Synthesis and solid state structures of two new copper(II) complexes of Schiff bases derived from furfuryl and tetrahydrofurfurylamine

Article abstract of DOI:10.1134/S1070328410120110

Two Schiff base copper(II) complexes, bis(N-furfurylsalicylaldiminato) copper(II) (I) and bis(N-tetrahydrofurfurylsalicylaldiminato)copper(II) (II), were synthesized and their solid state structures were determined by X-ray crystallography. Complex I has

Full text of DOI:10.1134/S1070328410120110

ISSN 1070ꢀ3284, Russian Journal of Coordination Chemistry, 2010, Vol. 36, No. 12, pp. 929–933. © Pleiades Publishing, Ltd., 2010.
Synthesis and Solid State Structures of Two New Copper(II)
Complexes of Schiff Bases Derived from Furfuryl
and Tetrahydrofurfurylamine1
W. Chena, b, P. Miaoa, Y. G. Lia, H. L. Zhua, b, *, and Q. F. Zenga
a Engineering Research Center for Clean Production of Textile Printing, Ministry of Education, Wuhan Textile University,
Wuhan 430073, P.R. China
b Institute of Functional Biomolecules, State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University,
Nanjing 210093, P.R. China
*Eꢀmail: hlzhu@wuse.edu.cn
Received March 3, 2010
Abstract—Two Schiff base copper(II) complexes, bis(Nꢀfurfurylsalicylaldiminato)copper(II) (
tetrahydrofurfurylsalicylaldiminato)copper(II) (II), were synthesized and their solid state structures were
determined by Xꢀray crystallography. Complex
I) and bis(Nꢀ
I
has a square planar geometry. In contrast, complex II disꢀ
plays a distorted square planar geometry. Thus, the geometry around copper in the solid state structures of
I
and II is determined by a combination of steric and electronic effects, as well as by crystal packing forces.
DOI: 10.1134/S1070328410120110
1
INTRODUCTION
Recently, some salenꢀtype Schiff base complexes as
the potent inhibitor against xanthine oxidase and antiꢀ
bacterial activities have been investigated by our
group [25, 26]. In addition, we have also reported
Transition metal complexes of Schiff bases derived
from salicylaldehyde and its derivatives become the
hot topics of contemporary research because of their
promising use foreground [1–3]. For example, they
act as singleꢀmolecule magnets (SMM) [4–6], lumiꢀ
nescent probes [7, 8], and catalysts for specific DNA
[9, 10] and RNA [11] cleavage reactions. Salenꢀtype
Schiff bases may act as bidentate N,Oꢀ [12], tridenꢀ
some dꢀtransition metal complexes (M = Cu, Co, Ni,
etc.) of such Schiff bases with the potent inhibitory
activities against urease [27, 28]. Interestingly, monoꢀ
nuclear copper(II) complexes show better inhibitory
activities among them. In this paper, we reported two
new Schiff base copper(II) complexes with a mononuꢀ
tate, and so on N,O,Oꢀdonor ligands [13], to yield clear metal center, bis(Nꢀfurfurylsalicylaldimiꢀ
monoꢀ, biꢀ, dimeric, 1D, 2D, and 3D complexes [14, nato)copper(II) (
and bis(Nꢀtetrahydrofurfurylꢀsalicyꢀ
laldiminato)copper(II) (II).
I
)
15] together with other coordinating moieties, such as
an azide ion, and thiocyanate and carboxylic group.
Among them, bis(bidentate) Schiff base copper(II)
complexes derived from the condensation of salicylaꢀ
dehyde with various primary amines have attracted
considerable interest, because in the solid state they
display a wide range of stereochemistries going from
square planar to pseudotetrahedral [16–20]. It has
been proposed that the degree of distorting from the
square planar geometry in these molecules results from
the volume of the substituent at the coordinating
nitrogen [18], sometimes electronic effects take place
[19], and crystal packing forces occur in some cases
[20–22]. For example, pseudotetrahedral distortion in
the solid state structures of some copper(II) complexes
EXPERIMENTAL
Materials and measurements. Salicyladehyde, furfuꢀ
ryl, and tetrahydrofurfurylamine were purchased from
Aldrich and used without further purification. Eleꢀ
mental analyses for C, H, and N were carried out on a
PerkinElmer 2400 analyzer. Xꢀray crystallography was
carried out using a Bruker SMART APEX II CCD difꢀ
fractometer.
Synthesis of complex I. Salicyladehyde (24 mg,
0.2 mmol) and furfurylamine (19 mg, 0.2 mmol) were
dissolved in an aqueous methanol solution (5 ml). The
mixture was stirred for 5 min to give an orange solution,
which was added to a methanol solution (2 ml) of
with tetradentate thiolate Schiff base ligands (N2S2
)
has been reported to depend on the backbone flexibilꢀ
ity. As the backbone becomes more flexible, distortion
grows [23, 24].
Cu(NO3)2 3H2O (24 mg, 0.1 mmol). The mixture was
⋅
stirred for another 5 min at room temperature to give a
yellowꢀgreen solution and then filtered. The filtrate was
kept in air for 7 days, forming brown block crystals. The
1
The article is published in the original.
929

930
CHEN et al.
Table 1. Crystallographic data and experimental details for complexes I and II
Value
Parameter
I
II
Molecular weight
Crystal system
463.96
472.02
Triclinic
Triclinic
Space group
P1
P1
a,
b,
c,
Å
Å
Å
5.3443(4)
9.8669(8)
10.1392(8)
10.1138(9)
10.8471(9)
10.9296(9)
80.019(2)
74.937(2)
73.286(2)
1102.60(16)
2
α
, deg
, deg
, deg
104.1080(10)
95.8300(10)
100.1260(10)
504.58(7)
1
β
γ
V, Å3
Z
ρcalcd, g cm–3
1.527
1.422
F(000)
239
494
µ
(MoK
α
), mm–1
1.117
1.024
Crystal size, mm
range for data collection
0.32
×
0.22
×
0.20
0.33
×
0.25 × 0.20
θ
2.18–25.99
1.97–25.99
–12/12, –13/13, –12/13
Multiscan
Index range
Type of scan
h
,
k
,
l
–6/6, –12/12, –12/12
Multiscan
Data/restraint/parameters
Rint
1975/0/142
0.0469
4282/0/280
0.0570
Goodnessꢀofꢀfit on F2
1.016
1.001
Final R1
,
wR2
(
I
> 2
σ
(
I
))
0.0383, 0.0979
0.711, –0.320
0.0627, 0.0952
0.345, –0.373
Δρmax and Δρmin
,
e
Å–3
crystals were isolated, washed three times with distilled water and dried in a vacuum desiccator containing anhyꢀ
drous CaCl2. The yield was 72%.
water, and dried in a vacuum desiccator containing anhyꢀ
drous CaCl2. The yield was 78%.
For C24H28N2O4Cu
anal. calcd., %:l C, 61.07;
Found, %: C, 61.11;
H, 5.98;
H, 5.80;
N, 5.93.
N, 5.89.
For C24H20N2O4Cu
anal. calcd., %: C, 62.13;
Found, %: C, 62.00;
H, 4.34;
H, 4.38;
N, 6.04.
N, 5.98.
Xꢀray structure determinations [29]. Crystalloꢀ
graphic data were collected on a Bruker SMART Apex
II CCD diffractometer at 291(2) K using graphiteꢀ
Synthesis of complex II. Salicyladehyde (24 mg,
0.2 mmol) and tetrahydrofurfurylamine (20 mg, 0.2 mmol)
were dissolved in an aqueous methanol solution (5 ml).
monochromated Mo
K
(
λ
= 0.71073
Å) radiation. The
α
collected data were reduced using the SAINT proꢀ
The mixture was stirred for 5 min to give an orange soluꢀ gram, and empirical absorption corrections were perꢀ
formed using the SADABS program. The structures
were solved by direct methods and refined against F2
by fullꢀmatrix leastꢀsquares methods using the
SHELXTL version 5.1. All of the nonꢀhydrogen atoms
were refined anisotropically. All hydrogen atoms were
placed in geometrically ideal positions and conꢀ
tion, which was added to a methanol solution (2 ml) of
Cu(NO3)2 3H2O (24 mg, 0.1 mmol). The mixture was
stirred for another 5 min at room temperature to give a
yellowꢀgreen solution and then filtrated. The filtrate was
kept in air for 7 days, forming brown block crystals. The
⋅
crystals were isolated, washed three times with distilled strained to ride on their parent atoms. The crystalloꢀ
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 36
No. 12
2010

SYNTHESIS AND SOLID STATE STRUCTURES
Table 2. Selected bond lengths and angles for structures and II
931
I
Bond
d
, Å
Bond
d, Å
Cu(1)–O(1)
Cu(1)–N(1)
N(1)–C(7)
Cu(1)–O(1)
Cu(1)–O(3)
1.8959(18)
1.999(2)
1.292(3)
1.888(3)
1.893(3)
Cu(1)–N(1)
Cu(1)–N(2)
N(1)–C(7)
N(2)–C(19)
1.993(4)
1.994(4)
1.291(5)
1.296(5)
Angle
ω
, deg
Angle
ω
, deg
O(1)Cu(1)N(1)
O(1)Cu(1)N(1)
O(3)Cu(1)N(2)
91.69(8)
91.72(15)
92.50(16)
O(1)Cu(1)N(2)
O(3)Cu(1)N(1)
89.17(15)
90.25(15)
graphic data for compounds I and II are summarized soluble in water and Me2O. Complexes I and II were
in Table 1. Selected bond lengths and angles are given obtained from the reaction of Schiff base ligands with
in Table 2. Supplementary material has been deposited Cu(NO3)2
3H2O in MeOH. The elemental analysis is
with the Cambridge Crystallographic Data Centre in good agreement with the chemical formulas proꢀ
⋅
(nos. 761916 (I) and 761917 (II); deposit@ posed for complexes
ccdc.cam.ac.uk or http://www.ccdc .cam.ac.uk).
I and II.
Xꢀray single crystal diffraction reveals that comꢀ
P 1.
I and II crystallize in triclinic space group
plexes
The crystal structures of two Schiff base copper comꢀ
plexes and II are shown in Figs. 1 and 2, respectively.
Both and II are the mononuclear copper complexes
of Schiff bases derived from the condensation of saliꢀ
cylaldehyde with furfuryl and telrahydrofurfuryꢀ
RESULTS AND DISCUSSION
I
I
In this paper, Schiff base ligands were prepared by
the reactions of salicylaldehyde with furfuryl and tetꢀ
rahydrofurfurylamine in 82–90% yield in an absolute
MeOH solution. These ligands are the yellow crystalꢀ
lites, stable compounds in air at room temperature.
They are easily soluble in common polar organic solꢀ
vents, such as MeCN, MeOH, EtOH, etc., but poorly
lamine, respectively. In I and II, the copper(II) atom
is fourꢀcoordinated by two N atom and two O atoms
from two bidentate ligand molecules in the usual trans
arrangement. It is interesting to point out that the copꢀ
O(2)
N(1)
O(2)
N(1)
O(1A)
Cu(1)
O(3)
Cu(1)
O(1)
O(1)
N(2)
N(1
A)
O(2A
)
O(4)
Fig. 1. An ORTEP diagram showing the molecular strucꢀ
ture of
level.
Fig. 2. An ORTEP diagram showing the molecular strucꢀ
ture of II. Thermal ellipsoids are shown at 30% probability
level.
I. Thermal ellipsoids are shown at 30% probability
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 36
No. 12
2010

932
CHEN et al.
z
y
0
x
z
0
x
y
Fig. 4. Molecular packing of II viewed along the xꢀaxis of
the unit cell.
Fig. 3. Molecular packing of
the unit cell.
I
viewed along the zꢀaxis of
help of electronic effects. Interestingly, the results in
this study indicate that the crystal packing forces play
a key role in the formation of such copper(II) species.
per(II) atom of complex I lies on a center of inversion
with a square planar geometry and the adjacent moleꢀ
cules are connected through intermolecular
C(7)⎯H(7)···O(2)# bond (C···O 3.452(4) Å) (Fig. 3). In
contrast, the [CuO2N2] unit of complex II is slightly
distorted from square planar toward tetrahedral geomꢀ
etry with the tetrahydrofurfuryl rings displaced above
and below the plane. The dihedral angle between two
planes O(1)–Cu(1)–N(1) and O(3)–Cu(1)–N(2) of
ACKNOWLEDGMENTS
The work was supported by the National Natural
Science Foundation of China and the Natural Science
Foundation
of
Hubei
Province
(project
nos. 50978208, 30772627, and 2009CDA022).
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