.04; monoclinic; space group,
a (8)
b (8)
g (8)
V (A )
Z
˚
˚
P21/n (No. 14); aꢃ
/
14.299(2) A; bꢃ
92.23(2)8; Vꢃ
cmꢂ3
m(MoꢀKa)ꢃ
3440; Tꢃ301 K. A colorless crystal of
dimensions 0.40ꢄ0.15ꢄ
0.10 mm3 inside a glass capil-
/
22.501(3) A; cꢃ
/
92.23(2)
90
3
˚
˚
19.906(3) A; bꢃ
Dcalc 1.886
F(0 0 0)ꢃ
/
/
6399(1) A ; Zꢃ
/
4;
3
˚
6399(1)
4
3440
ꢃ
/
g
;
/
/
93.13 cmꢂ1
;
/
/
F(0 0 0)
M (cmꢂ1
/
/
)
93.13
1.886
Dcalc (g cmꢂ1
Temperature (K)
)
lary was used for data collection at 28 8C on a MAR
diffractometer with a 300 mm image plate detector using
301
0.71069
˚
Wavelength (A)
graphite monochromatized Moꢀ
/
Ka radiation (lꢃ
0.71069 A). 7169 reflections with I ꢀ3s(I) were con-
sidered observed and used in the structural analysis.
These reflections were in the range, h: 0ꢀ15; k: 0ꢀ27;
l: ꢂ24ꢀ23 with 2umax 518. The space group was
/
Collection range
2umax
ꢃ/51.18; h: 0ꢀ
/
15, k: 0ꢀ27, l:
/
˚
/
ꢂ
/
24ꢀ/23
Reflections collected
No. of observations
No. of variables
11 163
7169
703
/
/
/
/
ꢃ
/
Refinement method
Goodness-of-fit on F2
Full-matrix least-squares on F2
determined based on a statistical analysis of intensity
distribution and the successful refinement of structure
solved by Patterson methods and expanded by Fourier
methods (PATTY [16]) and refinement by full-matrix
least-squares using the software package TEXSAN [17] on
a Silicon Graphics Indy computer. The non-hydrogen
1.85
Final R indices [I ꢀ
/
3s(I)]a
R1ꢃ/0.066, wR2ꢃ
/
0.084
Largest difference peak and hole 2.19 and ꢂ
/3.95
ꢂ3
˚
(e A
)
a
/
wꢃ4Fo2=s2(Fo2); where s2(Fo2)ꢃ[s2(I)ꢁ(0:040Fo2)2] with Iꢀ3s(I):
/

198
V.W.-W. Yam et al. / Journal of Organometallic Chemistry 681 (2003) 196ꢀ209
/
turned pale yellow after 30 min. After stirring for 4 h,
the solvent was evaporated to dryness and the resulting
solid was recrystallized from dichloromethane-n-hexane
to give yellow crystals of 1 (45 mg, 41% yield). 1H-NMR
(300 MHz, CDCl3, 298 K, relative to Me4Si, d ppm):
ml; 1:1, v/v) and stirred at room temperature. The
colourless solution turned to pale yellow after 30 min.
After stirring for 4 h, the solvent was evaporated to
dryness and the resulting solid was recrystallized from
dichloromethane-n-hexane to give orange crystals of 5
(61 mg, 58% yield). 1H-NMR (300 MHz, CDCl3, 298 K,
0.97 (t, 3H, Jꢃ
CH2CH2CH3), 2.30 (t, 2H, Jꢃ
7.45ꢀ7.61 (m, 15H, PPh3). Positive ion FABMS; m/z:
525 [M]ꢁ. IR (KBr disc, n (cmꢂ1)): 2209 (w, Cꢀ
C),
C). Elemental analysis: Anal. Found: C,
/
7.3 Hz, ꢂ
/
CH3), 1.36ꢀ
/
1.46 (m, 2H, ꢂ
/
/
6.8 Hz, ꢂ
/
CꢀCCH2ꢂ),
/
/
relative to Me4Si, d ppm): 0.97 (t, 6H, Jꢃ
CH3), 1.25ꢀ1.65 (m, 16H, ꢂCH2CH2CH2CH2CH3),
2.31 (t, 4H, Jꢃ6.9 Hz, ꢂCꢀCCH2ꢂ), 2.62 (s, 4H, ꢂ
PCH2CH2Pꢂ), 7.43ꢀ7.52 (m, 12H, ꢂPPh2), 7.63ꢀ7.77
(m, 8H, ꢂ
PPh2). Positive ion FABMS; m/z: 1058 [M]ꢁ.
IR (KBr disc, n (cmꢂ1)): 2203 (w, Cꢀ
C), 2140 (w, CꢀC).
Elemental analysis: Anal. Found: C, 54.65; H, 5.46.
Calc. for C46H48Au2P2×C6H14: C, 54.65; H, 5.47%.
/
7.2 Hz, ꢂ
/
/
/
/
/
/
/
/
/
/
2141 (w, Cꢀ
52.18; H, 3.94. Calc. for C25H22AuP×
52.59; H, 3.95%.
/
/
/
/
/
/
1/3CH2Cl2: C,
/
/
/
2.4.1.2. [(Ph3P)Au(Cꢀ
/
CCꢀ
/
CC6H13)] (2). The proce-
/
dure was similar to that for 1 except 1,3-decadiyne (28
mg, 0.21 mmol) was used in place of 1,3-heptadiyne to
2.4.2.2. [(dppe)Au2{Cꢀ
/
CC(ꢁ
/
CH2)Me}2] (6). The
1
give yellow crystals of 2 (41 mg, 35% yield). H-NMR
(300 MHz, CDCl3, 298 K, relative to Me4Si, d ppm):
procedure was similar to that for 5 except 2-methyl-
but-1-en-3-yne (14 mg, 0.21 mmol) was used in place of
1,3-decadiyne to give air-stable pale orange crystals of 6
(61 mg, 66% yield). 1H-NMR (300 MHz, CDCl3, 298 K,
1.87 (t, 3H, Jꢃ
CH2CH2CH2CH2CH3), 2.25 (t, 2H, Jꢃ
CCH2ꢂ), 7.46ꢀ7.57 (m, 15H, PPh3). Positive ion
FABMS; m/z: 593 [M]ꢁ. IR (KBr disc, n (cmꢂ1)):
C). Elemental analysis:
/
7.1 Hz, ꢂ
/
CH3), 1.27ꢀ
/
1.57 (m, 8H, ꢂ
/
/
6.7 Hz, ꢂCꢀ
/
/
/
/
relative to Me4Si, d ppm): 1.97(s, 6H, ꢂ
4H, ꢂPCH2CH2Pꢂ), 5.16 (d, 2H, Jꢃ1.9 Hz, ꢁ
5.32 (d, 2H, Jꢃ1.9 Hz, ꢁCH2), 7.40ꢀ7.50 (m, 12H, ꢂ
PPh2), 7.53ꢀ7.64 (m, 8H, ꢂPPh2). Positive ion FABMS;
m/z: 922 [M]ꢁ. IR (KBr disc, n (cmꢂ1)): 2105 (w, Cꢀ
C). Elemental analysis: Anal. Found: C, 42.78; H, 3.59.
Calc. for C36H34Au2P2×1.5CH2Cl2: C, 42.89; H, 3.55%.
/CH3), 2.59 (s,
/
/
/
/CH2),
2201 (w, Cꢀ
/
C), 2140 (w, Cꢀ
/
/
/
/
/
Anal. Found: C, 56.85; H, 4.86. Calc. for C28H28AuP:
/
/
C, 56.76; H, 4.76%.
/
2.4.1.3. [(Ph3P)Au(Cꢀ
/
CCꢀ
/
CPh)] (3). The procedure
/
was similar to that for 1 except phenylbutadiyne (26 mg,
0.21 mmol) was used in place of 1,3-heptadiyne to give
2.4.2.3. [(dppf)Au2(Cꢀ
/
CC4H3S)2] (7). The procedure
1
yellow crystals of 3 (39 mg, 33% yield). H-NMR (300
was similar to that for 5 except [(dppf)Au2Cl2] (100 mg,
0.10 mmol) and 2-ethynylthiophene (23 mg, 0.21 mmol)
were used in place of [(dppe)Au2Cl2] and 1,3-decadiyne,
respectively, to give orange crystals of 7 (85 mg, 73%
MHz, CDCl3, 298 K, relative to Me4Si, d ppm): 7.24ꢀ
7.33 (m, 3H, ꢂPh), 7.45ꢀ7.57 (m, 17H, ꢂPh). Positive
ion FABMS; m/z: 585 [M]ꢁ. IR (KBr disc, n (cmꢂ1)):
C). Elemental analysis:
/
/
/
/
1
2181 (w, Cꢀ
/
C), 2134 (w, Cꢀ
/
yield). H-NMR (300 MHz, CDCl3, 298 K, relative to
Anal. Found: C, 57.56; H, 3.55. Calc. for C28H20AuP:
C, 57.55; H, 3.45%.
Me4Si, d ppm): 4.29 (m, 4H, ꢂ
6.92 (dd, 2H, Jꢃ1.2 and 3.9 Hz, 3-thienyl protons), 7.12
(dd, 2H, Jꢃ3.9 and 5.1 Hz, 4-thienyl protons), 7.18 (dd,
2H, Jꢃ1.2 and 5.1 Hz, 5-thienyl protons), 7.41ꢀ7.55
(m, 20H, ꢂPPh2). Positive ion FABMS; m/z: 1055 [Mꢂ
(Cꢀ
CC4H3S)]ꢁ. IR (KBr disc, n (cmꢂ1)): 2097 (w, Cꢀ
C). Elemental analysis: Anal. Found: C, 45.29; H, 2.68.
/
Cp), 4.73 (m, 4H, ꢂ
/
Cp),
/
/
2.4.1.4. [(Tol3P)Au(Cꢀ
/
CCꢀ
/
CPh)] (4). The proce-
/
/
dure was similar to that for 3 except [(Tol3P)AuCl]
/
/
(107 mg, 0.2 mmol) was used in place of [(Ph3P)AuCl] to
/
/
1
give yellow crystals of 4 (36 mg, 29% yield). H-NMR
(300 MHz, CDCl3, 298 K, relative to Me4Si, d ppm):
Calc. for C46H34Au2P2S2Fe×
/CH2Cl2: C, 45.25; H,
2.38 (s, 9H, ꢂ
ion FABMS; m/z: 626 [M]ꢁ. IR (KBr disc, n (cmꢂ1)):
2180 (w, CꢀC), 2134 (w, CꢀC). Elemental analysis:
/
CH3), 7.23ꢀ
/
7.53 (m, 17H, ꢂ/Ph). Positive
2.91%.
/
/
2.4.2.4. [(dppf)Au2(Cꢀ
/
CC4H2SC4H3S)2] (8). The
5
Anal. Found: C, 53.99; H, 3.99. Calc. for C31H26AuP×
/
procedure was similar to that for
except
CH2Cl2: C, 54.03; H, 3.97%.
[(dppf)Au2Cl2] (100 mg, 0.10 mmol) and 5-ethynyl-
2,2?-bithienyl (39 mg, 0.21 mmol) were used in place of
[(dppe)Au2Cl2] and 1,3-decadiyne, respectively, to give
2.4.2. Synthesis of dinuclear gold(I) phosphine alkynyl
complexes
1
orange crystals of 8 (77 mg, 68% yield). H-NMR (300
MHz, CDCl3, 298 K, relative to Me4Si, d ppm): 4.30 (m,
2.4.2.1. [(dppe)Au2(Cꢀ
/
CCꢀ
/
CC6H13)2] (5). An etha-
4H, ꢂ
/
Cp), 4.73 (m, 4H, ꢂ
/
Cp), 6.30 (d, 2H, Jꢃ
/
4.1 Hz, 4-
nolic solution (5 ml) of 1,3-decadiyne (28 mg, 0.21
mmol) and sodium ethoxide (0.30 mmol, prepared in
situ from Na in EtOH) was added to a solution of
bithienyl protons), 6.70 (d, 2H, Jꢃ
/
4.1 Hz, 3-bithienyl
protons), 6.80 (dd, 2H, Jꢃ
protons), 6.90 (dd, 2H, Jꢃ
protons), 7.20 (dd, 2H, Jꢃ
/
4.0 and 5.3 Hz, 4?-bithienyl
1.1 and 4.0 Hz, 3?-bithienyl
1.1 and 5.3 Hz, 5?-bithienyl
/
[(dppe)Au2Cl2] (87 mg, 0.1 mmol) in EtOHꢀ
/THF (10
/

V.W.-W. Yam et al. / Journal of Organometallic Chemistry 681 (2003) 196ꢀ
/209
199
protons), 7.42ꢀ
FABMS; m/z: 1137 [Mꢂ
(KBr disc, n (cmꢂ1)): 2095 (w, Cꢀ
analysis: Anal. Found: C, 49.92; H, 3.56. Calc. for
C54H38Au2P2S4Fe×0.5C6H14: C, 49.97; H, 3.31%.
/
7.56 (m, 20H, ꢂ
(Cꢀ
CC4H2SC4H3S)]ꢁ. IR
C). Elemental
/
PPh2). Positive ion
Jꢃ
Hz, 3-thienyl protons), 7.09 (dd, 4H, Jꢃ
4-thienyl protons), 7.10 (dd, 4H, Jꢃ1.2 and 5.1 Hz, 5-
thienyl protons). Positive ion FABMS; m/z: 1622
[(dcpm)2Au3(Cꢀ
CC4H3S)2]ꢁ. Positive ESIMS; m/z:
1621 [(dcpm)2Au3(Cꢀ
CC4H3S)2]ꢁ. Negative ESIMS;
m/z: 412 [Au(Cꢀ
CC4H3S)2]ꢂ. IR (KBr disc,
(cmꢂ1)): 2105 (w, Cꢀ
C). Elemental analysis: Anal.
/
10.2 Hz, ꢂ
/
PCH2Pꢂ
/
), 6.84 (dd, 4H, Jꢃ
/
1.2 and 3.9
/
/
/3.9 and 5.1 Hz,
/
/
/
/
/
2.4.3. Synthesis of trinuclear gold(I) phosphine alkynyl
complexes
/
n
/
Found: C, 43.75; H, 5.15. Calc. for C74H104Au4P4S4:
2.4.3.1. [(dcpm)2Au3(Cꢀ
/
CCꢀ
/
CC6H13)2][Au(Cꢀ
/
CCꢀ
/
C, 43.70; H, 5.16%.
CC6H13)2] (9). An ethanolic solution (5 ml) of 1,3-
decadiyne (28 mg, 0.21 mmol) and sodium ethoxide
(prepared in situ from Na in EtOH) was added to a
2.4.3.4. [(dcpm)2Au3(Cꢀ
/
CC4H2SC4H3S)2][Au(Cꢀ
/
CC4H2SC4H3S)2] (12). The procedure was similar to
that for 9 except 5-ethynyl-2,2?-bithienyl (39 mg, 0.21
mmol) was used in place of 1,3-decadiyne to give yellow
solution of [(dcpm)Au2Cl2] (88 mg, 0.1 mmol) in EtOHꢀ
/
THF (10 ml; 1:1, v/v) and stirred at room temperature.
The colourless solution turned to pale yellow after 30
min. After stirring for 4 h, the solvent was evaporated to
dryness and the resulting solid was recrystallized from
dichloromethane-n-hexane to give yellow crystals of 9
(70 mg, 33% yield). 1H-NMR (300 MHz, CDCl3, 298 K,
1
crystals of 12 (77 mg, 32% yield). H-NMR (300 MHz,
CDCl3, 298 K, relative to Me4Si, d ppm): 1.25ꢀ
40H, ꢂC6H11), 1.80ꢀ2.04 (m, 48H, ꢂC6H11), 2.22 (t, 4H,
Jꢃ10.9 Hz, ꢂPCH2Pꢂ), 6.48 (d, 4H, Jꢃ4.2 Hz, 4-
bithienyl protons), 6.87 (d, 4H, Jꢃ4.2 Hz, 3-bithienyl
/1.58 (m,
/
/
/
/
/
/
/
/
relative to Me4Si, d ppm): 0.88 (t, 12H, Jꢃ
CH3), 1.25ꢀ1.58 (m, 72H, C6H11;
CH2CH2CH2CH2CH3), 1.80ꢀ2.04 (m, 48H, ꢂ
2.30 (t, 8H, Jꢃ6.9 Hz, ꢂCꢀCCH2ꢂ
10.8 Hz, ꢂPCH2Pꢂ). Positive ion FABMS; m/z: 1674
[(dcpm)2Au3(CꢀCCꢀ
CC6H13)2]ꢁ. Positive ESIMS; m/
z: 1674 [(dcpm)2Au3(CꢀCCꢀ
CC6H13)2]ꢁ. Negative
ESIMS; m/z: 463 [Au(CꢀCCꢀ
CC6H13)2]ꢂ. IR (KBr
disc, n (cmꢂ1)): 2141 (w, Cꢀ
C), 2060 (w, CꢀC).
Elemental analysis: Anal. Found: C, 49.42; H, 6.74.
Calc. for C90H144Au4P4×CH2Cl2: C, 49.17; H, 6.62%.
/
7.2 Hz, ꢂ
/
protons), 7.15 (dd, 4H, Jꢃ
protons), 7.39 (dd, 4H, Jꢃ
protons), 7.67 (dd, 4H, Jꢃ
/
3.9 and 5.3 Hz, 4?-bithienyl
1.2 and 3.9 Hz, 3?-bithienyl
1.2 and 5.3 Hz, 5?-bithienyl
/
ꢂ
/
ꢂ
/
/
/
/C6H11),
/
/
/
/
/
). 3.65 (t, 4H, Jꢃ
/
protons). Positive ion FABMS; m/z: 1786
[(dcpm)2Au3(Cꢀ
CC4H2SC4H3S)2]ꢁ. Positive ESIMS;
m/z: 1786 [(dcpm)2Au3(Cꢀ
CC4H2SC4H3S)2]ꢁ. Nega-
tive ESIMS; m/z: 575 [Au(Cꢀ
CC4H2SC4H3S)2]ꢂ. IR
(KBr disc, n (cmꢂ1)): 2090 (w, Cꢀ
C). Elemental
analysis: Anal. Found: C, 44.62; H, 4.73. Calc. for
C90H112Au4P4S8×CH2Cl2: C, 44.66; H, 4.70%.
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
2.4.3.5. [(dppm)2Au3(Cꢀ
/
CCꢀ
/
CC6H13)2][Au(Cꢀ
/
CCꢀ
/
2.4.3.2. [(dcpm)2Au3{Cꢀ
/
CC(ꢁ
/
CH2)Me}2][Au{Cꢀ
/
CC6H13)2] (13). The procedure was similar to that for
9 except [(dppm)Au2Cl2] (85 mg, 0.10 mmol) was used in
place of [(dcpm)Au2Cl2] to give yellow crystals of 13 (70
mg, 34% yield) after recrystallized from chloroform-n-
CC(ꢁCH2)Me}2] (10). The procedure was similar to
/
that for 9 except 2-methylbut-1-en-3-yne (14 mg, 0.21
mmol) was used in place of 1,3-decadiyne to give pale
1
yellow crystals of 10 (85 mg, 46% yield). H-NMR (300
1
hexane. H-NMR (300 MHz, CDCl3, 298 K, relative to
MHz, CDCl3, 298 K, relative to Me4Si, d ppm): 1.15ꢀ
1.80 (m, 56H, ꢂC6H11), 1.85ꢀ2.10 (m, 32H, ꢂC6H11,
12H, ꢂCH3), 2.31 (t, 4H, Jꢃ10.1 Hz, ꢂPCH2Pꢂ), 5.03
(d, 4H, Jꢃ1.8 Hz, ꢁCH2), 5.23 (d, 4H, Jꢃ1.8 Hz, ꢁ
CH2). Positive ion FABMS; m/z: 1537 [(dcpm)2Au3{Cꢀ
CC(ꢁ
CH2)Me}2]ꢁ. Positive ESIMS; m/z: 1537
[(dcpm)2Au3{CꢀCCꢂ(ꢁ
CH2)Me}2]ꢁ. Negative ESIMS;
m/z: 327 [Au{CꢀCC(ꢁ
CH2)Me}2]ꢂ. IR (KBr disc, n
(cmꢂ1)): 2102 (w, Cꢀ
C). Elemental analysis: Anal.
Found: C, 44.31; H, 6.29. Calc. for C70H112Au4P4×
2H2O: C, 44.20; H, 6.15%.
/
Me4Si, d ppm): 0.90 (t, 12H, Jꢃ
1.65 (m, 32H, ꢂCH2CH2CH2CH2CH3), 2.30 (t, 8H, Jꢃ
6.9 Hz, ꢂCꢀCCH2ꢂ), 3.65 (t, 4H, Jꢃ10.8 Hz, ꢂ
PCH2Pꢂ), 7.38ꢀ7.58 (m, 24H, ꢂPPh2), 7.60ꢀ7.70 (m,
16H, PPh2). Positive ion FABMS; m/z: 1625
[(dppm)2Au3(CꢀCCꢀ
CC6H13)2]ꢁ. Positive ESIMS; m/
z: 1625 [(dppm)2Au3(CꢀCCꢀ
CC6H13)2]ꢁ. Negative
ESIMS; m/z: 463 [Au(CꢀCCꢀ
CC6H13)2]ꢂ. IR (KBr
disc, n (cmꢂ1)): 2139 (w, Cꢀ
C), 2054 (w, CꢀC).
Elemental analysis: Anal. Found: C, 45.71; H, 3.71.
Calc. for C90H96Au4P4×3CHCl3: C, 45.70; H, 4.09%.
/
7.1 Hz, ꢂ
/
CH3), 1.28ꢀ
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
ꢂ
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
2.4.3.3. [(dcpm)2Au3(Cꢀ
/
CC4H3S)2][Au(Cꢀ
/
2.4.3.6. [(dppm)2Au3{Cꢀ
/
CC(ꢁ
/
CH2)Me}2][Au{Cꢀ
/
CC4H3S)2] (11). The procedure was similar to that for
9 except 2-ethynylthiophene (23 mg, 0.21 mmol) was
used in place of 1,3-decadiyne to give pale yellow
CC(ꢁCH2)Me}2] (14). The procedure was similar to
/
that for 9 except [(dppm)Au2Cl2] (85 mg, 0.10 mmol)
and 2-methylbut-1-en-3-yne (14 mg, 0.21 mmol) were
used in place of [(dcpm)Au2Cl2] and 1,3-decadiyne,
respectively, to give air-stable pale yellow crystals of
14 (52 mg, 29% yield). 1H-NMR (300 MHz, CDCl3, 298
1
crystals of 11 (63 mg, 31% yield). H-NMR (300 MHz,
1.54 (m,
CDCl3, 298 K, relative to Me4Si, d ppm): 1.25ꢀ
/
40H, ꢂC6H11) 1.73ꢀ2.17 (m, 48H, ꢂC6H11), 2.25 (t, 4H,
/
/
/

200
V.W.-W. Yam et al. / Journal of Organometallic Chemistry 681 (2003) 196ꢀ209
/
K, relative to Me4Si, d ppm): 1.95 (s, 12H, ꢂ
(t, 4H, Jꢃ11.3 Hz, ꢂPCH2Pꢂ), 5.08 (d, 4H, Jꢃ
CH2), 5.30 (d, 4H, Jꢃ1.8 Hz, ꢁCH2), 7.30ꢀ7.50 (m,
PPh2), 7.60ꢀ7.70 (m, 16H, ꢂPPh2). Positive
1490 CC(ꢁ
[(dppm)2Au3{Cꢀ
Positive ESIMS; m/z: 1489
CC(ꢁ
CH2)Me}2]ꢁ. Negative ESIMS;
m/z: 327 [Au{CꢀCC(ꢁ
CH2)Me}2]ꢂ. IR (KBr disc, n
(cmꢂ1)): 2100 (w, Cꢀ
C). Elemental analysis: Anal.
Found: C, 45.49; H, 3.33. Calc. for C70H64Au4P4×
0.5CH2Cl2: C, 45.54; H, 3.52%.
/
CH3), 3.56
2-methylbut-1-en-3-yne (14 mg, 0.21 mmol) were used in
place of [(dcpm)Au2Cl2] and 1,3-decadiyne, respectively,
to give air-stable pale yellow crystals of 17 (53 mg, 27%
/
/
/
/1.8 Hz,
ꢁ
/
/
/
/
1
24H, ꢂ
/
/
/
yield). H-NMR (300 MHz, CDCl3, 298 K, relative to
FABMS;
m/z:
/
/
Me4Si, d ppm): 1.95 (s, 12H, ꢂ
C6H4CH3), 3.43 (t, 4H, Jꢃ10.3 Hz, ꢂ
4H, Jꢃ1.9 Hz, ꢃCH2), 5.26 (d, 4H, Jꢃ
CH2), 7.17 (d, 16H, Jꢃ7.7 Hz, ꢂC6H4ꢂ
16H, Jꢃ7.7 Hz, ꢂC6H4ꢂ). Positive ion FABMS; m/z:
1601 CC(ꢁ
[(dtpm)2Au3{Cꢀ
ESIMS; m/z: 1601 [(dtpm)2Au3{Cꢀ
Negative ESIMS; m/z: 327 [Au{Cꢀ
IR (KBr disc, n (cmꢂ1)): 2087 (w, Cꢀ
/
CH3), 2.35 (s, 24H, ꢂ
PCH2Pꢂ), 5.09 (d,
1.9 Hz, ꢃ
), 7.53 (d,
/
CH2)Me}2]ꢁ.
[(dppm)2Au3{Cꢀ
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
CH2)Me}2]ꢁ.
Positive
/
CC(ꢁ
/
CH2)Me}2]ꢁ.
CH2)Me}2]ꢂ.
/
CC(ꢁ
/
2.4.3.7. [(dppm)2Au3(Cꢀ
/
CC4H3S)2][Au(Cꢀ
/
/
C). Elemental
analysis: Anal. Found: C, 47.20; H, 4.13. Calc. for
C78H80Au4P4×CH2Cl2: C, 47.11; H, 4.10%.
CC4H3S)2] (15). The procedure was similar to that for
9 except [(dppm)Au2Cl2] (85 mg, 0.10 mmol) and 2-
ethynylthiophene (23 mg, 0.21 mmol) were used in place
of [(dcpm)Au2Cl2] and 1,3-decadiyne, respectively, to
/
2.4.3.10. [(dtpm)2Au3(Cꢀ
/
CC4H3S)2][Au(Cꢀ
/
1
give pale yellow crystals of 15 (73 mg, 37% yield). H-
NMR (300 MHz, CDCl3, 298 K, relative to Me4Si, d
CC4H3S)2] (18). The procedure was similar to that for
9 except [(dtpm)Au2Cl2] (91 mg, 0.10 mmol) and 2-
ethynylthiophene (23 mg, 0.21 mmol) were used in place
of [(dcpm)Au2Cl2] and 1,3-decadiyne, respectively, to
ppm): 3.62 (t, 4H, Jꢃ
4H, Jꢃ1.2 and 4.1 Hz, 3-thienyl protons), 7.06 (dd, 4H,
Jꢃ3.9 and 5.1 Hz, 4-thienyl protons), 7.19 (dd, 4H, Jꢃ
1.2 and 5.1 Hz, 5-thienyl protons), 7.42ꢀ7.58 (m, 24H, ꢂ
PPh2), 7.68ꢀ7.73 (m, 16H, PPh2). Positive ion
FABMS; m/z: 1467 [Mꢂ(Cꢀ
CC4H3S)]ꢁ. Positive
ESIMS; m/z: 1574 [(dppm)2Au3(Cꢀ
CC4H3S)2]ꢁ. Nega-
tive ESIMS; m/z: 412 [Au(Cꢀ
CC4H3S)2]ꢂ. IR (KBr
disc, n (cmꢂ1)): 2093 (w, Cꢀ
C). Elemental analysis:
/
11.3 Hz, ꢂ
/
PCH2Pꢂ/), 6.90 (dd,
/
/
/
1
give pale yellow crystals of 18 (72 mg, 34% yield). H-
NMR (300 MHz, CDCl3, 298 K, relative to Me4Si, d
/
/
/
ꢂ
/
ppm): 2.37 (s, 24H, ꢂ
Hz, ꢂPCH2Pꢂ), 6.84 (dd, 4H, Jꢃ
thienyl protons), 7.03 (dd, 4H, Jꢃ
thienyl protons), 7.19 (dd, 4H, Jꢃ
thienyl protons), 7.20 (d, 16H, Jꢃ
7.50ꢀ7.62 (m, 16H, ꢂC6H4ꢂ). Positive ion FABMS; m/
z: 1685 [(dtpm)2Au3(Cꢀ
CC4H3S)2]ꢁ. Positive ESIMS;
m/z: 1685 [(dtpm)2Au3(Cꢀ
CC4H3S)2]ꢁ. Negative
ESIMS; m/z: 412 [Au(Cꢀ
CC4H3S)2]ꢂ. IR (KBr disc,
n (cmꢂ1)): 2091 (w, Cꢀ
C). Elemental analysis: Anal.
Found: C, 45.91; H, 3.36. Calc. for C82H72Au4P4S4×
CH2Cl2: C, 45.68; H, 3.42%.
/
C6H4CH3), 3.47 (t, 4H, Jꢃ
/10.1
/
/
/
/
/
1.2 and 3.9 Hz, 3-
/
/
3.9 and 5.1 Hz, 4-
1.2 and 5.1 Hz, 5-
/
/
/
/
7.5 Hz, ꢂ
/
C6H4ꢂ
/),
Anal. Found: C, 44.53; H, 2.70. Calc. for C74H56
Au4P4S4: C, 44.77; H, 2.84%.
/
/
/
/
/
2.4.3.8. [(dppm)2Au3(Cꢀ
/
CC4H2SC4H3S)2][Au(Cꢀ
/
/
CC4H2SC4H3S)2] (16). The procedure was similar to
that for 9 except [(dppm)Au2Cl2] (85 mg, 0.10 mmol)
and 5-ethynyl-2,2?-bithienyl (39 mg, 0.21 mmol) were
used in place of [(dcpm)Au2Cl2] and 1,3-decadiyne,
respectively, to give yellow crystals of 16 (79 mg, 34%
/
/
1
yield). H-NMR (300 MHz, CDCl3, 298 K, relative to
2.4.3.11. [(dmpm)2Au3{Cꢀ
/
CC(ꢁ
/
CH2)Me}2][Au{Cꢀ
/
Me4Si, d ppm): 3.60 (t, 4H, Jꢃ
6.73 (d, 4H, Jꢃ4.2 Hz, 4-bithienyl protons), 6.92 (d,
4H, Jꢃ4.2 Hz, 3-bithienyl protons), 7.05 (dd, 4H, Jꢃ
3.9 and 5.3 Hz, 4?-bithienyl protons), 7.04 (dd, 4H, Jꢃ
1.2 and 3.9 Hz, 3?-bithienyl protons), 7.11 (dd, 4H, Jꢃ
1.2 and 5.3 Hz, 5?-bithienyl protons), 7.42ꢀ7.58 (m,
24H, ꢂPPh2), 7.68ꢀ7.73 (m, 16H, ꢂPPh2). Positive ion
FABMS; m/z: 1743
[(dppm)2Au3(Cꢀ
CC4H2SC4H3S)2]ꢁ. Positive ESIMS; m/z: 1744
[(dppm)2Au3(Cꢀ
CC4H2SC4H3S)2]ꢁ. Negative ESIMS;
m/z: 575 [Au(Cꢀ
CC4H2SC4H3S)2]ꢂ. IR (KBr disc, n
(cmꢂ1)): 2093 (w, Cꢀ
C). Elemental analysis: Anal.
Found: C, 45.60; H, 2.54. Calc. for C90H64Au4P4S8×
CH2Cl2: C, 45.57; H, 2.77%.
/
11.2 Hz, ꢂ
/
PCH2Pꢂ
/),
CC(ꢁCH2)Me}2] (19). The procedure was similar to
/
/
that for 9 except [(dmpm)Au2Cl2] (60 mg, 0.10 mmol)
and 2-methylbut-1-en-3-yne (14 mg, 0.21 mmol) were
used in place of [(dcpm)Au2Cl2] and 1,3-decadiyne,
respectively, to give off-white crystals of 19 (47 mg,
39% yield). The complex would slowly decompose on
standing in air at room temperature. 1H-NMR (300
MHz, CDCl3, 298 K, relative to Me4Si, d ppm): 1.74 (s,
/
/
/
/
/
/
/
/
/
6H, ꢂ
1.89 (s, 6H, ꢂ
4H, Jꢃ10.9 Hz, ꢂ
CH2), 5.07 (d, 2H, Jꢃ
2.0 Hz, ꢁCH2), 5.16 (d, 2H, Jꢃ
ion FABMS; m/z: 993 [(dmpm)2Au3{Cꢀ
CH2)Me}2]ꢁ.
Positive ESIMS; m/z:
[(dmpm)2Au3{CꢀCC(ꢁ
CH2)Me}2]ꢁ. Negative ESIMS;
m/z: 327 [Au{CꢀCC(ꢁ
CH2)Me}2]ꢂ. IR (KBr disc, n
(cmꢂ1)): 2101 (w, Cꢀ
C). Elemental analysis: Anal.
/
PCH3), 1.77 (s, 6H, ꢂ
CH3), 2.07ꢀ2.15 (m, 12H, ꢂ
PCH2Pꢂ), 4.97 (d, 2H, Jꢃ
2.0 Hz, ꢁCH2), 5.11 (d, 2H, Jꢃ
2.0 Hz, ꢁCH2). Positive
CC(ꢁ
993
/
PCH3), 1.87 (s, 6H, ꢂ
PCH3), 2.91 (t,
2.0 Hz, ꢁ
/
/
CH3),
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
2.4.3.9. [(dtpm)2Au3{Cꢀ
CC(ꢁCH2)Me}2] (17). The procedure was similar to
that for 9 except [(dtpm)Au2Cl2] (91 mg, 0.10 mmol) and
/
CC(ꢁ
/
CH2)Me}2][Au{Cꢀ
/
/
/
/
/
/
/

V.W.-W. Yam et al. / Journal of Organometallic Chemistry 681 (2003) 196ꢀ
/209
201
Found: C, 20.35; H, 3.52. Calc. for C20H38Au4P4: C,
20.18; H, 3.22%.
nuclear [(PfflP)2Au3(Cꢀ
/
CR)2]ꢁ cation and the [Au(Cꢀ
/
CR)2]ꢂ counter-anion could be observed in the respec-
tive positive ESIMS and negative ESIMS detection
mode.
2.4.3.12. [(dmpm)2Au3(Cꢀ
/
CC4H3S)2][Au(Cꢀ
/
CC4H3S)2] (20). The procedure was similar to that for
9 except [(dmpm)Au2Cl2] (60 mg, 0.10 mmol) and 2-
ethynylthiophene (23 mg, 0.21 mmol) were used in place
of [(dcpm)Au2Cl2] and 1,3-decadiyne, respectively, to
give off-white crystals of 20 (42 mg, 28% yield). The
complex was found to slowly decompose on standing in
3.2. Structural characterization
The perspective drawing of complex 14 is depicted in
Fig. 1 and their selected bond distances and bond angles
are collected in Table 2. The complex cation consists of
three gold(I) atoms arranged in a triangular array with
short AuÁ Á ÁAu contacts of 3.1152(9), 3.1538(9)
1
air at room temperature. H-NMR (300 MHz, CDCl3,
298 K, relative to Me4Si, d ppm): 1.71 (s, 12H, ꢂ
2.15 (s, 12H, ꢂPCH3), 2.93 (t, 4H, Jꢃ10.9 Hz, ꢂ
PCH2Pꢂ), 6.87 (dd, 4H, Jꢃ1.2 and 3.9 Hz, 3-thienyl
protons), 6.99 (dd, 4H, Jꢃ
protons), 7.09 (dd, 4H, Jꢃ
/PCH3),
˚
/
/
/
and 3.1490(9) A, indicative of the presence of weak
/
/
AuÁ Á ÁAu interactions. Two of the gold(I) atoms were
coordinated to one alkynyl carbon and one phosphorus
atom, while the other gold(I) atom was coordinated to
two phosphorus atoms of two dppm ligands. The
counter-anion is a two-coordinate bis(alkynyl)gold(I).
Similar findings have been observed in a related tri-
nuclear complex [18]. The coordination geometry of all
the gold atoms are essentially linear, typical of sp
/3.9 and 5.1 Hz, 4-thienyl
/1.2 and 5.1 Hz, 5-thienyl
protons). Positive ion FABMS; m/z: 1077
[(dmpm)2Au3(Cꢀ
CC4H3S)2]ꢁ. Positive ESIMS; m/z:
1077 [(dmpm)2Au3(Cꢀ
CC4H3S)2]ꢁ. Negative ESIMS;
m/z: 411 [Au(Cꢀ
CC4H3S)2]ꢂ. IR (KBr disc, n (cmꢂ1)):
2091 (w, CꢀC). Elemental analysis: Anal. Found: C,
CH2Cl2: C,
/
/
/
/
26.86; H, 2.50. Calc. for C34H40Au4P4S4×
/
hybridization of gold(I), with Pꢂ
(172.5(5)8, 171.8(5)8) showing a slight deviation from the
ideal 1808, probably as a result of the steric demand of
/
Auꢂ/C bond angles
26.71; H, 2.69%.
the ligands and crystal packing forces. The Cꢀ
/C bond
3. Results and discussion
3.1. Syntheses and characterization
The schematic drawings of the structures of the
mono-, di-, and trinuclear gold(I) phosphine alkynyl
complexes are summarized in Scheme 1. All the gold(I)
complexes were prepared from the reaction of their
chloro precursor complexes with organic alkynes in the
presence of freshly prepared sodium ethoxide in EtOHꢀ
/
THF (1:1, v/v). The use of a mixed EtOHꢀTHF (1:1, v/
/
v) solvent, which renders the starting materials soluble
in the reaction mixture, serves to provide a homoge-
neous medium for the reaction to occur. All the newly
synthesized compounds gave satisfactory elemental
analyses and have been characterized by 1H-NMR
spectroscopy, FABMS, ESIMS and IR spectroscopy.
The structure of complex 14 was determined by X-ray
crystallography.
The IR spectra of all the alkynyl complexes show
weak absorption bands at ca. 2060ꢀ
of n(CꢀC) stretch of the alkynyl unit. In general, the
monoynyl complexes show one n(CꢀC) stretch at ca.
/
2200 cmꢂ1, typical
/
/
2090ꢀ
/
2105 cmꢂ1 while the diynyl complexes show two
n(CꢀC) stretches at ca. 2060ꢀ
/
/
2200 cmꢂ1, characteristic
1
of the terminal monoynyl and diynyl systems. The H-
NMR spectra of all the complexes show resonance
signals and coupling patterns that are consistent with
their chemical formulations. The identities of the tri-
nuclear gold(I) alkynyl complexes have further been
confirmed by ESIMS studies, in which both the tri-
Scheme 1. Schematic drawings of complexes 1ꢀ20.
/

202
V.W.-W. Yam et al. / Journal of Organometallic Chemistry 681 (2003) 196ꢀ209
/
in dichloromethane at room temperature are summar-
ized in Table 3. The electronic absorption spectra of the
mononuclear gold(I) complexes 1ꢀ
show high-energy absorption bands at ca. 250ꢀ
and low-energy absorptions at ca. 300ꢀ400 nm. The
high-energy absorptions at ca. 250ꢀ270 nm, which are
/
4 in dichloromethane
/
270 nm,
/
/
also present in the free phosphines, are assigned as
phosphine-centered intraligand (IL) transitions. The
intense absorptions at ca. 270ꢀ300 nm, which appear
/
at similar energies as the absorptions of alkynes and
show an energy dependence on the alkynyl ligands
present, are assigned as IL p0
/
p*(Cꢀ
/
C) transition,
400 nm,
while the less intense absorptions at ca. 300ꢀ
/
which also show an energy dependence on the nature of
the alkynyl ligand, in which the energy follows the
order: Cꢀ
CC6H13ꢀCꢀ
orbital energy of the alkynyl ligands, are tentatively
assigned as metal-perturbed IL p0p*(CꢀC) transitions
/
CPh [21]ꢀ
/
Cꢀ
/
Cꢂ
/
Cꢀ
/
CC3H7:
/
Cꢀ
/
Cꢂ
/
Cꢀ
/
Fig. 1. Perspective view of complex 14 with atomic numbering. Only
the ipso-carbons of the phenyl rings that are bonded to the phosphorus
atoms are shown and hydrogen atoms have been omitted for clarity.
Thermal ellipsoids are shown at 50% probability level.
/
/
CꢂCꢀCPh that is in line with the p*
/
/
/
/
with some metal-to-alkynyl metal-to-ligand charge
transfer (MLCT) character. This has further been
supported by the observation of vibronic structures in
the phenylbutadiynyl complexes 3 and 4, with vibra-
˚
lengths of 1.18(2), 1.22(2), 1.17(3) and 1.27(3) A in 14
are typical of terminal alkynyl gold(I) systems [19,20].
tional progressional spacings in the range 1730ꢀ
/
2190
C) in the excited state, and
3.3. Photophysical properties
cmꢂ1, typical of n(Cꢀ
/
indicative of the involvement of the alkynyl ligand in
the transition. Fig. 2 shows the electronic absorption
spectrum of complex 3 in dichloromethane at 298 K.
The relative insensitivity of the electronic absorption
bands to the nature of the phosphine ligands, as
reflected by the similar absorption patterns and energies
of complexes 3 and 4, is in line with the domination of
3.3.1. Electronic absorption spectroscopy
3.3.1.1. Mononuclear gold(I) phosphine alkynyl com-
plexes. The newly synthesized gold(I) alkynyl complexes
Table 2
˚
Selected bond distances (A) and bond angles (8) for complex 14
IL p0
/
p*(Cꢀ
/
C) and metal-perturbed IL p0
/
p*(Cꢀ
/
C)
Bond distances
transitions in the electronic absorption spectra.
Au(1)ꢂ
Au(1)ꢂ
Au(2)ꢂ
Au(4)ꢂ
Au(4)ꢂ
C(61)ꢂ
C(66)ꢂ
Au(1)ꢂ
Au(2)ꢂ
C(1)ꢂ
C(6)ꢂ
Au(1)ꢂ
Au(2)ꢂ
Au(3)ꢂ
Au(3)ꢂ
/
Au(2)
Au(3)
Au(3)
C(61)
C(66)
3.1152(9)
3.1538(9)
3.1490(9)
2.14(3)
/
/
3.3.1.2. Dinuclear gold(I) phosphine alkynyl complexes.
The electronic absorption spectra of the dinuclear
/
/
1.92(3)
/C(62)
1.17(3)
gold(I) complexes 5ꢀ
high-energy absorptions at ca. 260ꢀ
intense low-energy absorptions at ca. 300ꢀ
/
8 in dichloromethane show intense
290 nm and less
440 nm.
/C(67)
1.27(3)
/
/
C(1)
C(6)
1.99(2)
2.01(1)
/
/
The electronic absorption spectra of the dppe-con-
taining dinuclear complexes 5 and 6 show similar
absorption patterns as that of their mononuclear
analogues. For example, the electronic absorption
/
C(2)
1.18(2)
/
C(7)
1.22(2)
/
P(1)
P(2)
P(3)
P(4)
2.293(4)
2.290(4)
2.312(4)
2.312(4)
/
/
spectra of [(Ph3P)Au{Cꢀ
/
CC(ꢁ/CH2)Me}] [6] and com-
/
plex 6 are almost identical and are dominated by intense
IL transitions, except that the dinuclear complex shows
larger extinction coefficients for all the bands. Similarly,
the high-energy absorption at ca. 260 nm is assigned as
phosphine IL transitions. The intense absorptions at ca.
Bond angles
Au(1)ꢂAu(2)ꢂ
Au(2)ꢂAu(1)ꢂ
P(1)ꢂAu(1)ꢂ
P(2)ꢂAu(2)ꢂ
P(3)ꢂAu(3)ꢂ
Au(1)ꢂC(1)ꢂ
Au(2)ꢂC(6)ꢂ
Au(4)ꢂ
Au(4)ꢂ
/
/
Au(3)
60.46(2)
60.30(2)
172.5(5)
171.8(5)
166.3(2)
175(2)
/
/Au(3)
/
/
C(1)
C(6)
P(4)
/
/
/
/
270ꢀ/300 nm are likely to be typical of the alkynyl ligand
/
/
C(2)
C(7)
and are assigned as IL p0
/
p*(CꢀC) transitions. The
/
/
/
177(2)
observation of a higher absorption energy in complex 6
than complex 5 is in line with the poorer p conjugation
in the enynyl group than in the hexadiynyl unit.
/
C(61)ꢂ
C(66)ꢂ
/
C(62)
C(67)
175(3)
168(2)
/
/

V.W.-W. Yam et al. / Journal of Organometallic Chemistry 681 (2003) 196ꢀ
/209
203
Table 3
Electronic absorption and emission data for complexes 1ꢀ
/20
Complex
Absorptiona
Emission
labs (nm) (omax, dm3 molꢂ1 cmꢂ1
)
Medium (T, K)
lem (nm) (t0, ms)
460 (B0.1)
464, 537, 595 (6.4)
1
2
3
260 (18440), 278 (4440),
318 sh (2250)
CH2Cl2 (298)
Solid (298)
Solid (77)
/
480, 526, 594
264 (9000), 274 (2300),
314 sh (540)
CH2Cl2 (298)
Solid (298)
Solid (77)
454 (B0.1)
460, 535, 594 (0.2)
474, 528, 600
/
252 (53350), 262 (48370),
278 (36930), 296 (22340),
314 (19140), 332 (9610),
358 (3600), 398 (560)
CH2Cl2 (298)
Solid (298)
Solid (77)
460, 522, 590 (6.6)
468, 520, 590, 673 (4.3)
454, 528, 595
4
252 (50220), 262 (43280),
278 (27150), 296 (17360),
314 (13180), 332 (5060),
358 (2060), 398 (230)
CH2Cl2 (298)
Solid (298)
Solid (77)
466, 524, 591 (6.6)
481, 529, 596, 680 (2.0)
472, 528, 596
5
260 (132270), 280 (33000),
304 (11310), 316 sh (7320)
CH2Cl2 (298)
Solid (298)
Solid (77)
420 (B0.1)
552 (0.4)
/
476, 530, 555, 598
422 (0.7)
625 (2.4)
6
260 (53170), 270 (56420),
298 sh (2880)
CH2Cl2 (298)
Solid (298)
Solid (77)
478, 558
7
287 sh (37940), 298 (44530),
312 sh (34510), 338 (3120),
442 (240)
CH2Cl2 (298)
Solid (298)
Solid (77)
418 (B
ꢀb
ꢀb
418 (B
ꢀb
ꢀb
/
0.1)
/
/
8
286 (47630), 298 (54260),
314 (44110), 348 (8260),
440 (270)
CH2Cl2 (298)
Solid (298)
Solid (77)
/0.1)
/
/
9
260 (105600), 270 (75540),
304 (34650), 314 sh (9360)
CH2Cl2 (298)
Solid (298)
Solid (77)
399 (0.7), 478, 533, 552, 600, 631 (3.4)
428 (0.3), 481, 507, 537, 560, 610, 630 (5.3)
440, 476, 531, 556, 600, 631
425 (0.3), 582 (1.2)
425 (0.3), 610 (10.3)
420, 563, 621
10
11
12
13
14
15
16
17
18
19
20
270 (38610), 282 (32790),
314 sh (13070)
CH2Cl2 (298)
Solid (298)
Solid (77)
256 (21950), 300 (23130),
312 sh (20330)
CH2Cl2 (298)
Solid (298)
Solid (77)
418 (0.3), 499, 519 (3.0)
423 (0.4), 535 (4.7)
418, 484, 496, 518, 538, 553, 581
429 (0.3)
280 (29250), 362 (50430),
384 sh (36230)
CH2Cl2 (298)
Solid (298)
Solid (77)
421 (0.2)
424
645 (3.9)
260 (89270), 270 (73130),
304 (18090), 318 sh (5390)
CH2Cl2 (298)
Solid (298)
Solid (77)
408 (0.5), 464, 538, 560, 606, 633 (3.0)
380,410, 480, 498,534, 555, 556, 602, 630
425 (0.7), 574 (1.6)
425 (0.3), 600 (7.7)
425, 553, 580
270 (36330), 294 (18270),
310 sh (16210)
CH2Cl2 (298)
Solid (298)
Solid (77)
252 (60240), 296 (32430),
312 sh (28330)
CH2Cl2 (298)
Solid (298)
Solid (77)
410 (0.3), 499, 519 (7.5)
421 (0.6), 525 (3.6)
418, 478, 492, 511, 528, 547, 570, 595
429 (0.2)
282 (27680), 356 (51370),
386 sh (34130)
CH2Cl2 (298)
Solid (298)
Solid (77)
420 (0.9)
424
276 (29050), 302 (14370),
314 sh (2880)
CH2Cl2 (298)
Solid (298)
Solid (77)
427 (0.9), 589 (5.0)
418 (0.8), 621 (3.9)
422, 630
258 (72370), 302 (55120),
320 sh (32810)
CH2Cl2 (298)
Solid (298)
Solid (77)
440 (0.5), 500 (4.3)
427 (0.4), 583 (1.2)
440, 476, 490, 510, 526, 544, 570, 592
425 (0.3), 618 (5.4)
424 (0.4), 622 (2.7)
413, 622
270 (37310), 280 (28350),
316 sh (11430)
CH2Cl2 (298)
Solid (298)
Solid (77)
250 (53570), 302 (61430),
CH2Cl2 (298)
416 (0.3), 503, 520 (5.8)

204
V.W.-W. Yam et al. / Journal of Organometallic Chemistry 681 (2003) 196ꢀ209
/
Table 3 (Continued)
Complex
Absorptiona
Emission
labs (nm) (omax, dm3 molꢂ1 cmꢂ1
)
Medium (T, K)
lem (nm) (t0, ms)
318 sh (34250)
Solid (298)
Solid (77)
423 (0.2), 582 (2.2)
420, 500, 513, 535, 554, 576, 597
a
In dichloromethane at 298 K.
Non-emissive.
b
On the other hand, intense vibronic-structured bands
at 262ꢀ298 nm were observed in the electronic absorp-
tion spectra of the dppf-containing complexes 7 and 8.
Fig. 3 depicts the electronic absorption spectrum of
complex 7 recorded in dichloromethane at 298 K. The
teristics of other related ferrocene-containing complexes
[20] including the [Au2(dppf)Cl2] precursor, which is
typical of the ferrocene moiety.
The close resemblance of the electronic absorption
patterns of the mono- and dinuclear complexes and the
larger extinction coefficients observed in the dinuclear
species suggest that the two Au units in the dinuclear
species are non-interacting in nature and can be treated
as two independent chromophores.
/
vibrational progressional spacings in the range 1280ꢀ
/
1560 cmꢂ1 are typical of n(C C) stretch in the excited
---/
*
state. The large extinction coefficients in the order of 105
dm3 molꢂ1 cmꢂ1 suggested that the transitions involve
---/
IL p0p*(C C) transitions, probably associated with
/
*
both the cyclopentadienyl and the thiophene moieties.
In addition, the complexes display a low-energy absorp-
3.3.1.3. Trinuclear gold(I) phosphine alkynyl complexes.
When comparing the trinuclear Au(I) complexes with
the same alkynyl ligands, the electronic absorption
spectra appeared to be very similar. Similar to the
mononuclear Au(I) alkynyl complexes, it appears that in
the trinuclear system a change in the phosphine ligand
imposes insignificant changes on both the high-energy
and low-energy absorption bands. On the contrary, the
electronic absorption spectra of the trinuclear complexes
with different alkynyl ligands show different absorption
patterns. In general, an absorption energy trend in line
tion shoulder at ca. 300ꢀ
observed in other related dppf-containing complexes
such as [(dppf)Au2(CꢀCPh)2] and [(dppf)Au2(Cꢀ
CtBu)2] [20]. With reference to previous spectroscopic
studies [20], this shoulder is assigned as a s0p*(Ar)
transition of the dppf ligands (s refers to the bonding
orbital of AuꢂP s bond and p*(Ar) denotes the
/350 nm, similar to that
/
/
/
/
antibonding molecular orbital of the phenyl ring in the
PPh2 units or Cp of dppf). Furthermore, the complexes
show a weak absorption at ca. 440 nm with extinction
with the p* orbital energy of the Cꢀ
observed, in which R?ꢃC(ꢁCH2)Me:
C4H2SC4H3S.
/
CR? unit is
coefficients of 210ꢀ
/
270 dm3 molꢂ1 cmꢂ1. Similar
/
/
/
C4H3Sꢀ
/
findings have been observed in the absorption charac-
Fig. 2. Electronic absorption spectrum of 3 in dichloromethane at 298 K.

V.W.-W. Yam et al. / Journal of Organometallic Chemistry 681 (2003) 196ꢀ
/209
205
Fig. 3. Electronic absorption spectrum of 7 in dichloromethane at 298 K.
The electronic absorption spectra of the oligothienyl
substituted alkynyl complexes 15 and 16 in dichloro-
bithienyl unit, which will cause a narrowing of the p0
/
p* energy gap.
methane at 298 K are shown in Fig. 4. The electronic
3.3.1.4. Effect of nuclearity. In order to study the effect
of nuclearity of the metal complexes on their electronic
absorption spectroscopy, a comparison of the electronic
absorption spectra of the mononuclear, dinuclear and
trinuclear Au(I) complexes is desirable. As an illustra-
absorptions at 294ꢀ
and 360ꢀ362 nm for the bithienyl complexes are
assigned as thiophene-based p0p* and n0p* transi-
tions of the respective CꢀCC4H3S and Cꢀ
CC4H2SC4H3S units. The low-energy absorption
shoulders at ca. 310 nm in the thienyl complexes and
at ca. 380 nm in the bithienyl complexes are likely to
/
302 nm for the thienyl complexes
/
/
/
/
/
tion, the mononuclear complex, [(Ph3P)Au{Cꢀ
/
CC(ꢁ
/
CH2)Me}] [6] or [(Tol3P)Au{CꢀCC(ꢁCH2)Me}] [6],
/
/
and their dinuclear analogue 6 and trinuclear analogue
14 were chosen. Although the phosphines employed in
the mono-, di- and trinuclear complexes are not exactly
identical, a comparison study is still possible, given the
insignificant effect of the phosphines on the electronic
absorption properties of the complexes as discussed
earlier. The electronic absorption spectra of
involve metal-perturbed IL p0
/
p*(Cꢀ
/
C) transitions.
The red shift in absorption energies of the bithienyl
complexes relative to their thienyl counterparts is in line
with an increase in the extent of p-conjugation in the
[(Ph3P)Au{Cꢀ
/
CC(ꢁ
/
CH2)Me}] [6], 6, and 14 in dichlor-
omethane at 298 K are depicted in Fig. 5. The electronic
absorption spectra are all very similar and are domi-
nated by intense absorptions at ca. 258ꢀ280 nm, typical
/
of IL transitions of the phosphines and the alkynyl
ligands. It is interesting to note that the extinction
coefficients of these high-energy absorptions increase
with an increase in the nuclearity of the complexes from
[(Ph3P)Au{Cꢀ
/
CC(ꢁ
/
CH2)Me}] to 6 to 14, in line with
the increase in the number of the chromophoric units
according to the additivity rule. A close scrutiny of the
low-energy region at ca. 290ꢀ316 nm shows that there
/
are differences. A red shift in the absorption shoulder/
tail is observed on going from the mono- and dinuclear
complexes to the trinuclear species. The observation of
short AuÁ Á ÁAu contacts in the trinuclear Au(I) com-
plexes, as reflected by the X-ray study on
Fig. 4. Electronic absorption spectra of complexes 15 (*
in dichloromethane at 298 K.
/) and 16 (---)

206
V.W.-W. Yam et al. / Journal of Organometallic Chemistry 681 (2003) 196ꢀ209
/
2100 cmꢂ1, typical of the n(Cꢀ
state, were observed in the solid-state emission spectra
of 1ꢀ4 both at room temperature and at 77 K. Fig. 6
/
C) stretch in the ground
/
displays the solid-state emission spectrum of complex 3
at 298 K. This is indicative of the involvement of the
alkynyl unit in the emissive state.
The solid-state emission maxima for complexes 1 and
2 were found to be very similar while complexes 3 and 4
were found to occur at different energies with emission
maxima at 468 and 481 nm, respectively. An emission
energy trend of 4B
/
3B
/
2$1 was observed. The similar
/
emission energies of 1 and 2 are in agreement with the
similar p-acceptor abilities of the heptadiynyl and
decadiynyl units. The red shift in emission energies
from 1 and 2 to 3 and 4 is in line with the low-lying
p*(Cꢀ
CCnH2nꢁ1, suggestive of an assignment of the emissive
state as derived from states of a s(AuꢂP)0p*(CꢀC)
p*(CꢀC) origin
/
C) orbital energy of Cꢀ
/
Cꢂ
/
Cꢀ
/
CPh than Cꢀ
/
Cꢂ
/
Cꢀ
/
Fig. 5. Electronic absorption spectra of [(PPh3)Au{Cꢀ
CH2)Me}] (*), 6 (---) and 14 (-×-×-×) in dichloromethane at 298 K.
/
CC(ꢁ
/
/
/
/
/
/
/
/
character, or a metal-perturbed IL p0
with MLCT character. The slight red shift in emission
/
/
[(dppm)2Au3{Cꢀ
CH2)Me}2] (14) and that previously reported on a
related [(dppm)2Au3(CꢀCPh)2][Au(CꢀCPh)2] [18], sug-
gests that weak AuÁ Á ÁAu interactions exist in these
complexes. This would lead to d2z(Au)ꢀdz2(Au) orbital
/
CC(ꢁ
/
CH2)Me}2][Au{Cꢀ
/
CC(ꢁ
/
energy on going from PPh3 in 3 to PTol3 in 4 is
consistent with an assignment of the emissive state as
/
/
3
/
derived from a (s0
/
p*) transition associated with the
overlap to give ds and ds* combinations, raising the
energy of the metal-centered ds* orbital which has a
substantial character in the HOMO. Thus, a red shift in
the transition with large metal-to-alkynyl MLCT char-
[Au(Cꢀ
donor than PPh3, would render the gold(I) center more
electron rich, making the 3[s(Auꢂ
P)0p*(CꢀC)] or
metal-perturbed 3IL [p0 C)]/3MLCT excited
p*(Cꢀ
/
CR)] groups, since PTol3, being a better electron
/
/
/
/
/
acter due to the presence of metalꢀmetal interactions or
/
state low-lying in energy. Similar trends have been
a metal-metal-to-ligand charge transfer (MMLCT)
transition is observed. On the other hand, the similarity
in the shapes between the electronic absorption spectra
of the mononuclear and the dinuclear complexes
bridged by the dppe or dppf ligand is suggestive of the
absence of short AuÁ Á ÁAu contacts in the dinuclear
complexes, as evidenced by the absence of AuÁ Á ÁAu
observed in the 77 K solid-state emission energies. A
comparison of the emission energies of 1ꢀ
related complexes shows that the emission energies of
[(R3P)Au(CꢀCR?)] in 77 K solid state are in the order:
R?ꢃCꢀCPh:C(ꢁCH2)Me [6]BPh [21] and CꢀCPhB
CꢀCC3H7:CꢀCC6H13BC(ꢁCH2)Me [6], in line with
/4 with other
/
/
/
/
/
/
/
/
/
/
/
/
/
the increasing p* orbital energy of the alkynyl group.
This is also supportive of an assignment of the emissive
interactions in a related [(dppe)Au2(Cꢀ
[(dppf)Au2{CꢀCC(ꢁ
Au(CꢀCR?) units in the dinuclear complexes would
/
CPh)2] [21a] and
states as derived from states of a 3[s(Auꢂ
/
P)0
/
p*(Cꢀ/C)]
/
/
CH2)Me}2] [6]. Thus, the two
/
behave as independent entities, giving rise to similar
absorption energies as the mononuclear counterparts.
3.3.2. Steady-state emission spectroscopy
Excitation of the gold(I) phosphine alkynyl complexes
both in the solid state and in fluid solutions showed
long-lived luminescence. The photophysical data are
summarized in Table 3.
3.3.2.1. Mononuclear gold(I) phosphine alkynyl com-
plexes. The mononuclear gold(I) phosphine alkynyl
complexes exhibit intense vibronic-structured emissions
at room temperature at ca. 460ꢀ/680 nm in the solid state
upon photoexcitation with l ꢀ/350 nm. Their lumines-
cence lifetimes in the microsecond range suggested that
the emissions are phosphorescence in nature. Vibronic
structures with vibrational progressional spacings of ca.
Fig. 6. Solid-state emission spectrum of complex 3 at 298 K.

V.W.-W. Yam et al. / Journal of Organometallic Chemistry 681 (2003) 196ꢀ
/209
207
character, or a metal-perturbed 3IL [p0
mixed with a MLCT 3MLCT character. In solution
state, the complexes emit at ca. 454ꢀ590 nm, also
/
p*(Cꢀ
/
C)]
3.3.2.3. Trinuclear gold(I) phosphine alkynyl complexes.
For the trinuclear Au(I) complexes, two emission bands
/
were observed. The high-energy band is at ca. 400ꢀ
nm, whereas the low-energy one appears at ca. 500ꢀ
nm. In the two series 9ꢀ12 and 13ꢀ
same kind of diphosphine ligands dcpm or dppm, the
emission energy follows the order: CꢀCC4H3SꢀCꢀ
CC(ꢁCH2)MeꢀCꢀCCꢀCC6H13, in line with the de-
/
480
dependent on the nature of the alkynyl ligand.
/
622
/
/16 that have the
3.3.2.2. Dinuclear gold(I) phosphine alkynyl complexes.
For the dinuclear dppe-containing gold(I) complexes 5
and 6, complex 5 was found to emit at 552 nm in the
solid state at 298 K, while complex 6 was found to emit
at 625 nm. In degassed dichloromethane solutions, both
5 and 6 emit at ca. 420 nm. The anomalous observation
that the diynyl complex 5 emits at higher energy than the
enynyl complex 6 in the solid state at 298 K may be
attributed to solid-state effects. Although no X-ray
quality crystals could be obtained for the structure
determination of complexes 5 and 6, based on previous
/
/
/
/
/
/
/
creasing p* orbital energy of the alkynyl ligands, and
similar to the trend observed in the electronic absorption
spectra. This is supportive of an assignment of the
emissive states as derived from states of a s(Auꢂ
/
P)0
/
p*(Cꢀ
/
C) transition, or a metal-perturbed IL [p0
/
p*(Cꢀ
/
3
C)] transition with MLCT MLCT character. The only
exception is complexes 12 and 16 with bithienyl ligand,
in which no emission band was found at 530ꢀ600 nm. It
/
studies on a related complex [(dppe)Au2(Cꢀ
[21a], which consists of two weakly interacting mole-
cules in an anti-configuration, with intermolecular Auꢂ
/CPh)2]
is likely that the introduction of bithienyl groups into
the Au(I) complexes quenches the emissive state, with
the low-energy emission band becomes undetectable.
The high-energy band, which is more intense than the
low-energy band, is logically assigned to be originated
from the anion as emission bands of similar energies are
/
˚
Au distance of 3.153(2) A, one may assume that
complex 6, similar to the [(dppe)Au2(CꢀCPh)2] analo-
/
gue, may possess short intermolecular AuÁ Á ÁAu con-
tacts, and gives rise to low-energy solid-state emission,
typical of the presence of AuÁ Á ÁAu interaction.
Although no short intramolecular AuÁ Á ÁAu contact
exists, it is likely that the presence of an intermolecular
short AuÁ Á ÁAu contact in 6 would also give rise to an
AuÁ Á ÁAu interaction in the solid state. On the other
hand, it is likely that no short AuÁ Á ÁAu contacts, both
intra- and intermolecular, exist in the solid-state struc-
ture of the diynyl complex 5 since the long alkyl chains
present may induce a steric hindrance with the adjacent
molecules to prevent any close AuÁ Á ÁAu contacts to
observed in the [Au(Cꢀ
/
CR)2]ꢂ [21a]. The low-energy
emission bands, which are red shifted with respect to
that of the corresponding mono- and dinuclear species,
are likely to be associated with the presence of metalꢀ
/
metal interactions in the trinuclear complexes. The
observation of short AuÁ Á ÁAu contacts in the trinuclear
Au(I) complexes, as reflected by X-ray study on com-
plex 14 and that previously reported on a related
[(dppm)2Au3(Cꢀ
that weak AuÁ Á ÁAu interactions exist in these complexes.
This would lead to a dz2(Au)ꢀd2z(Au) orbital overlap to
/
CPh)2][Au(Cꢀ/CPh)2] [18], suggests
/
occur. The low-energy emission of 6 is tentatively
3
give ds and ds* combinations, raising the energy of the
metal-centered ds* orbital which has substantial char-
acter in the HOMO. Thus, the observation of the low-
assigned as a metal-perturbed IL [p(Cꢀ
/
C)0
/
p*(Cꢀ
/
C)]
metal interactions or an
emission modified by metalꢀ
/
MMLCT 3[ds*(Au2)0
/
p*(CꢀC)] emission. Fig. 7 shows
/
the emission spectra of complex 6 in the solid state and
in dichloromethane solution. The absence of low-energy
emission in CH2Cl2 solution is attributed to the absence
of short AuÁ Á ÁAu contacts in solution and IL phosphor-
escence becomes dominant.
For the dinuclear dppf-containing gold(I) complexes 7
and 8, no emission was detected in the solid-state both at
298 and 77 K. A weak emission at ca. 418 nm was
observed in degassed dichloromethane solutions. With
reference to previous spectroscopic studies on
[(dppf)Au2(Cꢀ
the emission is assigned to be originated from a s(Auꢂ
P)0p*(Ar) excited state, of which s refer to the PꢂAu
/
CPh)2] and [(dppf)Au2(Cꢀ
/
CtBu)2] [20],
/
/
/
bonding orbital and p* refers to the antibonding orbital
of the phenyl or cyclopentadienyl ring on the phosphine
ligands. The lack of emission in the solid-state is
probably a result of the introduction of the ferrocenyl
unit, which would quench the emission via an intramo-
lecular reductive electron transfer quenching process.
Fig. 7. Normalized emission spectra of complex 6 in the solid state
(*) and in degassed dichloromethane solution (---) at 298 K.
/

208
V.W.-W. Yam et al. / Journal of Organometallic Chemistry 681 (2003) 196ꢀ209
/
energy emission in the trinuclear complex is in accor-
dance with the presence of weak AuÁ Á ÁAu interactions in
these trinuclear complexes, which gave rise to low-
energy emission that is of a metal-perturbed IL [p0
p*(CꢀC)] mixed with a metal-to-alkynyl MLCT char-
acter modified by metalꢀmetal interactions, or an
MMLCT nature.
/
/
/
3.3.2.4. Effect of phosphine substituents. When consider-
ing the influence of the phosphine ligands on the
emission energy of the trinuclear Au(I) complexes, the
high-energy emission does not seem to be much affected
by the nature of the phosphine ligands. This is further
supportive of an assignment that the origin of this
emission is from the [Au(Cꢀ
hand, the low-energy emission follows a subtle emission
energy trend of dppmꢀdtpm:dcpmꢀdmpm, in line
with an emission origin of 3[s(Auꢂ
P)0p*(CꢀC)] or
C)] excited states. Since
/
CR)2]ꢂ anion. On the other
/
/
/
/
/
/
Fig. 8. Normalized solid-state emission spectra of 6 (-×
/
-×-×), and 14
/
/
3
metal-perturbed IL [p0
/
p*(Cꢀ
/
(---) at 298 K.
dtpm, dcpm and dmpm are more electron-rich than
dppm, they would render the gold(I) center more
electron-rich, and hence give rise to a lower energy
It is interesting to note that the low-energy emission
band persists in the trinuclear complexes in the solution
state, while the low-energy emission band disappears in
the dinuclear complexes in solution. It is likely that the
intramolecular AuÁ Á ÁAu interaction remains intact in
solution in the trinuclear complexes while in the di-
nuclear system, the intermolecular AuÁ Á ÁAu interactions
are destroyed in solution and their emission resembles
that of their mononuclear counterpart.
3[s(Auꢂ
/
P)0
/
p*(Cꢀ
/
C)] emission.
3.3.2.5. Effect of nuclearity. In order to study the effect
of nuclearity of the metal complexes on their emission
spectroscopy, a comparison of the emission spectra of
the mononuclear Au(I) complexes, i.e. [(Ph3P)Au{Cꢀ
CC(ꢁCH2)Me}] [lem(solid state)$454 nm] or
[(Tol3P)Au{CꢀCC(ꢁCH2)Me}] [lem(solid state)$463
/
/
/
/
/
/
nm] [6], with that of the dinuclear complex 6 and the
trinuclear complex 14 was made. Fig. 8 shows the solid-
state emission spectra of 6 and 14 at 298 K.
4. Conclusion
For the solid-state emission spectra, the similarity in
A series of mono-, di- and trinuclear gold(I) phos-
phine alkynyl complexes has been synthesized and
structurally characterized. In general, the high-energy
the shapes and emission energies (600ꢀ625 nm) of the
/
band between complexes 6 and 14 is suggestive of their
common emission origin. It is likely that the presence of
short AuÁ Á ÁAu contacts in both the trinuclear and
dinuclear Au(I) complexes, as reflected by X-ray study
and that previously reported on the related
absorptions are due to IL phosphine-centered and p0
p*(CꢀC) transitions, whereas the low-energy absorp-
tions are assigned as s(AuꢂP)0p*(CꢀC) or metal-
perturbed IL p0p*(CꢀC) mixed with metal-to-alkynyl
/
/
/
/
/
/
/
[(dppm)2Au3(Cꢀ
/
CPh)2][Au(Cꢀ
/
CPh)2]
[18]
and
MLCT transitions. Both the electronic absorption and
emission energies are found to depend on the nature of
the alkynyl ligands. The nuclearity of the metal com-
plexes also has an influence on the electronic absorption
as well as emission behavior. The emission energies are
generally found to be lowest in the trinuclear complexes,
attributed to the presence of weak AuÁ Á ÁAu interactions.
[(dppe)Au2(CꢀCPh)2] [21a], whether intra- or intermo-
/
lecular in nature, would give rise to weak AuÁ Á ÁAu
interactions in these complexes. This would lead to a
d2z(Au)ꢀd2z(Au) orbital overlap to give ds and ds*
combinations, raising the energy of the metal-centered
/
ds* orbital which has substantial character in the
/
HOMO. Thus, a red shift in the 3[s(Auꢂ
/
/
P)0
p*(CꢀC)] mixed
metal
/
p*(Cꢀ
C)] or the metal-perturbed 3IL [p0
/
with metal-to-alkynyl 3MLCT modified by metalꢀ
/
interactions, or the MMLCT 3MMLCT emission energy
is observed relative to that of the mononuclear com-
plexes. This is understandable since the absence of short
AuÁ Á ÁAu contacts in the mononuclear complexes would
give rise to a higher energy emission that is mainly
5. Supplementary material
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC No. 213084 for complex 14. Copies
of this information may be obtained free of charge from
derived from a s(Auꢂ
/
P)0
/
p*(Cꢀ/C) excitation.

V.W.-W. Yam et al. / Journal of Organometallic Chemistry 681 (2003) 196ꢀ
/209
209
(1996) 4227;
(c) C.M. Che, H.Y. Chao, V.M. Miskowski, Y. Li, K.-K. Cheung,
J. Am. Chem. Soc. 123 (2001) 4985;
The Director, CCDC, 12 Union Road, Cambridge
CB2 1EZ, UK (Fax: 44-1223-336033; e-mail:
deposit@ccdc.cam.ac.uk or www: http://www.ccdc.cam.
ꢁ
/
(d) W. Lu, H.F. Xiang, N. Zhu, C.M. Che, Organometallics 21
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Acknowledgements
V.W.-W.Y. acknowledges support from The Univer-
sity of Hong Kong Foundation for Educational Devel-
opment and Research. The work described in this paper
has been supported by the Research Grants Council of
the Hong Kong Special Administrative Region, China
(Project No. HKU7123/00P). K.-L.C. and S.-K.Y.
acknowledge the receipt of a postgraduate studentship,
administered by The University of Hong Kong.
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