Luminescent gold(I) supermolecules with trithiocyanuric acid. Crystal structure, spectroscopic and photophysical properties

Article abstract of DOI:10.1039/a703891g

The first example of an ordered array of Au₆ clusters with trithiocyanuric acid, [(LAu)(AuPPhMe₂)₂]₂ (H₃L = trithiocyanuric acid), is prepared and characterized by X-ray crystallography; it has a two-dimensional structure via intermolecular Au^I...Au^I interactions and possesses photoluminescence properties; the ability of trithiocyanuric acid to act as a bridging ligand for molecular assembly of two-dimensional polymeric solids is demonstrated.

Full text of DOI:10.1039/a703891g

View Article Online / Journal Homepage / Table of Contents for this issue
Luminescent gold(i) supermolecules with trithiocyanuric acid. Crystal
structure, spectroscopic and photophysical properties
Biing-Chiau Tzeng,a Chi-Ming Che*a and Shie-Ming Pengb
a Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong
b Department of Chemistry, Natonal Taiwan University, Taipei, Taiwan
The first example of an ordered array of Au6 clusters with
trithiocyanuric acid, [(LAu)(AuPPhMe2)2]2 (H3L = trithio-
cyanuric acid), is prepared and characterized by X-ray
crystallography; it has a two-dimensional structure via
intermolecular AuI···AuI interactions and possesses photo-
luminescence properties; the ability of trithiocyanuric acid
to act as a bridging ligand for molecular assembly of two-
dimensional polymeric solids is demonstrated.
isolobal to a proton. A reaction scheme which rationalizes the
formation of the Au6 supermolecule is shown in Scheme 1.
Recently, the gold(i) complexes of two tridentate bridging
ligands,
1,3,5-tris(diphenylphosphino)benzene4b
and
C(10)
Molecular materials composed of discrete metal clusters
arranged in extended structures are useful model systems for
understanding surface chemistry and catalysis, but the synthesis
of such materials is usually serendipitous. Herein we show that
AuI···AuI interactions can provide a driving force for self-
assembly of such molecular solids,1–6 as well as the first
example of an ordered array of Au6 clusters arranged in a two-
dimensional structure via intermolecular AuI···AuI interactions.
While examples of one-dimensional gold(i) chains are not
uncommon in the literature,1a,2b,4–6 gold(i) solids with two-
dimensional structures are rare.1b
C(11)
C(5)
C(9)
P(2)
C(6)
C(8)
Au(3)
S(3)
S(2)
S(1)
C(7)
Au(1)
P(1)
C(2)
C(4)
N(3)
Au(2)
N(1)
Au(2)
C(1)
C(3)
Au(1)
P(2)
S(1)
N(2)
S(2)
S(3)
Au(3)
P(1)
C(13)
C(14)
C(15)
C(12)
Complexes L(AuPPh3)3 1 and L(AuPPhMe2)3 2 were
prepared by treating AuCl(PPh3) and AuCl(PPhMe2) respec-
tively with a methanolic solution of H3L (H3L = trithiocyanuric
acid) and NaOMe. Slow diffusion of diethyl ether into a
C(19)
C(18)
C(17)
C(16)
CH2Cl2–MeOH solution of complex
2 gave [(LAu)-
Fig. 1 A perspective view of complex 3 (bond lengths in Å, angles in °):
Au(1)···Au(3) 2.987(2), Au(1)···Au(3A) 2.964(2), Au(3)···Au(3A) 3.347(3),
Au(1)–S(1) 2.279(9), Au(1)–S(2) 2.280(9), Au(2)–P(1) 2.234(10), Au(2)–
S(3) 2.310(10), Au(3)–P(2) 2.210(11), Au(3)–N(1) 2.094(22); S(1)–Au(1)–
S(2) 168.1(3), S(3)–Au(2)–P(1) 174.7(5), P(2)–Au(3)–N(1) 160.4(7)
(AuPPhMe2)2]2 3 with low solubility.†
Complexes 1 and 3 have been characterized by X-ray
crystallography. The structure of complex 1 features a triazine
with three bent S–Au–PPh3 appendages pointing away from
each other. This is similar to that of the reported
[{CSAu(PPh3)}6] supermolecule,2c whereas there is no inter-
molecular close contact of the gold(i) atoms in both complexes.
Presumably, this is due to the steric hindrance provided by the
AuPPh3+ units.
Au(2)
Au(2)
A perspective view of complex 3 and its extended two-
dimensional structure are shown in Figs. 1 and 2, respectively.
Complex 3 is a hexanuclear gold(i) supermolecule with a
crystallographic centre of inversion at the centre of the
12-membered ring metallocycle. Four gold(i) centres are
arranged in the form of a parallelogram with AuI···AuI distances
of 2.964(2) and 2.987(2) Å, and a long transannular AuI···AuI
separation of 3.347(3) Å. A similar arrangement of Au4 has
been found in [{Au2(C6H4S2-1,2)(PEt3)}2]2d and [Au4(m-
S2C6H3Me)2(PEt3)2].7 Notably, there is an intermolecular
AuI···AuI close contact of 3.130(2) Å resulting in a novel two-
dimensional structure with the Au6 supermolecule as the
repeating unit. One recent novel example is [LA(AuCl)4]H [LA
Au(2)
Au(1)
Au(1)
Au(3)
Au(3)
Au(3)
Au(3)
Au(2)
Au(1)
Au(1)
Au(2)
Au(2)
Au(1)
Au(2)
Au(3)
Au(3)
Au(1)
Au(2)
Au(2)
Au(2)
Au(1)
=
1,4,8,11-tetrakis(diphenylphosphinomethyl)-1,4,8,11-tetra-
Au(1)
Au(3)
azacyclotetradecane].1b The intermolecular AuI···AuI sepa-
Au(3)
Au(3)
ration in complex 3 is comparable to related values in one- and
Au(3)
Au(1)
two-dimensional gold(i) solids such as 3.104(1)
Å
in
[Au2(C·CPh)2(m-
in [Au2(p-
p-thiocresol; dpppn 1,5-
Another important
Au(1)
[LA(AuCl)4]H,1b
3.174(1)
Å
in
5a
C·NBut2C6H2N·C]H
tc)2(dpppn)]H [p-tc
and 3.200(1)
Å
Au(2)
Au(2)
=
=
bis(diphenylphosphino)pentane].6b
Fig. 2 An extended two-dimensional structure of complex 3 with
intermolecular Au···Au distances of 3.130(2) Å (the phenyl and methyl
groups are omitted for clarity)
structural feature is coordination of Au(PPhMe2)+ units to one
of the nitrogen atoms in each of the triazine rings, which is
Chem. Commun., 1997
1771

View Article Online
PPhMe2Au
S
N
S
S AuPPhMe2
Footnotes and References
* E-mail: cmche@hkucc.hku.hk
N
N
2
† [L(AuPPh3)3] 1: the reaction of Na3L [61 mg, obtained from H3L (44 mg)
and NaOMe (41 mg) in MeOH (25 ml)] with Au(PPh3)Cl (148 mg) in
CH2Cl2–MeOH (1:1, 50 ml) at room temp. for 4 h gave a pale-yellow solid
which was recrystallized by diffusion of diethyl ether into CH2Cl2–dmf.
AuPPhMe2
–2 PPhMe2
Pale yellow crystals of [L(AuPPh3)3] were obtained in ca. 80% yield. Its 31
P
NMR spectrum recorded in CDCl3 shows a singlet at d 37.01. Anal. Calc.:
C, 44.07; H, 2.90; N, 2.71. Found: C, 44.28; H, 2.74; N, 2.57%. FAB:
{[L(AuPPh3)3]}, m/z = 1552, 40%.
Au
S
S
Me2PhP
AuPPhMe2
N
Au
N
N
N
N
[L(AuPPhMe2)3] 2: It was similarly prepared to give a pale-yellow solid
in ca. 75% yield, and its 31P NMR spectrum recorded in CDCl3 shows a
singlet at d 10.78. Anal. Calc.: C, 27.48; H, 2.80: N, 3.56. Found: C, 27.25;
H, 2.64; N, 3.27% FAB: {[L(AuPPhMe2)3]}, m/z = 1180, 80%.
[(LAu)(AuPPhMe2)2]2 3: slow diffusion of diethyl ether into a CH2Cl2–
dmf solution of complex 2 gave yellow crystals in ca. 40% yield. Anal.
Calc.: C, 21.88; H, 2.11; N, 4.03. Found: C, 22.13; H, 2.34; N, 3.77% FAB:
{[(LAu)(AuPPhMe2)2]2}, m/z = 2082, 15%.
S
N
S
Me2PhPAu
Au
Scheme 1
Au
PPhMe2
S
S
Crystal data: 1·2C3H7NO: Au3C63H59Au3N5O2P3S3, M = 1698.18,
[C6H3(C·C)3]325b are shown to form interesting one-dimen-
sional polymeric solids via AuI···AuI interactions. Here, the
trithiocyanuric acid demonstrates its ability to act as a bridging
ligand for molecular assembly of two-dimensional polymeric
solids.
monoclinic, space group P21/n,
c = 19.245(6) Å, b = 92.07(3)°, U = 6267(3) Å3, Z = 4, Dc = 1.800
g cm23, m(Mo-Ka) 71.90 cm21, F(000)
3249. Intensity data
a = 13.993(4), b = 23.289(6),
=
=
were collected on Enraf-Nonius CAD4 diffractometer with graphite-
monochromated Mo-Ka radiation (l = 0.7107 Å), 8173 unique reflection
(2q < 45°) were measured 4828 with I > 2s(I) were used in the refinement.
Refinement of positional and anisotropic thermal parameters for all non-
hydrogen atoms (713 variables) converged to R = 0.047 and Rw = 0.043.
The final Fourier difference map showed residual extrema in the range of
The absorption spectra of complexes 1 and 2 measured in
CH2Cl2 are very similar. As shown in Fig. 3 (insert), both
complexes exhibit an intense absorption band at ca. 295 nm
(emax = 51320 and 45650 dm3 mol21 cm21 for complexes 1
and 2, respectively). However, complex 3 shows intense
absorption at 320 nm (emax = 44870). This red shift in
transition energy is not uncommon in d10–d10 systems and
hence the 320 nm band in complex 3 is assigned to the
5d(ds*) ? 6p(s) tansition modified by AuI···AuI interactions.8
As with most gold(i) complexes, complexes 1–3 are emissive
both in solution and in the solid state, showing a broad emission
at ca. 520–530 nm with long lifetimes (0.37, 0.34, 0.34 ms in
degassed CH2Cl2; 3.7, 10.4, 11.6 ms in the solid state for
complexes 1, 2, and 3, respectively) upon photoexcitation at
300–400 nm (shown in Fig. 3), and these emissions are assigned
to the S ? Au excitation.9
1.57 to 22.07 e Å23
.
3·2MeOH: C40H52Au6N6O2P4S6, M = 2146.93, monoclinic, space group
P21/c, a = 10.951(3), b = 18.827(3), c = 15.193(2) Å, b = 105.90(2)°,
U = 3013(1) Å3, Z = 2, Dc = 2.367 g cm23, m(Mo-Ka) = 149.15 cm21
,
F(000) = 1936. Intensity data were collected on Enraf-Nonius CAD4
diffractometer with graphite-monochromated Mo-Ka radiation
(l = 0.7107 Å), 3926 unique reflection (2q < 45°) were measured and
2206 with I > 2s(I) were used in the refinement. Refinement of positional
and anisotropic thermal parameters for all non-hydrogen atoms (290
variables) converged to R = 0.061 and Rw = 0.054. The final Fourier
difference map showed residual extrema in the range of 1.80 to 22.05
e Å23. CCDC 182/541.
1 (a) S.-J. Shieh, X. Hong, S.-M. Peng and C.-M. Che, J. Chem. Soc.,
Dalton Trans., 1994, 3067; (b) B.-C. Tzeng, K.-K. Cheung and
C.-M. Che, Chem. Commun., 1996, 1681; (c) B.-C. Tzeng, C.-M. Che and
S.-M. Peng, J. Chem. Soc., Dalton Trans., 1996, 1769.
2 (a) H. Schmidbaur, Chem. Soc. Rev., 1995, 391; (b)
W. Schneider, A. Bauer and H. Schmidbaur, Organometallics, 1996, 15,
5445; (c) H.-K. Yip, A. Schier, J. Riede and H. Schmidbaur, J. Chem.
Soc., Dalton Trans., 1994, 2333; (d) M. Nakamoto, A. Schier and
H. Schmidbaur, J. Chem. Soc., Dalton Trans., 1993, 1347.
3 D. M. P. Mingos, J. Yau, S. Menzer and D. J. Williams, Angew. Chem.,
Int. Ed. Engl., 1995, 34, 1894.
This work highlights the application of AuI···AuI interactions
as well as the judicious choice for bridging ligands in the
formation of a two-dimensional array of luminescent metal
clusters.
We acknowledge support from The University of Hong
Kong, the Hong Kong Research Grants Council, and the
Croucher Foundation.
4 (a) P. M. V. Calcar, M. M. Olmstead and A. L. Balch, J. Chem. Soc.,
Chem. Commun., 1995, 1773; (b) P. M. V. Calcar, M. M. Olmstead and
A. L. Balch, Chem. Commun., 1996, 2597.
(a)
5 (a) M. J. Irwin, G. Jia, N. C. Payne and R. J. Puddephatt, Organome-
tallics, 1996, 15, 51; (b) M. J. Irwin, L. M. Muir, K. W. Muir,
R. J. Puddephatt and D. S. Yufit, Chem. Commun., 1997, 219.
6 (a) M. Contel, J. Garrido, M. C. Gimeno, P. G. Jones, A. Laguna and
M. Laguna, Organometallics, 1996, 15, 4939; (b) 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.
(c)
(b)
(c)
(b)
(a) × 3
250
300
350
λ / nm
400
7 R. M. Da´vila, A. Elduque, T. Grant, R. J. Staples and J. P. Fackler, Jr.,
Inorg. Chem., 1993, 32, 1749.
8 (a) C.-M. Che, H.-L. Kwong and C.-K. Poon, J. Chem. Soc., Dalton
Trans., 1990, 3215; (b) C.-M. Che, H.-L. Kwong, V. W.-W. Yam and
K.-C. Cho, J. Chem. Soc., Chem. Commun., 1989, 885; (c) C. King,
J. C. Wang, M. N. I. Khan and J. P. Fackler, Jr., Inorg. Chem., 1989, 28,
2145.
450
550
650
750
400
500
600
λ / nm
700
9 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.
Fig. 3 The emission spectra of complexes 1–3 measured in degassed
CH2Cl2 at room temp. (insert is the absorption spectra of complexes 1–3
(3.5 3 1025 m) in CH2Cl2); (a) 1 (b) 2, (c) 3
Received in Cambridge, UK, 4th June 1997; Com. 7/03891G
1772
Chem. Commun., 1997