Synthesis and crystal structure of gold(I) complexes with triazole and triphenylphosphine ligands: Monomeric complex [Au(1,2,3-L)-(PPh3)] and dimeric complex [Au(1,2,4-L)(PPh3)]2 (HL = triazole) through an Au-Au bond in the solid state

Article abstract of DOI:10.1039/a806283h

Two novel gold(I)-triphenylphosphine complexes with nitrogen-containing heterocycles, [Au(1,2,3-L)(PPh₃)] 1 and [Au(1,2,4-L)(PPh₃)]₂·xH₂O (x = 0.5-1.0) 2 (HL = triazole) were synthesized from stoichiometric reactions of a precursor complex [AuCl(PPh₃)] with HL in acetone in the presence of NaOH, and isolated as colorless needles and cubic crystals, respectively. The crystal structures of 1 and 2 were determined by single-crystal X-ray diffraction. Complexes 1 and 2 were also fully characterized by complete elemental analyses, TG/DTA and FT-IR in the solid state and by solution NMR (³¹P, ¹H and ¹³C) spectroscopies and solution molecular-weight measurements. Complex 1 consisted of a monomeric 2-coordinate AuNP core both in the solid state and in solution, while, in contrast, 2 comprised a dimeric (AuNP)₂ core through an Au-Au bond in the solid state, but a monomeric AuNP core in solution. Within the two gold(I) complexes composed of very closely related nitrogen-containing heterocycles and a common bulky PPh₃ ligand, it was found that aggregation through the Au ... Au interaction in 2 was overruled in 1. The molecular structures of 1 and 2 were also compared with those of the corresponding silver(I) analogs, [Ag(1,2,3-L)(PPh₃)₂]_n 3 and [Ag(1,2,4-L)(PPh₃)₂]_n 4, the molecular structures of which have been recently determined as helical polymers in the solid state.

Full text of DOI:10.1039/a806283h

View Article Online / Journal Homepage / Table of Contents for this issue
Synthesis and crystal structure of gold(I) complexes with triazole
and triphenylphosphine ligands: monomeric complex [Au(1,2,3-L)-
(PPh3)] and dimeric complex [Au(1,2,4-L)(PPh3)]2 (HL ؍ triazole)
through an Au–Au bond in the solid state
Kenji Nomiya,* Ryusuke Noguchi, Katsunori Ohsawa and Kazuhiro Tsuda
Department of Materials Science, Faculty of Science, Kanagawa University, Tsuchiya,
Hiratsuka, Kanagawa 259-1293, Japan. E-mail: nomiya@info.kanagawa-u.ac.jp
Received 10th August 1998, Accepted 21st October 1998
Two novel gold()–triphenylphosphine complexes with nitrogen-containing heterocycles, [Au(1,2,3-L)(PPh3)] 1
and [Au(1,2,4-L)(PPh3)]2ؒxH2O (x = 0.5–1.0) 2 (HL = triazole) were synthesized from stoichiometric reactions of
a precursor complex [AuCl(PPh3)] with HL in acetone in the presence of NaOH, and isolated as colorless needles
and cubic crystals, respectively. The crystal structures of 1 and 2 were determined by single-crystal X-ray diffraction.
Complexes 1 and 2 were also fully characterized by complete elemental analyses, TG/DTA and FT-IR in the solid
state and by solution NMR (31P, 1H and 13C) spectroscopies and solution molecular-weight measurements. Complex
1 consisted of a monomeric 2-coordinate AuNP core both in the solid state and in solution, while, in contrast,
2 comprised a dimeric (AuNP)2 core through an Au–Au bond in the solid state, but a monomeric AuNP core in
solution. Within the two gold() complexes composed of very closely related nitrogen-containing heterocycles and
a common bulky PPh3 ligand, it was found that aggregation through the Au ؒ ؒ ؒ Au interaction in 2 was overruled
in 1. The molecular structures of 1 and 2 were also compared with those of the corresponding silver() analogs,
[Ag(1,2,3-L)(PPh3)2]n 3 and [Ag(1,2,4-L)(PPh3)2]n 4, the molecular structures of which have been recently determined
as helical polymers in the solid state.
Over the past 30 years, interest has increased in the coordin-
ation chemistry of silver() and gold() complexes with bio-
logical or medicinal activities.1–7 The molecular design and
structural determination of such silver() and gold() complexes
with common ligands are an intriguing aspect of bioinorganic
chemistry, inorganic syntheses and metal-based drugs. For
example, the thiosulfato complexes of silver() and gold(), [Ag-
(S2O3)2]3Ϫ (STS) with anti-ethylene activity8 and [Au(S2O3)2]3Ϫ
(Sanocrisin) with anti-arthritic activity,1,9 are a classical, but
prototypic case; the former has 4-coordinate silver() with
tetrahedral geometry caused by a bridging thiosulfate ligand,10
while the latter has been established as a 2-coordinate linear
structure with an AuS2 core.9c Recently, we have realized a com-
bination of several silver() and gold() complexes with common
thiol ligands, such as {Na[Ag(Htma)]ؒ0.5H2O}n (n = 24–34;
H3tma = thiomalic acid)11a and gold thiomalate, {Na2[Au-
(tma)]ؒ1.75H2O}n (n = 3–10),3,9a,12a and of {Na[Ag(tsa)]ؒH2O}n
(n = 21–27; H2tsa = thiosalicylic acid)13 and Na3[Au(tsa)2]ؒ
5H2O.14 These oligomeric silver() complexes have displayed
effective antimicrobial activities against selected bacteria, yeast
and mold,11a,13 whereas the corresponding gold() complexes
have shown effective anti-arthritic activities.15 Structure deter-
mination with X-ray analysis of these complexes has been
unsuccessful because most of them were hard to crystal-
lize,3,9a,11b the exception being gold thiomalate, {Na2Cs[Au2-
(Htma)(tma)]}n, the crystal structure of which was very recently
solved.12k On the other hand, tertiary phosphine ligands have
been utilized in order to limit polymerization of the [Au(SR)]
unit (HSR = thiol ligand).16 Thus, we have also substantiated
another combination of silver() and gold() complexes con-
sisting of a thiol or N-containing heterocyclic ligand with an
auxiliary ligand (PPh3) such as in [Ag(Htsa)(PPh3)3] and
[Au(Htsa)(PPh3)],17 and [Ag(im)(PPh3)3] (Him = imidazole)
and [Au(im)(PPh3)].18,19
flexible metal–metal bonding modes exhibited by this element.20
Particular attention has been paid to compounds which contain
weak intermolecular metal–metal interactions with gold–gold
separations typically in the range 2.5–3.5 Å, which are less than
3.60 Å, twice the van der Waals radii for gold.21,22 Schmidbaur
et al. have suggested that steric effects play a decisive role, since
the weak forces associated with the Au ؒ ؒ ؒ Au contacts are
easily overruled by steric repulsion and other factors such as
packing forces. In solution, it is the solvation by solvent
molecules which overrules the aggregation through Au ؒ ؒ ؒ Au
contacts.23
The affinity of gold for the nitrogen atom, in comparison
with sulfur and phosphorus atoms, is very low indeed, and most
compounds with gold–nitrogen bonds are of limited stability.23
Nevertheless, a number of neutral or ionic gold() complexes
with nitrogen centers in the presence of the auxiliary P-donor
ligands have been prepared, e.g., as neutral complexes such as
[Au(pyrmd)(PPh3)]
(Hpyrmd = 5-fluoro-1-(tetrahydrofuran-
2-yl)-(1H,3H-pyrimidine-2,4-dione),24
[Au(im-2-R)(PPh3)]
(R = H, Me, i-Pr, Ph),25 and [Au(pz)(PPh3)] (Hpz = pyrazole),26
and as ionic species such as [Au(Him)(PPh3)]ϩ[Z]Ϫ (HZ =
picric acid),27a [Au(NMe3)(PPh3)]ClO4,28 [Au(qncd)(PPh3)]BF4
(qncd = quinuclidine),29 [Au(Q)(PPh3)]ClO4 [Q = 2,6-dimethyl-
pyridine, naphthyridine, 2-(2-pyridyl)benzimidazole].30 How-
ever, in gold() complexes with N-donor ligands, Au ؒ ؒ ؒ Au
interactions are scarce and only a few examples have been
recently found such as in [Au(NH2But)(PMe3)]BF4 and [{Au-
(PMe3)}2NH(CH2Ph)]BF4,23 and [{Au(PPh3)}4(µ-bbzim)]-
(ClO4)2 (H2bbzim = 2,2Ј-bibenzimidazole).31
On the other hand, examples of the corresponding neu-
tral silver() complexes with an AgN(PPh3) unit have been
recently reported, e.g., such as [Ag2(pz)2(PPh3)2] and [Ag2(pz)2-
(PPh3)3].32a Very recently, we have isolated two other neutral
silver() complexes with a 4-coordinate Ag(N)2(PPh3)2 core
using 1,2,3-triazole and 1,2,4-triazole ligands, i.e., [Ag(1,2,3-L)-
Recent advances in gold chemistry have highlighted the
J. Chem. Soc., Dalton Trans., 1998, 4101–4108
4101

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structure analysis whether an Au ؒ ؒ ؒ Au interaction occurs in
them, (iii) comparing their molecular structures with those of
the silver() analogs 3 and 4 and (iv) elucidating the solution
behavior of 1 and 2.
Herein we report full details of the synthesis and isolation of
1 as colorless needle crystals and 2 as colorless cubic crystals.
The compositional characterization of 1 and 2 in the solid state
has been achieved by complete elemental analyses, FT-IR,
thermogravimetric and differential thermal analyses (TG/DTA)
and the structural characterization with single-crystal X-ray
crystallography. The Au ؒ ؒ ؒ Au interaction found in 2 in the
solid state is a rare example. Also reported are the characteriz-
1
ation of 1 and 2 by solution NMR (31P, H and 13C) spectro-
scopies and solution molecular-weight measurements.
Results and discussion
Compositional characterization
Two gold() complexes with triazole (HL) and triphenylphos-
phine ligands, 1 and 2, were synthesized by stoichiometric reac-
tions in acetone of the precursor complex [AuCl(PPh3)] with
HL in the presence of NaOH, and isolated in 51.0% (0.29 g)
and 53.6% (0.29 g) yields, respectively, as colorless crystals
soluble in most organic solvents, by a vapor diffusion method
with benzene/hexane as the internal/external solvents.
Complete elemental analyses of 1 and 2 for C, H, N, P and
Au, for the samples dried overnight at room temperature under
10Ϫ3–10Ϫ4 Torr, showed that their compositions had molar
ratios of AuI :L:PPh3 = 1:1:1. Their TG/DTA measurements
done under atmospheric conditions confirmed the absence of
any solvated molecules for 1 because no weight loss was
observed below the decomposition temperature 198 ЊC and the
presence of 0.5–1.0 hydrated water for 2 because 1.31% weight
loss was observed below the decomposition temperature 195 ЊC.
IR measurements confirm the presence of coordinated PPh3
molecules in 1 as typical vibrational bands at 1479, 1435, 748,
711, 691, 547 and 504 cmϪ1 and at 1487, 1436, 747, 712, 694,
544 and 500 cmϪ1 in 2. In both complexes, the IR measurements
also show that L coordinates to the gold() atom as a triazol-
ate anion, but not as a neutral triazole, because multiple
vibrational bands due to N–H stretchings observed in free HL
in the 3100–2600 cmϪ1 region disappear. Thus, molecular
formulae of 1 and 2 in the solid state can then be represented
as having a general formula of [AuL(PPh3)]n.
Fig. 1 (a) Molecular structure of the local coordination around each
silver() center of [Ag(1,2,3-L)(PPh3)2]n 3 with 50% probability ellips-
oids (symmetry operations; i; x, Ϫy, z Ϫ 0.5, ii; x, Ϫy, z ϩ 0.5) and its
helical polymer structure. (b) Molecular structure of the local coordin-
ation around each silver() center of [Ag(1,2,4-L)(PPh3)2]n 4 with
50% probability ellipsoids (symmetry operations iii; 1.5 Ϫ x, y Ϫ 0.5,
0.5 Ϫ z, iv; 1.5 Ϫ x, y ϩ 0.5, 0.5 Ϫ z) and its helical polymer structure.33
In both polymeric structures, black circles represent silver atoms, and
small and large gray circles represent nitrogen and phosphorus atoms,
respectively.
From single-crystal X-ray analysis, described later, the gold()
compounds 1 and 2 are a monomer and dimer in the solid state,
respectively, which is in contrast with the silver() analogs 3 and
4 which are helical polymers in the solid state (Fig. 1).33
(PPh3)2]n 3 and [Ag(1,2,4-L)(PPh3)2]n 4 (HL = triazole), as crys-
tals and characterized them both to be helical polymers in the
solid state by single-crystal X-ray diffraction (Fig. 1).33
On the other hand, molecular weight measurements in acet-
one solution revealed that both 1 and 2 were present as a
monomeric species in solution. Probably these complexes are
H
also monomeric in CH2Cl2 solution, because their solution 31
NMR spectra are virtually identical.
P
H
N
N
5
5
N
N
3
4
N
N
Molecular structures
1,2,3-triazole
1,2,4-triazole
Single crystals suitable for single-crystal X-ray analysis were
obtained for 1 and 2. The molecular structures of 1 and 2 with
the atom numbering scheme are depicted in Figs. 2 and 3,
respectively. Selected bond distances and angles with their
estimated standard deviations are listed in Table 1.
The neutral complex 1 is a monomer consisting of an
AuL(PPh3) core coordinated by a triazolate anion, in which the
geometry around the gold() atom is described as almost linear
coordination, the P–Au–N angle being 178.7(5)Њ. Among the
three nitrogen atoms of 1,2,3-triazolate, the N(2) and N(3)
atoms do not participate in the coordination. In Table 2, bond
distances and angles of the previously reported neutral and
ionic gold() complexes are listed. The bond distance Au–N
[1.98(2) Å] in 1 is slightly shorter, but the distance Au–P
In a separate account, the development of crystalline AuI
compounds with a 2-coordinate AuSP core stems from the
discovery of auranofin [(tetraacetylthioglucose)(triethylphos-
phine)gold()],4 which has been used in chemotherapy as an
effective anti-arthritic agent for oral administration, although
the mechanism of the action is not established yet. We have also
been interested in the anti-arthritic activity of the crystalline
nitrogen-centered gold() complexes described here.
Thus, in the present work, we have aimed at (i) preparing the
neutral gold() complexes [Au(1,2,3-L)(PPh3)] 1 and [Au(1,2,
4-L)(PPh3)]2ؒxH2O (x = 0.5–1.0) 2 with two nitrogen-containing
heterocyclic ligands, 1,2,3- and 1,2,4-triazole, in the presence of
an auxiliary P-donor ligand, (ii) determining by their crystal
4102
J. Chem. Soc., Dalton Trans., 1998, 4101–4108

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Table 1 Selected bond lengths (Å) and angles (Њ) for complexes 1 and 2
1
2
Au–P1
Au–N1
P1–C11
P1–C21
P1–C31
N1–N2
N2–N3
N1–C5
N3–C4
2.229(5)
1.98(2)
1.80(2)
1.83(2)
1.82(3)
1.31(2)
1.33(2)
1.36(3)
1.35(4)
Au1–Au2
Au1–P1
Au2–P2
Au1–N1a
Au2–N1b
P1–C11
P1–C21
P1–C31
P2–C41
P2–C51
3.1971(6)
2.243(2)
2.238(2)
2.026(7)
2.037(7)
1.826(9)
1.807(8)
1.795(9)
1.831(9)
1.803(9)
1.826(8)
1.364(9)
1.32(1)
1.31(1)
1.32(1)
1.367(10)
1.34(1)
1.33(1)
1.32(1)
1.30(1)
P2–C61
N1a–N2a
N1a–C5a
N4a–C3a
N4a–C5a
N1b–N2b
N1b–C5b
N2b–C3b
N4b–C3b
N4b–C5b
Fig.
2
Molecular structure of [Au(1,2,3-L)(PPh3)] 1 with 50%
probability ellipsoids.
P1–Au–N1
Au–P1–C11
Au–P1–C21
Au–P1–C31
Au–N1–N2
Au–N1–C5
N1–N2–N3
C11–P1–C21
C11–P1–C31
C21–P1–C31
N2–N1–C5
N2–N3–C4
178.7(5)
111.9(8)
114.2(7)
112.6(9)
121(1)
130(1)
111(1)
108(1)
103(1)
104(1)
107(2)
104(2)
P1–Au1–N1a
P2–Au2–N1b
Au1–Au2–P2
Au2–Au1–P1
Au1–Au2–N1b
Au2–Au1–N1a
Au1–N1a–N2a
Au1–N1a–C5a
Au2–N1b–N2b
Au2–N1b–C5b
Au1–P1–C11
Au1–P1–C21
Au1–P1–C31
Au2–P2–C41
Au2–P2–C51
Au2–P2–C61
177.1(2)
172.7(3)
101.06(6)
98.21(6)
85.0(2)
83.7(2)
121.6(6)
132.4(8)
122.7(7)
130.1(8)
114.8(3)
110.2(3)
113.1(3)
108.7(3)
117.0(3)
113.3(3)
complex 1, there exists neither an intermolecular nor intra-
molecular gold()–gold() interaction. The AuNP core with the
gold()–gold() interaction is not very common as listed in Table
3; the only precedents are the ionic complexes, [Au(NH2But)-
(PMe3)]ϩBFϪ with the Au–Au distance of 3.047(1) Å and
4
[{Au(PMe3)}2NH(CH2Ph)]ϩBF4Ϫ with 3.171(1) and 3.143(1) Å,
Table 3.23 Thus, the gold()–gold() interaction within the
neutral N–Au–P complex found in 2 is a very rare case.
Fig.
3
Molecular structure of [Au(1,2,4-L)(PPh3)]2 2 with 50%
probability ellipsoids.
The pairing of gold() atoms either intra- or inter-
molecularly and the formation of polymers via metal–metal
interactions are well-established phenomena in gold() coordin-
ation chemistry.21a As to the gold()–gold() interaction, it has
been suggested that neither is there a correlation between the
nature of the gold()–gold() interaction, i.e., intramolecular vs.
intermolecular, and the Au–Au distance. Recently it has been
suggested, however, that the steric effects play a decisive role in
the formation of gold()–gold() contacts.23
[2.229(5) Å] in 1 is similar to those in the reported neutral
complexes; [Au(L1)(PPh3)] (HL1 = 1-methylthymine) [Au–N and
Au–P, 2.20(1) and 2.240(5) Å, respectively],36n [Au(L2)(PPh3)]
(HL2 = 6-methylpyridone) [2.077(9) and 2.236(3) Å],27b
[Au(pyrmd)(PPh3)] [2.042(24) and 2.235(7) Å],24 [Au(L3)-
(PPh3)] (HL3 = 3,7-dihydro-1,3-dimethyl-1H-purine-2,6-dione)
[2.047(6) and 2.231(2) Å]35 and [Au(L4)(PPh3)] (HL4 = 7-aza-
indole) [2.033(5) and 2.233(1) Å].34
The most interesting feature in 2 is the presence of an intra-
molecular Au(1)–Au(2) distance of 3.1971(6) Å, which is sig-
nificantly less than twice the van der Waals radii for gold, 3.60
Å, indicating a weak intramolecular interaction between the
two AuL(PPh3) cores. This complex with one water of hydra-
tion in the crystals has an isolated dimeric unit without any
intermolecular interaction. In this dimeric complex 2, the N(2)
and N(4) atoms of 1,2,4-triazolate similarly do not participate
in the coordination to the gold(). The two Au–N distances
[Au(1)–N(1a) 2.026(7), Au(2)–N(1b) 2.037(7) Å] and the two
Au–P distances [Au(1)–P(1) 2.243(2), Au(2)–P(2) 2.238(2) Å]
are comparable with those of 1. The geometry around each
gold() atom was also described as almost linear coordination,
the P(1)–Au(1)–N(1a) and P(2)–Au(2)–N(1b) angles being
177.1(2) and 172.7(3)Њ, respectively. In the very closely related
In the present complexes 1 and 2 with a common bulky PPh3
ligand, the difference between their ligands is only in the
position of one nitrogen atom, i.e., N(3) or N(4), within the tri-
azolate ring. The difference in basicity of their nitrogen atoms
should not be very large, because both nitrogen atoms can
coordinate to silver() atoms as recently found in the corre-
sponding silver() analogs 3 and 4, where the triazolate ligands
bridge two silver() atoms to form helical polymer structures.
In 2, one triazolate ring (N1b–C5b) nearly overlaps with one
(C31–C36) of phenyl rings in the PPh3 group with a separation
in the range of 3.4–4.0 Å, suggesting the possibility of stabiliz-
ation by a stacking interaction between them. However, since
this complex is not symmetrical, the stacking of the other tri-
azolate ring (N1a–C5a) is not observed. Thus, the features
observed in 1 and 2 are in contrast to those of [Au(NH2But)-
Ϫ
Ϫ
(PMe3)]ϩBF4 and [Au(NH2But)(PMePh2)]ϩBF4 with and
J. Chem. Soc., Dalton Trans., 1998, 4101–4108 4103

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Table 2 Comparison of Au–N and Au–P distances (Å) and P–Au–N angle (Њ) for structures containing AuNP core
Au–N
Au–P
P–Au–N
Ref.
[Au(NMe3)(PPh3)]ClO4
[Au(qncd)(PPh3)]BF4
[Au(dmpy)(PPh3)]ClO4
[Au(napy)(PPh3)]ClO4
[Au(pbzim)(PPh3)]ClO4
[{Au(PPh3)}4(µ-bbzim)](ClO4)2
2.108(7)
2.11(1)
2.091(3)
2.093(13)
2.075(4)
2.03(2)
2.05(1)
2.06(1)
2.06(2)
2.13(1)
2.231(2)
2.240(4)
2.233(4)
2.230(4)
2.238(1)
2.236(6)
2.233(5)
2.239(5)
2.233(5)
2.236(4)
2.235(3)
2.235(3)
2.246(3)
2.248(3)
2.240(5)
2.236(3)
2.235(7)
2.233(1)
2.231(2)
2.228(3)
2.229(5)
2.243(2)
2.238(2)
179.3(2)
173.0(3)
178.8(3)
174.3(4)
172.4(1)
172.3(5)
173.9(5)
171.2(4)
174.7(5)
175.7(4)
174.8(3)
176.4(2)
28
29
30
30
30
31
[Au(NH2But)(PMe3)]BF4
23
2.11(1)
[Au(NH2But)(PPh2Me)]BF4
[{Au(PMe3)}2NH(CH2Ph)]BF4
2.105(8)
2.071(8)
2.073(8)
2.20(1)
2.077(9)
2.042(24)
2.033(5)
2.047(6)
2.053(9)
1.98(2)
23
23
[Au(L1)(PPh3)]
178.7(4)
173.4(3)
174.5(6)
176.6(2)
176.1(2)
176.9(3)
178.7(5)
177.1(2)
172.7(3)
36(n)
27(b)
24
34
35
[Au(L2)(PPh3)]
[Au(pyrmd)(PPh3)]
[Au(L4)(PPh3)]
[Au(L3)(PPh3)]
[{Au(PPh3)}2(µ-bbzim)]
[Au(1,2,3-L)(PPh3)] 1
[Au(1,2,4-L)(PPh3)]2 2
31
a
a
2.026(7)
2.037(7)
dmpy = 2,6-dimethylpyridine; napy = 1,8-naphthyridine; pbzim = 2-(2-pyridyl)benzimidazole. a This work.
without the gold()–gold() interaction, respectively, because
it has been considered that steric effects of the bulky But
and PMePh2 groups prevent the intimate approach required
Ϫ
for metal–metal contact in the [Au(NH2But)(PMePh2)]ϩBF4
complex.23
Solution NMR (31P, 1H and 13C)
The 31P NMR spectra (Fig. 4a, 4c) measured at room temper-
ature in CD2Cl2 of 1 and 2 show only one resonance at δ 31.1
and 31.5, respectively, the chemical shifts of which are in the
region usually observed for the PPh3 ligands coordinated to
gold() and can be compared with those of related compounds:
[Au(im)(PPh3)] at δ 32.46 and [AuCl(PPh3)] at δ 33.40.18,37 These
resonances are observed at much lower field than those of PPh3
coordinated to a silver() atom, e.g., 3 at δ 6.48,33 4 at δ 4.84,33
[Ag(im)(PPh3)3] at δ 3.71,18 [Ag2(pz)2(PPh3)2] at δ 9.87 and
[Ag2(pz)2(PPh3)3] at δ 6.13.32a
The low-temperature 31P NMR measurements showed that
(i) the single peak in 1 in CD2Cl2 observed at δ 31.1 at room
temperature was split into two peaks at δ 30.6 and 30.0 with an
intensity ratio of 2:1 at Ϫ90 ЊC (Fig. 4b), and (ii) the original
single-line spectrum was recovered at room temperature from
the low-temperature splitting 31P NMR spectrum. On the other
hand, the single peak in 2 in CD2Cl2 at δ 31.5 at room temper-
ature was observed as a single peak at δ 30.5 at Ϫ90 ЊC (Fig.
4d). Both complexes should be present as a monomer in solu-
tion, because of their solution molecular weight measurements.
Thus, the low-temperature 31P NMR measurements indicate
that, in solution at room temperature, the coordination of
nitrogen atoms on the triazolate ligand to the gold() atom
exchange dynamically; in 1 all three nitrogen atoms [N(1), N(2)
and N(3)] participate in coordination at room temperature,
while in 2 only two nitrogen atoms [N(1) and N(2)] do, but
N(4) does not.
1
The H and 13C NMR spectra of 1 and 2 measured at room
temperature in CD2Cl2 exhibit only one resonance for the
coordinating triazolate anion, respectively, also as a result
of dynamic exchange. However, in response to the low-
Fig. 4 31P-{1H} NMR spectra measured in CD2Cl2 of [Au(1,2,3-L)-
(PPh3)] 1 (a) at room temperature and (b) at Ϫ90 ЊC, and of [Au-
(1,2, 4-L)(PPh3)]2 2 (c) at room temperature and (d) at Ϫ90 ЊC.
1
temperature 31P NMR spectra, the single H NMR peak at
δ 7.80 at room temperature for the 1,2,3-triazolate ligand of 1
temperature of the corresponding silver() complexes 3 and 4
have been also interpreted as averaged signals resulting from
the rapid dynamic exchange among several unequivalent 109Ag
is changed to the splitting peaks at δ 7.75 and 7.82 at Ϫ90 ЊC.
1
The solution NMR (31P, 109Ag, H and 13C) spectra at room
4104
J. Chem. Soc., Dalton Trans., 1998, 4101–4108

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Table 3 Comparison of Au–Au interactions and distances (Å) for structures containing AuYP core (Y = Cl, SR and N)a
Entry
Complexes
Au–Au
Ref.
Intramolecular Au–Au interactions
1
2
3
4
5
6
7
[Au2(Cl)2(dppm)]
3.351(2)
3.000(1)
3.085(1)
3.05(1)
36(c)
36(b)
36(d)
36(e)
36(f)
22
[Au2(Cl)2{[(Ph2P)2C]PMe3}]
[Au2(Cl)2{1,1Ј-bis(diphenylphosphino)-1,1Ј-bicyclopropyl}]
[Au2(Cl)2(Ph2PCHCHPPh2)]
[Au2(SCH2CH2PEt2)2]
[Au2(3,4-S2C6H3CH3)(PPh3)2]
[Au3(3,4-S2C6H3CH3)(PPh3)3]
3.104
3.096(2)
2.9624(12)
3.1966(14)
2.7902(6)
3.104(6)
3.058(3)
3.116(6)
3.017(3)
3.2170(9)
3.2773(12)
3.157(1)
3.222(1)
3.171(1)
3.1971(6)
22
8
9
[Au2{S2CN(C2H4OMe)2}2]
[Au4(µ-S2C6H3CH3)2(PEt3)2]
20
36(o)
10
11
[Au4Ag(CH2SiMe3)4(µ-dppm)2]SO3CF3
[{Au(PPh3)}4(µ-bbzim)](ClO4)2
36(q)
31
12
13
[{Au(PMe3)}2NH(CH2Ph)]BF4
[Au(1,2,4-L)(PPh3)]2 2
23
b
Intermolecular Au–Au interactions
14
15
16
[Au(Cl){2,4,6-(But)3C6H2Ph2}]2
[Au2(Cl)2(dppe)]2
[Au2(Cl)2(dppe)]2
3.440(1)
3.189(1)
3.187(1)
3.221(1)
3.21
36(g)
36(h)
36(i)
17
18
19
20
21
[Au2(Cl)2{Ph2P(CH2)2AsPh2}]2
[Au2(Cl)2{Ph2PCH2As(Ph)CH2PPh2}]2
[Au2(1,3-S2C6H4)(PPh3)2]
[Au2{S2CN(C2H4OMe)2}2]
[AuSPh(o-OMe)(TPA)]
36(j)
36(a)
22
20
36(p)
3.141(1)
3.0834(8)
3.1572(7)
3.263(2)
3.341(2)
3.0468(10)
3.047(1)
3.143(1)
3.1663(5)
3.1705(5)
3.1244(10)
3.3633(5)
3.1944(5)
22
23
24
25
[AuSPh(3,5-Cl2)(TPA)]
36(p)
23
23
[Au(NH2But)(PMe3)]BF4
[{Au(PMe3)}2NH(CH2Ph)]BF4
[Au(NH᎐CMe2)2]CF3SO3
36(r)
᎐
t
᎐
26
27
28
[Au(C᎐CSiMe3)(CNBu )]
36(r)
36(s)
36(s)
᎐
[AuCl(Ph2C᎐NH)]
᎐
{[Au(Ph2C᎐NH)2][AuCl2]}2
᎐
Polymers
29
30
31
32
33
[Au2(Cl)2(Ph2PCHCHPPh2)]n
[Au2(Cl)2{Ph2PCH2C(CH2)CH2PPh2}]n
[Au2(Cl)2(dppp)]n
[Au2(p-tc)2(dppb)]n
[Au2(p-tc)2(dpppn)]n
3.043(1)
3.294
3.316
3.094(1)
3.200(1)
36(k)
36(l)
36(m)
21(a)
21(a)
dppp = 1,3-bis(diphenylphosphino)propane; dppb = 1,4-bis(diphenylphosphino)butane; dpppn = 1,5-bis(diphenylphosphino)pentane; p-tc = p-
thiocresol; TPA = 1,3,5-triaza-7-phosphaadamantanetriylphosphine; SPh(o-OMe) and SPh(3,5-Cl2) are benzenethiolate ligands with substituent
groups as indicated. a This table is made by supplementing many additional data to the table previously reported by Narayanaswamy et al.21a b This
work.
species containing ionic species such as [Ag(PPh3)4]ϩLϪ and
[Ag(PPh3)2]ϩLϪ.33
1 and 2 in solution were present as a monomeric species. Their
1
solution (31P, H and 13C) NMR spectra measured at room
temperature were interpreted based on the presence of an
equilibrium due to the rapid dynamic exchange on the NMR
timescale, the presence of which was evidenced from low-
temperature 31P NMR measurements. The title complexes are
also of interest as a possible new type of metal-based drug;
studies of their biological activities are planned.
Conclusion
Using nitrogen-containing heterocycles, 1,2,3-triazole and
1,2,4-triazole (HL), in the presence of PPh3, two novel neutral
complexes [Au(1,2,3-L)(PPh3)] 1 and [Au(1,2,4-L)(PPh3)]2ؒ
xH2O (x = 0.5–1.0) 2 were isolated as colorless crystals in good
yields and their crystal structures determined by single-crystal
X-ray diffraction. Two heterocyclic ligands in these complexes
act as anionic monodentate ligands. Complex 1 consisted of a
monomeric 2-coordinate AuNP core in the solid state, while 2
comprised of a dimeric (AuNP)2 core through an Au–Au bond
in the solid state. The Au ؒ ؒ ؒ Au interaction found in 2 in the
solid state is rare. These features were in contrast to the fact that
the two corresponding silver() analogs [Ag(1,2,3-L)(PPh3)2]n 3
and [Ag(1,2,4-L)(PPh3)2]n4 are helical polymers constituted by
bridging triazolate ligands in the solid state. On the other hand,
Experimental
Materials
The following were used as received: 1,2,4-triazole, NaAuCl4ؒ
2H2O, NaOH, triphenylphosphine, dichloromethane, ethanol,
methanol, diethyl ether, hexane, light petroleum (bp: 30–60 ЊC),
acetone, benzene (all from Wako); 1,2,3-triazole (Aldrich);
CD2Cl2, acetone-d6 (Isotec). [AuCl(PPh3)] was prepared accord-
ing to the literature.37 Benzene should be used in a fume hood as
it is toxic.
J. Chem. Soc., Dalton Trans., 1998, 4101–4108
4105

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Instrumentation/analytical procedures
cmϪ1. 1H NMR measured in CD2Cl2 with reference to internal
SiMe4 at room temperature: δ 7.50 (15H, m, aryl protons), 7.80
(2H, s, H4 ϩ H5 of L). 1H NMR in CD2Cl2 at Ϫ90 ЊC: δ 7.52,
7.61 (15H, m, aryl), 7.82, 7.75 (2H, s, H4 ϩ H5 of L). 13C NMR
measured in CD2Cl2 with reference to internal SiMe4 at room
temperature: δ 131.51 (C4 ϩ C5 of L), 128.79 (d, JCP 64.3,
phenyl), 129.74 (d, JCP 11.0, phenyl), 132.53 (s, phenyl), 134.67
(d, JCP 13.1 Hz, phenyl). 31P NMR measured at room temper-
ature with reference to an external 25% aqueous H3PO4 in a
sealed capillary: δ 31.1 in CD2Cl2 and δ 32.1 in acetone-d6. 31P
NMR measured in CD2Cl2 at Ϫ90 ЊC by a substitution method:
δ 30.6, 30.0.
Elemental analyses after overnight drying under 10Ϫ3–10Ϫ4
Torr were carried out by Mikroanalytishes Labor Pascher
(Remagen, Germany). Thermogravimetric (TG) and differen-
tial thermal analysis (DTA) were carried out using a Rigaku
TG 8101D and TAS 300 data processing system. TG/DTA
measurements were run under air with a temperature ramp
of 1 ЊC minϪ1 between 20 and 500 ЊC. Infrared spectra were
recorded on a Nicolet 510 FT-IR spectrometer in KBr disks at
room temperature.
Molecular weight measurements in acetone solutions based
on the vaporimetric method using a vapor pressure osmometer
were done by Mikroanalytishes Labor Pascher (Remagen,
Germany) and evaluated for 11.285 mg of the complex 1 dis-
solved in 0.9367 g of acetone and for 11.309 mg of the complex
2 dissolved in 0.8301 g of acetone.
[Au(1,2,4-L)(PPh3)]2ؒxH2O (x ؍ 0.5–1.0) 2. Compound 2
was isolated in a similar manner to the work-up described
above using 0.040 g (1.00 mmol) of solid NaOH, 0.069 g (1.00
mmol) of 1,2,4-HL in 10 mL methanol and 0.495 g (1.00 mmol)
of [AuCl(PPh3)] suspended in 20 mL methanol, instead of 1.0
M aqueous NaOH, 1,2,3-HL and 100 mL acetone as the initial
solvent. Yield was 0.29 g (53.6% with respect to one hydrated
species). Relatively light- and thermally-stable, colorless cubic
crystals were soluble in methanol, ethanol, acetone, dichloro-
methane, chloroform, benzene and DMSO, but insoluble in
diethyl ether, light petroleum, hexane and water.
1H NMR (399.65 MHz), 13C-{1H} NMR (100.40 MHz) and
31P-{1H} NMR (161.70 MHz) spectra in solution were recorded
at 22 ЊC in 5 mm outer diameter tubes on a JEOL JNM-EX 400
FT-NMR spectrometer with a JEOL EX-400 NMR data pro-
1
cessing system. H and 13C-{1H} NMR spectra of the com-
plexes were measured in CD2Cl2 solution with reference to
internal SiMe4. Chemical shifts are reported on the δ scale and
resonances downfield of SiMe4 (δ 0) are recorded as positive.
31P-{1H} NMR (161.70 Hz) spectra were measured in CD2Cl2
or acetone-d6 solution with reference to an external standard of
25% H3PO4 in H2O in a sealed capillary. Chemical shifts are
reported as negative for resonances upfield of H3PO4 (δ 0).
For the sample dried overnight at room temperature under
10Ϫ3–10Ϫ4 Torr: Found: C, 45.24; H, 3.05; N, 7.90; P, 5.80;
Au, 37.20, total 99.19%. Calc. for C20H17N3PAu or [Au(1,2,
4-L)(PPh3)] as a monomer unit: C, 45.56; H, 3.25; N, 7.97; P,
5.87; Au, 37.35%. TG/DTA data under atmospheric conditions:
1.31% weight loss was observed below the decomposition tem-
perature; calc. 0.85% for x = 0.5 and 1.68% for 1.0 in [Au(1,2,4-
L)(PPh3)]ؒxH2O; decomposition began around 195 ЊC with an
endothermic peak at 195 ЊC and exothermic peaks at 324 and
470 ЊC. Molecular weight measurement: 545 in acetone; calc.
527.3 for [Au(1,2,4-L)(PPh3)] as a monomer unit. Some prom-
inent IR bands in the 1700–400 cmϪ1 region (KBr disk): 1487s,
1436s, 1375w, 1284w, 1255m, 1192m, 1154m, 1101s, 1082m,
1027w, 997m, 964w, 867m, 854m, 747s, 712m, 694vs, 544vs,
Preparations
[Au(1,2,3-L)(PPh3)] 1. 0.495 g (1.00 mmol) of [AuCl(PPh3)]
and 0.072 g (1.04 mmol) of 1,2,3-HL were dissolved in 100 mL
acetone. To the solution 1.0 mL of 1.0 M NaOH aqueous solu-
tion (1.00 mmol) was added. During 1 h stirring, white powder
of NaCl was produced and it was filtered off using a folded
filter paper (Whatman No. 2). The obtained colorless clear
filtrate was evaporated to dryness at 50 ЊC with a rotary-
evaporator. The residue was dissolved in 30 mL benzene. The
clear filtrate obtained through a folded filter paper (Whatman
No. 2) was added dropwise to 200 mL hexane. White precipi-
tates formed, which were collected on a membrane filter (JG
0.2 µm), washed twice with 20 mL light petroleum and dried
thoroughly by suction.
Crystallization was performed by vapor diffusion method.
The obtained white powder was redissolved in 15 mL benzene
and the solution was filtered through a folded filter paper
(Whatman No. 2). The colorless filtrate was placed in an
internal small vial and hexane used as an external solvent with-
in a screw-capped vial for the vapor diffusion. After 6 h at room
temperature, colorless needle crystals began to form. After a
few days, the crystals were collected on a membrane filter (JG
0.2 µm), washed twice with 100 mL light petroleum, and dried
in vacuo for 2 h. Yield was 0.29 g (51.0%). Relatively light- and
thermally-stable, colorless needle crystals obtained as com-
pound 1 were soluble in methanol, ethanol, acetone, dichloro-
methane, chloroform, benzene and DMSO, but insoluble in
diethyl ether, light petroleum, hexane and water.
For the sample dried overnight at room temperature under
10Ϫ3–10Ϫ4 Torr: Found: C, 45.33; H, 3.22; N, 7.92; P, 5.80;
Au, 37.40, total 99.67%. Calc. for C20H17N3PAu or [Au(1,2,3-
L)(PPh3)]: C, 45.56; H, 3.25; N, 7.97; P, 5.87; Au, 37.35%. TG/
DTA data under atmospheric conditions: no weight loss was
observed below the decomposition temperature; decomposition
began around 198 ЊC with an endothermic peak at 198 ЊC and
exothermic peaks at 212 and 258 ЊC. Molecular weight meas-
urement: 512 in acetone; calc. 527.3 for [Au(1,2,3-L)(PPh3)].
Some prominent IR bands in the 1700–400 cmϪ1 region (KBr
disk): 1479m, 1435vs, 1400w, 1309w, 1226w, 1184w, 1101s,
1070w, 1043s, 998m, 795m, 748s, 711s, 691vs, 547vs, 504vs
1
500s cmϪ1. H NMR measured in CD2Cl2 with reference to
internal SiMe4 at room temperature: δ 7.50 (15H, m, aryl pro-
tons), 8.05 (2H, s, H3 ϩ H5 of L), 2.15 (H2O). 13C NMR meas-
ured in CD2Cl2 with reference to internal SiMe4 at room tem-
perature: δ 150.79 (C3 ϩ C5 of L), 128.80 (d, JCP 62.3, phenyl),
129.77 (d, JCP 13.1, phenyl), 132.53 (s, phenyl), 134.66 (d, JCP
15.1 Hz, phenyl). 31P NMR measured at room temperature with
reference to an external 25% aqueous H3PO4 in a sealed capil-
lary: δ 31.5 in CD2Cl2 and δ 32.4 in acetone-d6. 31P NMR meas-
ured in CD2Cl2 at Ϫ90 ЊC by a substitution method: δ 30.5.
X-Ray crystallography
Compounds 1 and 2 formed colorless needle crystals and color-
less cubic crystals, respectively, by vapor diffusion of the
benzene–hexane system. During a few days standing of the
solutions at room temperature, crystals of sufficient quality for
single-crystal X-ray diffraction studies were grown.
Each single-crystal of 1 and 2 was mounted on glass fiber and
transferred to a Rigaku AFC5S diffractometer. Cell contents
and orientation matrix of 1 and 2 were obtained from the least-
squares refinement of 18 and 25 reflections, respectively. The
reflection data were collected using ω–2θ scan with graphite-
monochromated Mo-Kα radiation at room temperature. The
intensities of three standard reflections which were measured
after every 150 reflections remained constant throughout data
collection. The data were corrected for Lorentz and polariz-
ation effects and empirical absorption corrections based on ψ
scans were applied to the data. For the overall averaged trans-
mission curve, the transmission factors of 1 and 2 were in the
range of 0.49–1.00 and 0.65–1.00, respectively. The structures
were solved by direct methods followed by subsequent differ-
4106
J. Chem. Soc., Dalton Trans., 1998, 4101–4108

View Article Online
M. Oda and S. Sakuma, Polyhedron, 1995, 14, 1359. The described
Table 4 Summary of crystal data
[Au(1,2,3-L)(PPh3)] [Au(1,2,4-L)(PPh3)]2ؒH2O
n = 15–19 should be corrected to n = 24–34 as shown in Polyhedron,
1996, 15, 2303; (b) K. Nomiya, Y. Kondoh, H. Nagano and M. Oda,
J. Chem. Soc., Chem. Commun., 1995, 1679; (c) G. R. Lenz and A. E.
Martell, Inorg. Chem., 1965, 4, 378; (d) F. Secheresse, J. Lemerle and
J. Lefebvre, Bull. Soc. Chim. Fr., 1974, 2423; (e) K. J. Ellis and
A. McAuley, J. Inorg. Nucl. Chem., 1975, 37, 567; ( f ) O. P. Agrawal,
K. K. Verma and S. Bhayana, Curr. Sci., 1989, 58, 1201.
12 (a) K. Nomiya, H. Yokoyama, H. Nagano, M. Oda and S. Sakuma,
Bull. Chem. Soc. Jpn., 1995, 68, 2875 and refs. therein; (b)
M.Delepine, US Pat., 1 994 213, 1935; (c) A. A. Isab and P. J. Sadler,
J. Chem. Soc., Dalton Trans., 1976, 1051; (d) C. F. Shaw III,
G. Schmitz, H. O. Thompson and P. Witkiewicz, J. Inorg. Biochem.,
1979, 10, 317; (e) A. A. Isab and P. J. Sadler, J. Chem. Soc., Dalton
Trans., 1982, 135; ( f ) D. H. Brown, M. Paton and W. E. Smith,
Inorg. Chim. Acta, 1982, 66, L51; (g) G. Otiko, M. T. Razi, P. J.
Sadler, A. A. Isab and D. L. Rabenstein, J. Inorg. Biochem., 1983,
19, 227; (h) D. T. Hill, B. M. Sutton, A. A. Isab, T. Razi, P. J. Sadler,
J. M. Trooster and G. H. M. Calis, Inorg. Chem., 1983, 22, 2936;
(i) S. M. Cottrill, H. L. Sharma, D. B. Dyson, R. V. Parish and C. A.
McAuliffe, J. Chem. Soc., Perkin Trans. 2, 1989, 53; (j) M. D.
Rhodes, P. J. Sadler, M. D. Scawen and S. Silver, J. Inorg. Biochem.,
1992, 46, 129; (k) R. Bau, J. Am. Chem. Soc., 1998, 120, 9380.
13 K. Nomiya, Y. Kondoh, K. Onoue, N. C. Kasuga, H. Nagano,
M. Oda, T. Sudoh and S. Sakuma, J. Inorg. Biochem., 1995, 58, 255.
The described n = 12–14 should be corrected to n = 21–27.
14 K. Nomiya, H. Yokoyama, H. Nagano, M. Oda and S. Sakuma,
J. Inorg. Biochem., 1995, 60, 289.
15 K. Dairiki, Proc. Jpn. Soc. Immunology, 1995, 25, 316 (in Japanese).
16 J. L. Clement and P. S. Jarrett, J. Inorg. Biochem., 1993, 51, 105; P. D.
Cookson and E. R. T. Tiekink, J. Coord. Chem., 1992, 26, 313; C. S.
W. Harker, E. R. T. Tiekink and M. W. Whitehouse, Inorg. Chim.
Acta, 1991, 181, 23; P. D. Cookson and E. R. T. Tiekink, J. Chem.
Soc., Dalton Trans., 1993, 259; B. F. Hoskins, L. Zhenrong and
E. R. T. Tiekink, Inorg. Chim. Acta, 1989, 158, 7; E. R. T. Tiekink,
Z. Kristallogr., 1989, 187, 79; P. D. Cookson and E. R. T. Tiekink,
J. Crystallogr. Spectrosc. Res., 1993, 23, 231; F. Bonati, A. Burini,
B. R. Pietroni and E. Giorgini, Inorg. Chim. Acta, 1987, 137, 81.
17 K. Nomiya, N. C. Kasuga, I. Takamori and K. Tsuda, Polyhedron,
1998, 17, 3519.
Formula
M
C20H17N3PAu
527.31
C40H36N6P2Au2O
1072.64
Crystal system
Space group
a/Å
b/Å
c/Å
Orthorhombic
P212121 (no. 19)
12.689(4)
13.660(7)
10.93(1)
Monoclinic
P21/c (no. 14)
13.575(3)
11.623(3)
24.739(2)
101.35(1)
3827(1)
β/Њ
V/Å3
1894(1)
F(000)
Z
1008
4
2056
4
Dc/g cmϪ1
Crystal size/mm
No. of reflections
used for unit cell
dimension
(2θ range/Њ)
Radiation (λ/Å)
Scan mode
Scan width/Њ
Scan speed/minϪ1
2θ Range/Њ
µ/cmϪ1
1.849
0.3 × 0.2 × 0.2
18
1.861
0.3 × 0.3 × 0.3
25
(20.1–25.9)
Mo–Kα (0.71069)
ω–2θ
1.26 ϩ 0.30 tan θ
(26.6–29.1)
Mo-Kα (0.71069)
ω–2θ
0.73 ϩ 0.30 tan θ
8
6–55
78.08
9602
4
6–55
78.85
2492
2492
Total reflections
Unique reflections
9225
Observed reflections 1561 [I > 2.00σ(I)]
4609 [I > 2.00σ(I)]
0.037, 0.028
1.31
R,RЈ
0.052, 0.055
1.46
Goodness of fit
¹
2
R = Σ[|Fo| Ϫ |Fc|]/Σ|Fo|, RЈ = [Σ(w[|Fo| Ϫ |Fc|]2/[Σw(|Fo|)2]², with w = 4Fo /
[σ2(Fo )].
2
ence Fourier calculation and refined by a full-matrix least-
squares procedure using TEXSAN package.38 All non-
hydrogen atoms, except carbon atoms in the phenyl group of 1,
were refined anisotropically, and all hydrogen atoms and the
phenyl carbon atoms of 1 isotropically.
A summary of crystal data, data collection, and refinement
for 1 and 2 is given in Table 4.
18 K. Nomiya, K. Tsuda, Y. Tanabe and H. Nagano, J. Inorg.
Biochem., 1998, 69, 9.
19 K. Nomiya, K. Tsuda, T. Sudoh and M. Oda, J. Inorg. Biochem.,
1997, 68, 39.
20 P. Bishop, P. Marsh, A. K. Brisdon, B. J. Brisdon and M. F. Mahon,
J. Chem. Soc., Dalton Trans., 1998, 675.
CCDC reference number 186/1210.
21 (a) R. Narayanaswamy, M. A. Young, E. Parkhurst, M. Ouellette,
M. E. Kerr, D. M. Ho, R. C. Elder, A. E. Bruce and M. R. M.
Bruce, Inorg. Chem., 1993, 32, 2506; (b) W. B. Jones, J. Yuan,
R. Narayanaswamy, M. A. Young, R. C. Elder, A. E. Bruce and
M. R. M. Bruce, Inorg. Chem., 1995, 34, 1996.
22 M. C. Gimeno, P. G. Jones, A. Laguna, M. Laguna and R. Terroba,
Inorg. Chem., 1994, 33, 3932.
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