Gold(I)-isocyanide and gold(I)-carbene complexes as substrates for the laser decoration of gold onto ceramic surfaces

Article abstract of DOI:10.1039/b617347k

Gold-isocyanide complexes XAu(RNC) (X = halide, pseudohalide, R = alkyl, aryl) and water soluble gold-carbene complexes XAuC(NHPh)[MeN(CH ₂CH₂O)_nMe] (X = Cl, n = 1-11) have been prepared and evaluated as substrates for the direct laser writing of gold decoration onto ceramics. The Royal Society of Chemistry 2007.

Full text of DOI:10.1039/b617347k

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PAPER
www.rsc.org/dalton | Dalton Transactions
Gold(I)–isocyanide and gold(I)–carbene complexes as substrates for the laser
decoration of gold onto ceramic surfaces†
Robert Heathcote,a James A. S. Howell,*b Nicola Jennings,b David Cartlidge,c Lisa Cobden,c Simon Colesd and
Michael Hursthoused
Received 28th November 2006, Accepted 24th January 2007
First published as an Advance Article on the web 14th February 2007
DOI: 10.1039/b617347k
Gold–isocyanide complexes XAu(RNC) (X = halide, pseudohalide, R = alkyl, aryl) and water soluble
gold–carbene complexes XAuC(NHPh)[MeN(CH2CH2O)nMe] (X = Cl, n = 1–11) have been prepared
and evaluated as substrates for the direct laser writing of gold decoration onto ceramics.
measured relative to tetramethylsilane (TMS) and calibrated
Introduction
against the residual solvent resonance. Infrared spectra were
The chemistry of gold has enjoyed a renaissance over the
recorded on a Thermo Nicolet FT-IR spectrometer. MALDI
last decade or so due to developing interests in areas as di-
(matrix assisted laser desorption ionisation) spectra were ob-
tained on a Voyager-DE-STR instrument using trans-2-[3-(4-tert-
verse as luminescent1a,b and nonlinear optical properties,2a,b drug
therapy,3a,b and homogeneous4 and heterogeneous catalysis.5a,b
butylphenyl)-2-methylprop-2-enylidene]malononitrile (DCTB) as
Another area of gold chemistry with a much longer history is that
the matrix material. TGA/DSC studies were performed on a
of gold decoration of ceramics and glass.6 Developed in the 19th
Rheometric Scientific STA 1500 instrument. Surface profilometry
century, the method still used today involves application of a gold
was performed using a Planar Products SF200 Surfometer.
sulforesinate dissolved in an organic solvent mixture, followed by
FESEM (field emission scanning electron microscopy) pho-
firing. The problems of dealing with volatile organic compounds
tographs were obtained using an XTEK HMXST 225 instrument.
during both application and firing, together with wastage of wares
Tetrahydrofuran and diethyl ether were distilled from sodium
due to failure during the firing stage has stimulated the search for
wire and dichloromethane was distilled from CaH2. Isocyanides
alternative procedures, amongst them MOCVD (metal–organic
were prepared following literature procedures and distilled before
use.9a–d (Me2S)AuCl was prepared using a literature procedure.10
The polyethylene glycol monomethyl ethers HO(CH2CH2O)nMe
(n = 1, 2, 3, 5 and 11 3a–d,f) were obtained commercially. The
n = 9 compound 3e was prepared by chain extension through the
reaction of Me(OCH2CH2)7OSO2C6H4Me-p 4e with the sodium
chemical vapour deposition). Whilst gold may be deposited by
conventional MOCVD or laser induced MOCVD, these tech-
niques have not been widely applied because of the instability and
low synthetic yields of the most common precursor Me2Au(acac).7
Hence gold films required for electronic applications are produced
mainly by plating or sputtering methods.8a,b
We wish to report here on the preparation and use of gold(I)–
isocyanide and gold(I)–carbene complexes as substrates for the
laser writing of gold patterns on ceramic surfaces, thus eliminat-
ing the need for final firing. Furthermore, the gold(I)–carbene
complexes which have been developed exhibit sufficient water
solubility for use in laser writing, thus eliminating the need for
organic solvents.
R
R
alkoxide derived from diethylene glycol.11 Wetꢀ and Foamexꢀ
products were obtained from Goldschmidt UK Limited (Tego
House, Chippenham Drive, Milton Keynes, UK MK10 0AF).
R
Epolightꢀ 2340 was obtained from Epolin Limited (358–364
Adams Street, Newark, New Jersey 07105, USA). ITA 324 was
obtained from Emery Colours Limited (Podmore Street, Burslem,
Stoke-on-Trent, UK ST6 2EZ).
A. Synthesis of (MeNC)AuCl 2a12
Experimental
MeNC (0.7 ml) in dichloromethane (10 ml) was added drop-
wise to a suspension of (Me2S)AuCl (2.00 g, 6.80 mmol) in
dichloromethane (50 ml) under nitrogen and maintained at room
temperature in the absence of light with stirring for 4 h. After
overnight refigeration, the product was filtered off and washed
with petroleum ether (bp 40–60 ◦C) and to give (MeNC)AuCl 2a
(1.65 g, 89%) as a white solid. Other (isocyanide)AuCl complexes
were prepared in the same way. A full listing of characterisation
data is given in the ESI.†
NMR spectra were recorded using a Bruker DPX300 spectrometer
at 298 K (1H, 300 MHz; 13C, 75 MHz). Chemical shifts were
aErigal Limited, Keele University Science Park, Keele, Staffordshire, UK
ST5 5BX
bSchool of Physical and Geographical Sciences, Lennard Jones Labo-
ratories, Keele University, Keele, Staffordshire, UK ST5 5BG. E-mail:
j.a.s.howell@keele.ac.uk; Fax: +44 (0)1782 712378; Tel: +44 (0)1782
583041
cCERAM, Queens Road, Penkhull, Stoke-on-Trent, Staffordshire, UK ST4
7LP
B. Synthesis of (MeNC)AuBr 2b12
dSchool of Chemistry, University of Southampton, Highfield, Southampton,
UK SO17 1BJ
(MeNC)AuCl (0.5 g, 1.83 mmol) was suspended in
dichloromethane (25 ml). With stirring, KBr (0.218 g, 1.83 mmol)
dissolved in water (25 ml) was added and the biphasic system was
† Electronic supplementary information (ESI) available: Characterising
data for 4a–4g, 5a–5f, 6a–f, 2a–o and 7. See DOI: 10.1039/b617347k
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stirred for 3 h. The organic phase was separated and washed with
water. After removal of solvent, the residue was recrystallised
from CHCl3–petroleum ether (bp 40–60 ◦C) to give (MeNC)AuBr
2b as a white solid (0.489 g, 84%). Other halide and pseudohalide
compounds were prepared from the analogous chloride in the
same way. A full listing of characterisation data is given in the
ESI.†
The compounds XAuC(NHPh)[MeN(CH2CH2O)nMe] (X = Cl,
n = 2, 3, 5, 9, 11; X = Br, n = 5) 6b–g were isolated as yellow oils
after purification by chromatography on silica gel 60 PF254 (98 :
2 chloroform–methanol eluent). A full listing of characterisation
data is given in the ESI.†
G. Synthesis and crystal structure of
{(NCS)AuC(NHMe)(NEt2)}2 7
C. Synthesis of Me(OCH2CH2)nSO3C6H4Me-p (n = 1–3) 4a–c13
To a solution of MeOCH2CH2OH 3a (4.3 ml, 60 mmol) in pyridine
(NCS)Au(MeNC) 2d (100 mg, 0.34 mmol) was dissolved in
CH2Cl2 (20 ml) and HNEt2 (0.3 ml, 2.3 mmol) was added dropwise.
After stirring for 4 h, the solvent and excess HNEt2 were removed
under vacuum. The residual white solid was recrystallised from
petroleum ether (bp 40–60 ◦C) to give 7 (95 mg, 78%, mp 109–
◦
(9.7 ml, 120 mmol) at 0 C was added p-C6H4MeSO3Cl (12.5 g,
66 mmol). The reaction mixture was left to stir at 0 ◦C for 3.5 h.
Toluene (100 ml) and 10% HCl (100 ml) were added. After drying
the organic layer with MgSO4, the solvent was removed from
the organic layer to yield MeOCH2CH2OSO3C6H4Me-p 4a as a
colourless oil (13.9 g, 100%). Compounds 4b, 4c (n = 2, 3) were
prepared as viscous liquids in a similar fashion. A full listing of
characterisation data is given in the ESI.†
◦
110 C). CHN calculated C 22.8%, H 3.82%, N 11.4%; found C
23.1%, H 3.65%, N 11.2%. NMR and IR data are given in the ESI.†
X-Ray diffraction data for 7 were collected by means of combined
phi and omega scans on a Bruker-Nonius KappaCCD area
detector situated at the window of a rotating anode (k Mo-Ka =
˚
0.71073 A). The structure was solved by direct methods, refined by
full matrix least squares on F2 and corrected for absorption effects.
Hydrogen atoms were included in the refinement, but thermal
parameters and geometry were constrained to ride on the atom to
which they are bonded.
D. Synthesis of Me(OCH2CH2)nSO3C6H4Me-p (n = 5, 7, 9, 11)
4d–g14
Sodium hydroxide (7.8 g, 196.0 mmol) in water (40 ml) and PEG
550 (for 4g) (38.0 g, 70.0 mmol) in THF (40 ml) were cooled
in an ice–water bath with stirring and p-C6H4MeSO3Cl (24.0 g,
126.0 mmol) in THF (40 ml) was added dropwise over 2 h. The
reaction mixture was stirred for an additional 2 h at 5 ◦C, poured
into ice–water (100 ml) and extracted with dichloromethane (2 ×
50 ml). The combined organic extracts were washed with water
(2 × 50 ml) and saturated sodium chloride (1 × 50 ml), dried with
MgSO4 and the solvent removed in vacuo to yield 4g as a colourless
oil (40.7 g, 99%). Compounds 4d–f were prepared similarly. A full
listing of characterisation data is given in the ESI.†
Crystal data for 7: C14H28Au2N6S2, monoclinic, P21/n, a =
◦
˚
7.1104(6), b = 7.5366(6), c = 19.7004(15) A, b = 96.569(5) ,
3
−3
˚
T = 150 K, U = 1048.78(15) A , Z = 2, Dc = 2.338 Mg m ,
l = 14.180 mm−1, hmax = 25.02◦, 3311 measured, 1635 unique
(Rint = 0.0661) and 1213 (I >2r(I)) reflections, R1 (obs) = 0.0469
−3
˚
and wR2 (all data) = 0.1125, qmax/qmin = 2.154/−2.084 e A .
CCDC reference number 629185.
For crystallographic data in CIF or other electronic format see
DOI: 10.1039/b617347k
H. Adhesion testing to European Standard (part 4 of EN 12875)
E. Synthesis of Me(OCH2CH2)nNHMe (n = 1, 2, 3, 5, 9, 11)
The gold film was immersed in a static solution of a specified
alkaline dishwashing detergent (containing phosphate as given in
IEC (International Electrotechnical Commission), amendment 3)
at 75 ◦C for 8 h (roughly equivalent to 75 dishwasher cycles).
(Precious metal decorations are generally quite susceptible to
damage during this test due to the softness of gold and attack
at the bonded ceramic surface leading to peeling.) The film was
then removed, washed and rubbed dry. The samples were then
examined visibly in comparison to starting samples. For optimised
films, there was little or no deterioration in film colourisation.
5a–f11
Compound 4a (4.73 g, 21.88 mmol) was dissolved in 33% methy-
◦
lamine in ethanol (8.9 ml) and refluxed for 23 h at 74 C. After
evaporation of the solvent, the resultant residue was dissolved in
5% HCl (6 ml) and extracted with chloroform (3 × 10 ml). The
chloroform extracts were washed separately with 5% HCl (2 ×
8 ml) and all the HCl extracts were combined, made basic with
30% sodium hydroxide (5 ml) and extracted with chloroform (3 ×
15 ml). The chloroform extracts were washed separately with water
(5 ml) and the solvent was removed in vacuo to yield 5a as a pale
yellow oil (1.4 g, 72%). Compounds 5b–f were prepared similarly.
A full listing of characterisation data is given in the ESI.†
Results and discussion
A. Synthesis and characterisation of (RNC)AuX complexes
F. Synthesis of XAuC(NHPh)[MeN(CH2CH2O)nMe] (X = Cl,
n = 1)15
As RAu(CNMe) complexes (R = Me, CF3, C2Rꢀ) have previously
been shown to be useful precursors for conventional MOCVD,16a,b
a variety of LAuX (L = isocyanide, X = halide, pseudohalide)
compounds 2a–n (Table 1) were prepared using ligand exchange
of (Me2S)AuCl 1 followed (if necessary) by metathesis of LAuCl
with the appropriate potassium halide or pseudohalide.
The thermal stability and decomposition pathway for the
XAu(RNC) comlpexes have been studied by TGA/DSC (Fig. 1).
The majority of the isocyanide complexes [together with
Compound 5a (1.18 g, 13.24 mmol) was added to ClAu(PhNC) 2n
(0.500 g, 1.49 mmol) in CH2Cl2 (100 ml) and the reaction mixture
was stirred for 3 h at room temperature under N2. The solvent
was then removed to give a residue which was recrystallised from
CH2Cl2–hexane (1 : 1) to yield 6a as white crystals (0.20 g, 45%,
◦
mp 127–129 C). CHN calculated C 31.1%, H 3.79%, N 6.59%;
found C 30.9%, H 3.90%, N 6.46%.
1310 | Dalton Trans., 2007, 1309–1315
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Table 1 Melting point and decomposition temperature data
Ligand
X
Melting point/◦C
Decomposition temperature/◦C
a
2a
2b
2c
2d
MeNC
MeNC
MeNC
MeNC
Cl
Br
I
210–290
220–290
175–220
(a) 190–210
(b) 210–500
193–290
204
175
149
SCN
2e
2f
2g
EtNC
EtNC
tBuNC
Cl
I
Cl
119
73
175–230
a
(a) 160–200
(b) 210–240
120–180
2h
2a
2j
tBuNC
cyclohexylNC
cyclohexylNC
I
Cl
I
92
136
60
200–290
(a) 190–210
(b) 210–310
270–310
(a) 290–350
(b) 350–550
(a) 200–250
(b) 250–500
210–290
290–340
110–160
140–350
120–250
90–260
260–350
120–320
120–290
(a) 190–220
(b) 230–290
2k
2l
2,6-Me2C6H3NC
2,6-Me2C6H3NC
Cl
Br
142
134
2m
2,6-Me2C6H3NC
I
157
181
2m
2o
C6H5NC
PMe3
Me2S
C(NHPh)[MeNCH2CH2OMe]
C(NHPh)[MeN(CH2CH2O)2Me
C(NHPh)[MeN(CH2CH2O)3Me
C(NHPh)[MeN(CH2CH2O)5Me
C(NHPh)[MeN(CH2CH2O)9Me
C(NHPh)[MeN(CH2CH2O)11Me
—
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
—
215
a
2p
6a
132
6b
Liquid
Liquid
Liquid
Liquid
6c
6d
6e
6f
Liquid
a
AuCl
a Decomposes before melting.
ClAu(Me2S) and ClAu(PMe3) for comparison] decompose after
melting in a single stage endothermic process corresponding to:
B. Synthesis, solubility and thermal stability of water soluble
XAuC(NHPh)(MeNR) complexes
(RNC)AuX → Au + RNC + 0.5 X2
Water solubility in molecular gold(I) complexes has previously
been imparted through the use of ionisable or solubilising groups
in complexed ligands such as phosphines19a–c or (mimicking gold
sulforesinates) through the introduction of ionisable groups into
the thiolate residue of Au–SR complexes.20a–c We have chosen to
use the well documented solubilising effect of poly(oxyethylene)
chains to impart water solubilty through reaction of the
functionalised secondary amine series HMeN(CH2CH2O)nMe
AuCl decomposes initially to an AuCl/AuCl3 eutectic mixture of
composition AuCl1.5 which then undergoes further decomposition
to gold:17
2 AuCl → AuCl1.5 + 0.25 Cl2 + Au
AuCl1.5 → Au + 0.75 Cl2
5a–f with (PhNC)AuX (X
the carbene series XAuC(NHPh)[MeN(CH2CH2O)nMe] 6a–g
(Scheme 1).
=
Cl, Br) 2n,o to give
Decomposition of the ClAu(RNC) complexes occurs at a temper-
ature very similar to the decomposition temperature of AuCl and
therefore it is not possible to determine whether loss of isocyanide
precedes or follows elimination of chlorine. Analysis of volatile
products by pyrolysis-GC/MS shows the presence of C6H5NC
and C6H5CN in a ratio of 5 : 1,18 together with a small amount
of phenylcarbonimidic acid chloride (C6H5NCCl2). The broad
decomposition process from 200–600 ◦C for (NCS)Au(MeNC)
corresponds to decomposition of poly(thiocyanogen) which may
be observed as an orange solid in the platinum crucible. Residual
weights of gold are within 5% of calculated values.
For the alkyl isocyanide series, the decomposition temperatures
and melting points increase in the order I < Br < Cl and in the
order Bu < Et < Me. For the aryl isocyanide series, both the
melting points and decomposition temperatures are much higher.
Laser deposition work was carried out mostly with ClAu(2,6-
Me2C6H3NC) as it exhibits the longest liquid range (140–270 ◦C)
of all the precursors studied.
Whereas 6a–c were prepared from monomethyl ethers
containing single chain lengths (n = 1, 2, 3), compounds
6d–g (n = 5, 9 and 11) were prepared from monomethyl
ethers 3d–f containing a mixture of chain lengths averaging
approximately to
n
=
5, 9 and 11 respectively. These
compounds were best characterised through their MALDI
spectra which exhibit abundant [Au(carbene)2]+ ions arising from
ionisation/desorption in the MALDI matrix. Thus the MALDI
spectrum of HMeN(CH2CH2O)9Me 5e exhibits peaks of varying
intensity corresponding to the range of chain lengths n = 5 to
n = 13 (Fig. 2). The MALDI spectrum of the gold complex
ClAuC(NHPh)(MeN(CH2CH2O)9Me) 6e prepared from 5e
shows twelve of the fifteen peaks expected for ions of composition
{AuC(NHPh)(MeN(CH2CH2O)n1 Me)}{C(NHPh)(MeN(CH2CH2-
t
O)n Me})]+ where n1 + n2 = 10 to 26. Other carbene complexes
2
exhibit similar MALDI spectra.
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Scheme
1
Synthesis
of
XAuC(NHPh)[MeN(CH2CH2O)nMe]
compounds.
Fig. 1 TGA/DSC Traces for (a) ClAuC(NHPh)(MeNCH2CH2OMe), (b)
AuCl and (c) BrAu(MeNC).
Except for 6a, all of the gold–carbene complexes were isolated
as oils which could not be crystallised. 13C NMR spectra of 6a–g
all show two Au–C carbene resonances of approximately equal
intensity in the range 185–195 ppm assignable to two of the four
possible conformational isomers I–IV (Scheme 2). Though not
interconverting fast enough to average NMR resonances, the
Fig.
2
MALDI Spectra of (a) MeHN(CH2CH2O)9Me and (b)
ClAuC[(NHPh)(MeN(CH2CH2O)9Me].
1312 | Dalton Trans., 2007, 1309–1315
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Scheme 2 Conformation isomerism in ClAuC(NHPh)(MeNR) com-
plexes.
Fig. 4 Water solubility of XAuC(NHC6H5)[MeN(CH2CH2O)nMe] com-
plexes as a function of chain length.
rate of interconversion is sufficiently fast to preclude chemical
separation by chromatography. We have, however, characterised
the solid state structure of (CNS)AuC(NHMe)(NEt2) 7 prepared
from the reaction of (NCS)Au(CNMe) with HNEt2 (Fig. 3).
laser writing work due to its greater water solubility and high
preparative yield.
C. Laser writing using gold–isocyanide and gold–carbene
complexes22
1
In solution, this complex exhibits a single H N–H resonance
consistent with the presence of only one conformer, shown to
be I. The methyl groups of the ethyl substituents are oriented
perpendicular to the Au–C2N2N3 plane, thus minimising their
steric influence. Thus, in solution, we assign the doubling of many
NMR resonances for 6a–g to the presence of an approximately
equal population of conformers I and II. The solid state structure
of 7 also demonstrates the weak aurophilic interaction present in
many AuI compounds of this type.21a–g
A schematic diagram of the laser writing process is shown in Fig. 5.
As all the gold precursors are transparent at 1064 nm (continuous
wave Nd:YAG), an absorption enhancer (finely divided SiO2) was
used.23 Decomposition of the gold precursor is thus photothermal,
involving photochemical absorption by the enhancer followed by
transfer of heat energy to cause thermal decomposition of the
organogold compound. Movement of the beam head is software
controlled; the key variables are power output (up to 5 W) and
writing speed (up to 25 cm s−1) and the hatch spacing. The nominal
beam width at the focal point is 50 lm. Compounds 2k and 6f
were chosen for most trials because of their high synthetic yield;
however, other complexes in both the isocyanide and carbene series
give similar deposition results. The quality of the metal film (colour
Fig. 3 Molecular structure of {(CNS)AuC(NHMe)(NEt2)}2.
Pyrolysis-GC/MS and TGA/DSC studies of 6a (Fig. 1) also
show the production of a mixture of C6H5NC and C6H5CN, thus
indicating that the primary step in the decomposition of the gold–
carbene complexes is elimination of HMeN(CH2CH2O)nMe. The
residual weights of gold obtained are again within 5% of the
calculated values.
A plot of water solubility as a function of chain length (Fig. 4)
shows an initial sharp increase in solubility (n = 2–5) followed
by a levelling off towards higher chain lengths (n = 9, 11). The
solubility of the bromo analogue where n = 11 is almost identical
to that of the chloride. Compound 6f was chosen for most of the
Fig. 5 Schematic diagram of the laser writing process.
Dalton Trans., 2007, 1309–1315 | 1313
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Table 2 Optimised conditions for gold deposition
Parameter
XAu(CNR) complexes
ClAuC(NHPh)[MeN(CH2CH2O)nMe] complexes
Medium
ITA 324
15–20
4, 5, 25
Water
10
% Gold in applied film by weight
Number of passes, power/W, writing speed/cm s−1
Hatch spacing/cm
2, 2, 6 followed by 2, 5, 20
0.0001
0.0001
Additives
AerosilꢀR R7200 (2%)
AerosilꢀR R7200 (0.5%), FoamexꢀR 842 (0.5%),
EpolightꢀR 2340 (2%), Wet 590ꢀR (1%)
brightness, adhesion, film thickness, homogeneity of coverage)
was maximised through variations in laser parameters, nature and
concentration of surfactant and defoamer, concentration of gold
precursor and other additives. Parameters for production of the
highest quality gold films are given in Table 2.
was added to reduce the proportion of SiO2 required. In the art
of ceramic decoration, SiO2 is known to reduce the brightness of
a gold finish. Samples of the above solution were pipetted into
3 cm2 moulds placed on the surface of the ceramic material and
were allowed to dry to thin films. Several passes of the laser were
required to completely eliminate carbonaceous material from the
films. Films produced from the isocyanide and carbene precursors
are similar in visual quality, giving a burnished gold colour.
Control studies on unmarked tiles show that there is no ablation or
cracking of the glaze surface on laser treatment. The films pass the
European Standard (part 4 of EN12875) for adhesion of domestic
ceramics (see Experimental section), FESEM photographs of
the films made from XAu(RNC) precursors reveal sub micron
sized spherical gold particles (Fig. 6a); similar dispersions of
spherical gold particles have previously been reported.24a–c The
films also exhibit a tracked appearance (Fig. 6b); depending on
the thickness of the applied precursor, the thicknesses of the
deposited gold films range from a mean height of between 0.69 to
5.06 lm, with corresponding maximum ridge heights of between
2.13 and 14.2 lm. The tracking is probably due to thermo-capillary
Marangoni flow of heated (low surface tension) to non-heated
(high surface tension) material during passage of the laser.25a,b
R
For the isocyanide complexes, a paste of SiO2 (Aerosilꢀ R7200,
average particle size 12 nm) and XAu(RNC) of appropriate
concentration in ITA 324 (a commercially available screen printing
medium) was applied to the ceramic substrate using a micrometer
adjustable film applicator to give a film of the desired thickness. For
the carbene complexes, saturated solutions of the organogold com-
R
R
pounds were mixed with SiO2 (Aerosilꢀ R7200) and Wetꢀ 590 and
R
Foamexꢀ 842 as wetting and antifoaming agents respectively. A
water soluble dye Epolightꢀ 2340 absorbing strongly near 1065 nm
R
Acknowledgements
We thank EPSRC for the award of CASE and PTP studentships to
N.J. and R.H. respectively and TherMark Corporation (University
Boulevard, Moon Township, PA 15108, USA) for financial
support. We also thank the EPSRC National Mass Spectrometry
Centre (Swansea) for MALDI spectra and the EPSRC Centre for
Crystallography (Southampton) for the crystal structure of 7. We
thank Professor Brigid Heywood and Dr Robert Gould for helpful
discussions.
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Fig. 6 FESEM photographs of deposited gold.
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7 B. R. Klassen and T. H. Baum, Organometallics, 1989, 82477 and
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21 Where known, all of the solid state structures of XAu(CNR) complexes
t
exhibit aurophilic interactions: (a) X = Cl, R = Bu, D. S. Eggleston,
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D. F. Chodosh, R. L. Webb and L. L. Davis, Acta Crystallogr., Sect.
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i
9 (a) C6H5NC: R. Obrecht, R. Herrmann and I. Ugi, Synthesis, 1985,
400; (b) 2,6-Me2C6H3NC: I. Ugi and R. Meyr, Chem. Ber., 1960, 93,
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10 M. I. Bruce, E. Horn, J. G. Matisons and M. R. Snow, Aust. J. Chem.,
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t
X = Cl, Br, R = MeO2CCH2; X = Br, R = Bu; X = Cl, R = 2,4,6-
Me3C6H2, W. Schneider, K. Angermaier, A. Sladek and H. Schmidbaur,
Z. Naturforsch., B: Chem. Sci., 1996, 51, 790; (f) X = Br, I, R = 2,6-
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11 Adapted from: M. Matter, B. Worb and A. Kohler, US Patent, 2798873,
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13 Adapted from: H. Ishida and S. Asaka, Chem. Abstr., 1968, 68, 5929k.
14 Adapted from: M. Ouichi, Y. Inoue, Y. Liu, S. Nagamune, S. Nakamura,
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15 Adapted from: J. Moc and M. S. Gordon, Organometallics, 1997, 16,
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22 For recent examples of the continuous laser writing of gold from solid
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16 (a) P. R. Norton, P. A. Young, Q. Cheng, N. H. Dryden and R. J.
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17 E. W. M. Jansen, F. Pohlman and G. E. Weigers, J. Less-Common Met.,
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23 For a review of the optical properties of SiO2, see: A. H. Guenther,
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18 C6H5NC is known to isomerise to C6H5CN at 200–220 ◦C: J. Wade,
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19 See, for example: (a) F. Mohr, S. Sanz, E. R. T. Tiekink and M. Laguna,
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20 See, for example: (a) F. Guissardi and V. Graziano, US Patent, 6607816,
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24 (a) M. Wehner, F. Legewie, B. Thiesen and E. Mayer, Appl. Surf. Sci.,
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25 For reviews of the Marangoni effect, see: (a) K. C. Mills, E. D. Hondros
and Z. Li, J. Mater. Sci., 2005, 40, 2403; (b) Y. Sha, H. Chemg and G. Z.
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