Unidimensional self-assembling of {HgII[NNN(PhBr) 2]2} through metal-η4-arene π-interactions: Synthesis and x-ray characterization of a bis diaryl symmetric-substituted triazenide complex polymer of mercury(II)

Article abstract of DOI:10.1002/zaac.200500460

A solution of deprotonated 1,3-bis(4-bromophenyl)triazene reacts with Hg(CH₃COO)₂ in methanol / tetrahydrofurane to give yellow crystalline needles of {Hg^II[NNN(PhBr)₂]₂} _n, a triazenide complex polymer of Hg^II with metal-η²,η²-arene π-interactions, performed by coordinated single triazenide chains. The crystal structure of the new polymeric complex of Hg^II belongs to the monoclinic space group P2 ₁/n. The lattice of [Hg^II(BrPhNNNPhBr)₂] _n can be viewed as a one-dimensional assembling of planar tectons [Hg^II(BrPhNNNPhBr)₂] linked through metalocene alike Hg^II-η²,η²-arene π-interactions along the crystallographic b axis.

Full text of DOI:10.1002/zaac.200500460

DOI: 10.1002/zaac.200500460
Unidimensional Self-assembling of {HgII[NNN(PhBr)2]2} through Metal-η4-
arene π-Interactions: Synthesis and X-Ray Characterization of a Bis Diaryl
Symmetric-substituted Triazenide Complex Polymer of Mercury(II)
Manfredo Hörner*, Gelson Manzoni de Oliveira*, Mariana Boneberger Behm, and Herton Fenner
´
Santa Maria, RS, Brazil, Departamento de QuımicaϪUniversidade Federal de Santa Maria
Received November 22nd, 2005.
Abstract. A solution of deprotonated 1,3-bis(4-bromophenyl)tri-
azene reacts with Hg(CH3COO)2 in methanol / tetrahydrofurane
to give yellow crystalline needles of {HgII[NNN(PhBr)2]2}n, a tri-
azenide complex polymer of HgII with metal-η2,η2-arene π-inter-
actions, performed by coordinated single triazenide chains.
The crystal structure of the new polymeric complex of HgII
belongs to the monoclinic space group P21/n. The lattice of
[HgII(BrPhNNNPhBr)2]n can be viewed as a one-dimensional
assembling of planar tectons [HgII(BrPhNNNPhBr)2] linked
through metalocene alike HgII-η2,η2-arene π-interactions along the
crystallographic b axis.
Keywords: Mercury; Triazenes; Triazenide complexes; Supramole-
cular assembling; π-Interactions
Introduction
ditionally coordinated by two peripheral phenyl rings of
two neighboring complexes. The two phenyl rings are lo-
cated parallel to the main molecular plane and coordinate
the HgII ion in a η2,η2 π type of bonding.
More recently we have described [7] the synthesis of poly-
meric {Hg[NNN(PhR)2]2}n (R ϭNO2, F), a new triazenide
complex of Mercury(II) with metal-arene π-interactions,
performed by coordinated (single) 1,3-diaryl-substituted
Selective, directional and strongly attractive noncovalent in-
teractions can induce the self-assembly of predictable
supramolecular aggregates. The molecules which play the
role of building blocks in a self-assembled, ordered supra-
molecular structure are called tectons [1Ϫ3]. According to
M. Simard and co-workers [2], a tecton (from Greek, tek-
ton, builder) is defined as any molecule whose interactions
are dominated by particular associative forces that induce
the self-assembly of an organized network with specific
architectural or functional features. The design and con-
struction of multicomponent supermolecules or supramol-
ecular arrays utilizing non-covalent bonding of tectons
would be called supramolecular synthesis [3]. Thus, the
supramolecular synthesis exploits successfully hydrogen-
bonding and other types of non-covalent interaction, in
building supramolecular systems [3Ϫ5].
Newly we have shown that triazenide complexes of Mer-
cury(II) are tectons with a remarkably good ability to self-
assemble of different manners through metal-η-arene π-in-
teractions: the synthesis of {Hg[PhN3C6H4N3(H)Ph]
(NO3)} [6] Ϫ a rare Mercury(II) complex containing two
phenyltriazenide chains Ϫ was one of the first evidences
that in this complex type besides Metal-N bonds also me-
tal-arene π-interactions perform a significant role in the
architecture (or self-assembling) of the crystalline lattice. In
this complex the HgII ions of the tectonic units are ad-
triazenide chains. In
a
tectonic molecule of
{HgII[NNN(PhR)2]2} two deprotonated asymmetric 1,3-di-
aryl-substituted triazenide ligands are coordinated in an op-
posite way to one HgII ion by means of primary and sec-
ondary bonds. The HgII ions are placed on the inversion
centers of translation operated {Hg[NNN(PhR)2]2} tectons
which are stacked along the crystallographic a axis forming
infinite unidimensional chains linked through metalocene
alike Hg-η2,η2-arene π-interactions. Secondary Hg···N and
CϪH···F interactions appear also within the tectons
{Hg[NNN(PhR)2]2}. In the reported compound [7] only the
planar coordination sites of the metal ion were compro-
mised, the two axial π-interacting positions were free.
The possibility to achieve a Hg-η2-arene dimerization by
blocking one of the axial positions of the HgII ion with
pyridine was also successfully investigated [8]. In the new
complex [HgII(RPhNNNPhRЈ)2Py]2 (R ϭ NO2, RЈ ϭ F),
the tectons [HgII(RPhNNNPhRЈ)2Py] are linked in pairs as
centrosymmetric dimers through reciprocal Hg-η2-arene
secondary interactions. The dimeric units attain addition-
ally intramolecular, secondary CϪH···F interactions and
are operated by translation in the crystallographic direction
* Prof. Dr. Manfredo Hörner, * Prof. Dr. G. Manzoni de Oliveira
Universidade Federal de Santa Maria
Departamento de Quımica Ϫ CCNE
Faixa de Cambi, Km 9 Ϫ Campus Ϫ Predio 18
97.105-900 Ϫ Santa Maria, RS / Brazil
Fax: ϩϩ55-55-3220-8031
[100],
assembling
unidimensional
chains
{[HgII(RPhNNNPhRЈ)2Py]2}n linked through non classical
CϪH···O hydrogen bonds. In the unit cell these chains are
related in pairs through an inversion centre, without bidi-
mensional interactions.
´
´
E-mail: hoerner@smail.ufsm.br; manzoni@quimica.ufsm.br
Z. Anorg. Allg. Chem. 2006, 632, 615Ϫ618
 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
615

M. Hörner, G. Manzoni de Oliveira, M. Boneberger Behm, H. Fenner
Giving sequence to our experiments involving the supra-
molecular syntheses of tectonic unidimensional Hg-triazen-
ide chains, we report now on the synthesis and the X-ray
characterization of a symmetric-substituted triazenide com-
plex polymer of HgII with metal-η2,η2-arene π-interactions,
performed by coordinated (single) triazenide chains. In the
title compound {HgII[NNN(PhBr)2]2}n the HgII ions rep-
resent the inversion center of tectons comprised by planar
HgII-bis 1,3-diaryl-substituted triazenide moieties, which
are disposed as unidimensional chains linked through meta-
locene alike Hg-η2,η2-arene π-interactions.
terminal aryl ring [C(21)ϪC(26)Br(2)] exhibits an appreci-
able deviation [10.9(2)°] from this plane. The linear coordi-
nation of the Hg2ϩ ion is achieved by two triazenide anions
˚
through N(11,11Ј) [HgϪN(11) ϭ 2.061(4) A] and the weak
˚
interactions Hg···N(13, 13Ј) with a distance of 2.771(5) A.
These HgϪN and Hg···N distances are similar to the corre-
sponding bond lengths in the triazenide complex
{HgII[NNN(PhR)2]2}n (R ϭ NO2, F) [7], HgϪN(11) ϭ
˚
2.077(4) and Hg···N(13) ϭ 2.768(3) A.
In the hitherto unknown structure of the polymeric title
complex intermolecular interactions are patent. The trans-
lation operated moieties are stacked unidimensionally along
the crystallographic b axis through Hg-η2,η2-arene π-inter-
actions between the HgII ion and carbon atoms of two per-
ipheral phenyl rings of two neighboring complexes. In the
unit cell packing the single chains are related through 21
screw axes parallel to the b axis. The tectonic moieties
{Hg[NNN(PhBr)2]2} attain furthermore intramolecular,
secondary Hg···N interactions (see Table 2 and Fig. 1), also
accountable for the planarity of the tectons. The two phenyl
rings of the metalocene alike Hg-η2,η2-arene π-interactions
are located parallel to the main molecular plane of the tec-
tons [HgII(RPhNNNPhRЈ)2] and coordinate the HgII ions
in a π type of bonding. In each single molecule the two
bromophenyl rings of the triazenide chains are linked to-
ward two metallic centres, above and below the plane, rein-
forcing the chaining of the lattice. Thus, each tecton [HgI-
I(BrPhNNNPhBr)2] is linked with two other ones through
four secondary interactions of the metal-η2 type. Two car-
bon atoms of the C21ϪC26 ring have remarkably short dis-
tances to the HgII ion: these shortest intermolecular dis-
tances from the HgII centres toward the phenyl rings are
Results and Discussion
Crystal data and experimental conditions are given in Table
1. Selected bond distances and angles of the title complex
are listed in Table 2; Figure 1 shows the molecular structure
ofthe tecton {Hg[NNN(PhBr)2]2} in a thermal ellipsoid
representation [9], Figure 2 shows a section of the polymeric
unidimensional lattice, linked through secondary metal-
η2,η2-arene π-interactions (dashed lines).
In a single tecton {Hg[NNN(PhBr)2]2} two deprotonated
symmetric 1,3-bis(4-bromophenyl)triazenide ligands are co-
ordinated to one HgII ion by means of two primary HgϪN
bonds and two secondary HgϪN interactions (dashed lines,
Fig. 1). The asymmetric unit is formally related with the
other half of the molecule through a crystallographic inver-
sion center, located on the Hg2ϩ ion. The complex
{Hg[NNN(PhBr)2]2} is essentially planar. The HgII ion, all
the six triazenide
N
atoms and the terminal
C(11)ϪC(16)Br(1) aryl ring, generate a plane with a maxi-
˚
mum deviation from coplanarity of 0.0364 A. The second
˚
3.297(6) [Hg(1)···C(21)Љ] and 3.429(6) A [Hg(1)···C(22)Љ,
symmetry code (Љ) x, yϩ1, z]. The distance from the met-
allic ion to the midpoint of the C(21)ЉϪC(22)Љ bond is
Table 1 Crystal data and structure refinement for {HgII[NNN
(PhBr)2]2}
I
I
˚
3.36 A, smaller than the midpoint distances C(31 )ϪC(36 )
˚
˚
[3.38 A, symmetry code (Ј) x, yϪ1, z] and C34ЈϪC35Ј
Empirical formula
Formula weight
T /K
C24H16Br4HgN6
908.66
293(2)
[3.51 A, symmetry code (Ј) Ϫxϩ1, Ϫy, Ϫz] in the complexes
{Hg[PhN3C6H4N3(H)Ph](NO3)}
[6]
and
[HgII
˚
Radiation, λ /A
0.71073
Crystal system, space group
Unit cell dimensions, a, b, c /A
monoclinic,P21/n
a ϭ 15.1741(6),
b ϭ 4.6587(2),
c ϭ 18.5342(7)
β ϭ 94.207(2)°
1306.68(9)
2, 2.309
12.031
844
(RPhNNNPhRЈ)2Py]2 (R ϭ NO2, RЈ ϭ F)[8] respectively, but
larger than the distance from the metallic ion to the midpoint
˚
II
˚
Table 2 Selected bond lengths /A and angles /° for {Hg [NNN
˚
Volume /A
(PhBr)2]2}
Z, Calculated Density /g.cmϪ3
Absorption coefficient /mmϪ1
F(000)
Bond lengths
Crystal size /mm
Theta range /°
Index ranges
0.38 x 0.10 x 0.09
1.68 Ϫ 25.50°
Ϫ18 Յ h Յ 18,
Ϫ5 Յ k Յ 5,
Ϫ22 Յ l Յ 22
18442
2433 [Rint ϭ 0.0322]
100.0 %
0.4106 and 0.0918
Full-matrix least-squares on F2
2433 / 0 / 160
1.343
C(14)ϪBr(1)
C(24)ϪBr(2)
N(11)ϪN(12)
N(11)ϪHg(1)
1.894(6)
1.896(7)
1.324(7)
2.061(4)
1.280(7)
2.771(5)
3.297(6)
3.429(6)
N(13)ϪN(12)ϪN(11)
N(12)ϪN(13)ϪC(21)
N(11)ЈϪHg(1)ϪN(11)
N(11)ЈϪHg(1)···N(13)Ј
N(11)ϪHg(1)···N(13)Ј
N(11)ЈϪHg(1)···C(21)Љ
N(11)ϪHg(1)···C(21)Љ
N(13)Ј···Hg(1)···C(21)Љ
N(11)ЈϪHg(1)···C(22)Љ
N(11)ϪHg(1)···C(22)Љ
N(13)Ј···Hg(1)···C(22)Љ
C(21)Љ···Hg(1)···C(22)Љ
111.9(5)
113.5(5)
180.0(2)
50.5(2)
129.5(2)
99.8(2)
80.2(2)
102.0(1)
84.9(2)
95.1(2)
106.4(2)
23.8(1)
N(12)ϪN(13)
Reflections collected
Hg(1)···N(13)Ј
Hg(1)···C(21)Љ
Hg(1)···C(22)Љ
Bond angles
N(12)ϪN(11)ϪC(11)
N(12)ϪN(11)ϪHg(1)
C(11)ϪN(11)ϪHg(1)
Independent reflections
Completeness to theta max.
Max. and min. transmission
Refinement method
Data / restraints / parameters
Goodness-of-fit on F2
Final R indices [I >2σ (I)]
R indices (all data)
117.7(4)
115.4(3)
126.8(4)
R1 ϭ 0.0278, wR2 ϭ 0.0798
R1 ϭ 0.0386, wR2 ϭ 0.1119
1.265 and Ϫ0.925
Symmetry transformations used to generate equivalent atoms: (Ј)
Ϫxϩ2, Ϫyϩ2, Ϫz; (Љ) x, yϩ1, z.
Ϫ3
˚
Largest diff. peak and hole /e·A
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Z. Anorg. Allg. Chem. 2006, 615Ϫ618

Unidimensional Self-assembling of {HgII[NNN(PhBr)2]2} through Metal-η4-arene π-Interactions
Fig. 1 The molecular structure with atom-labeling scheme of the tecton [HgII(BrPhNNNPhBr)2] [9]. Displacement ellipsoids at the 50 %
level. Dashed lines represent secondary interactions. Symmetry transformations used to generate equivalent atoms: (Ј) Ϫxϩ2, Ϫyϩ2, Ϫz.
˚
of the C25ЈϪC26Ј bond [3.24(3) A, symmetry code (Ј) 1Ϫx,
1Ϫy, Ϫz] in {Hg[NNN(PhR)2]2}n (R ϭ NO2, F) [7]. The
angles of the metal-arene
84.4(3), C25ЈϪC26Ј···Hg ϭ 71.0(3)°; symmetry code (Ј) 1Ϫx,
1Ϫy, Ϫz]. Since no other interactions besides Hg···π contacts
exist, the tectonic unidimensional chains can not extend to a
supramolecular bidimensional (2D) assembling. Finally, and
like the above mentioned examples, the asymmetry of the
Hg···Ph π contacts in [HgII(BrPhNNNPhBr)2]n allows to ex-
clude the possibility of occurrence of intermolecular interac-
tions of the type HgϪ-η6-arene.
π interactions are 23.8(1)°
[C(21)Љ···Hg(1)···C(22)Љ], 83.4(4)° [Hg(1)···C(21)ЉϪC(22)Љ] and
72.8(3)° [C(21)ЉϪC(22)Љ···Hg(1)], fairly close to the angles
found in [HgII(RPhNNNPhRЈ)2Py]2 (R ϭ NO2, RЈ ϭ F) [8]
[C34Ј···Hg···C35Ј ϭ 22.5(1)°, Hg···C34ЈϪC35Ј ϭ 74.3(3)°,
C34ЈϪC35Ј···Hg ϭ 83.3(3)°; symmetry code (Ј) Ϫxϩ1, Ϫy,
Ϫz], {Hg[PhN3C6H4N3(H)Ph](NO3)} [6] [C31I···Hg···C36I ϭ
23(3)°, Hg···C31IϪC36I ϭ 79(8)°, C31IϪC36I···Hg ϭ 78(7)°;
symmetry code (Ј) x, yϪ1, z] and {Hg[NNN(PhR)2]2}n (R ϭ
NO2, F) [7] [C25Ј···Hg···C26Ј ϭ 24.6(1)°, Hg···C25ЈϪC26Ј ϭ
Experimental Section
A single crystal fixed on a glass fiber was used for the X-ray data
collection. Data were collected with a Bruker APEX II CCD area-
detector diffractometer and graphite-monochromatized Mo-Kα
radiation. The data reduction and the absorption correction were
performed using SAINT [10] and SADABS [11] programs, respec-
tively. The structure of {HgII[NNN(PhBr)2]2} was solved by direct
methods [12] and refined on F2 with anisotropic temperature par-
ameters for all non H atoms [13]. H atoms of the phenyl groups
2
˚
were positioned geometrically (CϪH ϭ 0.93 A for Csp atoms) and
treated as riding on their respective C atoms, with Uiso(H) values
set at 1.2UeqCsp2. The crystallographic parameters and details of
data collection and refinement are given in Table 1.
Crystallographic data for the structural analyses have been de-
posited with the Cambridge Crystallographic Data Centre CCDC
no. 288836. Further details of the crystal structures investigations
are available free of charge via www.ccdc.cam.ac.uk/conts/retriev-
ing.html (or from the CCDC, 12 Union Road, Cambridge CB2
1EZ, UK; fax: ϩ44 1223 336033; e-mail: deposit@ccdc.cam.ac.uk).
Preparation of {Hg[NNN(PhBr)2]2}n trans-bis[1,3-
(4-bromophenyl)triazenide] mercury(II)
Fig. 2 Section of the supramolecular, unidimensional assembling
of [HgII(BrPhNNNPhBr)2]n. Intermolecular, centrosymmetric Hg-
η2,η2-arene π-interactions (along the a axis) in dashed lines. Sym-
metry transformations used to generate equivalent atoms: (Љ) x,
yϩ1, z.
To a solution of 0.050 g (0.14 mmol) of 1,3-bis(4-bromophenil)tri-
azene in 15 ml of pure acetone three drops of a methanolic solution
of KOH (0.1 %) were added. The addition of 0.022 g (0.070 mmol)
of Hg(CH3COO)2 dissolved in 5 ml of pure methanol and 1 ml of
Z. Anorg. Allg. Chem. 2006, 615Ϫ618
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617

M. Hörner, G. Manzoni de Oliveira, M. Boneberger Behm, H. Fenner
pyridine to the deprotonated light-orange mixture turned the color
yellow. After 24 h stirring the solvent was slowly evaporated. An
yellow solid was dissolved in 20 ml of pure tetrahydrofuran. The
evaporation of the solvent within 10 days at room temperature
gives light yellow crystalline needles suitable for X-ray analysis.
[5] G. M. Whitesides, E. E. Simanek, J. P. Mathias, C. T. Seto, D.
N. Chin, M. Maamen, D. M. Gordon, Acc. Chem. Res. 1995,
28, 37.
[6] M. Hörner, A. J. Bortoluzzi, J. Beck, M. Serafin, Z. Anorg.
Allg. Chem. 2002, 628, 1104.
[7] M. Hörner, G. Manzoni de Oliveira, J. S. Bonini, H. Fenner,
Properties:
vitreous,
crystalline
light-yellow
needles.
supramolecular assemblages through metal-η4-arene π-interac-
C24H16Br4HgN6 (908.66). Yield: 0.022 g (0.024 mmol), 35 % based
on Hg(CH3COO)2. Melting point: 235Ϫ238 °C.
tions:
synthesis
and
X-Ray
characterization
of
{HgII[NNN(PhR)2]2}n (R ϭ NO2, F), a bis diaryl-substituted
triazenide complex polymer of Hg(II), J. Organomet. Chem.,
in Press.
IR (KBr) free ligand 1,3-(4-bromophenyl)triazene: 3195 (vs,
ν(NϪH)), 1395 (m, νas(NϭN)), 1248 (s, νs(NϪN)), 1071 cmϪ1 (vs,
ν(BrϪCar)).
[HgII(RPhNNNPhR)2] [R ϭ Br]: the NϪH band is absent.
1329 cmϪ1 (s, νas(NNN)), a mean value with respect to the N-N
absorptions in the free ligand (average bond order), 1069 cmϪ1 (s,
ν(BrϪCar)). FIR (CsI): 579 cmϪ1 (s, ν(HgϪN)).
[8] M. Hörner, G. Manzoni de Oliveira, J. A. Naue, J. Daniels, J.
Beck, polymeric assembling through reciprocal metal-η2-arene
π-interactions: synthesis and X-ray characterization of
[HgII(RPhNNNPhR)2Py]2 (R ϭ NO2, R ϭ F), an asymmet-
ric bis diaryl-substituted triazenide-pyridinyl complex of
Hg(II), J. Organomet. Chem., submitted.
[9] L. Zsolnai, H. Pritzkow, ZORTEP, Program for Personal com-
puter, University of Heidelberg, Germany, 1996.
[10] Bruker AXS Inc., Madison, Wisconsin 53711-5373,2005,
SAINT V7.06A, Ϫ Bruker Nonius area detector scaling and
absorption correction Ϫ V2.10.
[11] G. M. Sheldrick, SADABS, Program for Empirical Absorption
Correction of Area Detector Data, University of Göttingen,
Germany, 1996.
[12] M. C. Burla, R. Caliandro, M. Camalli, B. Carrozzini, G. L.
Cascarano, L. De Caro, C. Giacovazzo, G. Polidori, R.
Spagna, SIR2004 Ϫ An Improved Tool for Crystal Structure
Determination and Refinement, J. Appl. Cryst. 2005, 38, 381.
[13] G. M. Sheldrick, SHELXL-97, Program for Crystal Structure
Refinement, University of Göttingen, Germany, 1997.
Acknowledgements. This work received partial support from CNPq
(Proc. 475294/2004-1). MH thanks CNPq (Proc. 301310/2003-3)
and MBB thanks CNPq for grants.
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