Synthesis, crystal structure, and luminescent properties of a helical complex [(CuL)2.5(H2O)0.375] (H2L = benzil bis[(5-bromo oxidobenzylidene)hydrazone])

Article abstract of DOI:10.1080/15533174.2011.609228

A new helical copper (II) complex [(CuL)_2.5(H₂O) _0.375] 1 (H₂L = benzil bis[(5-bromo oxidobenzylidene) hydrazone]) was synthesized and characterized by elemental analysis, IR spectra, UV-vis spectra, and single-crystal X-ray diffraction. Complex 1 exhibits a new single-stranded helix with the copper (II) atom having a four-coordination seesaw geometry. The cooperativity of intermolecular C-H...π interactions and C-H...O hydrogen bonds links the helices together to form a three-dimensional network structure. The thermogravimetric and luminescent properties in the solid state of complex 1 have been investigated.

Full text of DOI:10.1080/15533174.2011.609228

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Synthesis, Crystal Structure, and
Luminescent Properties of a Helical Complex
[(CuL)2.5(H2O)0.375] (H2L = Benzil Bis[(5-bromo
oxidobenzylidene)hydrazone])
Yan Bai a , Hui Gao a , Ze-Yan Qi a & Dong-Bin Dang a
a Institute of Molecular and Crystal Engineering, School of Chemistry and Chemical
Engineering , Henan University , Kaifeng , P. R. China
Published online: 31 Jan 2012.
To cite this article: Yan Bai , Hui Gao , Ze-Yan Qi & Dong-Bin Dang (2012) Synthesis, Crystal Structure, and Luminescent
Properties of a Helical Complex [(CuL)2.5(H2O)0.375] (H2L = Benzil Bis[(5-bromo oxidobenzylidene)hydrazone]), Synthesis and
Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 42:1, 53-58, DOI: 10.1080/15533174.2011.609228
To link to this article: http://dx.doi.org/10.1080/15533174.2011.609228
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Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 42:53–58, 2012
Copyright ꢀ Taylor & Francis Group, LLC
C
ISSN: 1553-3174 print / 1553-3182 online
DOI: 10.1080/15533174.2011.609228
Synthesis, Crystal Structure, and Luminescent Properties
of a Helical Complex [(CuL)2.5(H2O)0.375] (H2L = Benzil
Bis[(5-bromo oxidobenzylidene)hydrazone])
Yan Bai, Hui Gao, Ze-Yan Qi, and Dong-Bin Dang
Institute of Molecular and Crystal Engineering, School of Chemistry and Chemical Engineering,
Henan University, Kaifeng, P. R. China
arrays. The most intriguing structural feature of this type of
ligands in the solid state is that they should be able to show a
monohelix due to the constraint of the rotation around the C−C
bond. Their coordination to d group metals leads to a variety of
metal helices.[5–21] As a continuation of our research working on
metal helicates derived from multidentate diazine Schiff-base
ligands via self-assembly,[12−21] herein we report the synthesis
and characterization of a new neutral helical coordination com-
plex [(CuL)2.5(H2O)0.375] (1) displaying multiple fluorescent
emission bands at room temperature based on the ligand H2L,
benzil bis[(5-bromo oxido benzylidene)hydrazone].
A new helical copper (II) complex [(CuL)2.5(H2O)0.375] 1 (H2L
= benzil bis[(5-bromo oxidobenzylidene)hydrazone]) was synthe-
sized and characterized by elemental analysis, IR spectra, UV-vis
spectra, and single-crystal X-ray diffraction. Complex 1 exhibits a
new single-stranded helix with the copper (II) atom having a four-
coordination seesaw geometry. The cooperativity of intermolecular
C−H···π interactions and C−H···O hydrogen bonds links the he-
lices together to form a three-dimensional network structure. The
thermogravimetric and luminescent properties in the solid state of
complex 1 have been investigated.
Keywords copper(II), crystal structure, helical complex, luminescent
properties
EXPERIMENTAL
Materials and Measurements
INTRODUCTION
All the chemicals were of reagent-grade quality obtained
from commercial sources. Elemental analyses (C, H, and N)
were carried out on a Perkin-Elmer 240C analytical instrument.
IR spectra were recorded in KBr pellets with a Nicolet 170
SXFT-IR spectrophotometer in the 4000 ∼ 400 cm−1 region.
UV-vis spectrum were obtained on a Shimazu UV-250 spec-
trometer in the range of 600 ∼ 200 nm in MeOH solution.
The thermogravimetric analysis was carried out on a Perkin-
Elmer-7 thermal analyzer at a heating rate of 10◦C/min from
25 to 1000◦C, and the luminescent spectra were performed on
a Hitachi F-7000 fluorescence spectrophotometer.
The construction of coordination complexes via self-
assembly of predesigned ligands with appropriate metal ions is
a subject of current interest because of their unusual structures
and special physical properties such as luminescence, redox
activity, and magnetism.[1–4] Polydentate diazine Schiff-base
ligands with two symmetrically coordination portions derived
from benzil dihydrazone are excellent ligands. The simplicity
of the syntheses and the high yield in a single-step reaction
from inexpensive commercially available reagents allow us
the possibility to systematically probe the effects of modifying
the ligand backbone and through which we are attempting to
control the precise topography, or microarchitecture, of the
Preparation of H2L
Benzil dihydrazone (0.96 g, 4 mmol) and 5-bromosalicy
laldehyde (1.60 g, 8 mmol) were mixed in methanol (30 mL).
The solution was refluxed for 6 h, and then evaporated to a
small volume (10 mL). The yellow precipitation formed was
isolated and dried under vacuum. Yield: 63%. Anal. Calc. for
Received 29 May 2011; accepted 26 July 2011.
This work was supported by the National Natural Science Founda-
tion of China (No. 20701012), the Foundation of Henan Educational
Committee of China (No. 2007150003 and 2008B150002), the Foun-
dation for University Youth Key Teacher of Henan Province of China C28H18N4O2Br2 (%): C, 55.84; H, 3.01; N, 9.30: Found (%):
C, 55.82; H, 3.05; N, 9.35. IR (cm−1, KBr pellet): 3453(w),
and Innovation Experiment Program for University Students of Henan
University (No. 09NB021).
Address correspondence to Dong-Bin Dang, Institute of Molecu-
lar and Crystal Engineering, School of Chemistry and Chemical En-
gineering, Henan University, Kaifeng 475004, P. R. China. E-mail:
dangdb@henu.edu.cn
3056(m), 1891(w), 1759(w), 1620(vs), 1603(vs), 1565(m),
1473(vs), 1444(w), 1366(w), 1343(w), 1319(w), 1269(vs),
1236(w), 1182(s), 1131(w), 1078(m), 1042(w), 1005(w),
980(w), 906(w), 879(w), 823(m), 784(w), 771(w), 745(w),
53

54
Y. BAI ET AL.
TABLE 1
Crystallographic data and structure refinement parameters for
complex 1
729(w), 706(w), 688(m), 667(m), 629(m), 609(m), 582(w),
557(w), 465(w), 431(w).
Preparation of Complex 1
Chemical formula
Formula weight
Crystal system
Space group
a, Å
C70H45.75Br5Cu2.50N10O5.37
A solution of NaOH (0.02 g, 0.6 mmol) in MeOH (2 mL)
was added slowly to a stirring solution of ligand H2L (0.18 g,
0.3 mmol) in 25 mL MeOH solution, and then Cu(NO3)2·6H2O
(0.35 g, 1.5 mmol) methanol solution (15 mL) was added in
the previous solution. After refluxing for 4 h, the resulting
dark-brown solution was filtered and left for slowly evapo-
rating at room temperature to obtain dark-brown block crys-
tals suitable for single crystal X-ray structure determination.
Yield: 67%. Anal. Calc. for C70H45.75Br5Cu2.5N10O5.37 (%):
C, 50.31; H, 2.76; N, 8.38. Found (%): C, 50.27; H, 2.81;
N, 8.34. IR (cm−1, KBr pellet): 3432(m), 3041(w), 1893(w),
1606(vs), 1578(s), 1513(vs), 1513(vs), 1449(vs), 1407(w),
1384(m), 1369(m), 1306(s), 1242(w), 1176(s), 1136(w),
1074(w), 1001(w), 966(w), 822(m), 778(w), 768(w), 743(w),
710(m), 644(w), 588(w), 510(w), 479(w).
1671.31
Monoclinic
C2
46.708(5)
12.3990(11)
12.1268(10)
95.147(7)
6994.7(11)
4
b, Å
c, Å
β, ◦
Volume, Å3
Z
Dc, Mg m−3
Crystal size, mm
µ, mm−1
1.586
0.28 × 0.10 × 0.03
3.669
Theta Min-Max (◦)
F(000)
1.70 − 25.00
3302
Tot., Uniq. Data, R(int)
Observed data [I > 2.0
sigma(I)]
30067, 12268, 0.0996
4529
Crystallographic Data Collection and Refinement
A suitable sample of size 0.28 mm × 0.10 mm × 0.03 mm
was chosen for the crystallographic study and then mounted
on a Bruker SMART APEX CCD diffractometer with ω and ϕ
scan mode in the range of 1.70◦ < θ < 25.00◦. All diffraction
measurements were performed at room temperature using
graphite monochromatized Mo Kα radiation (λ = 0.71073 Å).
A total of 12268 (4529 independent, Rint = 0.0996) reflections
were measured. The structure was solved by direct methods and
refined by full-matrix least-squares on F2 using the SHELXL
97 program.[22] The Cu(3) atom is located on the C2 axis
special position. The O(1W) and O(2W) atoms are considered
as disorder site occupation factor of 0.25 and 0.125 in complex
1, respectively. Anisotropical thermal factors were assigned
to most of the non-disordered non-hydrogen atoms except the
H2O molecule. The water hydrogen atoms could not be located
and were not calculated. CCDC reference number: 752349 (1).
Space group, lattice parameters, and other relevant information
are listed in Table 1. The relevant bond lengths and bond angles
are listed in Table 2.
Nref, Npar
12268, 841
Final R, indicesa (I > 2σ(I)) R1 = 0.0676; wR2 = 0.1110
R indices (all data)
Min. and Max. Resd. Dens.
[e/Angˆ3]
R1 = 0.2022; wR2 = 0.1411
−0.329, 0.490
2
aR1
=
ꢁFo|
–|Fcꢁ/ |Fo|,
wR2
=
{
[w(Fo –
2
2
1/2
Fc ) 2]/ [w(Fo ) 2]}
.
TABLE 2
Selected bond distances (Å) and bond angles (◦) for complex 1
Bond length (Å)
Cu1–N1
Cu1–O1
Cu2–N5
Cu2–O3
Cu3–N9
1.936(7)
1.868(7)
1.944(7)
1.869(7)
1.927(8)
Cu1–N4
Cu1–O2
Cu2–N8
Cu2–O4
Cu3–O5
1.935(8)
1.891(7)
1.958(8)
1.874(7)
1.875(7)
RESULTS AND DISCUSSION
Bond angle (◦)
N4–Cu1–N1
O1–Cu1–N4
O2–Cu1–N1
N5–Cu2–N8
O3–Cu2–N8
O4–Cu2–N5
N9A–Cu3–N9
O5–Cu3–N9A
IR and UV Spectra
94.9(3)
154.8(4)
156.9(3)
95.2(3)
156.3(3)
152.0(4)
100.4(5)
150.0(3)
O1–Cu1–N1
O1–Cu1–O2
O2–Cu1–N4
O3–Cu2–N5
O3–Cu2–O4
O4–Cu2–N8
O5–Cu3–N9
O5–Cu3–O5A
93.2(3)
87.3(3)
94.3(3)
92.8(3)
89.6(3)
93.7(3)
92.9(3)
88.7(4)
In the IR spectrum, ν (C N) bands are exhibited at 1620
and 1603 cm−1 for H2L and at 1606 and 1578 cm−1 for the
title complex, respectively. From 1620 to 1578 cm−1, a 42 cm−1
blue-shifted strongly suggests coordination of the imine nitro-
gen atoms with copper atoms. The other ν (C N) band was
almost the same as that of the ligand. Their identity was finally
confirmed by X-ray crystallography. The UV absorption spec-
trum of H2L and the title complex were investigated in MeOH
solution (Figure 1). The UV spectra of complex 1 displays three
(Symmetry code A: 2 − x, y, 2 − z)

A NEW HELICAL COPPER(II) COMPLEX
55
and the coordination environment of Cu(II) atom is depicted in
Figure 2. The asymmetric unit consists of 2.5 neutral single-
stranded helices and each a helix contains one copper center
and one two net negative charge ligand, L2−. Each copper cen-
ter has a four-coordination environment, formed by two imine
nitrogen atoms and two phenolate oxygen atoms from a lig-
and. The values of the topological parameter τ of ca. 0.34,
0.36, and 0.43 indicate seesaw structure for Cu(1), Cu(2), and
Cu(3), respectively.[23] All the Cu–N and Cu–O bond distances
are in the range of 1.927(8)–1.958(8) and 1.868(7)–1.891(7),
respectively, and the bond angles around Cu(II) center range
from 87.3(3)◦ to 156.9(3)◦. These results agree well with those
of related compounds.[5–20] It should be pointed out that there
are weak interactions between copper and bromine atoms with
the Cu(1)···Br(2B) distances of 3.26 Å, the Cu(2)···Br(3C) dis-
tances of 3.36 Å, Cu(3)···Br(4D), and Cu(3)···Br(4E) distances
of 3.94 Å, respectively (symmetric code B: 3/2 – x, 1/2 + y, 2 –
z; C: 3/2 – x, – 1/2 + y, 3 – z; D: x, 1 + y, z; E: 2 – x, 1 + y, 2 –
z). In addition, two types of C−H···N hydrogen bonds between
the C(38) and C(66) atoms and the N(6) and N(10) are found
in the helices and also play an important role in stabilizing the
helical structure (Table 3).
FIG. 1. The UV-vis spectra of H2L ligand (dash) and complex 1 (solid) in
MeOH solution at room temperature (color figure available online).
absorption peaks at 233, 287, and 412 nm. Compared with 221,
300, and 363 nm assigned to the π-π∗ and n-π∗ transition of
H2L, 12 nm blue-shifted, 13 nm red-shifted, and 49 nm blue-
shifted are observed.[11]
Upon coordination, the rotating freedom of the lig-
and is restrained and the ligand can be locked in a
twist helical conformation. The torsion angle of carbon−
carbon bond is 65.6◦ for N(2) C(8)−C(15) N(3),
71.7◦ for N(6) C(36)−C(43) N(7), and 76.8◦ for
N(10) C(64)−C(64A) N(10A), respectively. The tor-
sion angle is 130.7◦, 127.7◦, 128.0◦, 138.6◦, and 137.3◦
around C(7) N(1)−N(2) C(8), C(15) N(3)−N(4) C(23),
Description of the Crystal Structure of the Title Complex
The structure analysis by X-ray diffraction reveals that title
complex crystallizes in the monoclinic space group C2. An OR-
TEP diagram of complex 1 with the atomic numbering scheme
FIG. 2. ORTEP drawing of complex 1 with the atom numbering scheme and the geometry of Cu atoms. The atoms are represented by 30% probability thermal
ellipsoids. Hydrogen atoms and solvent molecules are omitted for clarity (symmetry code: A: 2 − x, y, 2 − z).

56
Y. BAI ET AL.
TABLE 3
Hydrogen bonds for complex 1
D−H···A
d (D−H)
d (H···A)
d (D···A)
∠(DHA)
Symmetry transformation for A
C22–H22A···O3
C22–H22A···O4
C35–H35A···O1
C35–H35A···O2
C38– H38A···N6
C40–H40A···O5
C66–H66A···N10
0.93
0.93
0.93
0.93
0.93
0.93
0.93
2.48
2.42
2.36
2.48
2.42
2.54
2.55
3.327(11)
3.212(11)
3.151(12)
3.333(11)
2.746(14)
3.314(13)
2.857(14)
152
143
143
152
100
141
100
x, y, 1 + z
x, y, 1 + z
x, − 1 + y, 1 + z
z; G: x, y, z – 1).[24] Although these C−H···π interactions and
hydrogen bonds are weak compared with the metal-nitrogen
and metal-oxygen coordination bonds, they are important in
the formation of the 3D supramolecular network.
C(35) N(5)−N(6) C(36), C(43) N(7)−N(8) C(50), and
C(63) N(9)−N(10) C(64), respectively. The dihedral angle
between two benzene rings of a ligand is 94.4◦ of C(9)−C(14)
and C(16)−C(21), 92.2◦ of C(37)−C(42) and C(44)−C(49),
and 98.4◦ of C(65)−C(70) and C(65A)−C(70A), respectively.
These results are similar to the values in related compounds.[5–21]
Detailed structural analyses revealed that copper(II) helices
were further interacted each other feathering three-dimensional
network through five kinds of C−H···O hydrogen bonds
(Table 3) and eight kinds of C−H−π interactions (Figure 3).
The C···M distances and the C−H···M angels are 3.88 Å
and 124.9◦ for C(67E)–H(67E)···MI, 3.89 Å and 127.2◦
for C(66E)–H(66E)···MI, 3.96 Å and 136.8◦ for C(26B)–
H(26B)···MII, 3.72 Å and 167.6◦ for C(3F)–H(3F)···MIII,
3.53 Å and 118.2◦ for C(13)–H(13A)···MIV, 3.57 Å and
Thermal Analysis
In order to study the thermal stability of the title complex,
the thermal gravimetric analysis (TGA) was carried out in the
temperature range of 25–1000 ◦C (Figure 4). The title complex
keeps the weight until 212◦C. On raising the temperature further,
complex 1 loses 2.5 ligands and makes the weight lose 86.02%
till 700◦C, which is in good accordance with the calculated value
87.69%. The final residue after 700◦C should be CuO (found:
12.67%, calcd: 11.90%).
115.9◦ for C(46G)–H(46G)···MIV, 3.78
Å
and 170.2◦
Luminescence Properties
for C(54F)–H(54F)···MV, and 3.87 Å and 136.4◦ for
C(31C)–H(31C)···MIV, respectively (M: midpoint of the
aromatic ring, symmetric code E: 2 – x, y, 2 – z; F: x, y, 1 +
The solid-state luminescent spectra of the ligand and ti-
tle complex have been investigated in the solid state at room
temperature. H2L and complex 1 display multiple emission
FIG. 3. Packing diagram for complex 1 along the c-axis (color figure available online).

A NEW HELICAL COPPER(II) COMPLEX
57
nor metal-to-ligand charge transfer but the intraligand π∗−π
charge transfer.
In summary, we synthesized a neutral single-stranded helical
coordination complex [(CuL)2.5(H2O)0.375] in a MeOH environ-
ment with a new ligand H2L, benzil bis[(5-bromo oxidoben-
zylidene)hydrazone]. The structure of the complex has been
established by X-ray single-crystal diffraction analysis and also
characterized by IR, UV, elemental analysis, TG technique, and
luminescent properties. Each copper(II) center is bound to two
imine nitrogen atoms and phenolate oxygen atoms of one ligand
to form a neutral single-stranded helix. The copper helices were
further interacted each other feathering three-dimensional net-
work through extensive C−H···O hydrogen bonds and C−H−π
interactions. The fluorescence measurement of 1 showed the
multiple emission bands at 316, 468, and 561 nm.
FIG. 4. The TGA curve for complex 1.
bands at different excitations. As shown in Figure 5, the lumines-
cent spectra of H2L and complex 1 display emission maximum
(λem, max) at 314 and 316 nm with using excitation wavelengths
at 220 and 210 nm, respectively. Excitated at 360 nm, the H2L
shows weak emission band at 463 and strong emission band
559 nm (Figure 5). Excitated at 350 nm, complex 1 exhibits
emissions at 468 and 561 nm. Therefore, the emission bands of
the title complex should be ascribed to neither ligand-to-metal
REFERENCES
1. Ma, C.L.; Wang, Q.F.; Zhang, R.F. Self-assembly and characterization of a
novel 2D network polymer containing a 60-membered organotin macrocy-
cle. Inorg. Chem. 2008, 47, 7060–7061.
2. Zheng, Y.R.; Yang, H.B.; Northrop, B.H.; Ghosh, K; Stang, P.J. Size selec-
tive self-sorting in coordination-driven self-assembly of finite ensembles.
Inorg. Chem. 2008, 47, 4706–4711.
3. Zulkefeli, M.; Sogon, T.; Takeda, K.; Kimura, E.; Shin, A. Design and
synthesis of a stable supramolecular trigonal prism formed by the self-
assembly of a linear tetrakis(Zn2+−cyclen) complex and trianionic trithio-
cyanuric acid in aqueous solution and its complexation with DNA (cyclen
= 1,4,7,10-tetraazacyclododecane). Inorg. Chem. 2009, 48, 9567–9578.
4. Ma, L.F.; Wang, L.Y.; Wang, Y.Y.; Batten, S.R.; Wang, J.G. Self-assembly
of a series of cobalt(II) coordination polymers constructed from H2tbip and
dipyridyl-based ligands. Inorg. Chem. 2009, 48, 915–924.
5. Chowdhury, S.; Iveson, P.B.; Drew, M.G.B.; Tocher, D.A.; Datta, D. A
novel copper(I) complex that is a monomeric single helix in solid state but
a dimeric double helix in solution. New J. Chem. 2003, 27, 193–196.
6. Chowdhury, S.; Drew, M.G. B.; Datta, D. A case of four-coordinate silver(I)
adopting a high energy planar geometry. Experiment and theory. New J.
Chem. 2003, 27, 831–835.
7. Patra, G.K.; Goldberg, I. Supramolecular design of coordination complexes
of silver(I) with polyimine ligands: synthesis, materials characterization,
and structure of new polymeric and oligomeric materials. Cryst. Growth
Des. 2003, 3, 321–329.
8. Patra, G.K.; Goldberg, I. Coordination polymers of transition metal ions
with polydentate imine ligands. Syntheses, materials characterization, and
crystal structuresof polymeric complexes of copper(I), silver(I) and zinc(II).
Dalton Trans. 2002, 1051–1057.
9. Pal, P.K.; Chowdhury, S.; Drew, M.G.B.; Datta, D. Metal-assisted electro-
cyclic reaction in a C N−N C−C N system. New J. Chem. 2000, 27,
931–933.
10. Lo´pez-Torres, E.; Mendiola, M.A.; Pastor, C.J.; Pe´rez, B.S. Versatile chelat-
ing behavior of benzil bis(thiosemicarbazone) in zinc, cadmium, and nickel
complexes. Inorg. Chem. 2004, 43, 5222–5230.
11. Drew, M.G. B.; Parui, D.; De, S.; Naskar, J.P.; Datta, D. An eight-
coordinate mononuclear double helical complex. Eur. J. Inorg. Chem. 2006,
4026–4028.
12. Dang, D.B.; Sun, J.D.; Bai, Y.; Gao, H.; Shang, W.L. Synthesis, charac-
terization and crystal structure determination of a hepta-coordinated cad-
mium(II) complex with thiocyanatobridges. J Chem. Crystallogr. 2009, 39,
683–687.
13. Bai, Y.; Duan, C.Y.; Cai, P.; Dang, D.B.; Meng, Q.J. Enantiomeric in-
terpenetrating 3D nets with chiral silver helicates. Dalton Trans. 2005,
2678–2680.
FIG. 5. Emission spectrum of H2L (dash) and complex 1 (solid) in the solid
state at room temperature. (a) λex = 220 nm for H2L and λex = 210 nm for
1; (b) λex = 360 nm for H2L and λex = 350 nm for 1 (color figure available
online).

58
Y. BAI ET AL.
14. Sun, Q.Z.; Wei, M.L.; Bai, Y.; He, C.; Meng, Q.J.; Duan, C.Y. Entan-
glement of individual coordination polymers having helicates as building
intermediates. Dalton Trans. 2007, 4089–4094.
20. Dang, D.B.; Bai, Y.; Duan, C.Y. Bis{N-(2-hydroxybenzoyl)-Nꢂ-[1-
(2-pyridyl)ethylidene]ydrazinato}copper(II). Acta Cryst. 2006, E62,
m1567–m1568.
15. Sun, Q.Z.; Bai, Y.; He, G.J.; Duan, C.Y.; Lin Z.H.; Meng, Q.J.
Spontaneous resolution of silver double helicates consisting of achi-
ral ligands with several aromatic rings. Chem. Commun. 2006, 2777–
2779.
16. Dang, D.B.; Bai, Y.; Duan, C.Y. Crystal structure and magnetic properties
of a novel octa-coordinated manganese(II) complex. J. Chem. Crystallogr.
2008, 38, 557–560.
17. Bai, Y.; Li, H.Y.; Dang, D.B. Synthesis and crysta structure of
a three dimensional supramolecular structure constructed from heli-
cate silver(I) complex. Journal of Synthetic Crystals. 2008, 37, 781–
785.
18. Dang, D.B.; Bai, Y.; Li, H.Y. Synthesis and crystal structure of a helical
complex [Zn(C28H20N4O2)(CH3OH)]. Journal of Synthetic Crystals. 2007,
36, 1105–1108.
19. Dang, D.B.; Bai, Y.; Duan, C.Y. Bis{N-(2-hydroxybenzoyl)-Nꢂ-
[1-(2-pyridyl)ethylidene]ydrazinato}nickel(II). Acta Cryst. 2006, E62,
m2290–2292.
21. Bai, Y.; Dang, D.B.; Duan, C.Y. 1,2-Bis[(2-oxidobenzylidene)
hydrazono]1,2-diphenylethane (methanol)cobalt(II). Acta Cryst. 2006,
E62, m2599–m2601.
22. Sheldrick, G.M. SHELXL-97 and SHELXS-97, Program for X-ray Crys-
tal Structure Solution and Refinement; University of Go¨ttingen, Germany,
1997.
23. Yang, L.; Powell, D.R.; Houser, R.P. Structural variation in copper(I) com-
plexes with pyridylmethylamide ligands: structural analysis with a new
four-coordinate geometry index, τ4. J. Chem. Soc., Dalton Trans. 2007,
955–964.
24. For the title complex: plane I is defined by atoms C(1), C(2), C(3), C(4),
C(5) and C(6); plane II is defined by atoms C(9), C(10), C(11), C(12), C(13)
and C(14); plane III is defined by atoms C(16), C(17), C(18), C(19), C(20)
and C(21); plane IV is defined by atoms C(29), C(30), C(31), C(32), C(33)
and C(34); plane V is defined by atoms C(37), C(38), C(39), C(40), C(41)
and C(42); plane VI is defined by atoms C(44), C(45), C(46), C(47), C(48)
and C(49).