научная статья по теме SYNTHESES, CHARACTERIZATION, AND CRYSTAL STRUCTURES OF TWO DINUCLEAR NICKEL(II) AND COPPER(II) COMPLEXES WITH SCHIFF BASES Химия

Текст научной статьи на тему «SYNTHESES, CHARACTERIZATION, AND CRYSTAL STRUCTURES OF TWO DINUCLEAR NICKEL(II) AND COPPER(II) COMPLEXES WITH SCHIFF BASES»

КООРДИНАЦИОННАЯ ХИМИЯ, 2010, том 36, № 7, с. 528-532

УДК 541.49

SYNTHESES, CHARACTERIZATION, AND CRYSTAL STRUCTURES OF TWO DINUCLEAR NICKEL(II) AND COPPER(II) COMPLEXES

WITH SCHIFF BASES

© 2010 R. H. Hui1, *, P. Zhou1, 2, and Z. L. You2

department of Chemistry, Anshan Normal University, Anshan 114007, P.R. China 2Department of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian 116029, P.R. China

* E-mail: ruihua_hui@126.com Received November 23, 2009

The phenolic azide bridged dinuclear nickel(II) complex, [Ni2(L1)2(N3)(H2O)(^1 i-N3)] ■ EtOH (I), and the thiocyanate bridged dinuclear copper(II) complex, [Cu2(L2)2(^i i-NCS)2] (II), where L1 and L2 are the deprotonated forms of 2-mothoxy-6-[(2-piperidin-1-ylethylimino)methyl]phenol and 2,4-dichloro-6-[(2-methylaminoethylimino)methyl]phenol, respectively, were synthesized and characterized by elemental analysis, IR spectra, and single-crystal X-ray diffraction. The crystal of I is orthorhombic: space group Pbca, a = 12.172(1), b = 20.953(1), c = 29.779(2) Â, V = 7594.8(9) Â3, Z = 8. The crystal of II is monoclinic: space group P21/n, a = 8.7615(11), b = 19.672(2), c = 16.568(2) Â, в = 99.449(2)°, V = 2816.9(6) Â3, Z = 4. The Ni atoms in I are in octahedral coordinations, and the Cu atoms in II are in square-pyramidal coordinations.

INTRODUCTION

Polynuclear complexes with bridging groups are of great interest due to their versatile molecular topologies and wide applications [1—3]. The prime strategy for designing the polynuclear complexes is

to use suitable bridging ligands [4—6], such as N-, CN-, and NCS-. The azide and thiocyanate anions can link two or more metal atoms in the (end-on), ^13 (end-to-end), and many other modes, yielding various polynuclear and one-, two-, or three-dimensional species of different topologies, depending on the metal atom and the coli-gands used [7, 8]. The tridentate Schiff bases, 2-methoxy-6-[(2-piperidin-1-ylethylimino)me-thyl]phenol (HL1) and 2,4-dichloro-6-[(2-methy-laminoethylimino)methyl]phenol (HL2), may coordinate to the metal atoms through the phenolic O, imine N, and amine N atoms [9, 10]. Considering the few donor atoms of HL1 and HL2, other ligands easily coordinate to the metal atoms, forming versatile structures with mixed ligands. In this paper, the phenolic and azide bridged dinuclear nickel(II) complex, [Ni2(L1)2(N3)(H2O)(^1,1-N3)] ■ EtOH (I), and the thiocyanate bridged dinuclear copper(II) complex, [Cu2(L2)2(^11-NCS)2] (II), were synthesized and structurally characterized. To our knowledge, no complexes with HL1 and HL2 were reported so far.

Cl

H N

O

Cl

(HL1)

(HL2)

EXPERIMENTAL

Materials and measurements. 3-Methoxysalicylal-dehyde, 3,5-dichlorosalicylaldehyde, 4-(2-aminoeth-yl)piperidine, and N-methylethane-1,2-diamine were purchased from the Lancaster Company, and other chemicals were of analytical grade quality and used without further purification. Infrared spectra were recorded on a Bruker IFS-125 FT-IR spectrophotometer as KBr pellets. C, H, and N analyses were carried out using a PerkinElmer 240 analyzer.

(NaN3 and the complexes with azide ligands are potentially explosive. Although no problem has been encountered during the synthesis of the complexes, they should be prepared in small quantities and must be handled with proper care.)

Synthesis of HL1. To an ethanolic solution (10 ml) of 3-methoxysalicylaldehyde (1.0 mmol, 152.2 mg) was added an ethanolic solution (10 ml) of 4-(2-ami-noethyl)piperidine (1.0 mmol, 128.2 mg) with continuous stirring at room temperature. The mixture was

stirred for about 10 min to give a clear yellow solution, which was evaporated to give a yellow precipitate. The precipitate was washed three times with cold ethanol and dried in a vacuum over anhydrous CaCl2. The yield was 91%.

For C15H22N2O2

anal. calcd, %: C, 68.7; H, 8.4; N, 10.7. Found, %: C, 68.4; H, 8.6; N, 10.5.

IR spectrum (KBr; v, cm-1): 1641 v,(-C=N-).

Synthesis of HL2. To an ethanolic solution (10 ml) of 3,5-dichlorosalicylaldehyde (1.0 mmol, 190.0 mg) was added an ethanolic solution (10 ml) of N-methyl-ethane-1,2-diamine (1.0 mmol, 74.1 mg) with continuous stirring at room temperature. The mixture was stirred for about 10 min to give a clear yellow solution, which was evaporated to give a yellow precipitate. The precipitate was washed three times with cold ethanol and dried in a vacuum over anhydrous CaCl2. The yield was 93%.

For C10H12Cl2N2O

anal. calcd, %: C, 48.6; H, 4.9; N, 11.3. Found, %: C, 48.9; H, 5.0; N, 11.5.

IR spectrum (KBr; v, cm-1): 1645 v,(-C=N-).

Synthesis of I. To an ethanol solution (10 ml) of HL1 (0.1 mmol, 26.2 mg) and NaN3 (0.1 mmol, 6.5 mg) was added an aqueous solution (1 ml) of Ni(NO3)2 • • 6H2O (0.1 mmol, 29.0 mg) with continuous stirring at room temperature. The final clear green solution was allowed to stand at room temperature for several days. Green block-shaped crystals suitable for X-ray diffraction were collected and dried in air. The yield was 17.0 mg (43.1%) based on HL1.

For C32H50Nt0Ni2O6

anal. calcd, %: C, 48.8; H, 6.4; N, 17.8. Found, %: C, 48.3; H, 6.7; N, 18.2.

IR spectrum (KBr; v, cm-1): 3382 br, 2053 v.s, 1635 s, 1217 s.

Synthesis of II. To an ethanolic solution (10 ml) of HL2 (0.1 mmol, 24.6 mg) and NH4NCS (0.1 mmol, 7.6 mg) was added an ethanolic solution (1 ml) of Cu(CH3COO)2 • H2O (0.1 mmol, 19.9 mg) with continuous stirring at room temperature. The final clear blue solution was allowed to stand at room temperature for several days. Blue block-shaped crystals suit-

.c(12) )c(13)

c(10) c(9)

c(8)

c(6^c(22)c(2)

c(5)

c(26)

c(25) c(24)

c(7)

c(20)

Fig. 1. Structure of I showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. The disordered ethanol group and H atoms are omitted for clarity.

able for X-ray diffraction were collected and dried in air. The yield was 21.3 mg (57.9%) based on HL2.

For C22H22Cl4Cu2N6O2S2

anal. calcd, %: C, 35.9; H, 3.0; N, 11.4. Found, %: C, 36.3; H, 2.9; N, 11.1.

IR spectrum (KBr; v, cm-1): 2064 v.s, 1637 s, 1211 m.

X-ray structure determination. The crystals of I and II suitable for X-ray diffraction were each mounted on a thin glass fiber and aligned on a Bruker SMART 1000 CCD diffractometer equippted with graphite -monochromated Mo!a radiation (X = 0.71073 A). The 9 range for data collection was 1.37°-27.50° for I and 1.62°-27.50° for II. All data were corrected for Lorentz and polarization effects and for the effects of absorption. The structures were solved by a direct method and refined by least-square cycles. The non-hydrogen atoms were refined anisotropically. Water H atoms in I and amino H atoms in II were located from a difference Fourier map and refined isotropically with O-H, N-H, and H-H distances restrained to 0.85(1), 0.90(1), and 1.37(2) A, respectively. Other hydrogen atoms were included but not refined. All calculations were performed using the SHELXTL-97 package [11]. The data collection and refinement parameters are summarized in Table 1. Selected bond lengths and angles are given in Table 2. Atomic coordinates and other structural parameters of the complexes have been deposited with the Cambridge Crystallographic Data

4 КООРflHНАЦHОННА£ XHMH£ tom 36 № 7 2010

530 HUI et al.

Table 1. Crystallographic data and experimental details for complexes I and II

Parameter Value

I II

Fw 788.2 735.46

Crystal color/shape Green/block Blue/block

Crystal size, mm3 0.17 x 0.12 x 0.05 0.33 x 0.22 x 0.20

Crystal system Orthorhombic Monoclinic

Space group Pbca P2x/n

a, Â 12.172(1) 8.7615(11)

b, Â 20.953(1) 19.672(2)

c, Â 29.779(2) 16.568(2)

ß, deg 99.449(2)

V, Â3 7594.8(9) 2816.9(6)

Z 8 4

T, K 298(2) 298(2)

mm-1 (Mo^) 1.046 2.071

Pc, g cm-3 1.379 1.734

Reflections/parameters 8693/481 6424/351

Restraints 5 2

Independent reflections 6577 4498

F(000) 3328 1480

Index range (h, k, l) -15 < h < 1 5 -26 < k < 26 -38 < l < 38 -11 < h < 11 -25 < k < 25 -21 < l < 21

T J min 0.8422 0.5481

T J max 0.9496 0.6821

Goodness of fit on F2 1.093 1.017

R1, wR2 ((I> 2ü(T))* 0.0485, 0.0991 0.0416, 0.0916

R1, wR2 (all data)* 0.0708, 0.1081 0.0687, 0.1036

: Ri

(2)=

= ZiFoi - i^cii/Si^oi, wR2 = Ew(F02 - F2 )2/Ew(F02 )2]1/2, W(1) = [ct2(F,)2 + (0.0449(Fo2 + 2F2 )/3)2 + 0.9163F2 + 2F2 )/3]-1.

[a2(Fo)2 + (0.045(Fo2 + 2F; )/3)2 + 2.0906^ + 2F2 )/3]-

Center (nos. 638061 (I) and 638092 (II); depos-it@ccdc.cam.ac.uk or http://www.ccdc.cam.ac.uk).

RESULTS AND DISCUSSION

The molecular structure of I, except for the ethanol molecule, is shown in Fig. 1. The compound consists of the phenolic O, the end-on azide bridged dinuclear nickel(II) complex molecule, and the disordered eth-anol molecule of crystallization. The Ni—Ni distance is 3.189(2) A.

The Ni(1) atom in the complex is six-coordinated in an octahedral coordination with one phenolic O, one imine N, and one amine N atoms of the Schiff base ligand L1 with one phenolic O and one ether O atoms of another Schiff base ligand L1 and with one ter-

minal N atom of the bridging azide ligand. The Ni(2) atom is also six-coordinated in an octahedral coordination with one phenolic O, one imine N, and one amine N atoms of the Schiff base ligand L1 with one water O atom and with two terminal N atoms, respectively, from one bridging and one terminal azide ligands. The octahedral coordinations are distorted, as evidenced by the coordinate bond lengths and angles. As expected, the coordinate bonds containing the amine N atoms are much longer than those containing the imine N atoms.

The molecular structure of II is shown in Fig. 2. The compound is an end-on thiocyanate bridged dinuclear copper(II) complex. The Cu---Cu distance is 3.266(2) A.

Table 2. Selected bond lengths and bond angles for the complexes I and II

Bond d, Â Bond d, Â

Ni(1)—N(1) Ni(1)—O(3) Ni(1)—N(2) Ni(2)—N(3) Ni(2)—O(5) Ni(2)—N(5) Cu(1)—O(1) Cu(1)—N(5) Cu(1)-N(6) Cu(2)-N(

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