The coordination chemistry of fluorescent pyridinyl- and quinolinyl-phthalimide ligands with the {AuI-PPh3} cationic unit

Article abstract of DOI:10.1039/b905123f

The new mono-dentate ligands, 2-(2-aminoethyl)-N-phthalimido-pyridine (L⁴) and 8-amino-N-phthalimido-quinoline (L⁶), were synthesised using a solvent-free melt method. These ligands together with L ^1-3,5 (3-amino-N-phthalimido-pyridine; 3-aminomethyl-N-phthalimido- pyridine; 4-aminomethyl-N-phthalimido-pyridine; 3-amino-N-phthalimido-quinoline) were then used to access six luminescent Au^I complexes of the generic type {Ph₃P-Au-Lⁿ}(OTf). X-Ray crystallography has been used to structurally characterise three of the complexes showing that in the cases of L¹ and L³ the complexes adopt an approximately linear P-Au-N coordination geometry. However, in the case of the sterically demanding L⁶ the structure shows distortions within the ligand and deviations from a linear coordination geometry. Solution state ¹H and ³¹P{¹H} NMR confirmed that the proposed formulations and coordination modes exist in solution. At room temperature the photophysical studies showed that the emission from each of the six complexes was in the visible region (395-475 nm) and assigned to a ligand-centred fluorescence (τ < 10 ns) in each case. The Royal Society of Chemistry 2009.

Full text of DOI:10.1039/b905123f

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The coordination chemistry of fluorescent pyridinyl– and
quinolinyl–phthalimide ligands with the {AuI–PPh3} cationic unit†
Lucy A. Mullice,a Flora L. Thorp-Greenwood,a Rebecca H. Laye,b Michael P. Coogan,a Benson M. Kariukia
and Simon J.A. Pope*a
Received 12th March 2009, Accepted 18th June 2009
First published as an Advance Article on the web 17th July 2009
DOI: 10.1039/b905123f
The new mono-dentate ligands, 2-(2-aminoethyl)-N-phthalimido-pyridine (L4) and
8-amino-N-phthalimido-quinoline (L6), were synthesised using a solvent-free melt method. These
ligands together with L1–3,5 (3-amino-N-phthalimido-pyridine; 3-aminomethyl-N-phthalimido-pyridine;
4-aminomethyl-N-phthalimido-pyridine; 3-amino-N-phthalimido-quinoline) were then used to access
six luminescent AuI complexes of the generic type {Ph3P–Au–Ln}(OTf). X-Ray crystallography has
been used to structurally characterise three of the complexes showing that in the cases of L1 and L3 the
complexes adopt an approximately linear P–Au–N coordination geometry. However, in the case of the
sterically demanding L6 the structure shows distortions within the ligand and deviations from a linear
1
coordination geometry. Solution state 1H and 31P{ H} NMR confirmed that the proposed formulations
and coordination modes exist in solution. At room temperature the photophysical studies showed that
the emission from each of the six complexes was in the visible region (395–475 nm) and assigned to a
ligand-centred fluorescence (t < 10 ns) in each case.
et al. as recently as 2004.9 Relevant reports are confined to func-
Introduction
tionalised pyridines,10 triazoles,11 diimines,10d,12 benzimidazoles,13
Interest in AuI coordination chemistry is motivated by the range
of useful applications exploiting such complexes, including opto-
electrics, catalysis and cellular imaging. Luminescence from AuI
complexes can originate from a variety of excited states depending
upon the type and nature of the ligands coordinated to the AuI
centre. For instance, organometallic species based upon alkynyl
derivatives have shown potential in light-emitting diode (LED)
applications and benefit from tunability associated with spectral
absorption and emission (utilising a variety of excited states).1
Other emissive species have been exploited in chemosensors2 or
environmentally responsive probes.3
Therapeutics based upon gold coordination complexes have
been utilised for many years although the precise nature of action
is often unknown or unclear.4 The possibility of targetted uptake
by mitochondria has been realised by exploiting luminescent,
lipophilic di-gold(I) carbene complexes.5,6 The biological and
therapeutic activity of such species almost certainly exploits the
inherent thiophilicity of Au.7
pyrazole14 and N-bound phthalimido species15 as well as related
N-bound saccharinates16 and quinuclidine complexes.17 With these
limited examples in mind, we report the syntheses, structures
and spectroscopic properties of a series of luminescent, cationic
+
{PPh3–Au–(Ln)} complexes incorporating a lipophilic, planar ph-
thalimide fluorophore tethered via a AuI-coordinated pyridine or
quinoline donor (Scheme 1). We recently reported18 the structural
and spectroscopic properties of a related series of luminescent
ReI complexes of L1 and L2 since phthalimides are known to
have potent biological activity:19 four of the free ligands (L1–3 and
L5) utilised in this study have already shown moderate promise
in this regard.20 Related N-pyridyl and N-quinolyl substituted
phthalimides have also shown potent cytotoxicity towards a
variety of cell lines.21
In contrast to the numerous reports of thiolate and phosphine
coordination chemistry with AuI, the chemistry of N-donor het-
erocycles with AuI remains comparatively unexplored:8 the struc-
ture of {Ph3P–Au–pyridine}(BF4) was reported by Schmidbaur
aSchool of Chemistry, Main Building, Cardiff University, Cardiff, UK CF10
3AT. E-mail: popesj@cardiff.ac.uk; Fax: +44 (0)2920874030; Tel: +44
(0)2920879316
bDepartment of Chemistry, The University of Sheffield, Dainton Building,
Brook Hill, Sheffield, UK S3 7HF
† Electronic supplementary information (ESI) available: Selected bond
lengths and bond angles associated with the X-ray crystal structures
of L3, L4 and L6. CCDC reference numbers 723934–723939. For ESI
and crystallographic data in CIF or other electronic format see DOI:
10.1039/b905123f
Scheme 1 The phthalimide-derived ligands used within this study.
6836 | Dalton Trans., 2009, 6836–6842
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Table 1 Crystal data collection and refinement details for the crystal structures of the ligands and complexes
L3
L4
L6
Au–L1
Au–L3
Au–L6
Empirical formula C14H10N2O2
C15H12N2O2
C17H10N2O2
C32H23AuF3N2O5PS· C33H25AuF3N2O5PS C36H25AuF3N2O5PS·
CHCl3
CHCl3
Formula weight
Temperature/K
Wavelength/A
238.24
100(2)
252.27
100(2)
0.71073
Triclinic
¯
P1
5.3683(9)
10.1138(16)
12.1952(19)
69.049(11)
87.126(10)
82.370(17)
612.87(17)
2
274.27
100(2)
951.89
150(2)
846.55
150(2)
1001.94
150(2)
0.71073
Triclinic
¯
P1
11.2880(2)
11.50(2)
15.6380(4)
74.73(10)
72.1950(10)
81.1030(10)
1858.45(7)
2
˚
0.71073
Monoclinic
P2(1)/c
8.6402(6)
5.3085(4)
24.4905(16)
90.00
97.660(5)
90.00
1113.27(14)
4
0.71073
Monoclinic
P2(1)/n
7.9097(4)
16.4710(8)
10.1089(5)
90.00
99.700(3)
90.00
1298.17(11)
4
0.71073
Monoclinic
P2(1)/c
17.6586(10)
11.2141(6)
17.6983(10)
90.00
97.781(3)
90.00
3472.4(3)
4
0.71073
Monoclinic
P2(1)/c
8.5090(2)
21.2850(5)
18.1110(3)
90.00
95.8970(10)
90.00
3262.80(12)
4
Crystal system
Space group
˚
a/A
˚
b/A
˚
c/A
a/◦
b/◦
g /◦
V/A
Z
3
˚
Density (calcu-
lated)/Mg m-3
F(000)
1.421
1.367
1.403
1.821
1.723
1.790
496
264
568
1856
1656
0.2 ¥ 0.2 ¥ 0.2
2.22 to 27.52
980
Crystal size/mm3
Theta range for
data collection/◦
All reflections
Independent
reflections
0.42 ¥ 0.04 ¥ 0.04
1.68 to 29.17
0.25 ¥ 0.10 ¥ 0.06 0.20 ¥ 0.15 ¥ 0.08 0.27 ¥ 0.20 ¥ 0.05
1.79 to 27.74
0.15 ¥ 0.15 ¥ 0.05
2.66 to 27.42
2.39 to 31.17
1.16 to 27.59
14 941
2972
11 451
2827
22 786
4003
42 366
8025
12 672
7455
12 868
8401
Observed
reflections
Goodness-of-fit
on F
Rint
2292
2080
3203
6710
5781
1.04
7060
0.950
0.950
0.950
1.025
0.950
0.0479
0.0370
0.0307
0.0293
0.0394
0.0402
Final R indices
[I > 2s(I)]
R1 = 0.0439
R1 = 0.0393
wR2 = 0.0871
R1 = 0.0638
wR2 = 0.0991
R1 = 0.0422
wR2 = 0.1065
R1 = 0.0565
wR2 = 0.1148
R1 = 0.0212
wR2 = 0.0433
R1 = 0.0328
wR2 = 0.0478
R1 = 0.0380
wR2 = 0.0680
R1 = 0.0592
wR2 = 0.0746
R1 = 0.0452
wR2 = 0.0865
R1 = 0.0614
wR2 = 0.0933
wR2 = 0.0955
R indices (all data) R1 = 0.0641
wR2 = 0.1042
for X-ray diffraction studies. The parameters associated with the
data collections are shown in Table 1 with selected bond lengths
and bond angles reported in Table 2 and the ESI (Table S1).†
The crystallographic studies confirmed the proposed formulations
(Fig. 1). In the structure of L6 the phthalimide ring is positioned
orthogonally to the quinoline ring, presumably minimising the
steric interaction between the carbonyl groups and the ring-
nitrogen lone pair.
Single crystals of the complexes Au–L1, Au–L3 and Au–L6
were grown over the course of 24 h at room temperature, by
vapour diffusion of diethyl ether into a concentrated chloroform
solution. The structures (Fig. 2) of Au–L1 and Au–L3 revealed the
expected, approximately linear coordination geometry (P–Au–N
angles >175◦) for the two-coordinate AuI centres. Both structures
show the N-coordination mode of the pyridyl–phthalimide ligand
with the Au–N and Au–P bond lengths being typical (2.07 and
Syntheses
The ligands (L1–6) were synthesised using a solvent-free melt
method.18
The synthesis of the gold complexes was achieved by firstly
stirring one equivalent of AuCl(PPh3)22 with a chloride abstracting
agent (one equivalent of AgOTf) for 20 min in dichloromethane
at room temperature, in the absence of light, followed by one
equivalent of the ligand with stirring for another 16 h. The AgCl
precipitate was removed and the reaction solution concentrated
in vacuo. Addition of diethyl ether to the concentrate resulted in the
formation of a white precipitate which was isolated via filtration,
and dried in vacuo. With these reactions our investigations showed
that the order of reagent addition was important for the resultant
purity of the complexes. We found that a very minor impurity
(established as <5% via 31P{ H} NMR) of homoleptic species
1
= 45.10 ppm)23 was occasionally
31
{PPh3–Au–PPh3}(OTf) (d
˚
P
2.24 A respectively) of those observed in a closely related example
formed if the ligand (Ln) was added before halide abstraction,
presumably as a consequence of ligand lability at AuI. However,
(cf . 2.073(3) and 2.2364(8) for {Ph3P–Au–pyridine}(BF4)).9 In
each case the presence of one triflate anion per cation balances
the charge. The structure of Au–L6 is far more unusual. As
revealed by the structural determination of the corresponding
free ligand (L6), the quinoline ring nitrogen is sterically inhibited
by the phthalimide unit. Despite this Fig. 2 shows that the AuI
ion is able to participate in coordination to the quinoline. The
structure reveals four key attributes that allow this binding mode:
the complex adopts a distorted linear geometry (P–Au–N angle
170.77(12)◦); the steric requirements of the coordinated PPh3
in the absence of competing ligands 1H and 31P{ H} NMR studies
1
(in CDCl3) on the pure, isolated complexes showed no evidence
for disproportionation or decomposition over a period of 48 h.
Single crystal X-ray diffraction studies†
Recrystallisation of L3 and the new ligands L4 (colourless plate-
like) and L6 (colourless blocks) yielded single crystals suitable
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Table 2 Selected bond lengths and bond angles for the complexes†
Au–L1
Au–L3
Au–L6
C32H23AuF3N2O5PS·CHCl3
C33H25AuF3N2O5PS
C36H25AuF3N2O5PS·CHCl3
˚
Bond distances/A
Au1–N2
Au1–P1
2.073(2)
2.2394(7)
Au1–N2
Au1–P1
2.072(3)
2.2384(10)
Au1–N1
Au1–P1
2.101(4)
2.2382(13)
Bond angles/◦
N2–Au1–P1
178.25(6)
N2–Au1–P1
175.83(10)
N1–Au1–P1
170.77(12)
longer than the corresponding pyridyl donors reflecting the weaker
donating ability of the quinoline in L6.
Spectroscopic characterisation of the complexes
IR spectra were obtained on solid samples of the complexes and
showed the presence of vibrational absorptions associated with the
coordinated ligands and the triflate counter ions. In particular, the
n(CO) stretching frequency of the phthalimide unit (ca. 1700 cm-1)
showed subtle variations according to ligand type wherein the
potentially conjugated Au–L1 and Au–L3 revealed high energy
shifts for the carbonyl stretch when compared to the free ligands
(cf . 1694 and 1707 cm-1 respectively). The remaining complexes
showed only minor variations in n(CO) suggesting little change in
the electronic environment of the phthalimide carbonyls.
Each of the complexes Au–Ln gave 1H NMR consistent with the
1
formation of the 1 : 1 adduct. 31P{ H} NMR was used to probe
the electronic environment at the coordinated PPh3 and assess the
n
trans influence24 of L . Generally, all of the complexes gave d
31
P
typical of AuI-coordinated PPh3, in the range of +28 to +30 ppm:
the subtle differences can be rationalised in terms of Ln electron
2
3
4
31
donating ability. L , L and L induced upfield d whereas those
P
ligands with weaker donating ability, particularly the quinolyl-
6
31
derived L produced the largest downfield shift for d P, reflecting
a stronger donation from P as a consequence of the weaker trans
Au–N interaction.
All complexes were colourless in solution: UV-vis spectra
obtained for 10-4 M CHCl3 solutions showed transitions below
330 nm. Those at highest energy were attributed to singlet p–p*
transitions within each of the P-bound phenyl groups (ca. 250 nm)
with the intraligand transitions of the pyridyl–phthalimido units
at lower energy (260–300 nm). L5 and L6 (quinolyl-type ligands)
were slightly red-shifted in comparison to the pyridyl analogues
(270–320 nm). In contrast to related mixed phosphine–thiolate
complexes these spectra showed no evidence for any charge
transfer (CT) transitions involving AuI.
The free ligands were emissive in CHCl3 solution following
irradiation at 290 nm. For L2–4 the emission (ca. 400 nm)
was attributed to a singlet fluorescence originating from the
electronically insulated phthalimide chromophore. For L1, L5 and
L6 where the possibility of phthalimide–imine conjugation exists
in solution, emission was red-shifted to 470–500 nm. Within the
quinoline derivatives, L5 was more red-shifted than L6 suggesting
a more effective conjugation for the former. The fluorescence
lifetimes were all extremely short (<1 ns) in CHCl3.
Fig. 1 Structural representations of the free ligands L3 (top), L4 (middle)
and L6 (bottom). Probability ellipsoids are at 50% and solvent molecules
are omitted for clarity.
are accommodated by orienting the phenyl groups away from
the phthalimide ring; distortions within the twisted quinoline
rings and at the coordinated quinoline nitrogen, position the
Au–PPh3 unit away from the phthalimide moiety. As a con-
˚
sequence the Au–P distance of 2.2382(13) A compares very
1
3
˚
favourably to Au–L and Au–L . The Au–N 2.101(4) A is slightly
6838 | Dalton Trans., 2009, 6836–6842
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Fig. 2 Structural representations for (l to r) Au–L1, Au–L3 and Au–L6. Probability ellipsoids are at 50% whilst counter ions, solvent molecules and
hydrogen atoms are omitted for visual clarity.
Table 3 Luminescence data for the complexes
The complexes were also studied in aerated CHCl3 solution
(lex ca. 290–320 nm). It was noted that irradiation of MeCN
solutions of the complexes rapidly generated turbid solutions with
a pale brown hue, indicative of complex decomposition, presum-
ably via photoinduced reduction of AuI. However, in CHCl3 the
complexes showed no evidence of instability upon irradiation.
Each complex was emissive with a broad transition between
400–480 nm with short-lived (<10 ns) luminescence lifetimes
of single exponential character, indicative of an intraligand
fluorescence. In the cases of Au–L2–4 the position of the emission
wavelength was similar to the corresponding free ligands. In
contrast Au–L6 possessed a blue-shifted emission (Fig. 3) which
is attributed to a significant reduction in conjugation between the
quinoline and the phthalimide fluorophore, due to conformational
restrictions: the Au–PPh3 unit inhibits rotation of the phthalimide
moiety about the C–N bond. The two remaining complexes (which
should allow free rotation of the phthalimide) also showed an
unusual blue-shifted emission relative to the free ligands. Taken
Compound
Emission/nm 293 K (t/ns)a
Emission/nm 77 Kc
Au–L1
Au–L2
Au–L3
Au–L4
Au–L5
Au–L6
446 (3.4) (473)b
400 (2.3) (399)b
410 (5.9) (397)b
395 (<1) (405)b
474 (1.1) (497)b
427 (6.5) (484)b
446
452
445
451
478, 514
489, 519
a Recorded in aerated chloroform. b Emission maximum for corresponding
free ligand. c Ethanol : chloroform (95 : 5) glass.
{Au–PPh3} unit, which in these cases results in an increase in
the HOMO → LUMO energy gap of the luminophore and thus a
higher emission energy.
Additional measurements on the complexes were also con-
ducted at 77 K in an ethanol : chloroform (95 : 5) glass. Each
complex gave a phosphorescence (as determined by time-gated
phosphorimetry); the emission maxima associated with the spectra
are shown in Table 3. In comparison to the pyridyl-based com-
plexes, the quinolyl-based species Au–L5 and Au–L6 gave emission
profiles characterised with vibronic structure (Fig. 4 compares
the 77 K emission profiles of L6 and Au–L6). The profile of L6
1
together with the high energy n(CO) shift and the 31P{ H} data,
these observations suggests that the fluorescence from Au–L1
and Au–L5 is influenced by the electron rich character of the
Fig. 3 Main: excitation and emission spectra for Au–L6 in CHCl3. Inset:
decay profile (t = 6.5 ns).
Fig. 4 Steady state emission spectra recorded at 77 K.
Dalton Trans., 2009, 6836–6842 | 6839
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showed well-resolved vibrational features which are characteristic
of a quinoline-derived phosphorescence,25 whilst AuI coordination
of L6 results in a red-shift of the emission profile together with a
reduction in vibronic definition. These results suggest that at low
temperature the emission from Au–L5 and Au–L6 derives from a
quinoline-based IL 3pp* whereas for the remaining complexes the
emission at 77 K probably originates from phthalimide-centred
excited states.
Experimental
Synthesis of L4, 2-(2-aminoethyl)-N-phthalimido-pyridine
Equimolar quantities of phthalic anhydride (1.98 g, 8.19 ¥ 10-3mol)
and 2-(2-aminoethyl)-pyridine (1.65 g, 8.19 ¥ 10-3mol) were mixed
in a test tube. The mixture was heated to a melt with a hot air
gun with occasional agitation with a glass rod. Moderate heating
was continued until water vapour was produced and condensing
on the test tube wall [note: care must be taken not to overheat
the mixture and decompose the reactants and/or product]. Once
water vapour was no longer evident, heating was stopped and the
molten reaction mixture added to hot ethanol (ca. 50 cm3), filtered,
and the resultant solute allowed to cool to room temperature.
Upon cooling the product precipitated as a white crystalline solid.
Further crops of product were isolated following concentration
of the alcoholic solution and storage at 0 ◦C. The mixture was
filtered and washed with ether to give white crystals (1.44 g, 43%).
IR (solid) n 1704 (CO), 1385, 1062, 1016, 948, 859, 769 cm-1. 1H
Conclusions
This paper discusses a series of AuI complexes of the general
form {Ph3P–Au–(Ln)}(OTf) incorporating a range of pyridyl–
phthalimido and quinolyl–phthalimido ligands. The new ligands
were isolated utilising a solvent-free melt method which can be
applied to a variety of aminopyridines or aminoquinolines. The
complexes were characterised in solution and solid states. X-Ray
crystal structure determinations show that sterically challenged
ligands based on 8-aminoquinoline (L6) can still form stable
complexes with {Ph3P–AuI} via distortions within the ligand and
deviations from linear coordination geometry. In solution the
emission properties of the complexes were assigned to ligand-
centred processes in each case.
3
NMR (400 MHz, CDCl3): dH 3.10 (2H, t, –CH2–, JHH = 7.24
Hz), 4.03 (2H, t, –CH2–, 3JHH = 7.27 Hz), 7.07 (1H, m, py), 7.10
(1H, d, py, 3JHH = 7.27 Hz), 7.50 (1H, m, py), 7.62 (2H, m, phth),
7.74 (2H, m, phth), 8.44 (1H, d, py, 3JHH = 4.15 Hz) ppm. 13C{ H}
1
NMR (100 MHz, CDCl3): dC 37.03, 38.13, 122.03, 123.54, 123.61,
132.41, 134.25, 136.81, 149.84, 158.59, 168.46 ppm. ES MS found
+
m/z 253, calculated m/z 253 for {M + H} .
Synthesis of L6, 8-amino-N-phthalimido-quinoline
General physical measurements
All photophysical data were obtained on a JobinYvon-Horiba
Fluorolog spectrometer fitted with a JY TBX picosecond pho-
todetection module and a Hamamatsu R5509-73 detector (cooled
to -80 ◦C using a C9940 housing). Lifetimes were obtained using
the JY-Horiba FluoroHub single photon counting module in
conjunction with NanoLEDs for 295, 355 or 372 nm pulsed
(1 MHz) output. IR spectra were recorded on an ATR equipped
Varian 7000 FT-IR. Mass spectra on the ligands were obtained
using a Bruker MicroTOF LC. UV-Vis spectra were recorded using
a Jasco 630 UV-visible spectrophotometer.
The title compound was prepared as for L4 but using 8-
aminoquinoline (0.5 g, 3.47 ¥ 10-3mol) and phthalic anhydride
(0.51 g, 3.47 ¥ 10-3mol). Yield of sandy brown crystals (0.29 g,
29%). IR (solid) n 1707 (CO), 1499, 1465, 1394, 1375, 1109, 1088,
1
1069, 877, 822, 781, 757 cm-1. H NMR (250 MHz, CDCl3): dH
7.35 (1H, m, quin), 7.59 (2H, m, phth), 7.69 (2H, m, phth), 7.86
(1H, m, quin), 7.90 (2H, m, quin), 8.14 (1H, m, quin), 8.77 (1H, m,
1
quin) ppm. 13C{ H} NMR (89 MHz, CDCl3): dC 122.36, 124.29,
126.58, 129.71, 130.11, 130.18, 130.68, 132.81, 134.66, 136.65,
144.68, 151.37, 168.42 ppm. ES MS found m/z 275, calculated
+
m/z 275 for {M + H} .
Crystallography†
General procedure for complexes
Data collection and processing
CH2Cl2 (5 mL) was degassed by bubbling N2 for 10 min and then
cooled to 0 ◦C in an ice bath. To this was added AuPPh3Cl (0.05 g,
1.01 ¥ 10-4 mol) and AgOTf (1.1 eq., 0.03 g, 1.1 ¥ 10-4 mol) and the
mixture allowed to stir for 10 min. L2 (0.024 g, 1.01 ¥ 10-4 mol) was
then added slowly to the reaction mixture. The reaction was stirred
in the absence of light for a further 2 h. The reaction mixture was
filtered through Celite to remove AgCl and the solvent removed
in vacuo. The product was recrystallised by vapour diffusion of
diethyl ether into CHCl3 to yield the product [Au(PPh3)L2](OTf)
as white crystals. Yield: 0.071 g, 84%. IR (solid) n 1710 (CO),
1431, 1391, 1255, 1143, 1100, 1023 cm-1. UV-vis (CHCl3) lmax
(e/M-1cm-1) 247 (27 710), 268 (12 050), 295 (4700) nm. 1H NMR
(400 MHz, CDCl3): dH 8.75 (1H, d, 3JHH = 6 Hz, py–ArH), 8.70
(1H, s, py–ArH), 8.00 (1H, m, py–ArH), 7.80 (2H, m, AA¢ part
of AA¢XX¢ system, th–ArH), 7.70 (2H, m, XX¢ part of AA¢XX¢
system, th–ArH), 7.65–7.60 (1H, m, py–ArH), 7.55–7.40 (15H, m,
Diffraction data for L3, L4, L6 (100 K) and Au–L1 (150 K)
were collected on a Bruker KAPPA APEX 2 using graphite-
˚
monochromated Mo Ka radiation (k = 0.71073 A). Software
package Apex 2 (v2.1) was used for the data integration, scaling
and absorption correction. Au–L3 and Au–L6 were collected on
a Nonius KappaCCD using graphite-monochromated Mo Ka
˚
radiation (k = 0.71073 A) at 150 K.
Structure analysis and refinement
The structure was solved by direct methods using SHELXS-97
and was completed by iterative cycles of DF-syntheses and full-
matrix least squares refinement. All non-H atoms were refined
anisotropically and difference Fourier syntheses were employed in
positioning idealised hydrogen atoms and were allowed to ride on
their parent C-atoms. All refinements were against F2 and used
SHELX-97.26
1
PPh3), 4.85 (2H, s, CH2). 31P{ H} NMR (162 MHz, CDCl3): dP
29.06. MS (MALDI) m/z 697 (M - OTf).
6840 | Dalton Trans., 2009, 6836–6842
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76%. IR (solid) n 1713 (CO), 1252, 1153, 1097, 1026, 846 cm-1.
UV-vis (CHCl3) lmax (e/M-1 cm-1) 246 (27 740), 270 (12 600), 289
(9540), 307 (6370) nm. 1H NMR (400 MHz, CDCl3): dH 9.35–9.30
(1H, br, qu–ArH), 8.60–8.50 (1H, br, qu–ArH), 8.15–8.10 (1H,
br, qu–ArH), 8.00–7.95 (1H, br, qu–ArH), 7.80–7.70 (1H, br, qu–
ArH), 7.6–7.1 (20H, br-m, PPh3, 4 ¥ th–ArH and 1 ¥ py–ArH).
{Au(PPh3)L1}OTf. The reaction was performed as for L2
except using 0.022 g (1.01 ¥ 10-4 mol) of L1. The product was
recrystallised by vapour diffusion of diethyl ether into CHCl3 to
yield [Au(PPh3)L1](OTf) as white crystals. Yield: 0.062 g, 74%. IR
(solid) n 1713 (CO), 1484, 1428, 1366, 1261, 1143, 1094, 1023,
877 cm-1. UV-vis (CHCl3) lmax (e/M-1 cm-1) 252 (21 060), 271
1
31P{ H} NMR (162 MHz, CDCl3): dP 29.96. MS (MALDI) m/z
1
(12 620), 294 (6610) nm. H NMR (400 MHz, CDCl3): dH 9.00
3
733 (M - OTf).
(1H, d, JHH = 5 Hz, py–ArH), 8.95 (1H, s, py–ArH), 8.30 (1H,
d, 3JHH = 8 Hz, py–ArH), 7.95–7.90 (2H, m, AA¢ part of AA¢XX¢
system, th–ArH), 7.80–7.75 (2H, m, XX¢ part of AA¢XX¢ system,
th–ArH), 7.60–7.40 (15H, m, PPh3), 7.1 (1H, m, py–ArH). 31P
Acknowledgements
1
{ H} NMR (162 MHz, CDCl3): dP 29.48. MS (MALDI) m/z 683
We thank the Universities of Cardiff and Sheffield together with
the EPSRC for financial support. Johnson Matthey PLC are
thanked for the generous loan of hydrogen tetrachloroaurate(III).
We also thank the EPSRC Mass Spectrometry National Service
at the University of Swansea. S. J. A. P. additionally thanks
Prof. Michael D. Ward (Sheffield) for granting access to X-ray
diffraction facilities.
(M - OTf).
{Au(PPh3)L3}OTf. The reaction was performed as for L2
except using 0.024 g, (1.01 ¥ 10-4 mol) of the ligand, L3. The
product was recrystallised by vapour diffusion of diethyl ether into
CHCl3 to yield [Au(PPh3)L3](OTf) as white crystals. Yield: 0.051 g,
60%. IR (solid) n 1710 (CO), 1258, 1159, 1100, 1029, 933 cm-1.
UV-vis (CHCl3) lmax (e/M-1 cm-1) 246 (18 600), 294 (3980) nm. 1H
NMR (400 MHz, CDCl3): dH 9.60 (2H, d, 3JHH = 6 Hz, py–ArH),
7.85–7.80 (2H, m, AA¢ part of AA¢XX¢ system, th–ArH), 7.75–
7.70 (2H, m, XX¢ part of AA¢XX¢ system, th–ArH), 7.60–7.40
Notes and references
1 R. C. Evans, P. Douglas and C. J. Winscom, Coord. Chem. Rev., 2006,
250, 2093.
1
(17H, m, PPh3 and 2 ¥ py–ArH), 4.80 (2H, s, CH2). 31P{ H}
2 (a) V. W. W. Yam and E. C. C. Cheng, Chem. Soc. Rev., 2008, 37, 1806;
(b) M. C. Lagunas, C. M. Fierro, A. Pintado-Alba, H. de la Riva and
S. Betanzos-Lara, Gold Bull., 2007, 40, 135; (c) V. W. W. Yam, C. L.
Chan, C. K. Li and K. M. C. Wong, Coord. Chem. Rev., 2001, 216, 173.
3 (a) Q. M. Wang, Y. A. Lee, O. Crespo, J. Deaton, C. Tang, H. J.
Gysling, M. C. Gimeno, C. Larraz, M. D. Villacampa, A. Laguna
and R. Eisenberg, J. Am. Chem. Soc., 2004, 126, 9488; (b) Y. A. Lee
and R. Eisenberg, J. Am. Chem. Soc., 2003, 125, 7778; (c) M. J. Katz,
T. Ramnial, H. Z. Yu and D. B. Leznoff, J. Am. Chem. Soc., 2008, 130,
10662.
4 (a) W. F. Kean, L. Hart and W. W. Buchanan, Br. J. Rheumatol., 1997,
36, 560; (b) J. Tulib, J. L. Beck and S. F. Ralph, J. Biol. Inorg. Chem.,
2006, 11, 559; (c) P. C. A. Bruijincx and P. J. Sadler, Curr. Opin. Chem.
Biol., 2008, 12, 197.
5 M. J. McKeage, S. J. Berners-Price, P. Galettis, R. J. Bowen, W. Brouwer,
L. Ding, L. Zhuang and B. C. Baguley, Cancer Chemother. Pharmacol.,
2000, 46, 343.
6 (a) M. V. Baker, P. J. Barnard, S. J. Berners-Price, S. K. Brayshaw, J. L.
Hickey, B. W. Skelton and A. H. White, Dalton Trans., 2006, 3708;
(b) M. J. McKeage, L. Maharaj and S. J. Berners-Price, Coord. Chem.
Rev., 2002, 232, 127.
7 J. Talib, J. L. Beck and S. F. Ralph, J. Biol. Inorg. Chem., 2006, 11, 559.
8 J. Stra¨hle, in Gold, Progress in Chemistry, Biochemistry and Technology,
ed. H. Schmidbaur, Wiley, Chichester, 1999.
9 (a) S. E. Thwaite, A. Schier and H. Schmidbaur, Inorg. Chim. Acta,
2004, 357, 1549; (b) J. D. E. T. Wilton-Ely, A. Schier, N. W. Mitzel,
S. Nogai and H. Schmidbaur, J. Organometal. Chem., 2002, 643–644,
313.
10 (a) E. J. Fernandez, A. Laguna, J. M. Lopez-de-Luzuriaga, M. Monge,
M. Montiel, M. E. Olmos, J. Perez and M. Rodriguez-Castillo, Gold
Bull., 2007, 40, 172; (b) J. C. Y. Lin, S. S. Tang, C. Sekhar Vasam,
W. C. You, T. W. Ho, C. H. Huang, B. J. Sun, C. Y. Huang, C. S. Lee,
W. S. Hwang, A. H. H. Chang and I. J. B. Lin, Inorg. Chem., 2008, 47,
2543; (c) J. H. K. Yip, R. Feng and J. J. Vittal, Inorg. Chem., 1999, 38,
3586; (d) M. Munakata, S.-G. Yan, M. Maekawa, M. Akiyama and S.
Kitagawa, J. Chem. Soc., Dalton Trans., 1997, 4257.
NMR (162 MHz, CDCl3): dP 28.31. MS (MALDI) m/z 697
(M - OTf).
{Au(PPh3)L4}OTf. The reaction was performed as for L2
except using 0.025 g (1.01 ¥ 10-4 mol) of the ligand, L4. The product
was recrystallised by vapour diffusion of diethyl ether into CHCl3
to yield [Au(PPh3)L4]OTf as white crystals. Yield: 0.042 g, 49%.
IR (solid) n 1710 (CO), 1434, 1397, 1261, 1146, 1100, 1026 cm-1.
UV-vis (CHCl3) lmax (e/M-1 cm-1) 246 (34 130), 268 (16 800), 281
(9280), 294 (6520) nm. 1H NMR (400 MHz, CDCl3): dH 8.50 (1H,
d, 3JHH = 5 Hz, py–ArH), 7.75 (1H, m, py–ArH), 7.70–7.66 (2H,
m, AA¢ part of AA¢XX¢ system, th–ArH), 7.64–7.60 (2H, m, XX¢
part of AA¢XX¢ system, th–ArH), 7.55–7.30 (17H, br, PPh3 and
2 ¥ py–ArH), 3.4 (2H, b, –CH2), 4.11 (2H, t, –CH2–, 3JHH = 6.39
1
Hz). 31P{ H} NMR (162 MHz, CDCl3): dP 28.29. MS (MALDI)
m/z 711(M - OTf).
{Au(PPh3)L5}OTf. The reaction was performed as per L2
except using 0.030 g, (1.01 ¥ 10-4 mol) of the ligand, L5. The
product was recrystallised by vapour diffusion of diethyl ether
into CHCl3 to yield [Au(PPh3)L3]OTf as white crystals. Yield:
0.078 g, 88%. IR (solid) n 1719 (CO), 1369, 1258, 1150, 1100,
1026, 874 cm-1. UV-vis (CHCl3) lmax (e/M-1 cm-1) 255 (40 450),
1
295 (12 050), 317 (10 000) nm. H NMR (400 MHz, CDCl3): dH
3
3
9.50 (1H, d, JHH = 2 Hz, qu–ArH), 8.70 (1H, d, JHH = 2 Hz,
qu–ArH), 8.50 (1H, d, 3JHH = 8 Hz, qu–ArH), 8.05 (1H, m, qu–
ArH), 8.00–7.95 (1H, m, qu–ArH), 7.95–7.90 (2H, m, AA¢ part of
AA¢XX¢ system, th–ArH), 7.80–7.75 (2H, m, XX¢ part of AA¢XX¢
system, th–ArH), 7.7 (1H, s, py–ArH), 7.60–7.40 (15H, m, PPh3).
11 C. Yang, M. Messerschmidt, P. Coopens and M. A. Omary, Inorg.
Chem., 2006, 45, 6592.
1
31P{ H} NMR (162 MHz, CDCl3): dP 29.23. MS (MALDI) found
12 (a) R. H. Uang, C. K. Chan, S. M. Peng and C. M. Che, J. Chem. Soc.,
Chem. Commun., 1994, 2561; (b) W. H. Chan, K. K. Ceung, T. C. W.
Mak and C. M. Che, J. Chem. Soc., Dalton Trans., 1998, 873.
13 (a) J. Schneider, Y.-A. Lee, J. Perez, W. W. Brennessel, C. Flaschenriem
and R. Eisenberg, Inorg. Chem., 2008, 47, 957; (b) S. J. Hu, K. M. Hsu,
M. K. Leong and I. J. B. Lin, Dalton Trans., 2008, 1924.
14 P. Ovejero, M. J. Mayoral, M. Cano and M. C. Lagunas, J. Organometal.
Chem., 2007, 692, 1690.
m/z 733 (M - OTf).
{Au(PPh3)L6}OTf. The reaction was performed as per L2
except using 0.028 g, (1.01 ¥ 10-4 mol) of the ligand, L6. The
product was recrystallised by vapour diffusion of diethyl ether into
CHCl3 to yield [Au(PPh3)L6]OTf as white crystals. Yield: 0.068 g,
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15 P. Lange, A. Schier, J. Riede and H. Schmidbaur, Z. Naturforsch.
B. J. Chem. Sci., 1994, 49, 642.
16 M. A. Cinellu, L. Maiore, A. Schier, H. Schmidbaur and D. Rossi,
Z. Naturforsch. B. J. Chem. Sci., 2008, 63, 1027.
21 E. A. Carswell, I. J. Old, R. L. Kassel, S. Green, N. Foire and B.
Williamson, Proc. Natl. Acad. Sci. USA, 1975, 72, 3666.
22 R. Uson, A. Laguna and J. Vicente, J. Organomet. Chem., 1977, 131,
471.
17 A. Grohmann, J. Riede and H. Schmidbaur, Z. Naturforsch. B. J. Chem.
Sci., 1992, 47, 1255.
23 V. G. Albano, L. Busetto, M. C. Cassani, P. Sabatino, A. Schmitz and
V. Zanotti, J. Chem. Soc., Dalton Trans., 1995, 2087.
24 P. G. Jones and A. F. Williams, J. Chem. Soc., Dalton Trans., 1977,
1430.
25 S. Quici, M. Cavazzini, M. C. Raffo, M. Botta, G. B. Giovenzana, B.
Ventura, G. Accorsi and F. Barigelletti, Inorg. Chim. Acta, 2007, 360,
2529.
18 F. L. Thorp-Greenwood, M. P. Coogan, A. J. Hallett, R. H. Laye and
S. J. A. Pope, J. Organometal. Chem., 2009, 694, 1400.
19 S. M. McHugh and T. L. Rowland, Clin. Exp. Immun., 1997, 110, 151.
20 (a) X. Collin, J.-M. Robert, G. Wielgosz, G. Le Baut, C. Bobin-
Dubigeon, N. Grimaud and J.-Y. Petit, Eur. J. Med. Chem., 2001, 36,
639; (b) R. G. R. Bacon and A. Karin, J. Chem. Soc., Perkin Trans.,
1973, 1, 278.
26 SHELXL-PC Package, Bruker Analytical X-ray Systems, Madison,
WI, 1998.
6842 | Dalton Trans., 2009, 6836–6842
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The Royal Society of Chemistry 2009
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