Synthesis and structures of dinuclear copper(I) and silver(I) 1, 3-bis[(2-chloro)benzene]triazenide complexes

Article abstract of DOI:10.1002/zaac.201200187

In the presence of Et₃N, the reaction of 1, 3-bis[(2-chloro) benzene]triazene (HL) with CuCl or AgNO₃ gives the triazenide complexes {Cu₂(L)₂} (1) and {Ag₂(L) ₂} (2), respectively. The X-ray crystal structures of both complexes were obtained. The metal-metal distances (Cu...Cu and Ag...Ag) are 2.4974(5) and 2.7208(5) A, respectively. Copyright

Full text of DOI:10.1002/zaac.201200187

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ARTICLE
DOI: 10.1002/zaac.201200187
Synthesis and Structures of Dinuclear Copper(I) and Silver(I) 1,3-Bis-
[(2-chloro)benzene]triazenide Complexes
Zhan-Mao Cai,[a] Gang Yu,[a] Qi-Ying Lv,[a] Wen-Qing Jiang,[a] and Shu-Zhong Zhan*[a]
Keywords: Keywords. Triazene; Copper; Silver; Crystal structures; Metal–metal distances
Abstract. In the presence of Et3N, the reaction of 1,3-bis[(2-chloro)
benzene]triazene (HL) with CuCl or AgNO3 gives the triazenide com-
plexes {Cu2(L)2} (1) and {Ag2(L)2} (2), respectively. The X-ray crys-
tal structures of both complexes were obtained. The metal–metal dis-
tances (Cu···Cu and Ag···Ag) are 2.4974(5) and 2.7208(5) Å, respec-
tively.
of triazene group hydrogen atom, and in the range of 7.70–
7.10 ppm for the aromatic protons (Figure S1, Supporting In-
formation). Scheme 1 shows the procedure for the synthesis of
complexes 1 and 2. Complex 1 was obtained as red crystals by
the reaction of HL and CuCl in dichloromethane/acetonitrile in
43.1% yield, and complex 2 was obtained as red crystals by
the reaction of HL and AgNO3 in dichloromethane/THF in
41.2% yield.
Introduction
An approach toward the synthesis of complexes that exhibit
new chemical and physical properties is the design of ligands
that can be easily functionalized in order to modify the metal
coordination sphere. Anionic, bridging, nitrogen bonded li-
gands, such as triazenides have attracted our attention, since
they show a variety of bonding modes with distinct proper-
ties.[1–3] This versatile ligand has been employed in the synthe-
sis of complexes of transition metals[4–9] and main group ele-
ments.[10,11] Additionally, triazenide ligands can stabilize late
transition metal complexes showing only close metal–metal in-
teraction[12] or containing metal–metal bonds.[13] In our pre-
vious work, we have prepared some polynuclear complexes
with triazenide ligands.[14–16] On the basis of preliminary stud-
ies, we are interested in the synthesis and reactivity with transi-
tion metals of new triazenes.
In our lab, a triazene, namely 1,3-bis[(2-chloro)benzene]tria-
zene (HL) was synthesized and characterized. In the presence
of Et3N, the reaction of HL and CuCl or AgNO3 affords the
triazenide complexes {Cu2(L)2} (1) or {Ag2(L)2} (2), respec-
tively. In this paper, we present the synthesis and characteriza-
tion of HL, as well as complexes 1 and 2 thereof.
Scheme 1. Schematic representation of the synthesis of complexes 1
and 2.
Results and Discussion
Synthesis and Characterization
The electronic spectra of HL, 1, and 2 were recorded in
CH2Cl2 (Figure S2; Supporting Information). HL exhibits two
bands at 243 and 356 nm. Complex 1 exhibits four bands at
229, 268, 286, and 372 nm, and complex 2 shows two bands
at 240 and 363 nm. Compared with that of HL (356 nm), the
absorption maxima of the low-energy band of complex 1
(372 nm) and complex 2 (363 nm) are red-shifted to a longer-
wavelength region. This is assignable to intraligand transitions
of the L– ligands, as well as a MǞL MLCT transition from
the M(I) ion (M = Cu or Ag) to the deprotonated ligand (L–).
Copper(I) or silver(I), which has the d10 configuration, is
expected to exhibit diamagnetic behavior. Accordingly, com-
1,3-Bis[(2-chloro)benzene]triazene (HL) was synthesized by
the reaction of 2-chloroaniline and sodium nitrite in 64%
1
yield. H resonances are found at δ = 9.92 ppm for a singlet
* Dr. S.-Z. Zhan
Fax: +86-20-87112053
E-Mail: shzhzhan@scut.edu.cn
[a] College of Chemistry & Chemical Engineering
South China University of Technology
Guangzhou,510640, P. R. China
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/zaac.201200187 or from the au-
thor.
Z. Anorg. Allg. Chem. 0000, ᭿,(᭿), 0–0
© 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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plexes 1 and 2 are amenable to NMR analysis. The H NMR di-copper complex [Cu2(L)2], and a di-silver complex [Ag2(L)2],
spectroscopic data in [D2]methylene dichloride obtained for respectively. Table 1 lists details of the crystal parameters, data
complexes 1 and 2 are consistent with a single-ligand environ-
ment. In the case of both the copper and silver products,
1H NMR spectroscopy reveals a similar series of resonances.
collection and refinements for complexes 1 and 2. Table 2 lists
the selected bond lengths and angles for 1 and 2.
The molecular structure of the complexes [Cu2(L)2], and
[Ag2(L)2] are depicted in Figure 1 and Figure 2. The copper
and silver complexes [Cu2(L)2] and [Ag2(L)2] are isotypic, and
share many of the gross structural features of previously struc-
turally characterized CuI, and AgI di-metallic systems[17–20]
(Table 3), consisting of two central metal atoms bridged by
two triazenide ligands in an μ,η1,η1-fashion, with approxi-
mately linear two coordinate arrangements [N(1)–Cu(1)–
N(3#1): 171.00(7)° and N(1)–Ag(1)–N(3#1): 166.64(7)°,
respectively], with the deviation caused by the metal atoms
moving away from each other. The N–N–N angle in [Ag2(L)2]
is 117.47(18)°, larger than that observed in [Cu2(L)2]
[115.43(16)°], due to different sizes for silver and copper
atoms.
1
For complex 1, H resonances are found in the range of 7.68–
7.07 ppm for the aromatic protons (Figure S3). In complex 2,
1H resonances are found in the range of 7.56–7.11 ppm for the
aromatic protons (Figure S4).
Structural Analysis
Single crystal X-ray diffraction analysis of the two com-
plexes reveal the solid-state structure of the complexes to be a
Table 1. Crystallographic data for complexes 1 and 2.
1
2
Empirical formula
C24H16Cu2Cl4N6 C24H16Ag2Cl4N6
Both complexes are formed by the two N3 ligands and the
{M2} unit (M = Cu or Ag). The Cu–N and Ag–N bond lengths
in both [Cu2(L)2] and [Ag2(L)2] are within the expected ranges
for terminal M(I)–N bonds [Cu–N: 1.8966(16) Å and
1.8983(16) Å; Ag–N: 2.1666(18) Å and 2.1722(18) Å].[2,12,18]
Similarly the N–N bond lengths within the triazenide ligands
{N(1)–N(2): 1.302(2) Å, N(2)–N(3): 1.301(2) Å in [Cu2(L)2]
and N(1)–N(2): 1.302(3) Å, N(2)–N(3): 1.294(3) Å in [Ag2(L)2]}
are also comparable to those observed in related systems.[12,18]
A significant point of interest in these dimeric CuI and AgI
complexes is the presence of relatively short M···M intramolec-
ular distances. In both complexes, the metal–metal distances
[Cu(1)–Cu(1#): 2.4974(5) Å and Ag(1)–Ag(1#): 2.7208(5) Å]
are significantly shorter than the sum of the van der Waals
radii[21] of copper (1.40 Å) and silver (1.72 Å) and are directly
comparable to related dimeric complexes listed in Table 3. It
is not unusual for short metal–metal distances to be observed
in complexes with bridging ligands. For this reason the pres-
ence of true metallophilic interactions is often dubious.
Formula weight
λ /Å
Crystal system
Space group
a /Å
b /Å
c /Å
α /°
β /°
657.33
745.97
0.71073
0.71073
triclinic
monoclinic
P21/n
12.7951(17)
7.3076(10)
15.0536(15)
90
115.599(8)
90
1269.4(3)
2
¯
P1
7.5565(7)
9.0949(8)
9.8671(9)
70.866(2)
87.653(2)
76.804(2)
623.32(10)
1
γ /°
V /Å3
Z
Dc /Mg·m–3
F(000)
1.751
328
1.952
728
θ range for data collection /° 2.19 to 27.57
Reflections collected / unique 7688/2848
Data / restraints / parameters 2848/0/163
2.75 to 27.51
8344/2899
2899/0/163
0.999
R1 = 0.0263
wR2 = 0.0592
R1 = 0.0418
wR2 = 0.0653
Goodness-of-fit on F2
1.023
Final R indices [I Ͼ 2σ(I)]
R1 = 0.0282
wR2 = 0.0662
R1 = 0.0415
wR2 = 0.0716
R indices (all data)
Table 2. Selected bond lengths /Å and angles /° for complexes 1 and 2.
1
Cu(1)–N(1)
Cu(1)–Cu(1)#1
N(2)–N(3)
N(1)–Cu(1)–N(3)#1
N(3)#1–Cu(1)–Cu(1)#1
N(3)#1–Cu(1)–Cl(2)#1
N(2)–N(1)–Cu(1)
N(3)–N(2)–N(1)
1.8966(16)
2.4974(5)
1.301(2)
171.00(7)
85.08(5)
74.88(5)
126.24(13)
115.43(16)
Cu(1)–N(3)#1
N(1)–N(2)
N(3)–Cu(1)#1
N(1)–Cu(1)–Cu(1)#1
N(1)–Cu(1)–Cl(2)#1
Cu(1)#1–Cu(1)–Cl(2)#1
C(1)–N(1)–Cu(1)
N(2)–N(3)–Cu(1)#1
1.8983(16)
1.302(2)
1.8983(16)
85.94(5)
112.78(5)
139.78(2)
122.31(13)
127.17(13)
2
Ag(1)–N(3)#1
Ag(1)–Ag(1)#1
N(2)–N(3)
N(3)#1–Ag(1)–N(2)
N(2)–Ag(1)–Ag(1)#1
N(2)–Ag(1)–Cl(2)
N(3)#1–Ag(1)–Cl(3)#1
Ag(1)#1–Ag(1)–Cl(3)#1
N(3)–N(1)–N(2)
2.1666(18)
2.7208(5)
1.294(3)
166.64(7)
83.69(5)
71.28(6)
69.12(6)
136.12(3)
117.47(18)
Ag(1)–N(2)
N(1)–N(2)
N(3)–Ag(1)#1
N(3)#1–Ag(1)–Ag(1)#1
N(3)#1–Ag(1)–Cl(2)
Ag(1)#1–Ag(1)–Cl(2)
N(2)–Ag(1)–Cl(3)#1
Cl(2)–Ag(1)–Cl(3)#1
2.1722(18)
1.302(3)
2.1666(18)
83.02(5)
121.02(6)
142.84(3)
120.72(6)
80.98(3)
2
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Copper(I) and Silver(I) 1,3-Bis[(2-chloro)benzene]triazenide Complexes
dinuclear complexes 1 and 2, which were characterized by X-
ray crystallography and 1H NMR spectra. We are currently
preparing other new triazenide ligands and their transition
metal complexes.
Experimental Section
Data were collected with a Bruker SMART CCD area detector using
graphite monochromated Mo-K radiation (0.71073 Å) at room tem-
perature. All empirical absorption corrections were applied by using
the SADABS program.[22] The structures were solved by direct meth-
ods and the corresponding non-hydrogen atoms are refined anisotropi-
cally. All the hydrogen atoms of the ligands were placed in calculated
positions with fixed isotropic thermal parameters and included in the
structure factor calculations in the final stage of full-matrix least-
squares refinement. All calculations were performed using the
SHELXTL computer program.[23]
Crystallographic data (excluding structure factors) for the structures in
this paper have been deposited with the Cambridge Crystallographic
Data Centre, CCDC, 12 Union Road, Cambridge CB21EZ, UK. Copies
of the data can be obtained free of charge on quoting the depository
numbers CCDC-876006 and CCDC-876007. (Fax: +44-1223-336-033;
E-Mail: deposit@ccdc.cam.ac.uk, http://www.ccdc.cam.ac.uk)
Figure 1. Molecular structure of CuI2(L)2 (1).
Synthesis of 1,3-Bis[(2-chloro)benzene]triazene (HL): 2-Chloroani-
line (10 mmol) in water (5 mL) was mixed with HCl (1 mol·L–1,
30 mL, 30 mmol) at 0 °C. An aqueous solution (15%) of sodium nitrite
(15 mmol) was added dropwise with stirring. Once the amine was dis-
solved, a solution of 2-chloroaniline in ethanol (10 mmol) was added
at 0 °C and the mixture was stirred for 3 h. The reaction mixture was
neutralized with a 15% aqueous of NaCH3CO2 (15 mL) to give an
orange precipitate. The reaction mixture was filtered, and the solid was
purified by crystallization at –4 °C from 9:1 ethyl acetate/n-hexane to
obtain yellow crystals, which were collected and dried in vacuo (yield
1.7 g, 64%). C12H9Cl2N3: calcd. C 54.16; H 3.41; N 15.79%;
found: C, 54.07; H, 3.39; N, 15.66%. 1H NMR (CD2Cl2): δ = 9.92
(s, 1 H), 7.69 (d, J = 2.0 Hz, 2 H), 7.40 (d, J = 2.0 Hz, 2 H), 7.29
(t, J = 3.0 Hz, 2 H), 7.14 (t, J = 2 Hz, 2 H) ppm. UV/Vis [CH2Cl2,
λmax /nm (ε /L·mol–1·cm–1)]: 243 (3.5ϫ104), 356 (4.7ϫ104).
Synthesis of [Cu2(L)2] (1): To a solution, containing ligand (HL)
(0.266 g, 1 mmol) and triethylamine (0.10 g, 1 mmol) in dichlorometh-
ane/acetonitrile (20 mL, 1:1), CuCl (0.10 g, 1 mmol) was added and
the mixture was stirred for 15 min. The solution was allowed to slowly
evaporate, affording red crystals, which were collected and dried in
vacuo (yield 0.141 g, 43.1%). C24H16Cu2Cl4N6: calcd. C 43.85; H
2.45; N 12.79%; found: C, 43.79; H, 2.48; N, 12.81%. 1H NMR
(CD2Cl2): δ = 7.67 (d, J = 2.0 Hz, 4 H), 7.38 (d, J = 2.0 Hz, 4 H),
7.28 (t, J = 2.0 Hz, 4 H), 7.09 (t, J = 2 Hz, 4 H) ppm. UV/Vis [CH2Cl2,
λmax /nm (ε /L·mol–1·cm–1)]: 229 (6.2ϫ104), 268 (5.6ϫ104), 286
(5.3ϫ104), 372 (7.2ϫ104).
Figure 2. Molecular structure of AgI2(L)2 (2).
Table 3. Cu···Cu and Ag···Ag distances /Å in some bridged dinuclear
CuI and AgI complexes.
Complex
d(M···M)
Reference
[Cu2(μ-Ph-NNN-Ph)2]
2.4405(10)
2.4458(4)
2.4289(12)
[17]
[12]
[18]
[Cu2(μ-C6H3(iPr)2-NNN-C6H3(iPr)2)2]
[Cu2{μ-o-C6H4(CO2Me)-NNN-o-C6H4-
(CO2Me)}2]
Synthesis of [Ag2(L)2] (2): The procedure was performed in the same
way as that for the synthesis of 1 except that CuCl was replaced with
AgNO3. Red crystals characterized as [Ag2(L)2] 2 were obtained in
41.2% (0.154g). C24H16Ag2Cl4N6: calcd. C 38.64; H 2.16; N 11.27%;
[Cu2{μ-o-C6H4(Cl)-NNN-o-C6H4-(Cl)}2] 2.4974(5)
this work
[19]
[20]
[Ag2(μ-Ph-NNN-Ph)2]
[Ag2{μ-MeOC6H4-NNNC6H4OMe}
2.669(1)
2.680(2)
[Ag2{μ-o-C6H4(Cl)-NNN-o-C6H4-(Cl)}2] 2.7208(5)
this work
1
found: C 38.61; H 2.18; N 11.31%. H NMR (CD2Cl2): δ = 7.55 (d,
J = 2.0 Hz, 4 H), 7.47 (d, J = 2.0 Hz, 4 H), 7.31 (t, J = 2.0 Hz, 4 H),
Conclusions
7.13 (t,
J = 2 Hz, 4 H) ppm. UV/Vis [CH2Cl2, λmax/nm (ε
/L·mol–1·cm–1)]: 240 (8.0ϫ104), 363 (7.5ϫ104).
1,3-Bis[(2-chloro)benzene]triazene (HL) was synthesized by
the reaction of 2-chloroaniline and sodium nitrite. Deproton-
Supporting Information (see footnote on the first page of this article):
ated HL can bridge central copper and silver atoms to give two 1H NMR and electronic spectra of the ligand and complexes 1 and 2.
Z. Anorg. Allg. Chem. 0000, 0–0
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[9] G. Albertin, S. Antoniutti, M. Bedin, J. Castro, S. Garcia-Fontán,
Inorg. Chem. 2006, 45, 3816.
Acknowledgements
[10] P. Gantzel, P. J. Walsh, Inorg. Chem. 1998, 37, 3450.
[11] S. Westhusin, P. Gantzel, P. J. Walsh, Inorg. Chem. 1998, 37,
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[12] A. L. Johnson, A. M. Willcocks, S. P. Richards, Inorg. Chem.
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This work was supported by the Research Foundation for Returned
Chinese Scholars Overseas of Chinese Education Ministry (No.
B7050170), the National Natural Science Foundation of China (No.
20971045), and the Student Research Program (SRP) of South China
University of Technology.
[14] W. Lei, X. Tan, L. Han, S. Zhan, B. Li, Inorg. Chem. Commun.
2010, 13, 1325.
[15] W. Li, Y. Liu, S. Zhan, D. Cao, Inorg. Chem. Commun. 2011, 14,
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Received: April 22, 2012
Published Online: ᭿
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Copper(I) and Silver(I) 1,3-Bis[(2-chloro)benzene]triazenide Complexes
Z.-M. Cai, G. Yu, Q.-Y. Lv, W.-Q. Jiang, S.-Z. Zhan* ..... 1–5
Synthesis and Structures of Dinuclear Copper(I) and Silver(I)
1,3-Bis[(2-chloro)benzene]triazenide Complexes
Z. Anorg. Allg. Chem. 0000, 0–0
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