Toward rational construction of gold, gold-silver, and gold-mercury string complexes: Syntheses, structures, and properties of [Au(Tab)2] 2L2 (L = I and PF6), {[(Tab) 2M][Au(CN)2]}2 (M = Au and Ag), and {[Hg(Tab)2][Au(CN)2]2} [Tab = 4-(trimethylammonio)benzenethiolate]

Article abstract of DOI:10.1021/ic060655m

The reaction of Aul with 2 equiv of TabHPF₆ [TabH = 4-(trimethylammonio)benzenethiol] in the presence of excess Et₃N in dimethylformamide (DMF)/MeOH afforded a binuclear gold(I) complex [Au(Tab) ₂]₂I₂·2H₂O (1). Anion exchange of 1 with NH₄PF₆ in DMF gave rise to the more soluble complex [Au(Tab)₂]₂(PF₆)₂ (2). Treatment of 2 with K[Au-(CN)₂] produced a tetranuclear gold(I) complex {[(Tab)₂Au][Au(CN)₂]}₂ (3). Analogous reactions of two known mononuclear complexes [Ag(Tab)₂](PF ₆) (4) and [Hg(Tab)₂](PF₆)₂ (5) with 1 or 2 equiv of K[Au(CN)₂] generated one Ag₂Au ₂ complex {[(Tab)₂Ag][Au(CN)₂]}₂ (6) and one Au/Hg complex {[Hg(Tab)₂][Au(CN)₂]₂} (7), respectively. Compounds 1-3, 6, and 7 were fully characterized by elemental analysis, IR spectra, UV-vis spectra, ¹H NMR, and single-crystal X-ray crystallography. 1 and 2 have a similar [Au(Tab)₂] ₂²⁺ dimeric structure in which the two [Au(Tab) ₂]⁺ cations are connected via one Au-Au aurophilic interaction. In the structure of 3 or 6, each of the two pairs of [M(Tab) ₂]⁺ cation and [Au(CN)₂]^- anion is held together via ionic interactions to form a {[(Tab)₂M][Au-(CN) ₂]} species (M = Au, 3; Ag, 6). Two such species are further connected by one Au-Au aurophilic bonding interaction to form an uncommon Au₄ or Ag₂Au₂ linear string structure with three ligand-unsupported metal-metal bonds. For 7, the [Hg(Tab) ₂]²⁺ dication and the [Au(CN)₂] ^22- dianion are interconnected by the secondary Hg... N(CN) interactions to form a 1D chain structure. The thermal and luminescent properties of 1-3, 6, and 7 in solid state were also investigated.

Full text of DOI:10.1021/ic060655m

Inorg. Chem. 2006, 45, 7671−7680
Toward Rational Construction of Gold, Gold
String Complexes: Syntheses, Structures, and Properties of
[Au(Tab)2]2L2 (L I and PF6), [(Tab)2M][Au(CN)2] (M Au and Ag),
and [Hg(Tab)2][Au(CN)2]2 [Tab
4-(Trimethylammonio)benzenethiolate]
−Silver, and Gold−Mercury
)
{
}
)
2
{
}
)
Jin-Xiang Chen,† Wen-Hua Zhang,† Xiao-Yan Tang,† Zhi-Gang Ren,† Hong-Xi Li,† Yong Zhang,† and
Jian-Ping Lang*,†,‡
School of Chemistry and Chemical Engineering, Suzhou UniVersity, Suzhou 215123,
Jiangsu, People’s Republic of China, and State Key Laboratory of Coordination Chemistry,
Nanjing UniVersity, Nanjing 210093, Jiangsu, People’s Republic of China
Received April 17, 2006
The reaction of AuI with 2 equiv of TabHPF6 [TabH
Et3N in dimethylformamide (DMF)/MeOH afforded a binuclear gold(I) complex [Au(Tab)2]2I2
of 1 with NH4PF6 in DMF gave rise to the more soluble complex [Au(Tab)2]2(PF6)2 (2). Treatment of 2 with K[Au-
(CN)2] produced a tetranuclear gold(I) complex [(Tab)2Au][Au(CN)2] (3). Analogous reactions of two known
mononuclear complexes [Ag(Tab)2](PF6) (4) and [Hg(Tab)2](PF6)2 (5) with 1 or 2 equiv of K[Au(CN)2] generated
one Ag2Au2 complex [(Tab)2Ag][Au(CN)2] (6) and one Au/Hg complex [Hg(Tab)2][Au(CN)2]2 (7), respectively.
Compounds 1 3, 6, and 7 were fully characterized by elemental analysis, IR spectra, UV
vis spectra, 1H NMR,
and single-crystal X-ray crystallography. 1 and 2 have a similar [Au(Tab)2]2 dimeric structure in which the two
[Au(Tab)2]+ cations are connected via one Au
Au aurophilic interaction. In the structure of 3 or 6, each of the two
pairs of [M(Tab)2]+ cation and [Au(CN)2]- anion is held together via ionic interactions to form a
[(Tab)2M][Au-
(CN)2] species (M Au, 3; Ag, 6). Two such species are further connected by one Au Au aurophilic bonding
interaction to form an uncommon Au4 or Ag2Au2 linear string structure with three ligand-unsupported metal metal
bonds. For 7, the [Hg(Tab)2]2 dication and the [Au(CN)2]2 dianion are interconnected by the secondary Hg‚‚‚
)
4-(trimethylammonio)benzenethiol] in the presence of excess
‚2H2O (1). Anion exchange
{
}
2
{
}
{
}
2
−
−
2+
−
{
}
)
−
−
+
2-
N(CN) interactions to form a 1D chain structure. The thermal and luminescent properties of 1−3, 6, and 7 in solid
state were also investigated.
Introduction
For mixed gold-silver complexes,5a,c-f there was only one
string compound [Au2Ag2(C6F5)2(CF3CO2)2(PPh2CH2SPh)2],5a
in which the argentoaurophilic and argentophilic interactions
resulted in the formation of a folded Au-Ag-Ag-Au string
structure, while in the case of gold-mercury compounds,
there also existed one example {[HgAu(CHP(S)Ph)]PF6}2,
in which a bent Hg-Au-Au-Hg string structure may
contain aurophilic and hydrargoaurophilic interactions.5b
Although there are some gold string complexes with ligand-
unassisted Au-Au bonds,1g-j the known AuAg or AuHg
strings are all supported with bridging ligands.5 In this regard,
the synthesis of ligand-unsupported gold, gold-silver, and
gold-mercury string complexes is still a challenge.
In the past decades, the rational design and construction
of gold(I) complexes have received much attention because
of their interesting structural chemistry and their potential
applications in electronic, optical, and sensing devices.1-5
In many gold(I) complexes, the so-called aurophilic interac-
tions are observed to result in the formation of various
interesting structures.3 Among them, gold(I) string complexes
are not exceptional, but only several examples are observed
to have a linear or pseudolinear Au-Au-Au-Au structure.1g-j
* To whom correspondence should be addressed. E-mail:
jplang@suda.edu.cn.
† Suzhou University.
‡ Nanjing University.
10.1021/ic060655m CCC: $33.50
Published on Web 08/22/2006
© 2006 American Chemical Society
Inorganic Chemistry, Vol. 45, No. 19, 2006 7671

Chen et al.
Recently, we are interested in the chemistry of silver and
mercury thiolate complexes, [Ag(Tab)2](PF6) (4)6a and [Hg-
(Tab)2](PF6)2 (5),6b derived from a zwitterionic thiolate
TabHPF6 [Tab ) 4-(trimethylammonio)benzenethiolate].7 As
an extension of this study, we ran its reaction with AuI and
obtained a dimeric complex [Au(Tab)2]2I2‚2H2O (1). Because
1 has low solubility in common solvents, we attempted an
anion-exchange reaction of 1 with NH4PF6 and isolated a
more soluble analogue [Au(Tab)2]2(PF6)2 (2). On the other
hand, the [Au(CN)2]- anion in K[Au(CN)2] was sometimes
employed in anion-exchange reactions.4,8b If 2 is combined
with K[Au(CN)2], the ionic interaction between the [Au-
(Tab)2]+ cation and the [Au(CN)2]- anion may occur so as
to form {[(Tab)2Au][Au(CN)2]} species. Such species may
be further assembled into certain oligomers via Au-Au
aurophilic interactions. As discussed later in this paper,
compound 2 exhibited luminescence in the solid state at
ambient temperature and so did K[Au(CN)2]1a,2a and its
derived compounds.8 We anticipated that when 2 reacts with
K[Au(CN)2], the resulting products may modify or improve
their original luminescent properties. With all of these ideas
in mind, we carried out this reaction and a neutral tetranuclear
gold(I) string complex {[(Tab)2Au][Au(CN)2]}2 (3) was
isolated therefrom. The isolation of 3 activated us to run
analogous reactions of 4 or 5 with K[Au(CN)2], which gave
rise to an expected Au/Ag metal string compound {[(Tab)2Ag]-
[Au(CN)2]}2 (6) and an unexpected Au/Hg complex {[Hg-
(Tab)2][Au(CN)2]2} (7). Compounds 3, 6, and 7 did exhibit
different luminescent properties in the solid state with respect
to those of their corresponding precursors. Herein, we report
the syntheses, structures, and properties of 1-3, 6, and 7.
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391-400. (f) Payne, N. C.; Ramachandran, R.; Puddephatt, R. J. Can.
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Trans. 1996, 5, 561-566. (h) Hollatz, C.; Schier, A.; Schmidbaur, H.
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K.; Cheung, K. K.; Che, C. M.; Peng, S. M. Chem. Commun. 1997,
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Gysling, H. J.; Eisenberg, R. J. Am. Chem. Soc. 1998, 120, 1329-
1330. (k) Yam, V. W. W.; Li, C. K.; Chan, C. L. Angew. Chem., Int.
Ed. 1998, 37, 2857-2859. (l) Ferna´ndez, E. J.; Gimeno, M. C.;
Laguna, A.; Lo´pez-de-Luzuriaga, J. M.; Monge, M.; Pyykko¨, P.;
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Gussenboven, E. M.; Fettinger, J. C.; Pham, D. M.; Malwitz, M. M.;
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Experimental Section
General Procedures. TabHPF6 was prepared according to the
literature method.9 Other chemicals and reagents were obtained from
commercial sources and used as received. All solvents were predried
over activated molecular sieves and refluxed over the appropriate
drying agents under argon. The IR spectra were recorded on a
Nicolet MagNa-IR 550 as the KBr disk (4000-400 cm-1). The
elemental analyses for C, H, and N were performed on an EA1110
CHNS elemental analyzer. 1H NMR spectra were recorded at
1
ambient temperature on a Varian UNITY-400 spectrometer. H
(3) (a) Puddephatt, R. J. In ComprehensiVe Coordination Chemistry;
Wilkinson, G., Gillard, R. D., McCleverty, J. A., Eds.; Pergamon
Press: Oxford, U.K., 1987; Vol. 5, pp 861-923. (b) Schmidbaur, H.
Gold Bull. 1990, 23, 11-21. (c) Schmidbaur, H., Ed. Gold: Progress
in Chemistry, Biochemistry and Technology; Wiley: New York, 1999.
(4) (a) Brandys, M. C.; Puddephatt, R. J. Chem. Commun. 2001, 1280-
1281. (b) Han, W.; Yi, L.; Liu, Z. Q.; Gu, W.; Yan, S. P.; Cheng, P.;
Liao, D. Z.; Jiang, Z. H. Eur. J. Inorg. Chem. 2004, 2130-2136. (c)
Paraschiv, C.; Andruh, M.; Ferlay, S.; Hosseini, M. W.; Kyritsakas,
N.; Planeix, J. M.; Stanica, N. J. Chem. Soc., Dalton Trans. 2005,
1195-1202. (d) Galet, A.; Mun˜oz, M. C.; Mart´ınez, V.; Real, J. A.
Chem. Commun. 2004, 2268-2269.
(5) (a) Ferna´ndez, E. J.; Lo´pez-de-Luzuriage, J. M.; Monge, M.; Rod-
r´ıguez, M. A.; Crespo, O.; Gimeno, M. C.; Laguna, A.; Jones, P. G.
Chem.sEur. J. 2000, 6, 636-644. (b) Wang, S. N.; Fackler, J. P., Jr.
Organometallics 1988, 7, 2415-2417. (c) Mohammed, A. A.; Burini,
A.; Fackler Junior, J. P. J. Am. Chem. Soc. 2005, 127, 5012-5013.
(d) Wei, Q. H.; Zhang, L. Y.; Yin, G. Q.; Shi, L. X.; Chen, Z. N. J.
Am. Chem. Soc. 2004, 126, 9940-9941. (e) Teo, B. K.; Zhang, H.;
Shi, X. B. J. Am. Chem. Soc. 1993, 115, 8489-8490. (f) Copley, R.
C. B.; Mingos, D. M. P. J. Chem. Soc., Dalton Trans. 1996, 491-
500.
NMR chemical shifts were referenced to the deuterated dimethyl
sulfoxide (DMSO-d6) signal. UV-vis spectra were measured on a
Hitachi U-2810 spectrophotometer. The thermal analysis was
performed on a Perkin-Elmer TGA-7 thermogravimetric analyzer
at a heating rate of 10 °C/min and a flow rate of 100 cm3/min
(N2). The photoluminescent spectra were performed on a Hitachi
F-2500 spectrofluorometer.
Synthesis. [Au(Tab)2]2I2‚2H2O (1). To a suspension containing
TabHPF6 (0.625 g, 2 mmol) in MeOH (5 mL) was added Et3N
(2.5 mL). The resulting colorless solution was then treated with a
suspension containing AuI (0.323 g, 1 mmol) in dimethylformamide
(8) (a) Dunbar, K. R.; Heintz, R. A. Prog. Inorg. Chem. 1997, 45, 283-
391. (b) Leznoff, D. B.; Xue, B. Y.; Batchelor, R. J.; Einstein, F. W.
B.; Patrick, B. O. Inorg. Chem. 2001, 40, 6026-6034. (c) Leznoff,
D. B.; Xue, B. Y.; Patrick, B. O.; Sanchez, V.; Thompson, R. C. Chem.
Commun. 2001, 259-260. (d) Shorrock, C. J.; Xue, B. Y.; Kim, P.
B.; Batchelor, R. J.; Patrick, B. O.; Leznoff, D. B. Inorg. Chem. 2001,
41, 6743-6753. (e) Leznoff, D. B.; Xue, B. Y.; Stevens, C. L.; Storr,
A.; Thompson, R. C.; Patrick, B. O. Polyhedron 2001, 20, 1247-
1254. (f) Stender, M.; White-Morris, R. L.; Olmstead, M. M.; Balch,
A. L. Inorg. Chem. 2003, 42, 4504-4506. (g) Stork, J. R.; Rios, D.;
Pham, D.; Bicocca, V.; Olmstead, M. M.; Balch, A. L. Inorg. Chem.
2005, 44, 3466-3472.
(6) (a) Chen, J. X.; Xu, Q. F.; Zhang, Y.; Chen, Z. N.; Lang, J. P. J.
Organomet. Chem. 2004, 689, 1071-1077. (b) Chen, J. X.; Zhang,
W. H.; Tang, X. Y.; Ren, Z. G.; Zhang, Y.; Lang, J. P. Inorg. Chem.
2006, 45, 2568-2580.
(7) (a) Ahmed, L. S.; Clegg, W.; Davies, D. A.; Dilworth, J. R.; Elsegood,
M. R. J.; Griffiths, D. V.; Horsburgh, L.; Miller, J. R.; Wheatley, N.
Polyhedron 1998, 18, 593-600. (b) Zhou, C.; Raebiger, J. W.; Segal,
B. M.; Holm, R. H. Inorg. Chim. Acta 2000, 300-302, 892-902.
(9) DePamphilis, B. V.; Averill, B. A.; Herskovitz, T.; Que, L., Jr.; Holm,
R. H. J. Am. Chem. Soc. 1974, 96, 4159-4167.
7672 Inorganic Chemistry, Vol. 45, No. 19, 2006

Gold, Gold-SilWer, and Gold-Mercury String Complexes
Table 1. Crystallographic Data for 1-3, 6, and 7
compound
molecular formula
formula weight
cryst syst
space group
size (mm3)
a (Å)
1
2
3
6
7
C36H56Au2I2N4O2S4
1352.82
monoclinic
C2/c
0.37 × 0.25 × 0.25
27.775(2)
9.3233(7)
18.8006(16)
111.644(2)
4525.2(6)
4
C36H52Au2F12N4P2S4
1352.93
monoclinic
C2/c
0.28 × 0.25 × 0.24
30.225(3)
8.5291(7)
20.0928(19)
121.713(2)
4406.4(7)
4
C40H52Au4N8S4
1561.00
orthorhombic
Fdd2
0.23 × 0.23 × 0.22
18.1364(15)
32.230(3)
15.6796(14)
92.422(3)
9165.3(14)
8
C40H52Ag2Au2N8S4
1382.81
orthorhombic
Fdd2
C22H26Au2HgN6S2
1033.16
monoclinic
C2/c
0.12 × 0.12 × 0.11
17.113(2)
9.9190(12)
15.473(2)
0.19 × 0.16 × 0.15
18.073(2)
b (Å)
c (Å)
32.221(4)
15.6343(17)
â (deg)
V (Å3)
9104.3(18)
8
2624.0(6)
4
Z
T (K)
D
193
1.986
0.710 70
80.60
55.0
193
2.039
0.710 70
69.98
55.0
193
2.263
0.710 70
129.86
55.0
193
193
calc (g cm-3
)
2.018
0.710 70
74.95
50.6
2.615
0.710 70
171.72
55.0
λ(Mo KR) (Å)
µ (cm-1
)
2θmax (deg)
no. of reflns
collected
no. of unique
reflns
24385
23586
25257
21970
14188
5171 (Rint ) 0.0877)
4412 [I >2.00σ(I)]
5020 (Rint ) 0.0372)
4745 [I >2.00σ(I)]
5233(Rint ) 0.0488)
4047 [I >2.00σ(I)]
4011(Rint ) 0.0278)
3454 [I >2.00σ(I)]
2992(Rint) 0.0350)
2732 [I >2.00σ(I)]
no. of observed
reflns
no. of param
234
279
232
244
155
Ra
0.0374
0.0805
1.008
0.0277
0.0658
1.133
0.0380
0.0776
1.146
0.0248
0.0569
1.080
0.0295
0.0708
0.953
wRb
GOFc
largest residual
peaks, holes
0.872, -0.825
0.884, -0.697
0.983, -0.904
1.176, -0.887
0.971, -0.974
(e Å-3
)
2
2
2
a R ) ∑||Fo| - |Fc||/∑|Fo|. b wR ) {∑w(Fo2 - Fc )2/∑w(Fo )2}1/2
.
c GOF ) {∑w((Fo2 - Fc )2)/(n - p)}1/2, where n ) number of reflections and p ) total
numbers of parameters refined.
1
(DMF; 5 mL). The mixture was stirred for 0.5 h to dissolve the
AuI solid and then filtered. Slow evaporation of the solvents from
the filtrate in air at room temperature led to the formation of
colorless prisms of 1, which were collected by filtration, washed
with Et2O, and dried in vacuo. Yield: 0.588 g (87.0% based on
AuI). Anal. Calcd for C36H56Au2I2N4O2S4: C, 31.96; H, 4.17; N,
4.14. Found: C, 31.84; H, 4.28; N, 4.35. IR (KBr disk): 1580 (w),
1484 (m), 1407 (w), 1120 (w), 1010 (w), 949 (m), 817 (s), 744
(w), 547 (m) cm-1. UV-vis [DMF; λmax, nm (ꢀ, M-1 cm-1)]: 304
(175 800). 1H NMR (400 MHz, DMSO-d6): δ 7.53-7.65 (m, 4H,
Ph), 3.51 (s, 9H, NMe3).
[Au(Tab)2]2(PF6)2 (2). To a suspension of 1 (0.675 g, 0.5 mmol)
in DMF (5 mL) was added NH4PF6 (0.163 g, 1 mmol). The resulting
mixture was stirred for 1 h to form a colorless solution and filtered.
Diethyl ether (20 mL) was layered onto the filtrate to form colorless
prisms of 2 in several days, which were collected by filtration,
washed with Et2O, and dried in vacuo. Yield: 0.663 g (98.0% based
on 1). Anal. Calcd for C36H52Au2F12N4P2S4: C, 31.96; H, 3.87; N,
4.14. Found: C, 32.25; H, 3.42; N, 3.93. IR (KBr disk): 1581 (w),
1485 (m), 1408 (w), 1122 (w), 1006 (w), 960 (m), 841 (s), 744
(w), 559 (m) cm-1. UV-vis [DMF; λmax, nm (ꢀ, M-1 cm-1)]: 304
(263 800). 1H NMR (400 MHz, DMSO-d6): δ 7.51-7.63 (m, 4H,
Ph), 3.50 (s, 9H, NMe3).
{[(Tab)2Au][Au(CN)2]}2 (3). To a solution containing 2 (0.676
g, 0.5 mmol) in DMF (5 mL) was added a solution of K[Au(CN)2]
(0.288 g, 1 mmol) in MeOH (5 mL). The mixture was stirred for
5 min and then filtered to give a clear colorless solution. Layering
diethyl ether (20 mL) onto the filtrate formed block colorless
crystals of 3, which were collected by filtration, washed with
MeOH/Et2O (1:4), and dried in vacuo. Yield: 0.749 g (96.0% based
on 2). Anal. Calcd for C40H52Au4N8S4: C, 30.78; H, 3.36; N, 7.18.
Found: C, 30.52; H, 3.23; N, 7.43. IR (KBr disk): 2156 (w), 2137
(s), 1577 (m), 1485 (s), 1404 (s), 1234 (w), 1122 (s), 1010 (s), 952
(s), 837 (m), 744 (m), 551 (m) cm-1. UV-vis [DMF; λmax, nm (ꢀ,
M-1 cm-1)]: 302 (163 600). H NMR (400 MHz, DMSO-d6): δ
7.54-7.63 (m, 4H, Ph), 3.51 (s, 9H, NMe3).
{[(Tab)2Ag][Au(CN)2]}2 (6). To a solution containing 4 (0.587
g, 1 mmol) in DMF (5 mL) was added a solution of K[Au(CN)2]
(0.288 g, 1 mmol) in MeOH (5 mL). A workup similar to that
used in the isolation of 3 afforded colorless prisms of 6. Yield:
0.657 g (95.0% based on 4). Anal. Calcd for C40H52Ag2Au2N8S4:
C, 34.74; H, 3.79; N, 8.10. Found: C, 34.32; H, 3.53; N, 8.44. IR
(KBr disk): 2156 (w), 2133 (s), 1576 (m), 1485 (s), 1408 (s), 1234
(w), 1122 (s), 1010 (s), 952 (s), 837 (m), 744 (m), 551 (m) cm-1
.
UV-vis [DMF; λmax, nm (ꢀ, M-1 cm-1)]: 296 (308 700). 1H NMR
(400 MHz, DMSO-d6): δ 7.54-7.66 (m, 4H, Ph), 3.52 (s, 9H,
NMe3).
{[Hg(Tab)2][Au(CN)2]2} (7). To a solution containing 5 (0.824
g, 1 mmol) in DMF (5 mL) was added a solution of K[Au(CN)2]
(0.576 g, 2 mmol) in MeOH (5 mL). A workup similar to that
used in the isolation of 3 produced colorless prisms of 7. Yield:
0.961 g (93.0% based on 5). Anal. Calcd for C22H26Au2HgN6S2:
C, 25.58; H, 2.54; N, 8.13. Found: C, 25.41; H, 2.34; N, 8.59. IR
(KBr disk): 2156 (w), 2137 (s), 1581 (m), 1489 (s), 1404 (s), 1230
(w), 1126 (s), 1010 (s), 949 (s), 817 (m), 744 (m), 547 (m), 424
(m) cm-1. UV-vis [DMF; λmax, nm (ꢀ, M-1 cm-1)]: 276 (276 600).
1H NMR (400 MHz, DMSO-d6): δ 7.59-7.74 (m, 4H, Ph), 3.51
(s, 9H, NMe3).
X-ray Structure Determination. X-ray-quality crystals of 1-3,
6, and 7 were obtained directly from the above preparations. All
measurements were made on a Rigaku Mercury CCD X-ray
diffractometer by using graphite-monochromated Mo KR (λ )
0.710 70 Å). Crystals of 1-3, 6, and 7 were mounted with grease
at the top of a glass fiber and cooled at 193 K in a liquid-N2 stream.
Cell parameters were refined by using the program CrystalClear
(Rigaku and MSC, version 1.3, 2001). The collected data were
Inorganic Chemistry, Vol. 45, No. 19, 2006 7673

Chen et al.
Scheme 1
Scheme 2
Scheme 3
reduced by using the program CrystalStructure (Rigaku and MSC,
version 3.60, 2004) while an absorption correction (multiscan) was
applied.
The crystal structures of 1-3, 6, and 7 were solved by direct
methods and refined on F 2 by full-matrix least-squares methods
with the SHELXTL-97 program.10 All non-H atoms were refined
anisotropically. The H atoms of the solvated water molecule in 1
were located from the Fourier maps, and all of the other H atoms
were placed in geometrically idealized positions (C-H ) 0.98 Å
for methyl groups; C-H ) 0.95 Å for phenyl groups) and
constrained to ride on their parent atoms with Uiso(H) ) 1.2Ueq(C)
for phenyl groups and Uiso(H) ) 1.5Ueq(C) for methyl groups. A
summary of the key crystallographic information for 1-3, 6, and
7 was tabulated in Table 1.
complex {[(Tab)2Hg][Au(CN)2]}2(PF6)2 but generated com-
plex 7 in 93% yield (Scheme 3). As described later in this
paper, the failed formation of the Au/Hg string complex may
be ascribed to the fact that the hydrargoaurophilic interaction
is weaker than the aurophilic and argentoaurophilic interac-
tions and even the secondary Hg‚‚‚N interactions.
Results and Discussion
Synthesis. The reaction of AuI with 2 equiv of TabHPF6
under excess Et3N in MeOH/DMF resulted in a colorless
solution. Slow evaporation of solvents from the solution led
to the formation of colorless prisms of 1 in 87.0% yield
(Scheme 1). The existence of two solvated water molecules
in 1 may be attributed to the fact that excess Et3N readily
absorbs water from air. Compound 1 is slightly soluble in
DMF and DMSO and almost insoluble in common solvents
such as MeOH, MeCN, and CH2Cl2. Because of its poor
solubility, we attempted exchange of the iodides of 1 with
larger anions. The reaction of 1 with 2 equiv of NH4PF6
produced its analogue 2 in an almost quantitative yield. 2
was readily soluble in common solvents such as MeCN,
DMF, and DMSO and may be a suitable precursor for the
further assembly reaction. As shown in Scheme 2, treatment
of 2 with 2 equiv of K[Au(CN)2] followed by a standard
workup gave rise to a neutral tetranuclear gold(I) string
complex 3 in 96% yield. A similar reaction of 4 with
equimolar K[Au(CN)2] afforded a Au/Ag string analogue 6
in 95% yield. However, analogous reaction of 5 with 2 equiv
of K[Au(CN)2] did not yield our expected Au/Hg string
Crystal Structures of 1 and 2. Both 1 and 2 crystallize
in the monoclinic space group C2/c, and the asymmetric unit
2+
of 1 consists of half of the [Au(Tab)2]2 dication, one I-
anion, and one solvated water molecule, while that of 2 has
2+
-
half of the [Au(Tab)2]2 dication and one PF6 anion.
Because the structures of the dications of 1 and 2 are similar,
only the perspective view of the dication of 1 is depicted in
Figure 1. Selected bond lengths and angles for 1 and 2 are
2+
compared in Table 2. The [Au(Tab)2]2 dication of 1 or 2
consists of two [Au(Tab)2]+ cations that are linked via one
aurophilic Au-Au bonding interaction, forming a ligand-
unassisted dimeric structure with an inversion center lying
on the midpoint of the Au1‚‚‚Au2 line and a crystallographic
2-fold axis running along the line of the Au1 and Au2 atoms.
Such a dimeric structure resembles those of other diauro(I)
complexes such as [Au(2-Pys)(PPh2PyH)]2(PF6)2‚CH2Cl2‚
2H2O (PySH ) 2-mercaptopyridine),11a [AuCl(dppa)]2 (dppa
) diphenylphosphinous acid),11b [AuCl(tfdppp)]2(PF6)2‚0.5CH2-
Cl2 (tfdppp ) 1,1,2-trifluoro-3,3-diphenyl-3-phosphaprop-
(11) (a) Hao, L. J.; Mansour, M. A.; Lachicotte, R. J.; Gysling, H. J.;
Eisenberg, R. Inorg. Chem. 2000, 39, 5520-5529. (b) Hollatz, C.;
Schier, A.; Riede, J.; Schimidbaur, H. J. Chem. Soc., Dalton Trans.
1999, 111-114. (c) Banger, K. K.; Banhaun, R. P.; Brisdon, A. K.;
(10) Sheldrick, G. M. SHELX-97 and SHELXL-97, Program for Crystal
Structure Refinement; University of Go¨ttingen: Go¨ttingen, Germany,
1997.
7674 Inorganic Chemistry, Vol. 45, No. 19, 2006

Gold, Gold-SilWer, and Gold-Mercury String Complexes
vs 10.04 Å (2) (along the c axis), respectively. It is noted
that 1 and 2 have very different hydrogen-bound structures
in their crystals. For 1, the iodide interacts with the solvated
water molecule to afford one intramolecular hydrogen bond
3
and one intermolecular hydrogen bond [O1‚‚‚I1 (-x + /2,
1
y + -1/2, -z + /2)]. The O atom of the solvated water
molecule also interacts with the H atoms of the phenyl groups
to afford two intermolecular hydrogen bonds [C7‚‚‚O1 (-x
1
3
3
1
+ 1, y, -z + /2); C12‚‚‚O1 (-x + /2, y + /2, -z + /2)],
forming a 2D network extending along the ab plane (Figure
2).
In the case of 2, the hydrogen-bonding interactions are
rather complicated. The F atoms of the PF6- anion interacts
with the H atoms of the methyl group or the phenyl group
to afford one intramolecular hydrogen bond [C16‚‚‚F1] and
five intermolecular hydrogen bonds [C7‚‚‚F2 (x, 2 - y, z +
1/2); C7‚‚‚F4 (-x + 3/2, y + 3/2, -z + 1/2), C18‚‚‚F5 (x, y -
1, z); C5‚‚‚F6 (-x + 3/2, y + 1/2, -z + 1/2), C8‚‚‚F6 (x, 2 -
y, z + 1/2)], forming a 3D hydrogen-bound structure (Figure
3).
2+
Figure 1. Perspective view of the [Au(Tab)2]2 dimer of 1 with 50%
thermal ellipsoids. All H atoms are omitted for clarity. Symmetry
transformations used to generate equivalent atoms: A, -x + 1, y, -z +
1/2.
Table 2. Selected Bond Distances (Å) and Angles (deg) for 1 and 2
1
2
Au1-S1
Au2-S2
Au1-Au2
2.2950(13)
2.3055(13)
3.0184(4)
2.3032(9)
2.3046(9)
3.0146(3)
Crystal Structures of 3 and 6. Both 3 and 6 crystallize
in the orthorhombic space group Fdd2, and the asymmetric
unit consists of half of the {[(Tab)2M][Au(CN)2]}2 (M )
Au and Ag) molecule. 3 and 6 are isotypic, and their cell
parameters are essentially identical, as are their molecular
structures. Therefore, only the perspective view of 3 is
presented in Figure 4. The bond lengths and angles for 3
and 6 are compared in Table 3. In the structures of 3 and 6,
each of the two pairs of the [M(Tab)2]+ cation and the
[Au(CN)2]- anion are held together via ionic interaction
between the [Au(Tab)2]+ cation and the [Au(CN)2]- anion
to form a {[(Tab)2M][Au(CN)2]} species. Two such species
are further connected by one Au-Au aurophilic bonding
interaction to form an interesting Au4 or Ag2Au2 string
structure with three ligand-unassisted Au-Au or Au-Ag
bonds. There is a crystallographic 2-fold axis running along
the Au4 or Ag2Au2 string. The torsion angle for Au3‚‚‚Au1‚
‚‚Au2‚‚‚Au4 in 3 or Ag1‚‚‚Au1‚‚‚Au2‚‚‚Ag2 in 6 is 0°. The
length of the Au4 or Ag2Au2 string is 9.124 Å for 3 or 8.892
Å for 6. The linear Au4 structure of 3 resembles those
observed in [X2AuAu(Py)2]2 (X ) Cl, Br, and I).1h,i However,
the Ag2Au2 linear structure of 6 is different from those of
the known Ag2Au2 compounds, which usually consist of a
highly bent or zigzag Ag2Au2 core structure.5c-f
S1-Au1-S1A
S2-Au2-S2
177.81(6)
177.73(6)
177.41(5)
175.02(5)
1-en-3-yl),11c and [AuCl(o-xylylisocyano)]2.11d In the struc-
ture of 1 or 2, the Au-Au bond length, 3.0184(4) Å for 1
or 3.0146(3) Å for 2, is shorter than those found in [AuCl-
(dppa)]2 [3.111(2) Å], [AuCl(tfdppp)]2(PF6)2‚0.5CH2Cl2
[3.194(3) Å], and [AuCl(o-xylylisocyano)]2 [3.357(4) Å].
In each [Au(Tab)2]+ cation of 1 or 2, the Au atom is
strongly coordinated by two S atoms of the two Tab moieties,
forming an approximate linear AuS2 coordination geometry
[(S-Au-S)av ) 177.77(6)° for 1 and 176.22(6)° for 2]. The
S1-Au1-S1A and S2-Au2-S2A lines are not parallel but
are twisted by 56.9° for 1 and 56.6° for 2. The two
+
-SC6H4NMe3 groups in 4 or 5 are directed at opposite
directions. However, each cation in 1 or 2 has its two
+
-SC6H4NMe3 groups oriented in the same direction. The
dihedral angles between the two phenyl groups in each [Au-
(Tab)2]+ cation are quite different: 11.6° vs 40.2° for 1 and
6.6° vs 38.7° for 2. The mean Au-S bond lengths, 2.300(13)
Å for 1 and 2.304(9) Å for 2, are between [Au(tmtat)2](BF4)
[2.272(4) Å; tmtat ) bis(1,4,5-trimethyl-1,2,4-triazolium-3-
thiolate)]12a and [Au(Hdamp-C1)(HSthiaz)2]Cl2 [2.329(3) Å;
Hdamp ) 2-[(dimethylamino)methyl]phenyl-C1, HSthiaz )
2-mercapto-1,3-thiazoline].12b
The dications in the crystals of 1 or 2 are parallel to each
other. The solvated water molecules and iodides in 1 or the
associated [PF6]- anions in 2 are positioned between these
parallel dications. The separations between two neighboring
cations are 13.89 Å (1) vs 15. 11 Å (2) (along the a axis),
6.30 Å (1) vs 14.04 Å (2) (along the b axis), and 9.40 Å (1)
+
The four -SC6H4NMe3 and four CN- groups covering
the string of 3 and 6 are staggered to minimize their steric
hindrance. For 3, the two -SC6H4NMe3+ groups in each [Au-
(Tab)2]+ cation are oriented in the same direction, and the
dihedral angles between two phenyl rings in each [Au-
(Tab)2]+ cation are 14.0° and 53.6°, which are larger than
the corresponding values in 1 and 2. The two S-Au-S lines
are twisted by 47.9°, which is slightly smaller than those in
1 and 2. In the two [Au(Tab)2]+ cations of 3, the mean Au-S
distance [2.314(3) Å] is comparable to those of 1 and 2 while
the mean S-Au-S angle (173.86°) is smaller than those of
1 and 2. On the other hand, it is noted that the two
Cross, W. I.; Damant, G.; Parsons, S.; Pritchard, R. G.; Sousa-Pedrares,
A. J. Chem. Soc., Dalton Trans. 1999, 427-434. (d) Echen, H.;
Olmstead, M. M.; Noll, B. C.; Attar, S.; Schlyer, B.; Balch, A. L. J.
Chem. Soc., Dalton Trans. 1998, 3715-3720.
(12) (a) Deaton, J. C.; Luss, H. R. J. Chem. Soc., Dalton Trans. 1999, 18,
3163-3167. (b) Abram, U. J.; Ortner, M. K.; Mu¨ller, M. J. Chem.
Soc., Dalton Trans. 1998, 6, 1011-1019.
+
-SC6H4NMe3 groups in each [Ag(Tab)2] unit of 6 are
oriented in the same direction, which is different from that
Inorganic Chemistry, Vol. 45, No. 19, 2006 7675

Chen et al.
Figure 2. 2D network formed via hydrogen-bonding interactions in 1 (extended along the ab plane). All H atoms except those related to hydrogen-bonding
interactions are omitted for clarity.
Figure 3. 3D structure formed via hydrogen-bonding interactions in 2 looking down the b axis. All H atoms except those related to hydrogen-bonding
interactions are omitted for clarity.
(Tab)2] units in 6 are twisted by 47.2°, which is much smaller
than that in 4 (91.1°). The mean Ag-S distance [2.382(15)
Å] of 6 is almost the same as that of 4 [2.385(5) Å], while
the average S-Ag-S angle of 6 [171.46(3)°] is smaller than
that of 4 [178.29(8)°]. The dihedral angles between the two
phenyl rings in each [Ag(Tab)2] unit in 6 are 12.8° and 54.2°,
respectively.
In the [Au(CN)2]2 part of 3 or 6, the Au1-Au2 bond
length [3.0688(6) Å (3) or 3.0140(5) Å (6)] is shorter than
those of Tb[Au(CN)2]3‚3H2O [3.31(1) Å],13 [C36H48N18][Au4-
(CN)8]2(NO3)2‚2H2O [3.344(2) Å; C36H48N18 ) 6,12,18,24,
30,36-hexaamino-4,10,16,22,28,34-hexamethylcalix(6)-
pyrimidinium),14 Cs2Na[Au(CN)2]3 [3.448(1)-3.620(1) Å],15
Figure 4. Perspective view of the molecular structure of 3 with 50%
thermal ellipsoids. All H atoms are omitted for clarity. Symmetry
transformations used to generate equivalent atoms: A, -x + 1/2, -y + 1/2,
z.
of its precursor 4, implying that one of the two -SC6H4NMe3+
groups of 4 was rotated along the S-Ag-S line by 180°
during the reaction. The two S-Ag-S lines from two [Ag-
(13) Tanner, P. A.; Zhou, X. J.; Wong, W. T.; Kratzer, C.; Yersin, H. J.
Phys. Chem. B 2005, 109, 13083-13090.
7676 Inorganic Chemistry, Vol. 45, No. 19, 2006

Gold, Gold-SilWer, and Gold-Mercury String Complexes
Table 3. Selected Bond Distances (Å) and Angles (deg) for 3, 6, and 7
Compound 3
case of 6, lots of intermolecular hydrogen bonds formed from
interactions of the N atoms of cyanides or the S atoms of
Tab ligands with the methyl groups or phenyl groups of the
neighboring chains afford a more complicated 3D hydrogen-
bound structure (see the Supporting Information).
Au3-S1
2.316(2)
1.91(2)
Au4-S2
Au2-C20
Au4-Au2
2.312(3)
1.977(11)
3.0239(9)
Au1-C19
Au3-Au1
Au1-Au2
3.0311(11)
3.0688(6)
Crystal Structure of 7. Compound 7 crystallizes in the
monoclinic space group C2/c, and the asymmetric unit
consists of half of the [Hg(Tab)2]2+ dication and half of the
[Au(CN)2]22- anion. The [Hg(Tab)2]2+ dications are parallel
to each other, and the Hg‚‚‚Hg separation between two
S1-Au3-S1A
C19-Au1-C19A
Au3-Au1-Au2
175.91(12)
177.6(7)
180.0
S2-Au4-S2A
171.78(10)
179.7(5)
180.0
C20-Au2-C20A
Au4-Au2-Au1
Compound 6
Au1-S1
2.3841(15)
1.981(10)
2.9598(7)
3.0140(5)
Ag2-S2
Au2-C20
Ag2-Au2
2.3788(16),
1.989(7)
2.9185(7)
Au1-C19
Ag1-Au1
Au1-Au2
2-
neighboring cations is ca. 9.89 Å, whereas each [Au(CN)2]2
dianion is positioned between the dications, and thus two N
atoms from the cyanides of the two neighboring [Au(CN)2]22-
dianions have secondary interactions with the Hg1 atom,
forming a 1D chain structure extending along the [101] plane
(Figure 6). The Hg1 center may be viewed as having a
pseudo-square-planar coordination geometry. The Hg1‚‚‚N3B
contact is 3.1434(7) Å (Table 3), which is shorter than the
sum of the van der Waals radii of nitrogen (1.55 Å)19a and
mercury (1.73 Å).19b There is an inversion center lying on
the midpoint of the Hg1 atom and a crystallographic 2-fold
axis running through the Hg1 atom of 7.
S1-Ag1-S1A
C19-Au1-C19A
Ag1-Au1-Au2
177.36(8)
179.7(4)
180.0
S2-Ag2-S2A
C20-Au2-C20A
Ag2-Au2-Au1
165.55(8)
178.1(3)
180.0
Compound 7
2.3369(15)
1.990(6)
Hg1-S1
Au1-C11
Hg1‚‚‚N3B
Au1-C10
Au1-Au1A
1.979(7)
3.2619(7)
3.1434(7)
S1-Hg1-S1A
S1-Hg1-N3B
C10-Au1-C11
180.0
109.46(5)
175.3(3)
N3B-Hg1-N3D
S1-Hg1-N3D
180.00
70.53(4)
and K[Au(CN)]2 [3.64(3) Å].16 The mean Au-Au contact
[3.0412(9) Å] of 3 is slightly longer than those of 1 or 2.
The mean Ag-Au contact [2.9391(7) Å] of 6 is slightly
longer than that of [AgAu(mtp)2] [2.9124(13) Å; mtp )
diphenylmethylenethiophosphinate].17 In addition, the mean
Au-C bond length and C-Au-C angle are 1.94(6) Å and
178.65(8)° for 3 and 1.99(8) Å and 178.9(4)° for 6. The
twisted angle (90.7°) for the two CtNsAusCtN lines of
3 is similar to that of 6 (91.7°).
The structure of the dication of 7 retains the same structure
as its precursor 5 because their Hg-S bond lengths and
S-Hg-S bond angles are almost identical. An analogues
2-
dimeric [Au(CN)2]2 dianion is again formed from one
Au1-Au1A aurophilic interaction [3.2619(7) Å], which is
weaker than those found in 3 and 6. The two linear CtNs
AusCtN lines are twisted by 51.3°, which is 39-40°
smaller than those of the corresponding values in 3 and 6.
The average Au-C bond length and C-Au-C bond angle
are 1.9845(6) Å and 175.3(3)°, which are close to the
corresponding values in 3 and 6.
In the crystals of 3 and 6, the string molecules are parallel
to each other along the c axis and there are no additional
aurophilic bonds between the nearest molecules (see the
Supporting Information). It is noted that 3 or 6 contains some
nonconventional C-H‚‚‚Au(Ag) hydrogen-bonding interac-
tions.18 For 3, Au3 interacts the H atoms of the methyl group
to afford one intermolecular bond C16 [x, y, z - 1], forming
a 1D chain structure extending along the c axis. The
hydrogen-bonding interaction between Ag1 and the H atoms
of the methyl group with C18 [x, y, -1 + z] in 6 also forms
a similar 1D chain structure (see the Supporting Information).
The N atoms of cyanides or the S atoms of Tab ligands in
3 interact with the H atoms of the methyl groups or phenyl
groups of the neighboring chains [C16‚‚‚N4 (x + 1/4, -y +
In the crystal of 7, there is one hydrogen-bonding
interaction between N2 and the methyl group with C9 [-x,
y, -z + 1/2]. Four such symmetrically related hydrogen bonds
interconnect [Hg(Tab)2][Au(CN)2]2 species into a 2D network
(see the Supporting Information). Such 2D layers are further
linked by the Au-Au aurophilic interactions [3.2619(7) Å]
and hydrogen-bonding interactions between S1 and the
methyl group with C8 [-x, -y + 1, -z + 1] along the c
axis, forming a 3D structure (Figure 7).
Thermal Properties of 1-3, 6, and 7. The thermogravi-
metric analysis revealed that pure Tab decomposed at the
range of 169-400 °C. Compound 1 underwent decomposi-
tion at two stages within 46-500 °C. The first stage has a
weight loss of 2.65% in the region of 46-110 °C, which
corresponds to the loss of two H2O solvated molecules (calcd
2.66%). The second weight loss of 67.78% in the region of
150-450 °C roughly corresponds to the loss of I and Tab
ligands (calcd 68.22%). Compound 2 became decomposed
at 182 °C. The whole weight loss in 2 is 71.50%, which
3
1
1
3/4, -z - /4), C18‚‚‚N4 (x + /2, y, z + /2); C5‚‚‚S2 (x, y,
z - 1), and C7‚‚‚S2 (-x + 3/4, y - 1/4, -z - 3/4)] to afford
four intermolecular hydrogen bonds, thereby forming an
interesting 3D hydrogen-bound structure (Figure 5). In the
(14) Cramer, R. E.; Smith, D. W.; Van Doorne, W. Inorg. Chem. 1998,
37, 5895-5901.
(15) Blom, N.; Ludi, A. Acta Crystallogr. 1984, C40, 1770-1772.
(16) Rosenzweig, A.; Cromer, D. T. Acta Crystallogr. 1959, 12, 709-
712.
(17) Rawashdeh-Omary, M. A.; Omary, M. A.; Fackler, J. P., Jr. Inorg.
Chim. Acta 2002, 334, 376-384.
(18) (a) Kryachko, E. S.; Remacle, F. Nano Lett. 2005, 5, 735-739. (b)
Kryachko, E. S.; Karpfen, A.; Remacle, F. J. Phys. Chem. 2005, 109,
7309-7318. (c) Zhang, G. Q.; Yang, G. Q.; Chen, Q. Q.; Ma, J. S.
Cryst. Growth Des. 2005, 5, 661-666.
-
corresponds to the loss of Tab and PF6 (calcd 70.89%). 3
and 6 underwent decomposition at two stages. Because the
(19) (a) Bondi, A. J. Phys. Chem. 1964, 68, 441-451. (b) Canty, A. J.;
Deacon, G. B. Inorg. Chim. Acta 1980, 45, 225-230.
Inorganic Chemistry, Vol. 45, No. 19, 2006 7677

Chen et al.
Figure 5. 3D hydrogen-bound structure formed via hydrogen-bonding interactions in 3 looking along the a axis. All H atoms except those related to
hydrogen-bonding interactions are omitted for clarity.
Figure 6. 1D chain (extended along [101]) formed via Hg‚‚‚N secondary interactions in 7 with 50% thermal ellipsoids. All H atoms are omitted for clarity.
1
3
1
Symmetry transformations used to generate equivalent atoms: A, -x + /2, -y + /2, -z + 1; B, -x + 1, -y + 1, -z + 1; C, x, -y + 1, z + /2; D, x -
1
1
1
1
1/2, y + /2, z; E, -x + /2, y + /2, -z + /2.
Figure 7. 3D structure of 7 looking along the b axis. All H atoms except those related to hydrogen-bonding interactions are omitted for clarity.
20
coordinated CN- anions in 3 or 6 may be released as (CN)2
at a temperature overlapped with the decomposition tem-
perature of coordinated Tab ligand, the total weight losses
for 3 between 255 and 468 °C and for 6 between 191 and
290 °C are 49.09% and 55.51%, respectively, which corre-
sponds to the combined loss of Tab and CN (calcd 49.53%
for 3 and 55.91% for 6). In the thermogram of 7, only one
stage occurs around 250 °C. Because of the sublimation of
the mercury thiolate compound in 7,8a,21 the whole weight
loss in 7 is 61.16%, which corresponds to the loss of Hg-
(Tab)2 and cyanides (calcd 61.87%). Visual inspection and
X-ray fluorescence analysis revealed that the residue after
thermolysis was essentially metal. The remaining weights
of 1-3 and 7 are 29.57%, 28.50%, 50.91%, and 38.84%,
(20) Lefebvre, J.; Batchelor, R. J.; Leznoff, D. B. J. Am. Chem. Soc. 2004,
126, 16117-16125.
(21) Bharara, M. S.; Bui, T. H.; Parkin, S.; Atwood, D. A. Inorg. Chem.
2005, 44, 5753-5760.
7678 Inorganic Chemistry, Vol. 45, No. 19, 2006

Gold, Gold-SilWer, and Gold-Mercury String Complexes
450 nm and another more broad and intense emission band
at 674 nm with two small shoulders at 507 and 540 nm. 6
and 7 exhibited emission bands at 528 (6) and 522 (7) nm
with excitation at 380 (6) and 466 (7) nm. The lifetimes were
measured by time-resolved spectroscopy at room temperature
and calculated through the monoexponential decay method.
Being emitted at 450 nm, the lifetimes of 1-3 were measured
to be 0.42 µs (1), 3.10 µs (2), and 1.33 µs (3), while those
of 6 and 7 were 0.24 and 0.10 µs, respectively. The higher-
energy emission band at 450 nm in 1-3 may be due to the
metal-centered (MC) excited state,1k while the lower-energy
one at 534 nm in 1, 650 nm in 2, or 674 nm in 3 may be
due to the ligand-to-metal-metal charge transfer.24 The
different emission bands between 1 and 2 may be due to the
different anions as well as the H2O molecules.25 Solid K[Au-
(CN)2] had one emission band at 390 nm.1a,2a As discussed
previously, 4 showed weak emission bands at 442 and 533
nm6a while 5 had no luminescence. Thus, the emission bands
of 6 and 7 are likely to be the MC excited state (originated
Figure 8. Emission spectra of 1-3, 6, and 7 in the solid state at ambient
temperature.
which correspond to the pure Au (calcd 29.12% for 1,
29.11% for 2, 50.47% for 3, and 38.13% for 7), while the
remaining weight of 6 is 44.49%, which corresponds to the
mixed metals of AgAu (calcd 44.09%; see the Supporting
Information).
2-
from the [Au(CN)2]2 part), though the weak S f Ag
LMCT may not be ruled out in 6. In this context, the two
small shoulders in 3 may also be ascribed to the MC excited
Spectral Aspects of 1-3, 6, and 7. Solids 1-3, 6, and 7
are relatively stable toward oxygen and moisture. Compound
1 is slightly soluble in DMF and DMSO, while 2, 3, 6, and
7 are soluble in DMSO and DMF. The elemental analyses
of 1-3, 6, and 7 were consistent with their chemical
formulas. The IR spectrum of 2 showed the characteristic
P-F stretching vibrations of PF6- at 841 and 559 cm-1.6 In
the IR spectra of 3, 6, and 7, the ν(CtN) band of K[Au-
(CN)2]22 at 2141 cm-1 was split into one weak band at 2156
cm-1 (3, 6, and 7) and one strong band at 2137 cm-1 (3 and
5) and 2133 cm-1 (6) because the [Au(CN)2]- anion was
dimerized into the [Au(CN)2]22- dianion in 3, 6, and 7. The
1H NMR spectra of 1-3, 6, and 7 in DMSO-d6 at room
temperature showed a multiplet for protons of Ph groups at
7.59-7.74 ppm and a singlet related to protons of NMe3 at
ca. 3.51 ppm.
The electronic spectra of 1-3, 6, and 7 in DMF exhibited
strong and broad absorptions at 304 nm (1), 302 nm (2),
302 nm (3), 296 nm (6), and 268 nm (7) (see the Supporting
Information). Because the absorption spectral data for K[Au-
(CN)2] showed no absorption above 250 cm-1 with low
concentration (10-4 M)23 and the absorption spectrum of the
free Tab in DMF had a broad absorption band at 320 nm,6b
the peaks observed in the spectra of 1-3, 6, and 7 are all
blue-shifted and may be due to the ligand (Tab)-to-metal
charge transfer (LMCT).
2-
states derived from the [Au(CN)2]2 part. It is noted that
the solutions of 1-3, 6, and 7 did not show luminescence,
which may be due to the fact that these compounds, when
dissolved, tend to dissociate into nonemissive monomeric
species, in which the ionic interactions and aurophilic
bonding interactions may no longer be present.26
Conclusions
In this paper, we have demonstrated a route to rational
construction of two tetranuclear metal string compounds 3
and 6 from reactions of preformed complexes 2 and 4 with
K[Au(CN)2]. Compound 3 or 6 has a ligand-unassisted Au4
or Ag2Au2 string structure in which two {[(Tab)2M][Au-
(CN)2]} species (formed through ionic interaction between
the [M(Tab)2]+ cation and the [Au(CN)2]- anion) are held
together by one Au-Au aurophilic bonding interaction. 3
and 6 represent the interesting examples in which ionic
interactions and aurophilic interactions are designed to work
perfectly on a same string structure in a cooperative way. It
+
is noteworthy that the orientation of the -SC6H4NMe3
groups coordinated at Au atoms of 2 is retained in the
structure of 3 while those of 4 are reoriented in the same
direction during the reaction so as to facilitate the formation
of the string structure of 6. Although the reaction of 5 with
K[Au(CN)2] did not result in the formation of our expected
Preliminary photochemical and photophysical investigation
of 1-3, 6, and 7 revealed very interesting photoluminescent
(24) (a) Pan, Q. J.; Zhang, H. X. Organometallics 2004, 23, 5198-5209.
(b) Bardaji, M.; Calhorda, M. J.; Costa, P. J.; Jones, P. G.; Laguna,
A.; Perez, M. R.; Villacampa, M. D. Inorg. Chem. 2006, 45, 1059-
1068.
properties in the solid state at ambient temperature (Figure
max
ex
8). The emission spectrum (λ ) 375 nm) of 1 displayed
(25) (a) Charbonnie`re, L. J.; Ziessel, R.; Montalti, M.; Prodi, L.; Zaccheroni,
N.; Boehme, C.; Wipff, G. J. Am. Chem. Soc. 2002, 124, 7779-7788.
(b) Coker, N. L.; Krause Bauer, J. A.; Elder, R. C. J. Am. Chem. Soc.
2004, 126, 12-13. (c) Anzenbacher, P., Jr.; Tyson, D. S.; Jursikova,
K.; Castellano, F. N. J. Am. Chem. Soc. 2002, 124, 6232-6233. (d)
Supkowski, R. M.; Horrocks, W. D., Jr. Inorg. Chem. 1999, 38, 5616-
5619. (e) Klonkowski, A. M.; Lis, S.; Pietraszkiewicz, M.; Hnatejko,
Z.; Czarnobaj, K.; Elbanowski, M. Chem. Mater. 2003, 15, 656-663.
(26) King, C.; Wang, J. C.; Khan, M. N. I.; Fackler, J. P., Jr. Inorg. Chem.
1989, 28, 2145-2149.
one small band at 450 nm and another emission band at 534
max
nm, while (λ ) 360 nm) of 2 displayed one small band
ex
at 450 nm and another broad emission band at 650 nm.
Excitation of 3 at 399 nm resulted in one emission band at
(22) Chadwick, B. M.; Frankiss, S. G. J. Mol. Struct. 1976, 31, 1-7.
(23) Rawashdeh-Omary, M. A.; Omary, M. A.; Patterson, H. H. J. Am.
Chem. Soc. 2000, 122, 10371-10380.
Inorganic Chemistry, Vol. 45, No. 19, 2006 7679

Chen et al.
Au2Hg2 string complex, the unexpected complex 7 has an
interesting 1D chain structure where the [Hg(Tab)2]2+
dication and the [Au(CN)2]22- dianion are interconnected by
the secondary Hg‚‚‚N(CN) interactions. Relative to those of
their corresponding precursors, 3, 6, and 7 showed more
intensive luminescence in the solid state. The incorporation
of a preformed luminescent precursor such as 2 and
[Au(CN)2]- into the desired structures may be an effective
method for the preparation of other luminescent materials.
Works toward this respect are underway.
highly appreciated some useful suggestions from the Editor
and the reviewers.
Supporting Information Available: Crystallographic data of
compounds 1-3, 6, and 7 (CIF), hydrogen-bond geometry in 1-3,
6, and 7, the 2D structure formed via hydrogen-bonding interactions
in 1, the 3D structure formed via C-H‚‚‚F hydrogen-bonding
interactions in 2, the arrangement of the Au4 strings in the crystal
of 3, the 1D structure formed via C-H‚‚‚Au hydrogen-bonding
interactions in 3, the view of the molecular structure of 6, the 1D
structure formed via C-H‚‚‚Ag hydrogen-bonding interactions in
6, the 3D structure formed via all hydrogen-bonding interactions
in 6, the 2D network formed via Hg‚‚‚N secondary interactions
and hydrogen-bonding interactions in 7, the thermogravimetric
analysis curves for 1-3, 6, 7, and Tab, and the absorption spectra
of 1-3, 6, and 7 (in PDF format). This material is available free
of charge via the Internet at http://pubs.acs.org.
Acknowledgment. This work was supported by the
NNSF of China (Grants 20271036 and 20525101), the NSF
of Jiangsu Province (Grant BK2004205), the Specialized
Research Fund for the Doctoral Program of Higher Education
(Grant 20050285004), the Qin-Lan Project of Jiangsu
Province, and the State Key Laboratory of Coordination
Chemistry, Nanjing University, in China. The authors also
IC060655M
7680 Inorganic Chemistry, Vol. 45, No. 19, 2006