КООРДИНАЦИОННАЯ ХИМИЯ, 2011, том 37, № 5, с. 341-347
УДК 541.49
SYNTHESIS AND CRYSTAL STRUCTURES OF COBALT(III) AND ZINC(II)
COMPLEXES WITH SCHIFF BASES © 2011 Z. Hong*, C. L. Du, Y. P. Yu
School of Chemical Engineering & Material Science, Eastern Liaoning University, Dandong 118003, P.R. China *E-mail: hongzhe57@126.com Received July 8, 2010
Two new cobalt(III) and zinc(II) complexes, [Co(L1)2 (H2O)] • ClO4 (I) and [Ni(L2)2 (H2O)2] • 2ClO4 (II), where
L1 is the deprotonated form of 5-methoxy-2-[(2-morpholin-4-ylethylimino)methyl]phenol, and L2 is the zwitte-rionic form of 2-[(2-isopropylaminoethylimino)methyl]-5-methoxyphenol, were synthesized and structurally characterized by elemental analyses, IR spectra, and single-crystal X-ray diffraction. The crystal of I is monoclinic: space group P21/c, a = 11.1512(4), b = 28.2424(11), c = 10.9655(4) А, в = 95.746(2)°, V = 3436.1(2) A3, Z = 4. The crystal of II is triclinic: space group Pi, a = 8.1441(2), b = 10.4531(3), c = 10.8849(3) A, a = 84.0240(10)°, в = 76.9800(10)°, у = 74.2280(10)°, V = 867.92(4) A3, Z = 1. Complex I consists of a mononuclear cobalt(III) complex cation and a perchlorate anion. Complex II consists of a crystallographic centrosymmetric mononuclear nickel(II) complex cation and two perchlorate anions. Each metal atom in the complexes is in an octahedral coordination.
INTRODUCTION
Schiffbases prepared by the condensation of salicylal-dehydes with primary amines are an important class of versatile ligands. Schiff base complexes of transition metals have been extensively investigated due to their ready syntheses and myriad properties [1—3]. However, the search in the Cambridge Crystallographic Database (version 5.31 with addenda up to February 26, 2010) [4] has revealed that the metal complexes derived from the Schiff bases 5-methoxy-2-[(2-morpholin-4-ylethylimino)me-thyl]phenol (HL1) and 2-[(2-isopropylaminoethylimi-no)methyl]-5-methoxyphenol (HL2) have never been reported. In the present paper, two new cobalt(III) and zinc(II) complexes with HL1 and HL2, respectively, have been synthesized and structurally characterized.
EXPERIMENTAL
Materials and measurements. 4-Methoxysalicylalde-hyde, 2-morpholin-4-ylethylamine, and N-isopropyle-thane-1,2-diamine of AR grade were purchased from Lancaster. C, H, and N elemental analyses were performed with a PerkinElmer 240C elemental analyzer. IR spectra (KBr disks) were recorded on a PerkinElmer 257 spectrophotometer.
Synthesis of HL1 and HL2. The Schiff bases HL1 and HL2 were prepared by the condensation reaction of equimolar quantities of 4-methoxysalicylaldehyde with the corresponding amines, viz., 2-morpholin-4-ylethy-lamine for HL1 and N-isopropylethane-1,2-diamine for
HL2, in methanol at room temperature. The yield was 95% for HL1 and 97% for HL2.
For C14H20N2O3 (HL1)
anal. calcd., %: C, 63.6; H, 7.6; N, 10.6.
Found, %: C, 63.3; H, 7.7; N, 10.6.
For C13H20N2O2 (HL2)
anal. calcd., %: C, 66.1; H, 8.5; N, 11.8.
Found, %: C, 65.7; H, 8.5; N, 11.7.
Synthesis of [Co(L1)2(H2O)] • ClO4 (I). A methanol solution (50 ml) of Co(ClO4)2 • 6H2O (0.183 g, 0.5 mmol) was added to a methanol solution (50 ml) ofHL1 (0.264 g, 1.0 mmol), and the mixture was stirred at room temperature for 30 min. Red X-ray quality crystals of I were obtained after a week by allowing the solution to evaporate in air. The yield was 0.187 g (53%).
For C28H40N4O11ClCo
anal. calcd., %: Found, %:
C, 47.8; C, 48.2;
H, 5.7; H, 5.9;
N, 8.0. N, 7.8.
Synthesis of [Ni(L2)2(H2O)2] • 2ClO4 (II). A methanol solution (50 ml) of Ni(ClO4)2 • 6H2O (0.183 g, 0.5 mmol) was added to a methanol solution (50 ml) ofHL2 (0.236 g, 1.0 mmol), and the mixture was stirred at room temperature for 30 min. Green X-ray quality crystals ofII were ob-
Table 1. Crystallographic and experimental data for complexes I and II
Parameter Value
I II
Formula weight 703.0 766.3
Crystal shape, colour Block, red Block, green
Crystal size, mm 0.20 x 0.18 x 0.17 0.23 x 0.20 x 0.20
Crystal system Monoclinic Triclinic
Space group P21/c PI
a, A 11.1512(4) 8.1441(2)
b, A 28.2424(11) 10.4531(3)
c, A 10.9655(4) 10.8849(3)
a, deg 90 84.0240(10)
P, deg 95.746(2) 76.9800(10)
Y, deg 90 74.2280(10)
V, A3 3436.1(2) 867.92(4)
Z 4 1
mm-1 (Mola) 0.637 0.782
T J min 0.883 0.841
T J max 0.899 0.859
Reflections/parameters 6247/452 3642/260
Independent reflections 2909 3267
Restraints 97 69
/(000) 1472 402
Goodness-of-fit on F2 0.979 1.040
R1, wR2 (I> 2ct(I))* 0.0703, 0.1724 0.0406, 0.1043
R1, wR2 (all data)* 0.1652, 0.2326 0.0454, 0.1081
*R = Z||F„| - |Fc||/Z|F„|, wR2 =
I w (( - Fo2))1 w (()2
1/2
tained after a week by allowing the solution to evaporate in air. The yield was 0.223 g (58%).
For C26H44N4Oi4Cl2Ni
anal. calcd., %: C, 40.8; H, 5.8; N, 7.3. Found, %: C, 40.5; H, 5.9; N, 7.5.
Crystal structure determination. The single crystals of the two complexes were chosen and glued to thin glass fibers by epoxy glue in air for data collection. The diffraction data were collected on a Bruker Apex2 CCD instrument with Mo^ radiation (X = 0.71073 Â) at 298(2) K using the ® scan method. The structures were solved by direct methods and difference Fourier synthesis. Crystal data collection, parameters, and refinement statistics for the two complexes are listed in Table 1. All of the non-H atoms were refined anisotropically. The water H atoms in I were located from a difference electronic map and re-
fined isotropically with O—H and H-H distances restrained to 0.85(1) and 1.37(2) A, respectively. Other H atoms ofthe two complexes were included in calculated positions and assigned isotropic thermal parameters, which were set to ride on the parent atoms. The perchlorate anions ofthe complexes are disordered over two distinct sites with occupancies of 0.654(2) and 0.346(2) for I and 0.542(2) and 0.458(2) for II. All calculations were performed using the SHELXTL-97 package [5].
Supplementary material has been deposited with the Cambridge Crystallographic Data Centre (nos. 774794 (I) and 774795 (II); deposit@ccdc.cam.ac.uk or http:// www.ccdc.cam.ac.uk).
RESULTS AND DISCUSSION
The condensation reactions ofaldehydes with primary amines readily produce Schiff bases with quantitative
SYNTHESIS AND CRYSTAL STRUCTURES OF COBALT(III) AND ZINC(II) COMPLEXES
343
0(l0)
0(9)
0(8)
0(7)
0(2) C(5)
C(7)
C(21)
0(5) C(18)
C(19)
C(13)
C(26)
i(4) C(24) C(23) C(25)
C(12) 0(13)
Fig. 1. Molecular structure of I at 30% ellipsoid. Only the major component of the disordered perchlorate anion is shown.
yields and high purity. The Schiff bases HL1 and HL2 are and ethanol. Both complexes were synthesized according yellow crystallites, which can be dissolved in methanol to the procedure shown below:
MeO'
O
N
^OH
+ Co(ClO4)2
MeOH
Y + Ni(ClO4)2
The IR spectra of the Schiff bases show the characteristic v(O—H) absorption bands at about 3450 cm-1, which disappear after complexation. The absorption attributed to the v(C=N) vibrations are at 1638 cm-1 for HL1 and 1636 cm-1 for HL2, and the corresponding vibrations in the two complexes are shifted to lower wave numbers
MeO
MeOH
(I)
(II)
O
OMe
ClO4
2C1O-
(1627 cm-1 for I and 1623 cm-1 for II), which is generally observed in other similar Schiff base complexes [6, 7]. The strong absorption band observed for HL1 and HL2 at about 1280 cm-1 can be attributed to the phenolic stretch. The bands are observed at higher wave numbers at about 1300 cm-1 for both complexes, suggesting the involvement
+
+
Table 2. Selected bond lengths (À) and bond angles (deg) for complexes I and II
Bond d, Â Bond d, Â
Co(1)-O(1) Co(1)—O(11) Co(1)-N(2) Ni(1)-O(1) Ni(1)-N(1) 1.880(5) 1.938(4) 2.055(6) I 1.9851(16) 2.0821(18) Co(1)-O(4) Co(1)-N(1) Co(1)-N(3) I Ni(1)-O(2) 1.875(4) 1.901(5) 1.956(5) 2.1622(19)
Angle ro, deg Angle ro, deg
O(4)Co(1)O(1) O(1)Co(1)N(1) O(1)Co(1)O1(1) O(4)Co(1)N(3) N(1)Co(1)N(3) O(4)Co(1)N(2) N(1)Co(1)N2) N(3)Co(1)N(2) O(1)Ni(1)N(1) N(1)Ni(1)O(2) 92.0(2) 94.9(2) 88.7(2) 94.3(2) 178.1(3) 88.6(2) 85.7(2) 95.8(2) I 89.27(7) 91.06(7) O(4)Co(1)N(1) O(4)Co(1)O(11) N(1)Co(1)O(11) O(1)Co(1)N(3) O1(1)Co(1)N(3) O(1)Co(1)N(2) O(11)Co(1)N(2) I O(1)Ni(1)O(2) 84.6(2) 173.87(18) 89.3(2) 83.5(2) 91.9(2) 179.2(2) 90.8(2) 88.93(8)
of the oxygen atom of the C—O group in coordination. The intense absorption bands indicative of the perchlorate anions are at 1095 cm-1 for I and 1091 cm-1 for II.
Selected bond lengths and angles for I are listed in Table 2. The compound consists of a mononuclear co-balt(III) complex cation and a perchlorate anion as shown in Fig. 1. The Co atom has a slightly distorted octahedral geometry coordinated by three N atoms from two Schiff base ligands L1, two phenolate O atoms from two Schiff base ligands L1, and one water molecule. The three N atoms and one phenolate O atom from the two Schiff base ligands are almost on the same equatorial plane, while the other phenolate O atom and the water O atom are in the axial positions. The two Schiff base ligands are nearly perpendicular to each other, with the dihedral angle between the two benzene rings of 80.9(3)°. There is an intramolecular O—H-N hydrogen bond between the water and the N(4) atom of a Schiff base ligand as shown by a dashed line in Fig. 1. As expected, the morpholine rings adopt chair configuration. The coordinate
bond lengths in the complex are typical of and comparable to those observed in other cobalt(III) complexes with Schiff bases [8-10].
In the crystal structure of I, the perchlorate anions are linked to the complex cations through intermolecular O—H-O hydrogen bonds (Table 3) as shown in Fig. 2.
Selected bond lengths and angles for II are listed in Table 2. The compound possessing a crystallographic inversion center symmetry consists of a mononuclear nick-el(II) complex cation and two symmetry-related perchlorate anions as shown in Fig. 3. The Ni atom lying on the inversion cen
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