A novel ligand N,N′-di(2-pyridyl)-2,4-diamino-6-phenyl-1,3,5-triazine (dpdapt) and its complexes: [Cu(dpdapt)Cl2] and [Cu(dpdapt)(NO 3)(H2O)] · NO3 · H2O

Article abstract of DOI:10.1016/j.poly.2005.06.061

The novel ligand N,N′-di(2-pyridyl)-2,4-diamino-6-phenyl-1,3,5- triazine (dpdapt) has been synthesized and the reactions of CuCl₂ · 2H₂O and Cu(NO₃)₂ · 8H ₂O with the new ligand afforded two crystalline forms [Cu(dpdapt)Cl₂] (1) and [Cu(dpdapt)(NO₃)(H₂O)] · NO₃ · H₂O (2), respectively. The molecular structures of 1 and 2 were established by single-crystal X-ray diffraction studies. The copper(II) atoms in complexes 1 and 2 are both five-coordinated in trigonal bipyramidal environments. In 1, antiparallel dimers construct a two-dimensional supramolecular architecture by π-π stacking and hydrogen bonding, whereas 2 is connected by the same interactions to form a three-dimensional supramolecular framework. Quantum chemical calculations have been performed using Density Functional Theory (DFT) in order to gain some insight about the coordination behavior of dpdapt and complex 1.

Full text of DOI:10.1016/j.poly.2005.06.061

Polyhedron 25 (2006) 195–202
www.elsevier.com/locate/poly
A novel ligand
N,N0-di(2-pyridyl)-2,4-diamino-6-phenyl-1,3,5-triazine (dpdapt)
and its complexes: [Cu(dpdapt)Cl2] and
[Cu(dpdapt)(NO3)(H2O)] Æ NO3 Æ H2O
a
a,
a
a
Cui-Juan Wang , Yao-Yu Wang *, Hai-Rui Ma , Hui Wang ,
a
b
Qi-Zhen Shi , Shie-Ming Peng
a
Department of Chemistry, Shaanxi Key Laboratory of Physico-inorganic Chemistry, Northwest University, Xiꢀan 710069, PR China
Department of Chemistry, National Taiwan University, Taipei, Taiwan
b
Received 30 March 2005; accepted 23 June 2005
Available online 22 August 2005
Abstract
The novel ligand N,N0-di(2-pyridyl)-2,4-diamino-6-phenyl-1,3,5-triazine (dpdapt) has been synthesized and the reactions of
CuCl2 Æ 2H2O and Cu(NO3)2 Æ 8H2O with the new ligand afforded two crystalline forms [Cu(dpdapt)Cl2] (1) and [Cu(dpdapt)-
(NO3)(H2O)] Æ NO3 Æ H2O (2), respectively. The molecular structures of 1 and 2 were established by single-crystal X-ray diffraction
studies. The copper(II) atoms in complexes 1 and 2 are both five-coordinated in trigonal bipyramidal environments. In 1, antipar-
allel dimers construct a two-dimensional supramolecular architecture by p–p stacking and hydrogen bonding, whereas 2 is con-
nected by the same interactions to form a three-dimensional supramolecular framework. Quantum chemical calculations have
been performed using Density Functional Theory (DFT) in order to gain some insight about the coordination behavior of dpdapt
and complex 1.
ꢀ 2005 Elsevier Ltd. All rights reserved.
Keywords: Novel ligand; Copper(II) complexes; Crystal structure; Supramolecular compounds; DFT studies
1. Introduction
modified 1,3,5-triazine ligand 2,4,6-tris(2-pyridyl)-1,3,5-
triazine (tpt) [4] and several transition-metal complexes
using the ligand tpt have been reported [5,6]. We have
synthesized a novel modified 1,3,5-triazine ligand,
N,N0-di(2-pyridyl)-2,4-diamino-6-phenyl-1,3,5-triazine
(dpdapt). The ligand dpdapt is a versatile ligand like tpt,
but with more diversity than 2,2,:60,200-terpyridine (tpy).
Dpdapt, which functions as a tridentate or a bis-biden-
tate ligand, has gained our interest because of its use
as a spacer for designing supramolecular complexes.
Thus, dpdapt has its own coordination feature and func-
tions primarily as a tridentate ligand (Scheme 1(a);
anti–anti–anti–anti) forming complexes of the general
type ([Cu(dpdapt)]2+), as we described in this paper.
The crystal engineering of coordination polymers and
supramolecular compounds has attracted considerable
current attention, not only because of their fascinating
structural diversities [1], but also for their potential
applications in optical, electrical, magnetic and biologi-
cal materials [2]. The design of suitable organic ligands is
one of the important roles in the synthetic strategies for
these polymers and supramolecular compounds [3]. The
*
Corresponding author. Tel.: +86 29 88303097; fax: +86 29
88373398.
E-mail address: wyaoyu@nwu.edu.cn (Y.-Y. Wang).
0277-5387/$ - see front matter ꢀ 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2005.06.061

196
C.-J. Wang et al. / Polyhedron 25 (2006) 195–202
stirred for 148 h under reflux. The product was filtered
and washed three times each with methanol and water.
M
N
N
N
N
N
N
N
N
M
M
N
N
N
N
N
H
N
NH
HN
N
NH
N
H
N
N
H
M
M
N
N
N
N
Pd2(dba)3
N
N
a. anti-anti-anti-anti
b. syn-syn-anti-anti
c. syn-syn-syn-syn
HN
N
NH
2
BuOK, benzene, reflux 148h
N
Br
H2N
N
NH2
Scheme 1. Coordination modes of the ligand dpdapt.
The second coordination mode as a bis-bidentate ligand,
including syn–syn–anti–anti (b) and syn–syn–syn–syn (c),
is shown in Scheme 1. DFT studies have been applied to
dpdapt. Theoretical calculations illuminate the coordi-
nation modes of the ligand.
Herein, we report the copper(II) complexes with dpd-
apt as a tridentate ligand. The crystal structures of the
copper(II) complexes with the all-anti conformation of
the chelating ligand are presented. Complex 1 consists
of dimeric units, doubly bridged by p–p stacking and
hydrogen bonding, thus forming an unusual 1-D ladder
structure. Complex 2 self-assembles into a 1-D chain by
hydrogen bonding and p–p stacking, and a 3-D layer
structure which is sustained via hydrogen bonds. We
also employed DFT studies to 1 and explained its coor-
dination behavior.
Dpdapt was obtained as a white powder in 64% yield
(5.8 g). Anal. Calc. for C19H15N7: C, 66.86; H, 4.399; N,
28.74. Found: C, 66.87; H, 4.328; N, 28.56%. IR (KBr,
cmꢀ1): m = 3025(w), 2952(w), 1604(m), 1563(w), 1496-
(s), 1425(s), 1364(m), 1307(m), 1244(w), 1194(w),
1047(w), 989(m), 934(w), 770(s), 729(m), 693(w). MS
(FAB) m/z (%) 342.1 (dpdapt).
2.3. Synthesis of [Cu(dpdapt)Cl2] (1)
A green solution was obtained by adding a methanol
solution (10 ml) of CuCl2 Æ 2H2O (34.1 mg, 0.20 mmol)
to a methanol suspension (15 ml) of dpdapt (75.0 mg,
0.22 mmol) and stirring for 4 h. Diffused in Et2O, after
filtering green needle-shaped crystals of 1 were pro-
duced. Yield: 56%. Anal. Calc. for [Cu(C19H15N7)Cl2]:C,
47.92; H, 3.152; N, 20.60. Found: C, 47.86; H, 3.185; N,
20.52%.
2. Experimental
2.1. Materials and physical measurements
2.4. Synthesis of
[Cu(dpdapt)(NO3)(H2O)] Æ NO3 Æ H2O (2)
Commercially available chemicals were reagent grade
and were used without further purification. Infrared
spectra on KBr pellets were recorded on a Nicolet
170SX FT-IR spectrophotometer in the range 4000–
400 cmꢀ1. Elemental analyses were determined with a
Perkin–Elmer model 240C instrument. Electronic spec-
tra were recorded on a Cary 300 Bio UV–Vis spectro-
photometer. FAB-MS mass spectra were obtained with
a JEOL HX-110 HF double focusing spectrometer oper-
ating in the positive ion detection mode. Fluorescence
experiments used a HITACHI F-4500 Fluorescence
Spectrophotometer and were measured in methanol.
A suspension of Cu(NO3)2 Æ 8H2O (53.9 mg, 0.2
mmol) in 10 ml water was allowed to react with dpdapt
(75.0 mg, 0.22 mmol) dissolved in 20 ml methanol. The
resulting mixture was stirred for 3 h and the product was
removed by filtration. After a few days, dark green crys-
tals were obtained by diffusion in Et2O. Yield: 48%.
Anal. Calc. for [Cu(dpdapt)(NO3)(H2O)] Æ NO3 Æ H2O:
C, 40.36; H, 3.363; N, 22.30. Found: C, 40.46; H,
3.385; N, 22.52%.
2.2. Synthesis of N,N0-di(2-pyridyl)-2,4-diamino-6-
phenyl-1,3,5-triazine (dpdapt)
2.5. Crystal structures determination
X-ray diffraction data were collected on a BRUKER
SMART APEX-II diffractometer using graphite-
monochromated Mo Ka radiation (k = 0.71073 A) for
complexes 1 and 2. The structures were solved by direct
methods [7]. Then the structures were refined by the
least-squares method using SHELXL-97 [8] with aniso-
tropic temperature factors for all non-H atoms. Crystal
data and structure refinement details are summarized in
2,4-Diamino-6-phenyl-1,3,5-triazine (5.0 g, 26.7
mmol), BuOK (14.3 g, 127.7 mmol) and tris(dibenzylide-
neacetone)dipalladium (Pd2(dba)3) (2.0 g, 2.2 mmol)
were added to a 200 ml flask under nitrogen. Then 100
ml dry benzene and 2-bromopyridine (14 g, 13.5 ml,
88.6 mmol ) were injected into the former solid sequen-
tially also under nitrogen. The resulting solution was
˚

C.-J. Wang et al. / Polyhedron 25 (2006) 195–202
197
Table 1
Data collection and processing parameters for [Cu(dpdapt)Cl2] (1) and [Cu(dpdapt)(NO3)(H2O)] Æ NO3 Æ H2O (2)
Complex
1
2
Empirical formula
Formula weight
T (K)
C19H15Cl2CuN7
475.82
273(2)
C19H19CuN9O8
564.97
273(2)
˚
k (A)
0.71073
0.71073
Crystal system
Space group
a (A)
monoclinic
P21/c
8.374(2)
monoclinic
P21/c
12.156(5)
8.708(3)
˚
˚
b (A)
17.789(5)
˚
c (A)
12.647(4)
95.226(4)
1876.3(9)
21.327(8)
92.847(6)
2255(1)
b (ꢁ)
3
˚
V (A
)
Z
4
4
Dcalc (g/cm3)
1.684
1.471
964
0.37 · 0.11 · 0.07
1.98–29.22
ꢀ11 6 h 6 10,
ꢀ236 k 6 17,
ꢀ17 6 l 6 13
11889
1.664
1.037
1156
0.29 · 0.13 · 0.08
1.91–29.17
ꢀ16 6 h 6 13,
ꢀ11 6 k 6 11,
ꢀ27 6 l 6 27
13865
Absorption coefficient (nmꢀ1
F(000)
Crystal size (mm3)
h Range for data collection (ꢁ)
Limiting indices
)
Reflections collected
Independent reflections
Absorption correction
Maximum and minimum transmission
Refinement method
4671
5559
semi-empirical
0.9244 and 0.7557
full-matrix least-squares on F2
5559/0/364
semi-empirical
0.9040 and 0.6121
full-matrix least-squares on F2
4671/0/262
1.114
0.0321, 0.0859
0.0483, 0.0898
0.334 and ꢀ0.505
Data/restraints/parameters
Goodness-of-fit on F2
1.005
b
R1a, wR2 [I > 2r(I)]
0.0378, 0.1007
0.0605, 0.1082
0.400 and ꢀ0.614
b
R1a, wR2 (all data)
ꢀ3
˚
Largest difference in peak and hole (e A
)
P
P
a
R1 = iFoj ꢀ jFci/ jFoj.
P
P
2
2 1=2
b
wR2 ¼ ½ ½wðF 2o ꢀ F c2Þ ꢂ= ½ðF 2oÞ ꢂꢂ
.
Table 1. Selected bond lengths and bond angles are
given in Table 2.
existing in an all-anti configuration. The Cu(1) atom is
coordinated by three nitrogen atoms (N(3) of triazine
and N(5), N(1) of different pyridyls) with two additional
chloride atoms resulting in five-coordinated geometry
2.6. Computational details
˚
(Fig. 1). The Cu(1)–N(3) distance is 2.024(2) A and
The calculations were carried out using the GAUSSIAN-
03 program suite [9], including optimized geometries,
and calculation of vibrational frequencies were carried
out at the B3LYP [10,11] level of theory. Mulliken pop-
ulation analysis was also performed under this method.
We employed the 6-31G(d) basis set for H, C, N and Cl,
and the LANL2DZ effective core potential (ECP) set of
Hay and Wadt [12] for Cu. All of the results (structures
and energies) from the DFT calculations are available as
electronic supplementary information.
the distance to the pyridyl donors N(5) and N(1) are
˚
2.079(2) and 2.066(2) A, respectively. The distance of
˚
Cu(1)–Cl(2) is 2.288(1) A whereas Cu(1)–Cl(1) forms a
˚
long bond with a distance of 2.424(1) A. The average
˚
Cu–N bond length is observed to be 2.056 A while
˚
the average Cu–Cl bond length is 2.356 A. The bond
angles N(1)–Cu(1)–N(5) (124.53(7)ꢁ), N(5)–Cu(1)–Cl(1)
(113.66(5)ꢁ) and N(1)–Cu(1)–Cl(1) (120.32(5)ꢁ) sum up
approximately to 360ꢁ and the angle N(3)–Cu(1)–Cl(2)
(177.41(5)ꢁ) is approximately 180ꢁ, so the coordinated
geometry of Cu(II) may be described as distorted trigo-
nal bipyramidal with Cu(1), N(1), N(5) and Cl(1) form-
ing the equatorial plane and Cl(2), N(3) occupying the
axial positions. The dihedral angle between the plane
(Cu(1), N(1), N(5), Cl(1)) and the triazine plane is 86.7ꢁ.
Two molecules of 1 form an antiparallel dimer struc-
ture as a result of two N–Hꢁ ꢁ ꢁCl hydrogen bonds
3. Results and discussion
3.1. Description of structures
The crystal structure of complex 1 reveals that the
coordination geometry around the copper(II) atom is a
distorted trigonal bipyramid with the dpdapt ligand
˚
˚
(Cl(1A)ꢁ ꢁ ꢁN(4B) 3.258 A, N(4A)ꢁ ꢁ ꢁCl(1B ) 3.258 A)
which are symmetry related, then each dimer is linked

198
C.-J. Wang et al. / Polyhedron 25 (2006) 195–202
Table 2
˚
Selected bond lengths (A) and bond angles (ꢁ) of Cu(dpdapt)Cl2 (1) and [Cu(dpdapt)(NO3)(H2O)] Æ NO3 Æ H2O (2)
Cu(dpdapt)Cl2 (1)
[Cu(dpdapt)(NO3)(H2O)] Æ NO3 Æ H2O (2)
Experimental
Optimized
Experimental
Bond lengths
Cu(1)–N(3)
Cu(1)–N(1)
Cu(1)–N(5)
Cu(1)–Cl(1)
Cu(1)–Cl(2)
N(1)–C(1)
N(1)–C(5)
N(3)–C(8)
N(3)–C(6)
N(5)–C(15)
N(5)–C(19)
N(6)–C(7)
N(7)–C(8)
2.024(2)
2.066(2)
2.079(2)
2.4243(8)
2.2878(7)
1.351(3)
1.335(3)
1.364(2)
1.346(2)
1.331(2)
1.351(3)
1.346(2)
1.326(2)
2.095
2.175
2.246
2.363
2.333
1.360
1.351
1.362
1.358
1.348
1.359
1.355
1.352
Cu(1)–N(3)
Cu(1)–N(1)
Cu(1)–N(5)
Cu(1)–O(5)
Cu(1)–O(7)
N(9)–O(5)
N(8)–O(1)
N(1)–C(1)
N(1)–C(5)
N(3)–C(6)
N(3)–C(8)
N(5)–C(9)
N(5)–C(13)
2.018(2)
1.974(2)
1.980(2)
2.114(3)
2.225(2)
1.197(4)
1.250(3)
1.358(3)
1.337(3)
1.359(3)
1.364(3)
1.341(3)
1.365(3)
Bond angles
N(3)–Cu(1)–N(1)
N(3)–Cu(1)–N(5)
N(1)–Cu(1)–N(5)
N(1)–Cu(1)–Cl(1)
N(5)–Cu(1)–Cl(1)
N(5)–Cu(1)–Cl(2)
N(1)–Cu(1)–Cl(2)
N(3)–Cu(1)–Cl(2)
N(3)–Cu(1)–Cl(1)
Cl(2)–Cu(1)–Cl(1)
86.93(7)
87.79(7)
124.53(7)
120.32(5)
113.66(5)
94.13(5)
93.39(5)
177.41(5)
82.94(5)
94.69(3)
84.74
84.33
122.56
123.77
111.44
94.28
92.41
180.0
86.16
98.05
N(1)–Cu(1)–N(5)
N(1)–Cu(1)–N(3)
N(5)–Cu(1)–N(3)
N(1)–Cu(1)–O(5)
N(5)–Cu(1)–O(5)
N(3)–Cu(1)–O(5)
N(1)–Cu(1)–O(7)
N(3)–Cu(1)–O(7)
N(5)–Cu(1)–O(7)
O(5)–Cu(1)–O(7)
170.03(7)
92.90(7)
93.63(7)
88.40(9)
89.65(9)
150.3(1)
83.58(8)
116.54(7)
86.76(8)
93.10(1)
Hydrogen bonds
N(2)–H(2A)ꢁ ꢁ ꢁCl(2)#1
N(4)–H(4A)ꢁ ꢁ ꢁCl(1)#2
C(4)–H(4)ꢁ ꢁ ꢁCl(1)#3
3.588
3.258
3.405
N(2)–H(2)ꢁ ꢁ ꢁO(4)#4
O(7)–H(7A)ꢁ ꢁ ꢁO(1)
C(12)–H(12)ꢁ ꢁ ꢁO(2)#4
3.051
2.815
3.205
Symmetry codes: #1: 1/2 + x, 1/2 ꢀ y, ꢀ1/2 + z; #2: ꢀx, 1 ꢀ y, ꢀz; #3: 1 + x, y, z; #4: x, ꢀ1 + y, z.
˚
by face to face p–p stacking (3.461 A) (between the
triazine rings of two neighboring dimers) and two weak
˚
hydrogen bonds interactions (Clꢁ ꢁ ꢁH–C 3.405 A)
forming a 1-D supramolecular ladder structure along
the c-axis (Fig. 2). The structural characterization of
such hydrogen-bonded dimeric structures linked by
self-complementary donor/accepter groups is scarce for
metal organic framework [13]. On the other hand, the
1-D supramolecular stacking in the ab-plane using
N(2)–Hꢁ ꢁ ꢁCl(2) hydrogen bonds, thereby gives rise to
a 2-D layer structure (Fig. 3).
Complex 2 has the same coordination configuration
as 1. The Cu(1) atom sits in a five-coordinated environ-
ment composed of three nitrogen donors (N(3) of tri-
azine and N(5), N(1) of different pyridyls) with two
different oxygen atoms, one (O(7)) from a water mole-
cule, the other (O(5)) from a nitrate anion (Fig. 4).
The bond distance to the terminal triazine N(3),
˚
(Cu(1)–N(3)) is 2.018(2) A and the distance to the pyr-
idyl donors N(5) (Cu(1)–N(5)) and N(1) (Cu(1)–N(1))
˚
are 1.980(2) and 1.974(2) A, respectively. The average
˚
Cu–N bond length is observed to be 1.990 A, which is
Fig. 1. The ORTEP drawing of Cu(dpdapt)Cl2 (2). Thermal ellipsoids
are drawn at the 50% probability level. Hydrogen atoms are omitted
for clarity.
shorter than that of 1. Both Cu–N bond lengths are typ-
ical of those found for the five–coordinate Cu(II)-l-

C.-J. Wang et al. / Polyhedron 25 (2006) 195–202
199
Fig. 2. The one-dimensional ladder structure of [Cu(dpdapt)Cl2] (1) formed by hydrogen-bonding interactions (dashed lines) and p–p stacking along
the c-axis. Some hydrogen atoms are omitted for clarity.
Fig. 3. The layer structure of [Cu(dpdapt)Cl2] (1).
pmea analogues [14]. The Cu(1)–O(7) distance is
consists of alternate layers with an antiparallel align-
ment of the molecules, and each layer is built up via sol-
vent molecular interactions and hydrogen bonds in the
ac-plane as shown in Fig. 6. The adjacent layers are
interconnected by solvent molecules, resulting in a 3-D
structure.
Although the structures of 1 and 2 exhibit the coordi-
nation character of dpdapt in part, the framework struc-
tures of 1 and 2 are scarce for inorganic triazine
compounds. To the best of our knowledge, only one di-
meric unit of a transition-metal complex based on tpt
has been reported [6a], but no p–p interactions were dis-
cussed. Additionally, the ladder and layer frameworks
of 1 and 2 are exclusive and structures of this type con-
taining tpt have not been reported to date. The coordi-
nation of one metal ion, especially Cu(II), to tpt
induces the hydrolysis of tpt [5,6]. Dinuclear metal com-
plexes of tpt have also been described [6]. Although tpt
has a more versatile coordination ability [6b] than
˚
˚
2.225(2) A and Cu(1)–O(5) is 2.114(3) A. The coordina-
tion geometry of Cu(1) is also distorted trigonal bipyra-
midal with O(7), N(3), Cu(1) and O(5) in the equatorial
plane and the apical sites are occupied by the N(1) and
N(5) atoms of the pyridyl rings. The dihedral angle be-
tween the plane (Cu(1), O(5), O(7), N(3)) and the tri-
azine ring plane is 85.8ꢁ.
The crystal framework testifies a one-dimensional
chain along the b-axis with hydrogen bonds and p–p
stacking interactions. As depicted in Fig. 5, the one-
dimensional chains along the b-axis are formed by three
different types of hydrogen bonds involving the coordi-
nated molecular water, the coordinated nitrate anion
and the non-coordinated nitrate anion (N(2A)–
˚
˚
Hꢁ ꢁ ꢁO(4B), 3.051 A; O(7A)–Hꢁ ꢁ ꢁO(1A), 2.815 A;
˚
C(12B)–Hꢁ ꢁ ꢁO(2A), 3.201 A) as well as p–p stacking
˚
(3.345 A) between the phenyl and pyridyl rings of two
neighboring molecules. Moreover, the crystal structure

200
C.-J. Wang et al. / Polyhedron 25 (2006) 195–202
Fig. 6. Layer framework of [Cu(dpdapt)(NO3)(H2O)] Æ NO3 Æ H2O (2)
in the ac-plane.
The UV–Vis spectra of the complexes are recorded in
methanol and are characterised by several spectral re-
gions. The absorption bands in the region of 260 and
285 nm for the ligand dpdapt are ligand-centered (LC)
due to p–p* transitions [15,16]. The shoulder at 300
nm for complexes 1 and 2 is due to a d–d transition
and the low-energy bands at 341, 384 and 389 nm are
assigned to metal-to-ligand charge transfer (MLCT)
transitions [17,18].
Fig. 4. Molecular structure of [Cu(dpdapt)(NO3)(H2O)] Æ NO3 Æ H2O
(2) Thermal ellipsoids represent the 50% probability surfaces. Hydro-
gen atoms are omitted for clarity.
dpdapt, in theory, the dpdapt ligand has its intriguing
character revealed in this article.
3.2. Spectroscopic properties
The luminescence data were recorded in methanol at
room temperature. The excitation–emission spectrum of
dpdapt shows the strongest emission peak at 375.4 nm
with the excitation peak at 330.0 nm. The emission band
of dpdapt is attributed to the p*–n transitions. The
strongest excitation peak for complex 1 is at 310.0 nm
and for complex 2 at 300.0 nm, and their emission spec-
tra show a main strong peak at 413.6 and 438.0 nm,
respectively. These shoulder peaks of the emission spec-
tra are probably due to the ligand-to-metal charge-
transfer (LMCT) bands [19]. The strong fluorescent
emissions of the dpdapt supramolecular complexes 1
The IR spectra of the complexes exhibit several char-
acteristic strong bands. In complex 1, the bands around
1425 and 1496 cmꢀ1 in the ligand dpdapt, attributed to
the C@N groups, are shifted to 1464 and 1570 cmꢀ1
,
respectively, confirming the involvement of dpdapt in
the copper complexation. In complex 2, the correspond-
ing bands are shifted to 1580 and 1640 cmꢀ1. The bands
ꢀ
corresponding to NO3 are at 1421, 1382, 1022 and 775
cmꢀ1 and the broad band at 3290–3421 cmꢀ1 represents
the existence of m(H2O) in complex 2.
Fig. 5. The one-dimensional chain structure of [Cu(dpdapt)(NO3)(H2O)] Æ NO3 Æ H2O (2) formed by hydrogen-bonding interactions (dashed lines)
and p–p stacking along the b-axis. Some hydrogen atoms are omitted for clarity.

C.-J. Wang et al. / Polyhedron 25 (2006) 195–202
201
Table 3
Population analysis of 1
and
materials.
2 make them potentially useful photoactive
Bond
3.3. Computational results and discussion
Cu(1)–Cl(1)
Cu(1)–Cl(2)
Cu(1)–N(3)
Cu(1)–N(1)
Cu(1)–N(5)
N(3)–C(6)
N(3)–C(8)
N(6)–C(7)
N(7)–C(8)
0.2663
0.2275
0.1236
0.1123
0.1065
0.2716
0.2790
0.3589
0.4484
DFT calculations (B3LYP/6-31G(d)) have been car-
ried out for the coordination conformations of dpdapt,
and the optimized structures (verified by calculating
the vibrational frequencies that result in the absence of
imaginary eigenvalues) are shown in Fig. 7. The relative
energies of each conformation given in this article in-
clude zero-point corrections (ZPE). Eanti–anti–anti–anti
,
Esyn–syn–anti–anti and Esyn–syn–syn–syn equal ꢀ1115.698749,
ꢀ1115.700689 and ꢀ1115.699802 hartree, respectively.
It is found that the energies of the conformers are simi-
lar, while the syn–syn–anti–anti conformer is the most
stable by 5.09–2.33 kJ molꢀ1. Complexes 1 and 2 exist
with the ligand in the all-anti conformation. Clearly
the free ligand, with its preferred syn–syn–anti–anti con-
formation, does not effect the conformation change in 1
and 2 because of its minimal energy difference.
than that of Cu(1)–Cl(1). The bond intensity order is
Cu(1)–N(3) > Cu(1)–N(1) > Cu(1)–N(5) in accord with
that in the experimental results (Cu(1)–N(5) > Cu(1)–
N(1) > Cu(1)–N(3)). Because N(3) is coordinated to
the center Cu atom, the populations of N(3)–C(6) and
N(3)–C(8) are less than that of N(6)–C(7) and N(7)–
C(8).
The Mulliken charge of the central Cu metal (Table 4)
changes from +2 to 0.275. Obviously, Cu has been coor-
dinated by the ligand and its charge transfers to the li-
gand. The net atomic charge of the coordinated Cl(1),
Cl(2), N(1), N(3) and N(5) atoms are negative. Com-
pared to the dpdapt ligand (N(1), ꢀ0.259; N(3) and
N(5), ꢀ0.438; N(6) and N(7), ꢀ0.353), the change in
the charge distribution value of the donor nitrogen
atoms (N(1), N(3), N(5)) are more than that of the
non-coordinated nitrogen atoms (N(6), N(7)) in triazine.
Optimized geometries for 1 were verified by perform-
ing a frequency calculation. The optimized bond lengths
and angles are presented in Table 2. In general, the calcu-
lated bond lengthsand angles are in agreement with exper-
˚
imental crystal data and the large differences (ꢃ0.2 A, ꢃ3ꢁ)
may be noticed for deviations around the central copper
atoms. The deviations come mainly from two factors:
one is that the theoretical calculations do not consider
the effects of chemical environment (the complex is trea-
ted as a free molecule), and basis sets are still approximate
to a certain extent. However, the coordination geometry
of Cu(II) is also a distorted trigonal bipyramid. The bond
angles N(1)–Cu(1)–N(5) (121.56ꢁ), N(5)–Cu(1)–Cl(1)
(111.44ꢁ) and N(1)–Cu(1)–Cl(1) (124.77ꢁ) sum up
approximately to 360ꢁ and the angle N(3)–Cu(1)–Cl(2)
is 180ꢁ. So the results should be significant in computa-
tions of this large system.
Table 4
Mulliken atomic charges (e) for 1
Atom
Charge
Cu(1)
Cl(1)
Cl(2)
N(3)
N(5)
N(1)
N(6)
N(7)
0.275
ꢀ0.397
ꢀ0.383
ꢀ0.498
ꢀ0.518
ꢀ0.545
ꢀ0.432
ꢀ0.437
The overlap populations (Table 3) between Cu(1) and
Cl(1) (0.2663) is stronger than that of Cu(1)–Cl(2)
(0.2275), which is consistent with the experimental result
that the bond length of Cu(1)–Cl(2) is clearly longer
Fig. 7. Optimized structures of dpdaptꢀs coordination conformations.

202
C.-J. Wang et al. / Polyhedron 25 (2006) 195–202
Table 5
(d) D.N. Dybtsev, H. Chun, K. Kim, Chem. Commun. (2004)
1594.
[2] (a) S. Koner, S. Saha, K.L. Okamoto, J.P. Tuchagues, Inorg.
Chem. 42 (2003) 4668;
The energy (eV) and character of the selected molecular orbitals with a
spins for 1
Orbital
Energy
Character
(b) Y.Q. Zheng, J.L. Lin, Z.P. Kong, Inorg. Chem. 43 (2004)
2590;
(c) C.D. Wu, H.L. Ngo, W. Lin, Chem. Commun. (2004) 1588;
(d) I.G. Filippova, V.K. Kravtsov, M.R.J. Gdanec, Coord. Chem.
39 (2000) 1363.
HOMO ꢀ 3
HOMO ꢀ 2
HOMO ꢀ 1
HOMO
ꢀ6.126
ꢀ5.711
ꢀ5.472
ꢀ5.364
ꢀ3.096
ꢀ1.989
ꢀ1.686
ꢀ1.600
p(Cu–Cl), p(Cl)
dxz(Cu), p(Cl)
dyz(Cu), p(Cl)
dxy(Cu), p(Cl)
LUMO
p*(dpdapt), dxy(Cu)
p*(dpdapt)
p*(dpdapt), dxy(Cu)
dz2 ðCuÞ–rðClÞ
[3] (a) Z. Huang, H.B. Song, M. Du, S.T. Chen, X.H. Bu, Inorg.
Chem. 43 (2004) 932;
LUMO + 1
LUMO + 2
LUMO + 3
(b) C. Janiak, J. Chem Soc., Dalton Trans. (2003) 2781.
[4] F.H. Case, E.J. Koft, J. Am. Chem. Soc. 81 (1959) 905.
[5] (a) A. Cantarero, J.M. Amigo, J. Faus, M. Julve, T. Debaerde-
maeker, J. Chem. Soc., Dalton Trans. (1988) 2033;
(b) E.I. Lerner, S.J. Lippard, Inorg. Chem. 16 (1977) 1546;
(c) J. Faus, M. Julve, J.M. Amigo, T. Debaerdemaeker, J. Chem.
Soc., Dalton Trans. (1989) 1681;
All this data show strong complexation between Cu and
its coordinated atoms.
The energies and characters of the selected MOs for 1
are presented in Table 5. According to molecular orbital
theory, the frontier orbital and nearby molecular orbi-
tals are the most important factors to the activity. The
highest occupied molecular orbital (HOMO) and the
nearby occupied molecular orbitals are prone to donate
electrons, but the lowest unoccupied molecular orbital
(LUMO) and the nearby unoccupied orbitals are prone
to accept electrons. The more different the frontier orbi-
tals are, the more stable the molecular structure is [20].
The copper dp atomic orbitals (dxz,dyz and dxy) and p
orbitals of the chlorine atoms make the main contribu-
tions into the HOMO ꢀ 2 , HOMO ꢀ 1 and HOMO.
The LUMO orbital has predominantly p*(dpdapt) char-
acter. The results approved its coordination behavior
and the value of DE (DE = ELUMO ꢀ EHOMO) is 2.268
eV, which shows that the complex 1 can exist stably.
(d) N.C. Thomas, B.L. Foley, A.L. Rheingold, Inorg. Chem. 27
(1977) 1546;
(e) X.Y. Chen, F.J. Femia, J.W. Babich, J.A. Zubieta, Inorg.
Chem. 40 (2001) 2769.
[6] (a) G. Thorsten, L. Thomas, F. Roland, Eur. J. Inorg. Chem.
(2004) 394;
(b) N.C. Thomas, B.L. Foley, A.L. Rheingold, Inorg. Chem. 27
(1988) 3427.
[7] G.M. Sheldrick, SHELXL-97: Program for Crystal Structure Deter-
mination, University of Go¨ttingen, Go¨ttingen, Germany, 1997.
[8] G.M. Sheldrick, SHELXL-97: Program for Crystal Structure
Refinement, University of Go¨ttingen, Go¨ttingen, Germany, 1997.
[9] M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A.
Robb, J.R. Cheeseman, J.A. Montgomery Jr., T. Vreven, K.N.
Kudin, J.C. Burant, J.M. Millam, S.S. Iyengar, J. Tomasi, V.
Barone, B. Mennucci, M. Cossi, G. Scalmani, N. Rega, G.A.
Petersson, H. Nakatsuji, M. Hada, M. Ehara, K. Toyota, R.
Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O.
Kitao, H. Nakai, M. Klene, X. Li, J.E. Knox, H.P. Hratchian,
J.B. Cross, C. Adamo, J. Jaramillo, R. Gomperts, R.E. Strat-
mann, O. Yazyev, A.J. Austin, R. Cammi, C. Pomelli, J.W.
Ochterski, P.Y. Ayala, K. Morokuma, G.A. Voth, P. Salvador,
J.J. Dannenberg, V.G. Zakrzewski, S. Dapprich, A.D. Daniels,
M.C. Strain, O. Frakas, D.K. Malick, A.D. Rabuck, K. Ragh-
avachari, J.B. Foresman, J.V. Ortiz, Q. Cui, A.G. Baboul, S.
Clifford, J. Cioslowski, B.B. Stefanov, G. Liu, A. Liashenko, P.
Piskorz, I. Komaromi, R.L. Martin, D.J. Fox, T. Keith, K.A.
Allaham, C.Y. Peng, A. Nanayakkara, M. Challacombe, P.M.W.
Gill, B. Johson, W. Chen, M.W. Wong, C. Gonzalez, J.A. Pople,
GAUSSIAN-03. Revision B.03, Gaussian, Inc., Pittsburgh, PA, 2003.
[10] A.D. Becke, J. Chem. Phys. 98 (1993) 5648.
Appendix A. Supplementary data
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC No. 260645 for compound 1 and
260646 for compound 2. Copies of this information
may be obtained free of charge on application to
CCDC, 12 Union Road, Cambridge CB2 1EZ, UK
(fax: +44 1223 336 033; e-mail: deposit@ccdc.cam.ac.uk
or www: http://www.ccdc.cam.ac.uk). Supplementary
data associated with this article can be found, in the
online version at doi:10.1016/j.poly.2005.06.061.
[11] C.L.W. Yang, R.G. Parr, Phys. Rev. 37 (1988) 785.
[12] A.K. Vrkic, T. Taverner, J. Chem Soc., Dalton Trans. (2004) 197.
[13] H.-R. Ma, Y.-Y. Wang, P. Liu, D.-S. Li, G.-H. Lee, S.-M. Peng,
Polyhedron 24 (2005) 215.
[14] K.-Y. Choi, Y.-M. Jeon, H. Ryu, J.-J. Oh, H.-H. Lim, M.-W.
Kim, Polyhedron 23 (2004) 903.
[15] D.B. MacQueen, J.D. Petersen, Inorg. Chem. 29 (1990) 2313.
[16] R.M. Berger, J.R. Holcombe, Inorg. Chim. Acta (1995) 232.
[17] A. Juris, V. Balzani, F. Barigelletti, S. Campagna, P. Belser, A.V.
Zelewsky, Coord. Chem. Rev. (1998) 8485.
References
[18] R.M. Berger, D.D. Ellis, Inorg. Chim. Acta (1996) 241.
[19] Q.R. Fang, G.S. Zhu, M. Xue, J. Chem Soc., Dalton Trans.
(2004) 2205.
[20] K.C. Zheng, Z.N. Chen, Acta Phys. Chim. Sinica (Chinese) 15
(1999) 204.
[1] (a) Y.-Q. Sun, J. Zhang, G.-Y. Yang, J. Chem Soc., Dalton
Trans. (2003) 3634;
(b) B. Moulton, M.J. Zaworotko, Chem. Rev. 101 (2001) 1629;
(c) Y.B. Dong, P. Wang, R.Q. Huang, Inorg. Chem. 43 (2004)
4727;