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Acta Cryst. (2009). E65, m1585    [ doi:10.1107/S1600536809047436 ]

[N,N'-Bis(3-methoxy-2-oxidobenzylidene)ethylenediammonium-[kappa]4O,O',O'',O''']tris(nitrato-[kappa]2O,O')dysprosium(III)

T. Gao, G.-M. Li, P. Gao, P.-F. Yan and G.-F. Hou

Abstract top

In the title mononuclear Schiff base complex, [Dy(NO3)3(C18H20N2O4)], the DyIII ion is ten-coordinated in a distorted hexadecahedral geometry by six O atoms of three nitrate anions and four O atoms of the Schiff base ligand. An intramolecular N-H...O hydrogen bond occurs. The crystal structure is stabilized by intermolecular C-H...O hydrogen bonds.

Comment top

Schiff base lanthanide complexes are currently of great interest because of their unique physicochemical properties and various applications as new materials. Moreover, the luminescence and magnetic properties of lanthanide complexes have recently aroused much attention.

As shown in Fig. 1, the ten-coordinate dysprosium(III) ion adopts a hexadecahedron geometry provided by the O atoms of three bidentate nitrate anions and by one ligand that utilizes two hydroxyl and two methoxy oxygen atoms, while the protonated nitrogen atoms remain uncoordinated. The title compound is isostructural with the corresponding Nd, Eu and Tb complexes (Gao et al., 2008). The Dy—O bond distances (Table 1) range from 2.2718 (18) to 2.6794 (19) Å, the shorter bonds involving the O1 and O3 deprotonated phenol oxygen atoms. The crystal structure is stabilized by intra- and intermolecular N—H···O and C—H···O hydrogen bonds (Table 2).

Related literature top

For the synthesis and crystal structure of the isostructural Nd, Eu and Tb complexes, see: Gao et al. (2008).

Experimental top

The title complex was obtained by the treatment of dysprosium (III) nitrate hexahydrate (0.114 g, 0.25 mmol) with N,N'-ethylene-bis(3-methoxysalicylideneimine) (0.083 g, 0.25 mmol) in acetonitrile/methanol (10 ml/10 ml). The mixture was stirred for 3 h. The reaction mixture was then filtered and diethyl ether was allowed to diffuse slowly into the solution of the filtrate. Single crystals were obtained after several days. Analysis calculated for for C18H20Dy1N5O13: C 31.94, H 2.96, N 10.37%; found: C 32.08, H 3.00, N 10.48%.

Refinement top

H atoms bound to C atoms were placed in calculated positions and treated as riding on their parent atoms, with C—H = 0.93 Å (aromatic), C—H = 0.97Å (methylene), and with Uiso(H) = 1.2Ueq(C) or C—H = 0.96 Å (methly) and with Uiso(H) = 1.5Uiso(C). The N-bound H atoms were initially located in a difference Fourier map and refined with N—H = 0.85 Å. The N3, N4, O5, O7, O8 and O10 atoms were restrained to be nearly isotropic by the ISOR (tolerance 0.01) instruction of SHELXL-97 (Sheldrick, 2008)

Computing details top

Data collection: RAPID-AUTO (Rigaku, 1998); cell refinement: RAPID-AUTO (Rigaku, 1998); data reduction: CrystalStructure (Rigaku/MSC, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound, showing 30% probability displacement ellipsoids.
[N,N'-Bis(3-methoxy-2-oxidobenzylidene)ethylenediammonium- κ4O,O',O'',O''']tris(nitrato- κ2O,O')dysprosium(III) top
Crystal data top
[Dy(NO3)3(C18H20N2O4)]F(000) = 1332
Mr = 676.89Dx = 1.893 Mg m−3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 20034 reflections
a = 14.126 (5) Åθ = 6.7–55.0°
b = 11.860 (4) ŵ = 3.22 mm−1
c = 14.628 (4) ÅT = 291 K
β = 104.302 (12)°Block, brown
V = 2374.7 (13) Å30.29 × 0.28 × 0.24 mm
Z = 4
Data collection top
Rigaku R-AXIS RAPID
diffractometer		5430 independent reflections
Radiation source: fine-focus sealed tube4850 reflections with I > 2σ(I)
graphiteRint = 0.021
ω scansθmax = 27.5°, θmin = 3.4°
Absorption correction: multi-scan
(ABSCOR; Higashi, 1995)		h = −18→18
Tmin = 0.454, Tmax = 0.513k = −15→15
22587 measured reflectionsl = −18→18
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.020Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.045H atoms treated by a mixture of independent and constrained refinement
S = 1.10 w = 1/[σ2(Fo2) + (0.0164P)2 + 1.5062P]
where P = (Fo2 + 2Fc2)/3
5430 reflections(Δ/σ)max = 0.002
344 parametersΔρmax = 0.41 e Å−3
14 restraintsΔρmin = −0.54 e Å−3
Crystal data top
[Dy(NO3)3(C18H20N2O4)]V = 2374.7 (13) Å3
Mr = 676.89Z = 4
Monoclinic, P21/nMo Kα radiation
a = 14.126 (5) ŵ = 3.22 mm−1
b = 11.860 (4) ÅT = 291 K
c = 14.628 (4) Å0.29 × 0.28 × 0.24 mm
β = 104.302 (12)°
Data collection top
Rigaku R-AXIS RAPID
diffractometer		5430 independent reflections
Absorption correction: multi-scan
(ABSCOR; Higashi, 1995)		4850 reflections with I > 2σ(I)
Tmin = 0.454, Tmax = 0.513Rint = 0.021
22587 measured reflectionsθmax = 27.5°
Refinement top
R[F2 > 2σ(F2)] = 0.020H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.045Δρmax = 0.41 e Å−3
S = 1.10Δρmin = −0.54 e Å−3
5430 reflectionsAbsolute structure: ?
344 parametersFlack parameter: ?
14 restraintsRogers parameter: ?
Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
C10.29349 (17)0.18407 (19)0.20773 (16)0.0338 (5)
C20.28896 (19)0.1407 (2)0.11666 (17)0.0384 (5)
C30.2045 (2)0.0947 (2)0.06330 (19)0.0488 (7)
H30.20180.06830.00280.059*
C40.1218 (2)0.0874 (3)0.1004 (2)0.0542 (7)
H40.06460.05530.06430.065*
C50.12392 (19)0.1264 (2)0.1879 (2)0.0469 (6)
H50.06870.12010.21140.056*
C60.20936 (17)0.1765 (2)0.24346 (17)0.0362 (5)
C70.21298 (18)0.2144 (2)0.33610 (18)0.0385 (5)
H70.15850.20310.36000.046*
C80.3034 (2)0.2907 (2)0.48885 (18)0.0452 (6)
H8A0.24050.30020.50340.054*
H8B0.33910.36100.50280.054*
C90.3598 (2)0.1974 (2)0.54950 (18)0.0463 (6)
H9A0.37350.21920.61540.056*
H9B0.32050.12940.54150.056*
C100.5321 (2)0.1420 (2)0.57900 (17)0.0407 (6)
H100.53460.13280.64270.049*
C110.61751 (19)0.1191 (2)0.54777 (16)0.0377 (5)
C120.7035 (2)0.0798 (2)0.61169 (19)0.0469 (6)
H120.70330.06640.67430.056*
C130.7860 (2)0.0617 (2)0.5824 (2)0.0495 (7)
H130.84240.03750.62530.059*
C140.78698 (19)0.0792 (2)0.4876 (2)0.0452 (6)
H140.84400.06660.46820.054*
C150.70435 (19)0.1145 (2)0.42392 (17)0.0393 (5)
C160.61780 (18)0.1388 (2)0.45268 (16)0.0364 (5)
C170.7761 (3)0.1084 (4)0.2912 (3)0.0785 (11)
H17A0.82810.15920.31940.118*
H17B0.75840.11920.22410.118*
H17C0.79750.03210.30520.118*
C180.3786 (3)0.1133 (3)−0.00104 (19)0.0633 (9)
H18A0.36460.0340−0.00630.095*
H18B0.44230.1268−0.01090.095*
H18C0.33070.1534−0.04770.095*
Dy10.527482 (8)0.207652 (10)0.234090 (7)0.03310 (4)
H10.3368 (15)0.274 (2)0.3653 (19)0.049 (8)*
H20.452 (2)0.180 (2)0.4658 (9)0.050 (8)*
N10.28886 (15)0.26398 (19)0.38914 (15)0.0389 (5)
N20.45122 (17)0.1750 (2)0.52358 (14)0.0418 (5)
N30.5162 (2)−0.0351 (2)0.19797 (19)0.0643 (7)
N40.57521 (19)0.3122 (2)0.07175 (16)0.0477 (6)
N50.58626 (16)0.42878 (19)0.31539 (14)0.0412 (5)
O10.37477 (11)0.22948 (15)0.25585 (11)0.0371 (4)
O20.37584 (14)0.15168 (17)0.09135 (12)0.0464 (4)
O30.54183 (13)0.17845 (18)0.39131 (12)0.0480 (5)
O40.69309 (13)0.13026 (18)0.32846 (12)0.0483 (5)
O50.47264 (19)0.01237 (19)0.25317 (15)0.0697 (7)
O60.5109 (3)−0.1369 (2)0.1860 (2)0.1026 (10)
O70.56475 (17)0.02863 (18)0.15829 (15)0.0586 (5)
O80.62384 (19)0.2322 (2)0.11513 (17)0.0684 (7)
O90.5925 (2)0.3528 (2)0.00129 (17)0.0767 (7)
O100.50641 (15)0.3465 (2)0.10457 (15)0.0591 (5)
O110.49884 (14)0.39756 (17)0.29500 (16)0.0531 (5)
O120.61122 (16)0.52094 (17)0.35117 (14)0.0565 (5)
O130.64723 (13)0.35980 (17)0.29731 (15)0.0532 (5)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0348 (11)0.0314 (11)0.0346 (11)−0.0017 (9)0.0074 (9)0.0008 (9)
C20.0440 (13)0.0367 (13)0.0341 (11)−0.0039 (11)0.0091 (10)−0.0033 (10)
C30.0588 (17)0.0428 (14)0.0395 (13)−0.0086 (13)0.0020 (12)−0.0061 (11)
C40.0464 (15)0.0521 (16)0.0559 (16)−0.0168 (13)−0.0027 (13)−0.0037 (14)
C50.0362 (13)0.0471 (15)0.0557 (16)−0.0084 (12)0.0084 (12)0.0055 (13)
C60.0327 (11)0.0353 (12)0.0406 (12)−0.0043 (9)0.0091 (10)0.0028 (10)
C70.0349 (12)0.0386 (12)0.0460 (13)−0.0003 (10)0.0176 (10)0.0031 (11)
C80.0478 (14)0.0504 (15)0.0433 (13)−0.0048 (12)0.0225 (11)−0.0145 (12)
C90.0492 (14)0.0586 (17)0.0376 (12)−0.0106 (13)0.0231 (11)−0.0047 (12)
C100.0553 (15)0.0370 (13)0.0310 (11)−0.0091 (11)0.0128 (11)0.0011 (10)
C110.0473 (13)0.0319 (12)0.0323 (11)−0.0022 (10)0.0069 (10)0.0017 (10)
C120.0585 (17)0.0394 (14)0.0372 (13)−0.0020 (12)0.0014 (12)0.0035 (11)
C130.0491 (15)0.0404 (14)0.0510 (15)0.0051 (12)−0.0028 (12)0.0060 (12)
C140.0400 (13)0.0362 (13)0.0584 (16)0.0049 (11)0.0103 (12)0.0013 (12)
C150.0442 (13)0.0342 (12)0.0397 (12)0.0047 (11)0.0109 (11)0.0004 (10)
C160.0394 (12)0.0353 (12)0.0339 (11)0.0025 (10)0.0077 (10)0.0001 (10)
C170.060 (2)0.118 (3)0.069 (2)0.037 (2)0.0370 (17)0.013 (2)
C180.077 (2)0.082 (2)0.0358 (14)0.0003 (18)0.0229 (14)−0.0122 (15)
Dy10.03516 (6)0.03925 (7)0.02910 (6)0.00211 (5)0.01592 (4)−0.00037 (5)
N10.0366 (11)0.0468 (12)0.0382 (11)−0.0022 (9)0.0185 (9)−0.0047 (9)
N20.0471 (12)0.0519 (13)0.0294 (10)−0.0044 (10)0.0153 (9)−0.0019 (9)
N30.102 (2)0.0461 (14)0.0522 (14)0.0068 (15)0.0325 (15)−0.0015 (12)
N40.0601 (14)0.0470 (13)0.0439 (12)−0.0118 (11)0.0278 (11)−0.0022 (10)
N50.0432 (12)0.0462 (12)0.0361 (10)−0.0041 (10)0.0136 (9)−0.0033 (9)
O10.0298 (8)0.0492 (10)0.0333 (8)−0.0072 (7)0.0097 (7)−0.0093 (7)
O20.0515 (11)0.0581 (12)0.0320 (8)−0.0042 (9)0.0151 (8)−0.0092 (8)
O30.0409 (9)0.0740 (13)0.0309 (8)0.0142 (9)0.0126 (7)0.0078 (9)
O40.0438 (10)0.0643 (12)0.0418 (9)0.0167 (9)0.0199 (8)0.0047 (9)
O50.117 (2)0.0492 (12)0.0607 (13)0.0073 (12)0.0550 (14)0.0087 (10)
O60.162 (3)0.0501 (14)0.113 (2)−0.0049 (16)0.066 (2)−0.0142 (15)
O70.0759 (14)0.0541 (12)0.0556 (12)0.0009 (11)0.0345 (11)−0.0100 (10)
O80.0819 (16)0.0684 (14)0.0724 (15)0.0239 (13)0.0523 (13)0.0187 (12)
O90.1095 (19)0.0714 (15)0.0662 (14)−0.0062 (14)0.0538 (14)0.0168 (12)
O100.0497 (11)0.0750 (14)0.0583 (12)0.0095 (11)0.0243 (10)0.0189 (11)
O110.0401 (10)0.0494 (11)0.0741 (13)−0.0049 (9)0.0221 (9)−0.0172 (10)
O120.0668 (13)0.0481 (11)0.0540 (11)−0.0170 (10)0.0137 (10)−0.0135 (9)
O130.0377 (9)0.0549 (12)0.0677 (13)0.0011 (9)0.0142 (9)−0.0042 (10)
Geometric parameters (Å, °) top
C1—O11.306 (3)C15—O41.379 (3)
C1—C61.414 (3)C15—C161.417 (3)
C1—C21.415 (3)C16—O31.305 (3)
C2—C31.367 (4)C17—O41.434 (3)
C2—O21.373 (3)C17—H17A0.9600
C3—C41.409 (4)C17—H17B0.9600
C3—H30.9300C17—H17C0.9600
C4—C51.353 (4)C18—O21.436 (3)
C4—H40.9300C18—H18A0.9600
C5—C61.410 (3)C18—H18B0.9600
C5—H50.9300C18—H18C0.9600
C6—C71.416 (4)Dy1—O12.2718 (18)
C7—N11.299 (3)Dy1—O32.2847 (18)
C7—H70.9300Dy1—O102.472 (2)
C8—N11.457 (3)Dy1—O82.477 (2)
C8—C91.515 (4)Dy1—O52.480 (2)
C8—H8A0.9700Dy1—O132.490 (2)
C8—H8B0.9700Dy1—O112.492 (2)
C9—N21.458 (3)Dy1—O72.510 (2)
C9—H9A0.9700Dy1—O42.5740 (19)
C9—H9B0.9700Dy1—O22.6794 (19)
C10—N21.288 (3)N1—H10.843 (10)
C10—C111.418 (4)N2—H20.848 (10)
C10—H100.9300N3—O61.219 (4)
C11—C161.411 (3)N3—O71.255 (3)
C11—C121.416 (4)N3—O51.263 (3)
C12—C131.355 (4)N4—O91.216 (3)
C12—H120.9300N4—O81.248 (3)
C13—C141.404 (4)N4—O101.254 (3)
C13—H130.9300N5—O121.225 (3)
C14—C151.367 (4)N5—O111.253 (3)
C14—H140.9300N5—O131.262 (3)
O1—C1—C6122.3 (2)O3—Dy1—O8142.89 (8)
O1—C1—C2119.1 (2)O10—Dy1—O850.68 (7)
C6—C1—C2118.6 (2)O1—Dy1—O575.92 (7)
C3—C2—O2126.5 (2)O3—Dy1—O572.40 (7)
C3—C2—C1120.9 (2)O10—Dy1—O5136.61 (8)
O2—C2—C1112.6 (2)O8—Dy1—O5115.47 (7)
C2—C3—C4119.6 (3)O1—Dy1—O13116.54 (6)
C2—C3—H3120.2O3—Dy1—O1381.53 (7)
C4—C3—H3120.2O10—Dy1—O1375.16 (8)
C5—C4—C3121.1 (2)O8—Dy1—O1374.63 (8)
C5—C4—H4119.4O5—Dy1—O13146.88 (8)
C3—C4—H4119.4O1—Dy1—O1166.62 (6)
C4—C5—C6120.4 (3)O3—Dy1—O1176.05 (7)
C4—C5—H5119.8O10—Dy1—O1170.88 (8)
C6—C5—H5119.8O8—Dy1—O11108.11 (8)
C5—C6—C1119.4 (2)O5—Dy1—O11136.15 (7)
C5—C6—C7120.6 (2)O13—Dy1—O1150.77 (6)
C1—C6—C7119.9 (2)O1—Dy1—O7117.92 (7)
N1—C7—C6123.0 (2)O3—Dy1—O7109.89 (7)
N1—C7—H7118.5O10—Dy1—O7102.92 (8)
C6—C7—H7118.5O8—Dy1—O765.02 (8)
N1—C8—C9110.6 (2)O5—Dy1—O750.60 (7)
N1—C8—H8A109.5O13—Dy1—O7125.42 (7)
C9—C8—H8A109.5O11—Dy1—O7173.06 (7)
N1—C8—H8B109.5O1—Dy1—O4137.24 (6)
C9—C8—H8B109.5O3—Dy1—O464.10 (6)
H8A—C8—H8B108.1O10—Dy1—O4124.75 (6)
N2—C9—C8110.6 (2)O8—Dy1—O480.47 (7)
N2—C9—H9A109.5O5—Dy1—O482.78 (8)
C8—C9—H9A109.5O13—Dy1—O467.37 (7)
N2—C9—H9B109.5O11—Dy1—O4109.69 (7)
C8—C9—H9B109.5O7—Dy1—O470.93 (7)
H9A—C9—H9B108.1O1—Dy1—O262.19 (6)
N2—C10—C11123.3 (2)O3—Dy1—O2127.01 (6)
N2—C10—H10118.4O10—Dy1—O269.28 (7)
C11—C10—H10118.4O8—Dy1—O287.36 (8)
C16—C11—C12119.6 (2)O5—Dy1—O269.17 (7)
C16—C11—C10119.7 (2)O13—Dy1—O2143.90 (7)
C12—C11—C10120.6 (2)O11—Dy1—O2109.48 (6)
C13—C12—C11120.5 (3)O7—Dy1—O270.17 (7)
C13—C12—H12119.7O4—Dy1—O2140.83 (6)
C11—C12—H12119.7C7—N1—C8126.0 (2)
C12—C13—C14120.5 (2)C7—N1—H1117 (2)
C12—C13—H13119.7C8—N1—H1117 (2)
C14—C13—H13119.7C10—N2—C9126.7 (2)
C15—C14—C13120.2 (3)C10—N2—H2115 (2)
C15—C14—H14119.9C9—N2—H2118 (2)
C13—C14—H14119.9O6—N3—O7123.5 (3)
C14—C15—O4126.7 (2)O6—N3—O5120.7 (3)
C14—C15—C16120.9 (2)O7—N3—O5115.8 (2)
O4—C15—C16112.4 (2)O9—N4—O8122.1 (3)
O3—C16—C11122.4 (2)O9—N4—O10122.2 (3)
O3—C16—C15119.5 (2)O8—N4—O10115.7 (2)
C11—C16—C15118.1 (2)O12—N5—O11121.9 (2)
O4—C17—H17A109.5O12—N5—O13121.9 (2)
O4—C17—H17B109.5O11—N5—O13116.2 (2)
H17A—C17—H17B109.5C1—O1—Dy1128.06 (15)
O4—C17—H17C109.5C2—O2—C18117.2 (2)
H17A—C17—H17C109.5C2—O2—Dy1114.15 (13)
H17B—C17—H17C109.5C18—O2—Dy1127.57 (18)
O2—C18—H18A109.5C16—O3—Dy1126.91 (15)
O2—C18—H18B109.5C15—O4—C17117.4 (2)
H18A—C18—H18B109.5C15—O4—Dy1116.98 (14)
O2—C18—H18C109.5C17—O4—Dy1125.54 (18)
H18A—C18—H18C109.5N3—O5—Dy197.43 (18)
H18B—C18—H18C109.5N3—O7—Dy196.15 (16)
O1—Dy1—O374.18 (6)N4—O8—Dy196.75 (16)
O1—Dy1—O1095.32 (7)N4—O10—Dy196.83 (16)
O3—Dy1—O10146.76 (8)N5—O11—Dy196.59 (15)
O1—Dy1—O8142.24 (7)N5—O13—Dy196.40 (14)
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
N2—H2···O30.85 (2)1.87 (3)2.570 (3)139 (1)
C8—H8B···O12i0.972.513.245 (3)133
C10—H10···O5ii0.932.323.076 (3)138
C3—H3···O12iii0.932.513.351 (3)151
C7—H7···O9iv0.932.563.376 (3)147
Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) −x+1, −y, −z+1; (iii) x−1/2, −y+1/2, z−1/2; (iv) x−1/2, −y+1/2, z+1/2.
Table 1
Selected geometric parameters (Å) top
Dy1—O12.2718 (18)Dy1—O132.490 (2)
Dy1—O32.2847 (18)Dy1—O112.492 (2)
Dy1—O102.472 (2)Dy1—O72.510 (2)
Dy1—O82.477 (2)Dy1—O42.5740 (19)
Dy1—O52.480 (2)Dy1—O22.6794 (19)
Table 2
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
N2—H2···O30.85 (2)1.87 (3)2.570 (3)139 (1)
C8—H8B···O12i0.972.513.245 (3)133
C10—H10···O5ii0.932.323.076 (3)138
C3—H3···O12iii0.932.513.351 (3)151
C7—H7···O9iv0.932.563.376 (3)147
Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) −x+1, −y, −z+1; (iii) x−1/2, −y+1/2, z−1/2; (iv) x−1/2, −y+1/2, z+1/2.
Acknowledgements top

The authors gratefully acknowledge financial support from the National Natural Science Foundation of China (Nos. 20572018, 20672032 and 20872030), the Key Laboratory of Heilongjiang Province and the Education Department of Heilongjiang Province (Nos. ZJG0504, JC200605, 1152GZD02, GZ08A401, 2006FRFLXG031 and 2007RFQXG096) and Heilongjiang University.

references
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