Gold(I) coordination compounds with mesoionic thiolate ligands and the crystal and molecular structure of bis(1,4,5-trimethyl-1,2,4-triazolium-3-thiolate)gold(I) tetrafluoroborate

Article abstract of DOI:10.1039/a903597d

Two-coordinate gold(I) complexes involving mesoionic thiolate ligands have been synthesized, including homoleptic and mixed-ligand complexes. Many of these compounds have stability and solubility properties that are desirable for practical use as gold sensitizers for photographic silver halide dispersions. The crystal structure of bis(1,4,5-trimethyl-1,2,4-triazolium-3-thiolate)gold(I) tetrafluoroborate has been solved by single-crystal X-ray diffraction. Several structural parameters support the view that the mesoionic ligands possess substantial thiolate character as a result of the unusual conjugation present in these heterocyclic compounds. The Royal Society of Chemistry 1999.

Full text of DOI:10.1039/a903597d

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Gold(I) coordination compounds with mesoionic thiolate ligands
and the crystal and molecular structure of bis(1,4,5-trimethyl-
1,2,4-triazolium-3-thiolate)gold(I) tetrafluoroborate
Joseph C. Deaton*a and Henry R. Lussb
a Imaging Research and Advanced Development, Eastman Kodak Company, Rochester,
NY 14652-4708, USA. E-mail: 616647N.wgsln@kodak.com
b 72 Parkway Drive, N. Chili, NY 14514, USA
Received 5th May 1999, Accepted 27th July 1999
Two-coordinate gold() complexes involving mesoionic thiolate ligands have been synthesized, including homoleptic
and mixed-ligand complexes. Many of these compounds have stability and solubility properties that are desirable for
practical use as gold sensitizers for photographic silver halide dispersions. The crystal structure of bis(1,4,5-trimethyl-
1,2,4-triazolium-3-thiolate)gold() tetrafluoroborate has been solved by single-crystal X-ray diffraction. Several
structural parameters support the view that the mesoionic ligands possess substantial thiolate character as a result
of the unusual conjugation present in these heterocyclic compounds.
Introduction
Results and discussion
The coordination chemistry of gold() is of considerable inter-
est because of the application of gold() compounds to treat
rheumatoid arthritis1,2 and, potentially, as anti-cancer drugs.3
Gold compounds are also important to the photographic
industry.4,5 One of the principal means of increasing the general
sensitivity of silver halide microcrystals to light is the process of
chemical sensitization during which small quantities of labile
sulfur- and gold-containing compounds are digested with the
silver halide microcrystals.6 While the structures of the resulting
impurity ion defect sites on the surface of, or inside, the silver
halide microcrystals are not known with certainty, it is generally
believed that silver sulfide and mixed silver–gold sulfides are
formed during chemical sensitization.7–10
Mesoionic compounds are organic heterocycles that possess
unusual delocalization of the bonding electrons that cannot be
satisfactorily represented by conventional bonding schemes
without invoking charge separation.21 An example of a meso-
ionic thiolate is 1,4,5-trimethyl-1,2,4-triazolium-3-thiolate I.22
Two alternative Lewis bonding schemes (IA,IB) for this com-
pound are shown below.
The design of practical gold() sensitizers is subject to rather
stringent criteria. The compounds should preferably be soluble
to facilitate dispersal in aqueous dispersions of silver halide
microcrystals, and most preferably soluble in water to minimize
use of organic solvents. The compounds must be stable enough
that their solutions have good shelf life for robust use in manu-
facturing, yet be reactive during chemical sensitization. Among
sulfur-donor ligands, experience has shown that thiones and
thioureas impart inadequate stability to gold(). Alkyl or aryl
thiolates form oligomers of the general formula Au(SR) that
have poor solubility,11–13 unless solubilizing groups are
The high dipole moments measured for mesoionic com-
pounds23 support the charge separation shown by these repre-
sentations. Cheung et al.24 have proposed that the bonding in
these heterocyclic compounds is best viewed as two separate
conjugated systems: one bearing a negative charge comprising
the S atom, and the C and N atoms at the 3 and 2 ring positions,
respectively, and the other bearing a positive charge comprising
the N, C, and N atoms at the 1,5, and 4 positions, respectively.
Crystallographic studies of mesoionic thiolates reveal that C–S
bond lengths are intermediate between single and double
bonds, providing evidence that the compounds possess substan-
tial thiolate character.24,25
Reaction of 2 equiv. of I with bis(tetramethylthiourea)gold()
tetrafluoroborate 1 in water yielded bis(1,4,5-trimethyl-1,2,4-
triazolium-3-thiolate)gold() tetrafluoroborate 2. Reaction of
several other gold() precursor compounds with 2 equiv. of I
afforded the same complex as in 2, but isolated as different salts
3, 5, and 7. However, reaction of chloroauric acid, instead of a
gold(I) precursor compound, with 3 equiv. of I gave chloro-
(1,4,5-trimethyl-1,2,4-triazolium-3-thiolate)gold() 8 in 45%
yield rather than the homoleptic two-coordinate complex.
Analogous iodo- and bromo-complexes 4 and 6 were made by
limiting reaction of I to 1 equiv. with AuI and [NBu4][AuBr2],
respectively.
Ϫ
added.14,15 Mononuclear complexes Au(SR)2 can be made
under basic conditions,11,16,17 but the facile displacement of
thiols18 probably accounts for the formation of the Au(SR)
oligomers in many other environments.
Mesoionic thiolates are heterocyclic compounds having
unusual delocalization that results in charge separation and
substantial thiolate character in the neutral molecules. The
intriguing properties of these ligands relative to other sulfur-
donors were investigated in a search for more practical gold
sensitizers for photographic silver halide microcrystals. The
synthesis of two-coordinate gold() complexes with mesoionic
thiolates and the crystal and molecular structure of bis(1,4,5-
trimethyl-1,2,4-triazolium-3-thiolate)gold() tetrafluoroborate
are reported in this paper. The utility of these gold() com-
pounds as photographic sensitizers has been disclosed else-
where.19 More recently, Howe20 has reported another example,
chloro(2,3-diphenyl-1,3,4-thiadiazolium-5-thiolate)gold().
The two-coordinate, mononuclear complex 2 did not show
any tendency to lose one ligand to form oligomers in aqueous
J. Chem. Soc., Dalton Trans., 1999, 3163–3167
This journal is © The Royal Society of Chemistry 1999
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Table 1 Selected bond distances (Å) and angles (Њ) for compound 2a
study to form gold() complexes include a number of trisubsti-
tuted triazolium thiolates 9–14 and one tetrazolium thiolate
15. Mixed-ligand compounds including phosphine complexes
16–18 were also made by reaction of 1 equiv. of a mesoionic
thiolate with chloro(trimethylphosphine)gold().
Au–S1
Au–S2
S1–C1
S2–C6
N1–N2
N1–C1
N2–C2
N2–C3
N3–C1
N3–C2
N3–C5
N4–N5
2.270(4)
2.274(4)
1.73(1)
1.76(1)
1.39(1)
1.30(2)
1.33(2)
1.46(2)
1.38(1)
1.36(2)
1.47(2)
1.35(2)
N4–C6
N5–C7
N5–C8
N6–C6
N6–C7
N6–C10
C2–C4
C7–C9
1.26(2)
1.30(2)
1.49(2)
1.38(2)
1.33(2)
1.47(2)
1.45(2)
1.51(2)
The mesoionic thiolate gold() compounds are excellent
photographic sensitizers and possess good solution stability
compared to the tetramethylthiourea complex 1, as has been
previously disclosed.19 Practical use in silver halide photo-
graphic dispersions is facilitated by the good water solubility
(0.5 g LϪ1 or more) possessed by many of these compounds,
particularly the salts of the cationic, homoleptic complexes.
A single-crystal X-ray structure determination of 2 was
carried out in order to examine structural consequences of the
unusual delocalization in the mesoionic thiolate as compared to
reported structures of gold() complexes of thiolates, thioureas,
and heterocyclic thiones. The structure of 2 was orthorhombic,
space group Pna21, with Z = 4. The unit cell (Fig. 1) contained
mononuclear complexes with none of the sub-van der Waals
gold–gold interactions that have been observed fairly often for
gold() compounds.27,28 The molecular structure is illustrated in
Fig. 2 and selected bond distances and angles are listed in
Table 1, while crystal and refinement data are given in the
Experimental section. The coordination in the complex ion was
essentially linear with a S–Au–S angle of 179.6Њ. The two Au–S
bond lengths were within the range reported for many other
sulfur-donor ligands (Table 2).
S1–Au–S2
Au–S1–C1
179.6(2)
101.4(4)
Au–S2–C6
100.0(4)
a Numbers in parentheses are estimated standard deviations in the least
significant digits.
The C–S bond lengths provide an indication of thiolate
character in the mesoionic ligands. While the structure of the
free ligandIhas not been determined, the C–S bond lengths
in closely related mesoionic thiolates were reported to be
intermediate between single and double bond values (1.68–
1.69 Å).24,25 Thus the C–S bond values of 1.73(1) and 1.76(1)
Å found in the gold() complex 2 probably represent some
bond lengthening relative to the free ligand. The slightly
longer of these two C–S bonds was rather close to the C–S
bond lengths ranging from 1.78 to 1.80 Å that were reported
for three homoleptic two-coordinate thiolate complexes of
gold() (Table 2).11,17,29 The C–S bond lengths that have been
reported for a variety of thiourea and heterocyclic thione
complexes of gold() (Table 2) generally fall between 1.67 and
1.73 Å. One compound with a C–S bond falling outside this
range is bis(thiourea)gold() bromide,30 in which the C–S
values were 1.77(1) Å. Interestingly, the Au–S–C bond
angles in the latter compound and in 2 were significantly less
than those in most other gold() compounds referenced in
Table 2.
Fig. 1 Unit cell diagram for compound 2.
The orientation of the Au–S bond with respect to the planes
of the heterocyclic rings may also reflect the extent of thiolate
vs. thione character in the ligands. If there were substantial C–S
double bond character present, the Au–S bond would be
orthogonal to both the C–S σ and π bonds and consequently
would lie in the ligand plane. In 2, the AuS2C6N4 torsion angle
was 75.2Њ and the AuS1C1N1 angle was Ϫ3.8Њ. These results
suggest that at least one of the mesoionic ligands behaves as a
thiolate in the complex 2, while the second one may retain some
thione character.
Lastly, the bond lengths within the heterocyclic rings are
worthy of note. Cheung et al.24 based their view of the conju-
gation in mesoionic compounds in large part upon the intra-
ring distances in 1,4,5-triphenyl-1,2,4-triazolium thiolate. In 2,
most of the bond lengths within the rings of each ligand are
similar to the corresponding bond lengths reported by Cheung
et al.24 However, the C1–N1 bond length (1.30(2) Å) and espe-
cially the C6–N4 bond (1.26(2) Å) were even shorter than the
1.328(3) Å reported by Cheung et al.24 for the corresponding
atoms at the 3 and 2 ring positions in 1,4,5-triphenyl-1,2,4-
triazolium-3-thiolate. These short C–N bond lengths compared
to the 1.38(2) Å observed for both C6–N6 and C1–N3 (3 and 4
positions) suggest that structural representation IA for the
Fig. 2 Molecular structure of compound 2 showing the atomic label-
ling scheme. Thermal ellipsoids are drawn at the 50% probability level.26
solution at moderate pH (3 to 7). Thus the mesoionic thiolates
coordinated more strongly to gold() than tetramethylthiourea,
yet did not display the competing affinity for protons character-
istic of alkyl and aryl thiolates.18
Other examples of mesoionic ligands employed in the present
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Table 2 Bond distances and angles in gold() complexes with sulfur-donor ligands
Compound
Au–S/Å
C–S/Å
Au–S–C/Њ
Ref.
2
2.270(4), 2.274(4)
2.271(8), 2.262(8)
2.288(4)
2.298(4)
2.291(4)
2.289(3)
2.293(9), 2.271(9)
2.265(2)
2.258(3)
2.279(8), 2.278(9)
2.25(1)
1.73(1), 1.76(1)
1.79(1), 1.80(1)
1.78(1), 1.80(1)
1.80(1)
1.771(13)
1.728(7)
1.70(3), 1.67(3)
1.727(9)
1.70(1)
1.713(22), 1.723(20)
1.74(2)
1.67(1)
101.4(4), 100.0(4)
107.6(7), 108.9(6)
102.8(5), 107.1(5)
106.0(4)
101.4(4)
104.8(3)
107(1), 108(1)
109.6(3)
106.9(3)
111.2(7), 109.8(8)
106(1)
107(1)
This work
[P(C6H5)4][Au(SC6H5)2]
[NH4][2,4,6-iPr3C6H2S)2Au]
[NEt4][Au(SAd)2]a
[Au(Tu)2]Brb
17
11
29
30
31
31
32
33
34
35
36
37
38
39
40
c
[Au(Me2Tu)2]ClO4
d
[Au(Et2Tu)2]ClO4
[BrAu(Me4Tu)]e
[ClAu(Et2BzTu)]f
[Au(Imt)2]ClؒH2Og
[ClAu(EtImt)]h
[ClAu(PrImt)]i
2.26(1)
[Au(PrImt)2]Cli
2.283(3), 2.291(3)
2.281(5), 2.288(5)
2.278(2)–2.291(3)
2.277(3)
1.70(1), 1.73(1)
1.735(4), 1.716(14)
1.714(10)–1.739(10)
1.715(11)
107.0(4), 106.5(5)
106.6(5), 101.9(5)
104.8(4)–107.5(4)
105.3(4)
[Au(C3H5NS2)2]ClؒH2Oj
k
[Au(C5H5NS)2]ClO4
[Au(Tzt)2]Cli
a SAd = adamantyl thiolate. b Tu = thiourea. c Me2Tu = 1,3-dimethylthiourea. d Et2Tu = 1,3-diethylthiourea. e Me4Tu = tetramethylthiourea. f Et2-
BzTu = N,N-diethyl-NЈ-benzoylthiourea. g Imt = imidazolidine-2-thione. h EtImt = N-ethylimidazolidine-2-thione. i PrImt = N-propylimidazolidine-
2-thione. j C3H5NS2 = 1,3-thiazolidine-2-thione. k C5H5NS = pyridine-2-thione. l Tzt = 4-amino-3-methyl-1,2,4-∆2-triazoline-5-thione.
ligand does indeed play an important role in forming the gold()
complex 2.
(D2O): δ 3.863, 3.717, and 2.639. Compound 2 was also made
in 88% yield by an analogous procedure using bis(penta-
methylenesulfide)gold() tetrafluoroborate as starting material.
Experimental
Chemicals
Bis(1,4,5-trimethyl-1,2,4-triazolium-3-thiolate)gold(I) iodide
3. Solid AuI powder (0.256 g; 0.789 mmol) was added slowly to
5 mL of an acetonitrile solution containing I (1.578 mmol). The
solution developed a yellow-brown color. A small amount of
brown precipitate (metallic Au) was filtered off. The solvent was
evaporated and the white powder remaining was washed with
ethanol and dried to give 0.432 g (90% yield). Found (calc. for
AuS2C10H18N6I): C, 19.58 (19.68); H, 2.94 (2.97); N, 13.56
(13.77); S, 9.69 (10.51%).
Chemicals obtained from commercial sources were used with-
out further purification. HAuCl4ؒ3H2O and AuI were obtained
from Johnson Matthey, and ClAuPMe3 was from Strem.
Tetramethylthiourea, pentamethylene sulfide, 2,2Ј-thio-
diethanol, and HBF4 (48% aq) were all obtained from Aldrich.
[N(n-Bu)4][AuBr2],41 bis(pentamethylenesulfide)gold() tetra-
fluoroborate,42 and the mesoionic thiolates22 were prepared as
described in the literature.
Iodo(1,4,5-trimethyl-1,2,4-triazolium-3-thiolate)gold(I) 4. The
same reaction procedure as given above for the bis complex 3
was followed except that only one molar equivalent of the meso-
ionic thiolate I was used. After filtering a small amount of
metallic gold from the reaction solution, the filtrate was evap-
orated. The white powder residue was washed with ethanol and
dried (85% yield). Found (calc. for AuSC5H9N3I): C, 13.30
(12.86); H, 1.95 (1.94); N, 9.17 (9.00); S, 7.51 (6.86%).
1H NMR spectra were recorded on a Varian VXR-300S
spectrometer at 300 MHz. Chemical shifts in D2O (Cambridge
Isotopes) were referenced to an internal standard of 3-
(trimethylsilyl)propionic-2,2,3,3-d4 acid, sodium salt (Aldrich).
Synthesis of gold(I) compounds
Bis(tetramethylthiourea)gold(I) tetrafluoroborate 1. Com-
pound 1 was made by a modification of a procedure developed
by G. H. Hawks and W. W. White of these laboratories. Tetra-
methylthiourea (0.327 g; 2.47 mmol) was suspended in 10 mL
water and treated, dropwise, with a solution of HAuCl4ؒ3H2O
(0.255 g; 0.647 mmol) in 5 mL of water. A gummy orange
precipitate formed immediately, quickly turned dark red, and
dissolved with gentle warming and stirring. When a clear, color-
less solution was formed, 0.2 mL HBF4 (49% aq) was added
and soon white platelets formed. After further cooling to 5 ЊC,
0.297 g of the product was filtered and dried, 84% yield. Found
(calc. for AuS2C10H24N4BF4): C, 22.17 (21.91); H, 4.46 (4.41);
N, 10.14 (10.22); S, 11.65 (11.70%). 1H NMR (D2O): δ 3.257.
Bis(1,4,5-trimethyl-1,2,4-triazolium-3-thiolate)gold(I) brom-
ide 5. [NBu4][AuBr2] (0.304 g; 0.508 mmol) was dissolved in 2
mL acetonitrile and added dropwise to 3 mL of an acetonitrile
solution containing I (1.02 mmol) at about 50 ЊC. Within a few
minutes a white precipitate began to form. After further cooling
at Ϫ10 ЊC, 0.257 g white powder was filtered and dried (90%
yield). Found (calc. for AuS2C10H18N6Br): C, 21.07 (21.32); H,
3.19 (3.22); N, 14.62 (14.92); S, 10.56 (11.38%).
Bromo(1,4,5-trimethyl-1,2,4-triazolium-3-thiolate)gold(I) 6.
The same procedure as given above for the bis complex 5 was
followed except that only one molar equivalent of the meso-
ionic thiolate I was used. The solution was stirred for an hour at
about 50 ЊC, after which the solvent was concentrated until a
white precipitate began to form. The white powder was filtered,
washed with water and alcohol, and dried (82% yield). The
product was recrystallized from hot acetonitrile. Found (calc.
for AuSC5H9N3Br): C, 14.15 (14.30); H, 2.10 (2.16); N, 9.88
(10.00); S, 7.27 (7.63%).
Bis(1,4,5-trimethyl-1,2,4-triazolium-3-thiolate)gold(I)
tetrafluoroborate 2. A solution of 1 (0.228 g; 0.416 mmol) in 4
mL water, which was prepared by heating to ca. 60 ЊC, was
added dropwise to a solution containing the mesoionic thiolate
I (0.126 g; 0.874 mmol) in 4 mL water. A white precipitate soon
began to deposit. The solution was stirred for an additional
5 min after the addition was complete, and then cooled at
5 ЊC for several hours. The product was then filtered, washed
with ethanol, and dried under vacuum to give 0.203 g of white
powder, (86% yield). The product was recrystallized from warm
water. Found (calc. for AuS2C10H18N6BF4): C, 20.87 (21.06); H,
3.13 (3.18); N, 14.71 (14.74); S, 10.87 (11.25%). 1H NMR
Bis(1,4,5-trimethyl-1,2,4-triazolium-3-thiolate)gold(I) chloride
7. HAuCl4ؒ3H2O (0.325 g; 0.825 mmol) was converted in situ to
thiodiethanol gold() chloride43 in 5 mL of a 3:1 ethanol–water
solution by dropwise addition of neat thiodiethanol (2.48
J. Chem. Soc., Dalton Trans., 1999, 3163–3167
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mmol) and stirring until the solution turned colorless. This
reaction solution was, in turn, added dropwise to 2 mL of an
aqueous solution containing I (1.65 mmol). The solution
turned orange, but upon cooling to 5 ЊC a white precipitate
formed (0.310 g, 72% yield). Found (calc. as AuS2N6C10H18Cl):
C, 23.65 (23.15); H, 3.62 (3.50); N, 15.76 (16.20); Cl, 6.67 (6.83);
S, 12.04 (12.36%).
mmol) in 3 mL water at 60 ЊC was added dropwise to a suspen-
sion of 1,5-dimethyl-4-cyclohexyl-1,2,4-triazolium-3-thiolate
(0.160 g; 0.756 mmol) in 2 mL water at 60 ЊC. A white precipi-
tate began to form that had a different consistency from the
solid thiolate ligand that was initially present. After stirring an
additional few minutes, 0.204 g of white powder was filtered
off and dried (80% yield). The compound was recrystallized
from hot methanol. Found (calc. for AuS2C20H34N6BF4): C,
33.71 (34.00); H, 4.77 (4.85); N, 11.83 (11.90); S, 8.75 (9.08%).
Chloro(1,4,5-trimethyl-1,2,4-triazolium-3-thiolate)gold(I) 8.
HAuCl4ؒ3H2O (0.327 g; 0.831 mmol) was dissolved in 2 mL
water and added dropwise to a solution containing 3 molar
equiv. of the mesoionic thiolate I (2.49 mmol) in 2 mL water.
An orange, gummy material precipitated immediately from the
clear solution, but subsequently went into solution that also
took on an orange color. After stirring a few minutes, a white
precipitate formed and 0.14 g of white powder was collected
and dried (45% yield). Found (calc. for AuSC5H9N3Cl): C,
15.98 (15.99); H, 2.32 (2.42); N, 10.98 (11.19); Cl, 9.43 (9.44);
S, 7.86 (8.54%).
Bis(1-methyl-4,5-diphenyl-1,2,4-triazolium-3-thiolate)gold(I)
tetrafluoroborate 14. A solution of 1 (0.201 g; 0.367 mmol) was
dissolved in 3 mL methanol and added slowly to a partly dis-
solved suspension of 1-methyl-4,5-diphenyl-1,2,4-triazolium-
3-thiolate (0.216 g; 0.806 mmol) in 3 mL methanol. As the
addition proceeded, the initial suspension appeared to be
taken into solution while a new white precipitate formed. After
stirring 10 min, 0.272 g fine white powder was filtered off and
dried (91% yield). Found (calc. for AuS2C30H26N6BF4): C, 43.92
(44.02); H, 3.24 (3.20); N, 10.30 (10.27); S, 7.43 (7.83%).
Bis(1,5-dimethyl-4-allylmethyl-1,2,4-triazolium-3-thiolate)-
gold(I) tetrafluoroborate 9. A solution of 1 (0.231 g) in 2 mL
water at 60 ЊC was added dropwise to 3 mL of an aqueous
solution of 1,5-dimethyl-4-allylmethyl-1,2,4-triazolium-3-thio-
late (0.15 g, 0.886 mmol), also at about 60 ЊC. After stirring 10
min, the solution was cooled to 5 ЊC, whereupon colorless plate-
lets formed. The product (0.207 g) was filtered off and dried
(79% yield). Found (calc. for AuS2C14H22N6BF4): C, 26.96
(27.02); H, 3.54 (3.56); N, 13.59 (13.51); S, 10.03 (10.30%).
Bis(2,3-diphenyl-1,2,3,4-tetrazolium-5-thiolate)gold(I)
tetrafluoroborate 15. A solution of 1 (0.226 g; 0.413 mmol) in 3
mL acetone was added dropwise to a partly dissolved suspen-
sion of the dark orange 2,3-diphenyl-1,2,3,4-tetrazolium-5-
thiolate (0.210 g; 0.826 mmol) in 3 mL refluxing acetone. The
solution turned progressively lighter orange in color as the add-
ition proceeded. Near the end of the addition, a yellow precipi-
tate formed. The refluxing suspension was stirred an additional
few minutes until all of the solid dark orange specks of the
mesoionic thiolate were consumed. The solution was allowed to
cool and 0.253 g of fine yellow powder was filtered and dried
(77% yield). The material was recrystallized from hot
acetonitrile. Found (calc. for AuS2C26H20N8BF4): C, 39.85
(39.41); H, 2.79 (2.54); N, 13.85 (14.14); S, 6.83 (8.09%).
Bis(1,5-dimethyl-4-methoxyethyl-1,2,4-triazolium-3-thiolate)-
gold(I) tetrafluoroborate 10. Solid 1 (0.261 g; 0.476 mmol) was
very slowly added to 5 mL of an aqueous solution containing
1,5-dimethyl-4-methoxyethyl-1,2,4-triazolium-3-thiolate (0.178
g; 0.953 mmol). A white precipitate appeared and stirring was
continued for a half hour. White powder (0.211 g) was filtered
off, washed with ethanol, and dried. A second crop of 0.047 g
was obtained after concentrating the filtrate (82% yield total).
The compound was recrystallized from hot water. Found (calc.
for AuS2N6O2C14H26BF4): C, 25.42 (25.54); H, 3.97 (3.98); N,
12.79 (12.77); S, 8.45 (9.74%).
(1,4,5-Trimethyl-1,2,4-triazolium-3-thiolate)(trimethyl-
phosphine)gold(I) chloride 16. A solution of the mesoionic thio-
late I (0.0936 g; 0.652 mmol) in 2 mL water was added slowly to
a suspension of ClAuP(CH3)3 (0.201 g; 0.652 mmol) in 2 mL
methanol. As the addition continued, the ClAuP(CH3)3 was
taken into solution. After a few minutes stirring, the solution
was filtered of a few remaining particles of the starting com-
pound and then the solvent was evaporated. The residue was
redissolved in ethanol but had a cloudy or colloidal appearance
until a few drops of water were added to clarify. Ether was
added slowly until the cloud point was reached. A flocculant
white precipitate formed after standing at Ϫ10 ЊC overnight.
White powder (0.187 g) was filtered off and dried, and 0.0184 g
was obtained as a second crop (70% yield). Found (calc. for
AuClPSC8H18N3): C, 20.39 (21.27); H, 4.15 (4.02); N, 9.06
(9.30); S, 6.87 (7.10); Cl, 7.88 (7.85%).
Bis(1,5-dimethyl-4-amino-1,2,4-triazolium-3-thiolate)gold(I)
tetrafluoroborate 11. A solution of 1 (0.215 g; 0.391 mmol) in 3
mL water at 60 ЊC was added dropwise to 3 mL of an aqueous
solution of 1,5-dimethyl-4-amino-1,2,4-triazolium-3-thiolate
(0.119 g; 0.822 mmol), also at about 60 ЊC. Before the addition
was completed, a white precipitate began to form. The reaction
mixture was stirred an additional 10 min after the addition was
complete and then filtered, washed with water and alcohol, and
dried. A white powder (0.197 g) was obtained, and a second
crop of 0.029 g was recovered by concentrating the filtrate (88%
yield total). Found (calc. for AuS2C8H16N8BF4): C, 16.76
(16.79); H, 2.81 (2.82); N, 19.64 (19.58); S, 10.75 (11.21%).
(1,4,5-Trimethyl-1,2,4-triazolium-3-thiolate)(trimethylphos-
phine)gold(I) tetrafluoroborate 17. The reaction procedure given
for the chloride salt in the preceding paragraph was followed.
After the reaction was complete, approximately 4 molar equiv.
of HBF4 (49% aq.) were added. The solution was concentrated
to an oil, which had a slight yellow coloration. The oil was
triturated with ethanol, causing it to solidify, and the slightly
yellow powder was filtered off and dried (90% yield). It was
recrystallized from warm (50 ЊC) water. Found (calc. for
AuPSC8H18N3BF4): C, 18.99 (19.10); H, 3.46 (3.61); N, 8.56
(8.35); S, 6.24 (6.37%).
Bis(1,5-dimethyl-4-n-butyl-1,2,4-triazolium-3-thiolate)gold(I)
tetrafluoroborate 12. A solution of 1 (0.245 g; 0.447 mmol) in 2
mL water at 60 ЊC was added dropwise to 2 mL of an aqueous
solution of 1,5-dimethyl-4-n-butyl-1,2,4-triazolium-3-thiolate
(0.174 g; 0.939 mmol), also at 60 ЊC. After stirring an additional
few minutes, the reaction mixture was allowed to cool where-
upon a colorless oil separated. Upon standing at 5 ЊC overnight
the oil crystallized. Semi-crystalline white solid (0.183 g) was
filtered off and dried (62% yield). The compound was recrystal-
lized as long needles from boiling water. Found (calc. for
AuS2C16H30N6BF4): C, 29.28 (29.37); H, 4.53 (4.62); N, 12.81
(12.84); S, 9.66 (9.80%).
(1,5-Dimethyl-4-allylmethyl-1,2,4-triazolium-3-thiolate)-
(trimethylphosphine)gold(I) tetrafluoroborate 18. A solution of
1,5-dimethyl-4-allylmethyl-1,2,4-triazolium-3-thiolate (0.177 g;
0.694 mmol) in 2 mL methanol was added dropwise to a
suspension of ClAuP(CH3)3 (0.214 g; 0.694 mmol) in 2 mL
Bis(1,5-dimethyl-4-cyclohexyl-1,2,4-triazolium-3-thiolate)-
gold(I) tetrafluoroborate 13. A solution of 1 (0.198 g; 0.36
3166
J. Chem. Soc., Dalton Trans., 1999, 3163–3167

View Article Online
Table 3 Crystallographic parameters for bis(1,4,5-trimethyl-1,2,4-
triazolium-3-thiolate)gold() tetrafluoroborate 2
6 J. M. Harbison, in The Theory of the Photographic Process,
Macmillan, New York, 4th edn., 1977.
7 H. Kanzaki and Y. Tadakuma, J. Phys. Chem. Solids, 1997, 58, 221.
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9 L. Dupain-Klerkx and P. Faelens, J. Photogr. Sci., 1987, 35, 136.
10 M. Kawasaki, T. Yoshiaki and Y. Oku, J. Imaging. Sci. Technol.,
1993, 37, 568.
11 I. Schröter and J. Strähle, Chem. Ber., 1991, 124, 2161.
12 M. Lotze and M. Bauer, US Pat. 5 252 764, 1993.
13 M. A. Mazid, M. T. Razi, P. J. Sadler, G. N. Greaves, S. J. Gurman,
M. H. J. Koch and J. C. Phillips, J. Chem. Soc., Chem. Commun.,
1980, 1264.
14 B. H. Tavernier and A. J. DeMeyer, US Pat., 3 503 749, 1970.
15 P. Bishop, P. Marsh, A. K. Brisdon, B. J. Brisdon and M. F. Mahon,
J. Chem. Soc., Dalton Trans., 1998, 675.
16 G. A. Bowmaker and B. C. Dobson, J. Chem. Soc., Dalton Trans.,
1981, 267.
Molecular Formula
M
AuS2N6C10H18BF4
570.19
Lattice type
Space group
Orthorhombic
Pna21
T/ЊC
a/Å
b/Å
23(1)
23.121(6)
6.567(2)
11.971(4)
1818(2)
4
c/Å
V/Å3
Z
µ(Mo-Kα)/cmϪ1
83.4
No. unique reflections measured
No. reflections in refinement (I > σ (I))
R = Σ|Fo| Ϫ K|Fc|/|Fo|
2297
1946
0.045
0.057
Rw = [Σw(|Fo| Ϫ K|Fc|)2/ΣwFo ]1/2
2
17 P. A. Bates and J. M. Waters, Acta Crystallogr., Sect. C., 1985, 41,
862.
18 G. E. Coates, C. Kowala and J. M. Swan, Aust. J. Chem., 1966, 19,
539.
methanol. As the addition proceeded, the solid ClAuP(CH3)3
was taken into solution. After the addition was completed, 0.3
mL of HBF4 solution (49% aq.) was added. Concentration of
the solution, followed by addition of ether to the cloud point,
caused a white precipitate to form, and 0.295 g was filtered off
and dried (80% yield). This material was recrystallized from hot
ethanol. Found (calc. for AuSC10H20N3PBF4): C, 22.85 (22.70);
H, 3.69 (3.81); N, 8.46 (7.94); S, 6.23 (6.06%).
19 J. C. Deaton, US Pat., 5 049 485, 1991 and 5 220 030, 1993.
20 B. P. Howe, Metal Based Drugs, 1997, 4, 273.
21 W. D. Ollis and C. A. Ramsden, in Advances in Heterocyclic
Chemistry, Academic Press, London, 1976, vol. 19.
22 H. W. Altland, E. L. Dedio and G. J. McSweeney, US Pat., 4 378 424,
1983.
23 A. R. McCarthy and W. D. Ollis, J. Chem. Soc. B, 1969, 1185.
24 K.-K. Cheung, A. Echevarria, S. Galembeck, M. A. Maciel,
J. Miller, V. M. Rumjanek and A. M. Simas, Acta Crystallogr., Sect.
C, 1993, 49, 1092.
Single-crystal X-ray structure determination of bis(1,4,5-
trimethyl-1,2,4-triazolium-3-thiolate)gold(I) tetrafluoroborate 2
25 Y. Kushi and Q. Fernando, J. Am. Chem. Soc., 1970, 92, 1965.
26 C. K. Johnson, ORTEPII, ORNL-5138 Report, Oak Ridge
National Laboratory, Oak Ridge, TN, 1976.
Crystals of 2 were grown from a warm aqueous solution by
slow cooling in a Dewar flask. A single crystal was mounted on
a glass fiber and data were collected on an Enraf-Nonius CAD4
diffractometer. Programs used in the X-ray study were from the
Structure Determination Package (SDP).44 The structure was
solved by the heavy-atom method and refined by the full-matrix
least squares method with anisotropic thermal parameters
applied in the final cycles. Hydrogen atoms could not be
located. The crystal data and refinement parameters are sum-
marized in Table 3. An empirical absorption correction was
applied using the program DIFABS.45 The residual electron
27 S. S. Pathaneni and G. R. Desiraju, J. Chem. Soc., Dalton Trans.,
1993, 319.
28 M. Nakamoto, W. Hiller and H. Schmidbaur, Chem. Ber., 1993, 126,
605.
29 K. Fujisawa, S. Imai and Y. Moro-oka, Chem. Lett., 1998, 167.
30 L. C. Porter, J. P. Fackler, J. Costmagna and R. Schmidt, Acta
Crystallogr., Sect. C, 1992, 48, 751.
31 R. J. Staples, J. P. Fackler and J. Costamagna, Acta Crystallogr.,
Sect. C, 1997, 53, 1555.
32 A. C. Fabretti, A. Giusti and W. Malavasi, J. Chem. Soc., Dalton
Trans., 1990, 3091.
33 W. Bensch and M. Schuster, Z. Anorg. Allg. Chem., 1992, 611, 99.
34 P. G. Jones, J. J. Guy and G. M. Sheldrick, Acta Crystallogr., Sect. B,
1976, 32, 3321.
35 M. S. Hussain and A. A. Isab, Transition Met. Chem., 1984, 9, 398.
36 M. S. Hussain and A. A. Isab, J. Coord. Chem., 1985, 14, 17.
37 M. S. Hussain and A. A. Isab, Transition Met. Chem., 1985, 10, 178.
38 P. D. Akrivos, S. K. Hadjikakou, P. Karagiannidis, M. Gdaniec and
Z. Kosturkiewicz, Polyhedron, 1994, 13, 753.
Ϫ
density was primarily around the Au and S atoms and the BF4
ion.
CCDC reference number 186/1605.
Acknowledgements
39 R. Uson, A. Laguna, M. Laguna, J. Jimenez, M. P. Gomez, A. Sainz
and P. G. Jones, J. Chem. Soc., Dalton Trans., 1990, 3457.
40 M. B. Cingi, F. Bigoli, M. Lanfranchi, E. Leporati, M. A.
Pellinghelli and C. Foglia, Inorg. Chim. Acta, 1995, 235, 37.
41 P. Braunstein and R. J. H. Clark, J. Chem. Soc., Dalton Trans., 1973,
1845.
The authors thank Henry Gysling, Brian Cleary, and Thomas
Blanton, all of the Research and Development Laboratories of
Eastman Kodak Company, for thoughtful reading of this
manuscript and many helpful suggestions.
42 D. T. Hill, US Pat., 4 165 380, 1979.
43 A. K. Al-Sa’ady, C. A. McAuliffe, R. V. Parish and J. A. Sandbank,
Inorg. Synth., 1981, 23, 185.
44 Structure determination package, version 3.0, Enraf-Nonius
Corporation, Delft, Holland, 1985.
45 N. Walker and D. Stuart, DIFABS, Acta Crystallogr., Sect. A, 1983,
39, 158.
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