Solid and solution structures of ternary gold(I) complexes with triphenylphosphine and nitrogen-containing ligands

Article abstract of DOI:10.1039/a705177h

A series of gold(I) complexes [Au(PPh₃)L]ClO₄ (L = pyridine 1a, 2,6-dimethylpyridine 1b, 2,6-di-tert-butylpyridine 1c, quinoline 1d, acridine 1e, benzo[h]quinoline 1f, naphthyridine 2a, 1,10-phenanthroline 2b, 2,2′-biquinoline 2c, di

Full text of DOI:10.1039/a705177h

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Solid and solution structures of ternary gold(I) complexes with
triphenylphosphine and nitrogen-containing ligands
Megumu Munakata,*,a Sheng-Gang Yan,a Masahiko Maekawa,b Mamoru Akiyamaa and
Susumu Kitagawac
a Department of Chemistry, Kinki University, Kowakae, Higashi-Osaka, Osaka 577, Japan
b Research Institute for Science and Technology, Kinki University, Kowakae, Higashi-Osaka,
Osaka 577, Japan
c Department of Chemistry, Tokyo Metropolitan University, Minami-Ohsawa, Hachioji,
Tokyo 192-03, Japan
A series of gold() complexes [Au(PPh3)L]ClO4 (L = pyridine 1a, 2,6-dimethylpyridine 1b, 2,6-di-tert-butylpyridine
1c, quinoline 1d, acridine 1e, benzo[h]quinoline 1f, naphthyridine 2a, 1,10-phenanthroline 2b, 2,2Ј-biquinoline
2c, di-2-pyridyl ketone 2d, di-2-pyridylamine 3a or 2-(2-pyridyl)benzimidazole 3b) were prepared by reaction of L
with [Au(PPh3)(ClO4)] which was synthesized in situ. All complexes were characterized by IR, UV/VIS and 1H
NMR spectroscopy. The crystal and molecular structures of 1b, 2a and 3b were investigated by single-crystal
X-ray diffraction techniques. The gold() is co-ordinated to one nitrogen atom and one phosphine atom. Detailed
1H NMR studies suggested that linear two-co-ordinated structures persist in solution and further that all the
complexes [Au(PPh3)L]ClO4, (2a–2d), are fluxional species in which the co-ordination site of gold() rapidly
exchanges between two nitrogen atoms of the ligand.
A number of neutral gold() complexes with N-donor ligands
have been reported,1–5 whereas complexes [Au(PPh3)L]ϩ with
N-heterocyclic ligands L are rather rare.6,7 To the best of our
knowledge, only one such complex, [Au(PPh3)(qncd)]BF4
(qncd = quinuclidine) has been characterized by X-ray diffrac-
tion.8 By contrast to the trialkylphosphinegold() halides, the
stability constant of the [Au(PR3)L]ϩ complexes is generally not
as large and is dependent on the properties of the nitrogen
ligand. In this paper a series of triphenylphosphinegold() com-
plexes with nitrogen-containing ligands is prepared and charac-
terized to shed further light on the general principles governing
the bonding properties, Scheme 1. First, the preparation of
complexes 1 with pyridine and derivatives was undertaken to
understand the steric effects. Complexes 2 with bidentate lig-
ands containing two pyridine groups were prepared to explore
the ligand function of site opening and closing, and 3 with
ligands containing pyridine and benzimidazole or amine to
study the selective co-ordination of AuI to nitrogen atoms of
a multinitrogen ligand.
X
N
X
Au
N
N
Ph3P
Ph3P Au
X
1a pyridine (py)
1b 2,6-dimethylpyridine
(dmpy)
1c 2,6-di-tert-butylpyridine
(dbpy)
1d quinoline (quin)
1e acridine (acr)
1f benzo[h]quinoline (bquin)
2a 1,8-naphthyridine (napy)
2b 1,10-phenanthroline (phen)
2c 2 ,2′-biquinoline (biq)
2d di-2-pyridyl ketone (dpk)
Ph3P
Au
N
N′
3a di-2-pyridylamine (dpa)
3b 2-(2-pyridyl)benzimidazole (pbzim)
Scheme 1
Results and Discussion
Solid-state studies
and 1587 cmϪ1; this means that only one nitrogen is co-
ordinated to AuI, as indicated by the single-crystal X-ray
analysis.
(a) Infrared spectroscopy. The complexes were all prepared by
cleavage reaction of the chloride in [Au(PPh3)Cl] with AgClO4
and replacement of ClO4 in the resulting complex [Au(PPh3)-
ClO4] by ligand, equations (1) and (2). Preliminary character-
(b) Crystal structures of complexes 1b, 2a and 3b. Single
crystals suitable for single-crystal X-ray analysis were obtained
for complexes 1b, 2a and 3b. The structure of 1b is shown in
Fig. 1 and consists of the cation [Au(PPh3)(dmpy)]ϩ and a per-
chlorate anion. Selected interatomic distances and bond angles
are listed in Table 1. In the cation the gold atom is linearly co-
ordinated by PPh3 and dmpy, the P᎐Au᎐N angle being
178.8(3)Њ. The bond distances Au᎐N [2.091(13) Å] and Au᎐P
[2.233(4) Å] are similar to those in the complexes [Au-
[Au(PPh3)Cl] ϩ AgClO4 → [Au(PPh3)(ClO4)] ϩ
AgCl (↓) (1)
[Au(PPh3)(ClO4)] ϩ L → [Au(PPh3)L]ClO4
(2)
ization was done by elemental analysis. In all cases satisfactory
results for C, H and N were obtained. Infrared spectra of all
complexes showed the expected ligand and anion (ClO4
Ϫ
)
7
(PPh3)(NMe3)]ClO4 [2.108(7) and 2.231(2) Å] and [Au-
absorptions. The absorption of C᎐N of the N-ligands did not
(PPh3)(qncd)]BF4 8 [2.11(1) and 2.240(4) Å], respectively.
The molecular structure of complex 2a is shown in Fig. 2
and the bond parameters are listed in Table 2. The distances
Au᎐N(1) [2.093(13) Å] and Au᎐P [2.230(4) Å] are comparable
᎐
show significant changes upon complexation indicating that the
interaction between gold() and the nitrogen ligand is not
strong. The C᎐N absorption of 2a showed two peaks at 1602
᎐
J. Chem. Soc., Dalton Trans., 1997, Pages 4257–4262
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Table 1 Selected bond distances (Å) and angles (Њ) for complex 1b with
estimated standard deviations (e.s.d.s) in parentheses
Table 3 Selected bond distances (Å) and angles (Њ) for complex 3b with
e.s.d.s in parentheses
Au᎐P
P᎐C(7)
P᎐C(13)
N᎐C(23)
C(23)᎐C(25)
2.233(4)
Au᎐N
P᎐C(1)
N᎐C(19)
C(19)᎐C(24)
2.091(3)
Au᎐P
2.238(1)
Au᎐N(1)
P᎐C(13)
P᎐C(25)
C(1)᎐N(2)
2.075(4)
1.817(6)
1.828(6)
1.331(7)
1.813(14)
1.809(13)
1.323(22)
1.475(29)
1.803(15)
1.328(20)
1.511(27)
P᎐C(19)
C(1)᎐N(1)
C(2)᎐N(1)
1.804(6)
1.333(7)
1.388(7)
P᎐Au᎐N(1)
Au᎐P᎐C(19)
C(13)᎐P᎐C(19)
C(19)᎐P᎐C(25)
Au᎐N(1)᎐C(2)
172.4(1)
113.1(2)
106.1(3)
106.1(3)
124.9(4)
Au᎐P᎐C(13)
Au᎐P᎐C(25)
Au᎐N(1)᎐C(1)
C(1)᎐N(1)᎐C(2)
C(1)᎐N(2)᎐C(7)
113.0(2)
111.7(2)
128.7(4)
106.3(5)
108.9(5)
P᎐Au᎐N
178.8(3)
120.3(11)
118.3(16)
111.5(5)
110.1(5)
107.6(7)
Au᎐N᎐C(19)
N᎐C(19)᎐C(24)
C(19)᎐N᎐C(23)
Au᎐P᎐C(7)
C(1)᎐P᎐C(7)
C(7)᎐P᎐C(13)
119.6(11)
119.5(19)
120.1(14)
113.2(5)
107.2(6)
107.0(7)
Au᎐N᎐C(23)
N᎐C(23)᎐C(25)
Au᎐P᎐C(1)
Au᎐P᎐C(13)
C(1)᎐P᎐C(13)
Table 2 Selected bond distances (Å) and angles (Њ) for complex 2a with
e.s.d.s in parentheses
Au᎐P
2.230(4)
Au᎐N(1)
P᎐C(21)
C(1)᎐N(1)
C(8)᎐N(1)
2.093(13)
1.794(18)
1.297(19)
1.373(26)
P᎐C(11)
P᎐C(31)
C(8)᎐N(2)
1.807(11)
1.786(14)
1.338(18)
P᎐Au᎐N(1)
Au᎐P᎐C(21)
C(11)᎐P᎐C(21)
C(21)᎐P᎐C(31)
Au᎐N(1)᎐C(1)
174.3(4)
112.2(5)
105.1(9)
106.2(7)
120.3(14)
Au᎐P᎐C(11)
Au᎐P᎐C(31)
C(11)᎐P᎐C(31)
N(1)᎐C(8)᎐N(2) 116.6(14)
Au᎐N(1)᎐C(8) 119.1(8)
C(7)᎐N(2)᎐C(8) 117.2(15)
113.9(5)
112.7(6)
106.2(7)
C(1)᎐N(1)᎐C(8) 119.1(8)
Fig. 2 Structure of the cation [Au(PPh3)(napy)]ϩ 2a. Details as in
Fig. 1
Fig. 1 Structure of the cation [Au(PPh3)(dmpy)]ϩ in complex 1b with
hydrogen atoms omitted. The thermal ellipsoids correspond to 50%
probability
with those of 1b. However, the Au ؒ ؒ ؒ N(2) distance of 3.06 Å
indicates no co-ordination bond and the napy ligand behaves as
a monodentate ligand in 2a.
In complex 3b the most important feature is the co-
ordination of the imidazole group to AuI rather than the pyri-
dine group (Fig. 3). The Au᎐N (imidazole) bond distance of
2.075(4) Å (Table 3) is slightly shorter than the Au᎐N (pyridine)
distances in 1b and 2a. Thus gold() is more strongly co-
ordinated to imidazole than to pyridine. The P᎐Au᎐N angles in
the two-co-ordinate gold complexes 1b, 2a and 3b are not equal
and deviate from linearity in the order 3b [172.4(1)] < 2a
[174.3(4)] < 1a [178.8(3)Њ]. This is obviously related to the
steric effect of the N-ligand. In fact the P᎐Au᎐N angle
[179.3(2)Њ] in [Au(PPh3)(NMe3)]ϩ having a NMe3 ligand of
small steric hindrance is almost linear.
Fig. 3 Structure of the cation [Au(PPh3)(pbzim)]ϩ in complex 3b.
Details as in Fig. 1
the tertiary phosphine complexes [Au(PR3)(N-ligand)]ϩ (N-
ligand = bipyridyl,9 pyrimidines,10 or imidazole11) are stable,
whereas chloro(piperidine)gold() is stable only at Ϫ20 ЊC and
rapidly disproportionates in air.12
Solution studies
(a) 1H NMR spectroscopy. Binary gold() complexes with
N-ligands are generally unstable and become stable only when
a soft ligand such as PPh3 is also co-ordinated. For example,
The stability of these complexes is thus a reflection of the
donor properties of the N-ligand both from steric and elec-
1
tronic effects. The H NMR spectra of 1a, 1b and 1c were
4258
J. Chem. Soc., Dalton Trans., 1997, Pages 4257–4262

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3
2
Me
Me
N
N
N
4
N
6
5
2
3
3
5
3
5
5
8
4
4
4
6
7
py
quin
dmpy
dbpy
3
2
3
3
2
2
4
4
3
2
4
1
N
N
4
N
N
5
5
N
6
6
10
5
N
5
8
7
9
7
7
6
9
8
7
6
8
acr
bquin
phen
napy
6
7
5
5
6
4
5
4
5
8
4
7
4
3
6
3
3
6
N
N
N
N
N
N
N
N
N
O
HN
3′
4′
6′
5′
pbzim
biq
dpk
dpa
Scheme 2
measured at 23 and Ϫ90 ЊC, respectively; the ligand structures
with atom numbering are shown in Scheme 2. The resonances
of both the phenyl and N-ligand protons of 1a and 1b were
shifted downfield with no significant difference between 23 and
Ϫ90 ЊC. On the other hand the complex [Au(PPh3)(dbpy)]ClO4
1c at Ϫ60 ЊC in CDCl3–(CD3)2CO (8:12 v/v) exhibits 1H NMR
resonances of both free and co-ordinated dbpy. The intensity
ratio of the proton resonances indicates ca. 80% dissociation of
1c in solution. For comparison, the spectra of 1d, 1e and 1f
were obtained at 23, Ϫ60 and Ϫ90 ЊC respectively. The 1H NMR
resonances of the p-protons of the nitrogen ligands in 1d, 1e
Fig. 4 Proton NMR spectra for complexes 2a, 2b and 2c at 270 MHz
and 23, Ϫ60 and Ϫ90 ЊC (× represents the signal of CHCl3 contained as
an impurity in CDCl3)
N*
N
N
N
Ph3P Au N*
N
and 1f shift downfield, and the co-ordination shifts (δcomplex
Ϫ
δfree) are 0.63 (H4), 0.80 (H9) and 0.05 ppm (H4) at 23 ЊC. Large
co-ordination shifts were also observed for H8 of 1d (0.68),
H4,5 of 1e (0.96) and H10 of 1f (0.48 ppm) because of the
hydrogen–gold interaction.
Ph3P Au
Ph3P Au
A
B
C
1
Interestingly, the H NMR resonances of quinoline in com-
Scheme 3
plex 1d become broader as the temperature decreases, indicat-
ing that the ligand exchange takes place in solution, equation
(3). However in the case of acridine, in which the electron pair
13
napy was observed in [Hg2(napy)2][ClO4]2 (Hg᎐N 2.03 Å,
non-bonding distance 2.78 Å), but the phen in [Hg2-
(phen)(NO3)2]14 is clearly bidentate with Hg᎐N 2.30 and 2.48 Å.
The properties of site exchange (or fluxional behavior) of N-
ligands in square-planar and octahedral complexes in solution
have been well studied. For example, [Cr(CO)5(napy)],15 [Mn-
[Au(PPh3)(quin)]ClO4
[Au(PPh3)(ClO4)] ϩ quin (3)
of the nitrogen can be delocalized, no broadening of reson-
ances for complex 1e was observed due to the related strong
interaction of AuI with acridine. For 1f a rapid ligand exchange
was observed since the proton resonances of benzo[h]quinoline
broadened at Ϫ60 ЊC, and the co-ordination shift of the p-
hydrogen is much less than that of 1e, indicating that the second
benzene ring in the 7,8 position has a great steric effect on the
co-ordination of AuI to the nitrogen of quinoline. From the 1H
NMR studies the co-ordination shifts of 1a–1f were largest at
the para position to the nitrogen of the ligand system. The
stability decreases in the order 1a > 1b > 1c for the monocyclic
nitrogen ligand owing to the steric hindrance in these complexes
and 1e > 1d ӷ 1f for the multiring ligands.
17
(η1-napy)(η2-napy)(CO)3]ClO4,16 cis-[PtCl(PPh3)2(napy)]BF4
and [AuMe3(napy)]Cl18 exhibit site exchange in solution.
However, no site exchange of a linear complex has been found
so far. The 1H NMR spectrum of 2a exhibits a downfield shift
compared with free napy and basically is similar to that of
complexes 1c, but the narrow resonances of H2 and H7 at 23 ЊC
broaden at low temperature (Ϫ90 ЊC) as shown is Fig. 4(a)
and 4(b), indicating that the co-ordination site of napy rapidly
exchanges in solution. The site-exchange mode is represented in
Scheme 3. As reported by Kang et al.,19 the intermediate B is
very unstable due to the unfavorable orientation of the nitrogen
lone pairs of napy, when compared with that in 2,2Ј-bipyridine
and 1,10-phenanthroline. The larger angle of Au᎐N(1)᎐C(8) for
2a also indicates that intermediate B is higher in energy, because
the co-ordination of the lone-pair electron of the second nitro-
gen in napy to Au requires the bending of the Au᎐N(1)᎐C(8)
angle (Table 2).
The co-ordination chemistry of 1,8-naphthyridine and its
2,7-methyl derivative has been extensively studied in relation to
a variety of metal centers. These heterocycles are of consider-
able interest as ligands because they can act in bi- and mono-
dentate manners. For example, a monodentate behavior of
J. Chem. Soc., Dalton Trans., 1997, Pages 4257–4262
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The H2 and H9 NMR signals of [Au(PPh3)(phen)]ϩ 2b
at 23 ЊC in CDCl3–(CD3)2CO appeared at δ 9.24 as a single
resonance. Interestingly, as the temperature was decreased to
Ϫ60 ЊC this single resonance split into two at δ 9.28 and 9.07
[Fig. 4(c) and 4(d)]. This means the site-exchange reaction also
occurs in solution for 2b through the transition state B. As
indicated in Fig. 4(e) and 4(f ), a splitting of the resonances of
2c was also observed at Ϫ90 ЊC. This means that site exchange
is taking place in solution and the intermediate B may be
favorable due to the greater flexibility of the ligand biq.
ping, Ph), 8.11 (2 × 1 H, H3,5), 8.49 (1 H, H4) and 9.17 (2 × 1 H,
H2,6) (Found: C, 43.21; H, 3.09; N, 2.10. Calc. for C23H20Au-
ClNO4P: C, 43.31; H, 3.16; N, 2.20%).
[Au(PPh3)(dmpy)]ClO4 1b. A acetone solution (1 cm3) of
AgClO4 (24.9 mg, 0.12 mmol) was added dropwise to a stirred,
cooled (0 ЊC) chloroform solution (3 cm3) of [Au(PPh3)Cl] (59.4
mg, 0.12 mmol) under an argon atmosphere. The AgCl precipi-
tated was filtered off and the colorless solution was added to
2,6-dimethylpyridine (0.14 cm3, 0.12 mmol) in chloroform (3
cm3) and stirred for 30 min at room temperature. The colorless
solution of [Au(PPh3)(ClO4)] was sealed in a glass tube under
an argon atmosphere. After standing for 3 d at 5 ЊC colorless
As for complex 2d with one carbonyl group between the two
1
pyridines, the H NMR resonances show a downfield shift. It
would be of interest to see whether the gold() of 2d is co-
ordinated to one nitrogen of dpk in a linear geometry or to two
nitrogens in a trigonal geometry, since the intermediate is six
crystals were obtained (60%). IR, ν /cmϪ1: 1580w (νC᎐N), 1444s,
᎐
1437s (νP᎐Ph), 1145vs, 1119vs, 1105vs and 1094vs (νCl᎐O). 1H
NMR [23 ЊC, (CD3)2CO, 200 MHz]: δ 3.08 (2 × 3 H, for 2,6-
Me), 7.70–7.73 (overlapping, Ph), 7.76 (2 × 1 H, H3,5) and 8.14
(1 H, H4) (Found: C, 45.02; H, 3.58; N, 2.08. Calc. for
C25H24AuClNO4P: C, 45.10; H, 3.63; N, 2.10%).
membered and the C᎐N solid-state IR absorption showed only
᎐
one peak at 1584 cmϪ1. Unfortunately we have no single-crystal
structure data to support it.
The 1H NMR spectrum of complex 3a was obtained in
(CD3)2CO–CDCl3 (1:1) at 23 ЊC and showed a downfield shift.
The signal of the NH proton became very weak, indicating that
a bond from AuI to NH is formed. In this case gold() is prob-
ably bonded only to this nitrogen atom. A slight broadening of
the 1H NMR resonances of 3b at Ϫ90 ЊC in (CD3)2CO indicat-
ing site exchange. The resonances of all the protons of the 2-(2-
pyridyl)benzimidazole show a downfield shift except that of
proton H6 which is far from the center of co-ordination and
has a 0.1 ppm upfield shift. It is worth noting that almost all of
[Au(PPh3)(dbpy)]ClO4 1c. Colorless crystals (10%) of com-
plex 1c were obtained in a similar procedure to that for 1b,
using [Au(PPh3)(ClO4)] (44.67 mg, 0.08 mmol), and 2,6-di-tert-
butylpyridine (0.18 cm3, 0.08 mmol). IR, ν /cmϪ1: 1587w (νC᎐N),
᎐
1447s, 1440s (νP᎐Ph), 1146vs, 1120vs, 1105vs and 1095vs (νCl᎐O).
1H NMR [Ϫ60 ЊC, CDCl3–(CD3)2CO (80:1, v/v), 270 MHz]:
δ 1.64 (6 × 3 H, for 2,6-But), 7.50–7.54 (overlapping, Ph), 7.87
(2 × 1 H, H3,5) and 8.50 (1 H, H4) (Found: C, 48.86; H, 4.68; N,
1.84. Calc. for C31H36AuClNO4P: C, 49.64; H, 4.84; N, 1.87%).
1
the H NMR spectra discussed above show downfield shifts.
This is of interest for the co-ordination chemistry of gold()
since it was previously reported that the bonding of AuI to
nitrogen resulted in upfield shifts.20
[Au(PPh3)(quin)]ClO4 1d. Colorless crystals (21%) of com-
plex 1d were obtained in a similar procedure to that for 1b,
using [Au(PPh3)(ClO4)] (44.67 mg, 0.08 mmol) and quinoline
In summary, the co-ordination of gold() to nitrogen donor
atoms in complexes 1a–1f is affected by the steric effect of sub-
stituted groups in the N ligand; the stability is in the order
1a > 1b > 1c for monoring ligands and 1e > 1d > 1f for two-
ring ligands. In the solid state the favored co-ordination geom-
etry of gold() complexes with PPh3 and a N-ligand is two-co-
ordinate linear. Exchange of gold() at nitrogen co-ordination
sites in 2a–2d was found in solution. For 2b and 2c an
unstrained five-membered ring transition state results in more
rapid exchange of gold() between the two ligating nitrogens
than that of the strained four-membered ring of 2a.
(0.095 cm3, 0.8 mmol). IR, ν /cmϪ1: 1586w (νC᎐N), 1444s, 1440s
᎐
1
(νP᎐Ph), 1145vs and 1091vs (νCl᎐O). H NMR [23 ЊC, (CD3)2CO,
270 MHz]: δ 7.70–7.75 (overlapping, Ph), 7.82 (1 H, t, H3), 7.94
(1 H, t, H6), 8.04 (1 H, t, H7), 8.27 (1 H, d, H5), 8.73 (1 H, d, H8),
8.87 (1 H, d, H4) and 9.34 (1 H, d, H2) (Found: C, 46.89; H,
3.11; N, 2.06. Calc. for C27H22AuClNO4P: C, 47.14; H, 3.22; N,
2.04%).
[Au(PPh3)(acr)]ClO4 1e. Colorless crystals (50%) of complex
1e were obtained in a similar manner to that for 1b, using
[Au(PPh3)(ClO4)] (33.51 mg, 0.06 mmol) and acridine (10.8 mg,
0.06 mmol). IR, ν /cmϪ1: 1620w (νC᎐N), 1444s, 1437s (νP᎐Ph),
᎐
1
1125vs, 1115vs, 1105vs and 1094vs (νCl᎐O). H NMR [23 ЊC,
Experimental
(CD3)2CO, 270 MHz]: δ 7.73–7.76 (overlapping, Ph), 7.90 (1 H,
t, H2,7), 8.26 (1 H, t, H3,6), 8.54 (1 H, d, H1,8), 9.14 (1 H, d, H4,5
)
Preparations were carried out using standard Schlenk tech-
niques under an argon atmosphere. All solvents were dried by
standard methods before use. The HAuCl4ؒH2O was obtained
from Aldrich Chemicals and used to prepare the [Au(PPh3)Cl]
by the literature procedure.21 All nitrogen ligands (Wako Pure
Chemical Co., Japan) were used without further purification,
except for the bis(imidazol-2-yl)methane which was synthesized
according to the literature.22 Infrared spectra were measured as
KBr discs on a JASCO FT/IR-8000 spectrometer, and 1H NMR
spectra on JEOL FX 200 FT and GSX 270 FT spectrometers
respectively. CAUTION: AgClO4ؒH2O is potentially explosive.
and 9.83 (1 H, d, H9) (Found: C, 50.06; H, 3.17; N, 1.86. Calc.
for C31H24AuClNO4P: C, 50.46; H, 3.28; N, 1.90%).
[Au(PPh3)(bquin)]ClO4 1f. Colorless crystals (50%) of com-
plex 1f were obtained in a similar procedure to that for 1b, using
[Au(PPh3)(ClO4)] (33.51 mg, 0.06 mmol) and benzo[h]quino-
line (10.8 mg, 0.06 mmol). IR, ν /cmϪ1: 1590w (νC᎐N), 1437s
᎐
1
(νP᎐Ph), 1144vs and 1090vs (νCl᎐O). H NMR [Ϫ60 ЊC, CDCl3–
(CD3)2CO (80:1, v/v), 270 MHz]: δ 7.52–7.58 (overlapping,
Ph), 7.92–8.10 (6 × 1 H, overlapping, H3,6,7,8,9,10), 8.76 (1 H, d,
H5), 9.10 (1 H, s, H4) and 9.29 (1 H, s, H2) (Found: C, 50.12; H,
3.36; N, 1.78. Calc. for C31H24AuClNO4P: C, 50.46; H, 3.28; N,
1.90%).
Syntheses
[Au(PPh3)(py)]ClO4 1a. Chloro(triphenylphosphine)gold()
(69.3 mg, 0.14 mmol) was dissolved in dry tetrahydrofuran (2
cm3) at 0 ЊC and a tetrahydrofuran (1 cm3) solution of AgClO4
(29.0 mg, 0.14 mmol) was added. After filtration, a tetrahydro-
furan (1 cm3) solution of pyridine (0.36 cm3, 4.2 mmol) was
added, stirred for 30 min at 0 ЊC, and then transferred to a glass
tube (10 mm diameter) and sealed. After standing for 2 d at
0 ЊC a colorless crystal was obtained (20%). IR, ν /cmϪ1: 1609w
(νC᎐N), 1444s, 1439s (νP᎐Ph), 1145vs, 1114vs and 1091vs (νCl᎐O).
1H NMR [23 ЊC (CD3)2CO, 200 MHz]: δ 7.40–7.71 (overlap-
[Au(PPh3)(napy)]ClO4 2a. A solution of AgClO4 (12.5 mg,
0.06 mmol) in thf (1 cm3) was added dropwise to a solution
of [Au(PPh3)Cl] (29.7 mg, 0.06 mmol) in thf (2 cm3), stirred at
0 ЊC for 10 min, and then the resulting solution of [Au(PPh3)-
(ClO4)] was filtered. The filtrate was added to a solution of 1,8-
naphthyridine (7.8 mg, 0.06 mmol) in thf (1 cm3), stirred for 30
min, and filtered. The colorless filtrate was transferred to a glass
tube (10 mm diameter) and layered with diethyl ether (1.0 cm3)
as a diffusion solvent. After standing for 5 d at 5 ЊC colorless
4260
J. Chem. Soc., Dalton Trans., 1997, Pages 4257–4262

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Table 4 Crystal data and structure determination parameters for complexes 1b, 2a and 3b
1b
2a
3b
C25H24AuClNO4P
665.87
C26H21AuClN2O4P
688.87
C30H23AuClN3O4P
752.92
Formula
M
Orthorhombic
P212121
11.431(2)
19.984(8)
10.845(4)
Triclinic
P1
Monoclinic
P21/a
10.788(4)
8.373(3)
31.205(3)
Crystal system
Space group
a/Å
b/Å
c/Å
α/Њ
β/Њ
11.587(5)
12.805(5)
9.590(4)
93.52(5)
108.3(8)
67.69(4)
1246.5
98.24(2)
γ/Њ
U/Å3
2477.4
4
61.10
1300.0
1.790
Mo-Kα (0.710 73)
0.40 × 0.20 × 0.20
8
2θ (45)
2639
0.062
0.066
2789(1)
4
118.66
1472.0
1.795
Cu-Kα (1.541 78)
0.35 × 0.40 × 0.40
8
2θ (120)
3776
0.032
0.045
2
Z
µ/cmϪ1
60.77
666.0
1.840
Mo-Kα (0.739 30)
0.15 × 0.20 × 0.35
8
2θ (45)
4939
0.078
0.090
F(000)
Dc/g cmϪ3
Radiation (λ/Å)
Crystal dimensions/mm
Scan speed/Њ minϪ1
Scan mode (2 θmax/Њ)
Reflections used
Ra
RЈb
¹
a Σ Fo| Ϫ |Fc /Σ|Fo|. b [Σ(|Fo| Ϫ |Fc|)2/Σ|Fo|2]².
brick crystals were isolated (12%). IR, ν /cmϪ1: 1602w (νC᎐N),
1587w, 1445s, 1439s (νP᎐Ph), 1148vs, 1120vs, 1105 and 109᎐1vs
(νCl᎐O). 1H NMR [23 ЊC, (CD3)2CO, 270 MHz]: δ 7.71–7.85
[Au(PPh3)(dpa)]ClO4 3a. Di-2-pyridylamine (27.4 mg,
1.6 × 10Ϫ4 mol) in thf (5 cm3) was added to a solution of [Au-
(PPh3)ClO4)] (1.6 × 10Ϫ4 mol) prepared as for 1a in thf (4 cm3).
White precipitates were quickly formed and the colorless reac-
tion mixture was stirred for 30 min at room temperature. The
resulting yellow solution was filtered and yellow crystals (34%)
were obtained by evaporating this filtrate. IR, ν /cmϪ1: 3064w
(νH᎐N), 1610vs, 1599m (νC᎐N), 1441m, 1431m (νP᎐Ph), 1105vs and
(overlapping, Ph), 8.11 (2 × 1 H, t, H3,6), 9.03 (2 × 1 H, d, H4,5
)
and 9.53 (2 × 1 H, d, H2,7) (Found: C, 45.28; H, 3.24; N, 4.17.
Calc. for C26H21AuClN2O4P: C, 45.33; H, 3.07; N, 4.07%).
[Au(PPh3)(phen)]ClO4 2b. Crystals of complex 2c were
obtained by pouring a solution (1 cm3) of [Au(PPh3)(ClO4)]
(1.6 × 10Ϫ5 mol), prepared following the procedure as for 2a in
chloroform–acetone (50:1, v/v), into a glass tube (10 mm
diameter) and adding on top of it benzene (5 cm3). Then a
dilute solution (1 cm3) of 1,10-phenanthroline (2.88 mg,
1.6 × 10Ϫ5 mol) in acetone was added gently to avoid possible
mixing. The glass tube was sealed and after standing at room
temperature for 2 weeks yellow brick crystals (21%) grew in the
1
1093vs (νCl᎐O). H NMR [23 ЊC, (CD3)2CO–CDCl3 (1:1, v/v),
270 MHz]: δ 7.09 (2 × 1 H, br, H5), 7.58–7.60 (overlapping of
Ph with H3), 7.88 (2 × 1 H, t, H4), 8.34 (2 × 1 H, br, H6) and
9.67 (1 H, very weak, N᎐H) (Found: C, 46.10; H, 3.25; N, 5.68.
Calc. for C28H24AuClN3O4P: C, 46.07; H, 3.31; N, 5.76%).
[Au(PPh3)(pbzim)]ClO4 3b. 2-(2-Pyridyl)benzimidazole (15.6
mg, 8.0 × 10Ϫ5 mol) in chloroform (5 cm3) was added to a solu-
tion of [Au(PPh3)(ClO4)] (8.0 × 10Ϫ5 mol) prepared as for 1a in
chloroform–acetone (1:1 v/v, 5 cm3) and stirred for 30 min at
room temperature. The brown filtrate was transferred to a glass
tube and layered with n-pentane as a diffusion solvent. After
standing for 1 month at 5 ЊC brown crystals were isolated
buffer zone. IR, ν /cmϪ1: 1620w (νC᎐N), 1439s, 1433s (νP᎐Ph),
᎐
1
1143vs, 1118vs, 1102vs and 1087vs (νCl᎐O). H NMR [23 ЊC,
CDCl3–(CD3)2CO (50:1, v/v), 270 MHz]: δ 7.48–7.52 (over-
lapping, Ph), 7.68–7.84 (2 × 1 H, br, H3,8), 7.95 (2 × 1 H, s,
H5,6), 8.47 (2 × 1 H, br, H4,7) and 9.24 (2 × 1 H, br, H2,9) (Found:
C, 48.23; H, 3.08; N, 3.63. Calc. for C30H23AuClN2O4P: C,
48.76; H, 3.14; N, 3.79%).
(26%). IR, ν /cmϪ1: 1595w (νC᎐N), 1441m, 1439m (νP᎐Ph), 1144vs,
᎐
1103vs (νCl᎐O). 1H NMR [Ϫ90 ЊC, (CD3)2CO, 270 MHz]: δ 7.63
(1 H, H4,7), 7.83 (Ph), 7.89 (1 H, H5Ј), 7.91 (1 H, H5), 7.94 (1 H,
H6), 8.32 (1 H, H4Ј), 8.52 (1 H, H3Ј), 8.68 (1 H, H6Ј) and 14.68
(1 H, NH) (Found: C, 47.41; H, 3.11; N, 5.38. Calc. for
C30H23AuClN3O4P: C, 47.86; H, 3.08; N, 5.58%).
[Au(PPh3)(biq)]ClO4 2c. 2,2Ј-Biquinoline (20.5 mg, 10Ϫ5 mol)
in thf (5 cm3) was added to a solution of [Au(PPh3)(ClO4)]
(8.0 × 10Ϫ5 mol) prepared as for 2a in thf (3 cm3) and stirred for
30 min. A yellow crystal of 2d was obtained by slowly evaporat-
ing the reaction mixture. IR, ν /cmϪ1: 1612w (νC᎐N), 1434m,
1431m (νP᎐Ph), 1095vs, 1085vs and 1082vs (νCl᎐O)᎐. 1H NMR
[Ϫ90 ЊC, (CD3)2CO, 270 MHz]: δ 7.70–7.75 (overlapping, Ph),
8.32 (2 × 1 H, d, H6), 8.42 (2 × 1 H, t, H7), 9.04–9.10 (2 × 1 H,
overlapping of H5 and H8), 9.17 (2 × 1 H, d, H4) and 9.75
(2 × 1 H, d, H3) (Found: C, 53.26; H, 3.15; N, 3.38. Calc. for
C36H27AuClN2O4P: C, 53.05; H, 3.34; N, 3.44%).
Crystallography
Diffraction data for complexes 1b, 2a and 3b were obtained on
a Rigaku AFC-6B four-circle diffractometer at ambient tem-
perature. Experimental details are included in Table 4. Their
structures were solved by the heavy-atom method and refined
anisotropically for non-hydrogen atoms by block-diagonal
least-squares calculations. Atomic scattering factors and
anomalous dispersion terms were taken from ref. 23. Hydrogen
atoms were included in the last cycle; their positions were
obtained from Fourier-difference synthesis, and their thermal
parameters were assumed to be isotropic. The final Fourier-
difference maps were featureless. The calculations were carried
out on the FACOM 780 computer at the Data Processing
Center of Kyoto University by using the program system
KPPXRAY.24
[Au(PPh3)(dpk)]ClO4 2d. White solids (36%) of complex 2d
were obtained in a similar procedure to that for 2a, using [Au-
(PPh3)(ClO4)] (67.02 mg, 0.12 mmol) and di-2-pyridyl ketone
(22.1 mg, 0.12 mmol). IR, ν /cmϪ1: 1689m (νC᎐O), 1584w (νC᎐N),
᎐
᎐
1445s, 1439s (νP᎐Ph), 1114vs, 1105vs and 1094vs (νCl᎐O). 1H NMR
[23 ЊC, (CD3)2CO, 270 MHz]: δ 7.60–7.64 (overlapping, Ph),
7.96 (1 H, br, H5), 8.34–8.41 (2 × 1 H, m, H3,4) and 9.01 (1 H,
br, H6) (Found: C, 46.59; H, 3.39; N, 3.29. Calc. for C29H23-
AuClN2O5P: C, 46.89; H, 3.12; N, 3.77%).
CCDC reference number 186/703.
J. Chem. Soc., Dalton Trans., 1997, Pages 4257–4262
4261

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11 F. Bonati, M. Felici, B. R. Pietroni and A. Burini, Gazz. Chim. Ital.,
Acknowledgements
1982, 112, 5.
This work was partially supported by a Grant-in-Aid for
Science Research [Nos. 08231267 (priority areas) and 08454214]
from the Ministry of Education, Science and Culture in Japan.
We thank Kinki University for financial support (No. 9626).
12 J. J. Guy, P. G. Jones, M. J. Mays and G. M. Sheldrick, J. Chem.
Soc., Dalton Trans., 1977, 8.
13 J. C. Dewan, D. L. Kepert and A. H. White, J. Chem. Soc., Dalton
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16 M. J. Bermejo, J. I. Ruiz, X. Solans and J. Vinaixa, Inorg. Chem.,
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Received 18th July 1997; Paper 7/05177H
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J. Chem. Soc., Dalton Trans., 1997, Pages 4257–4262