catena-Poly[[[2,4-dichloro-6-(pyridin-2-ylmethyl­iminomethyl)phenolato]copper(II)]-μ-thio­cyanato]

The title complex, [Cu(C₁₃H₉Cl₂N₂O)(NCS)]_n, is a novel thio­cyanate-bridged polynuclear copper(II) compound. The Cu^II atom is five-coordinated in a square-pyramidal configuration, with one O and two N atoms of one Schiff base ligand and one terminal N atom of a bridging thio­cyanate ligand defining the basal plane, and one terminal S atom of another bridging thio­cyanate ligand occupying the axial position. The [2,4-dichloro-6-(pyridin-2-ylmethyl­imino­methyl)­phenolato]­copper(II) moieties are linked by the bridging thio­cyanate ligands, forming polymeric chains running along the a axis.

S1. Comment

The magnetic properties of extended coordination compounds featuring exchange-coupled magnetic centres have become a fascinating subject in recent years (Dalai et al., 2002; Bhaduri et al., 2003). The prime strategy for designing these molecular materials is to use a suitable bridging ligand that determines the nature of the magnetic interactions (Koner et al., 2003). Due to the versatile coordination modes of the ambidentate thiocyanate ligand and the wide range of magnetic coupling mediated by thiocyanate bridges, this pseudohalide ligand has become one of the most extensively studied building blocks in the field (Sailaja et al., 2003; Dey et al., 2004). Thiocyanate complexes of various dimensionalities have been obtained (Zurowska et al., 2002; Zhang et al., 2003; You, 2005a). These also include some examples of the so-called alternating one-dimensional magnetic systems, which have two or more different structural bridges and which are of considerable interest in terms of their magnetic behaviour (Vicente et al., 1992; Escuer et al., 1994; Ribas et al., 1995; Vicente & Escuer, 1995). A major obstacle to a more comprehensive study of such thiocyanate-based polymeric coordination compounds is the lack of rational synthetic procedures, since with the present state of knowledge it is not possible to determine which coordination mode will be adopted by the thiocyanate ligand and whether the sought-after alternating chain structure will finally be formed (Tercero et al., 2002; Ribas et al., 1999; Liu et al., 2003).

Our work is aimed at obtaining multidimensional polymetallic complexes. Based on the above considerations, we designed and synthesized a rigid tridentate ligand, 2,4-dichloro-6-[(pyridin-2-ylmethylimino)methyl]phenol (DPMP). The reason we do not use a flexible ligand is that the rigid DPMP ligand could adopt an almost fixed coordination mode through its three donor atoms (You, Chen et al., 2004; You & Zhu, 2004a,b). The second ligand, viz. thiocyanate, is a well known bridging group. It readily bridges different metal ions through its terminal donor atoms, forming polynuclear complexes (Kuang et al., 2001). Copper(II) is a good candidate for square-pyramidal coordination geometry. We report here the formation of novel one-dimensional infinite chains in the structure of the title compound, (I), which was formed by the reaction of the DPMP ligand, thiocyanate and copper(II) acetate.

Complex (I) is a polynuclear copper(II) compound (Fig. 1). The smallest repeat unit contains two DPMP–Cu^II cations and two bridging thiocyanate anions. The Cu^II atom is in a square-pyramidal coordination environment and is five-coordinated by one O atom and two N atoms of one Schiff base ligand and one N atom of a thiocyanate anion defining the basal plane, and by another different but symmetry-related terminal S atom occupying the axial position. The Schiff base acts as a tridentate ligand and ligates to the metal via the three O and N donor atoms. The thiocyanate anion acts as a bridging ligand and ligates to two different but symmetry-related copper(II) atoms via the terminal N and S atoms. The significant distortion of the square pyramid is revealed by the bond angles between the apical and basal donor atoms (Table 1). The bond angle N1—Cu1—N2 deviates from 90° by 8.08 (13)°, which is due to the strain created by the five-membered chelate ring Cu1/N1/C8/C9/N2. The apical bond [Cu1—S1ⁱ; symmetry code: (i) x − 1/2, 3/2 − y, z] is much longer than the basal bonds, indicating that the Cu—S bond is not very strong. The Cu—O and Cu—N bond lengths are comparable with the corresponding values observed in other Schiff base copper(II) complexes (You & Zhu, 2004c; You, Xiong & Zhu, 2004; Zhang et al., 2001; Elmali et al., 2000). The bridging NCS group is nearly linear and shows bent coordination modes with the metal atoms [N3—C14—S1, Cu1—N3—C14 and Cu1—S1ⁱ—C14ⁱ angles are 177.8 (3), 179.6 (3) and 92.19 (14)°, respectively].

The basal least-square planes defined by the four donor atoms of the two adjacent Cu^II centres are almost parallel and form a dihedral angle of 10.9 (3)°. The deviation of atom Cu1 from the best-fit square plane is 0.164 (3) Å. The CuN₃O basal plane forms dihedral angles of 7.6 (3) and 16.2 (3)° with the phenyl ring and the pyridine ring, respectively, which are inclined at 17.1 (3)° to each other. The two adjacent {2,4-dichloro-6-[(pyridin-2-ylmethylimino)methyl]phenolato}copper(II) moieties are almost vertical to each other, which can decrease the steric effects between the molecules.

In (I), the C7═N1 bond length [1.274 (5) Å] conforms to the normal value for a double bond, while the C8—N1 bond length [1.456 (4) Å] conforms to the normal value for a single bond (You, 2005b).

In the title crystal structure, the {2,4-dichloro-6-[(pyridin-2-ylmethylimino)methyl]phenolato}copper(II) moieties are linked by the bridging thiocyanate ligands, forming polymeric chains running along the a axis (Fig. 2).

S2. Experimental

3,5-Dichlorosalicylaldehyde (0.1 mmol, 19.1 mg) and pyridin-2-ylmethylamine (0.1 mmol, 10.8 mg) were dissolved in MeOH (10 ml). The mixture was stirred at room temperature for 10 min to give a yellow solution. To this solution was added with stirring a MeOH solution (10 ml) of Cu(CH₃COO)₂·H₂O (0.1 mmol, 19.9 mg). The mixture was stirred for another 10 min at room temperature. After keeping the filtrate in air for 12 d, blue block-shaped crystals of (I) were formed.

S3. Refinement

All H atoms were placed in geometrically idealized positions and allowed to ride on their parent atoms, with C—H distances in the range 0.93–0.97 Å and with U_iso(H) = 1.2U_eq(C).

Computing details

Data collection: SMART (Bruker, 1998); cell refinement: SMART; data reduction: SAINT (Bruker, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997a); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997a); molecular graphics: SHELXTL (Sheldrick, 1997b); software used to prepare material for publication: SHELXTL.

Figures

	Fig. 1. The structure of (I), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. Atoms labelled with the suffix i or unlabelled are at the symmetry position (x − 1/2, 3/2 − y, z).
	Fig. 2. The crystal packing of (I), viewed along the b axis.

catena-Poly[[{2,4-dichloro-6-[(pyridin-2-ylmethylimino)methyl]phenolato}- copper(II)]-µ-thiocyanato]

Crystal data

[Cu(C13H9Cl2N2O)(NCS)]	F(000) = 804
Mr = 401.74	Dx = 1.752 Mg m^−3
Orthorhombic, Pna21	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2c -2n	Cell parameters from 4105 reflections
a = 10.499 (2) Å	θ = 2.4–26.7°
b = 12.208 (2) Å	µ = 1.92 mm^−1
c = 11.886 (2) Å	T = 298 K
V = 1523.5 (5) Å^3	Block, blue
Z = 4	0.16 × 0.15 × 0.12 mm

Data collection

Bruker SMART CCD area-detector diffractometer	3431 independent reflections
Radiation source: fine-focus sealed tube	3175 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.036
ω scans	θmax = 27.5°, θmin = 2.4°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −13→13
Tmin = 0.748, Tmax = 0.802	k = −15→15
12153 measured reflections	l = −15→15

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.043	H-atom parameters constrained
wR(F^2) = 0.095	w = 1/[σ^2(Fo^2) + (0.0484P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.10	(Δ/σ)max < 0.001
3431 reflections	Δρmax = 0.66 e Å^−3
199 parameters	Δρmin = −0.37 e Å^−3
1 restraint	Absolute structure: Flack (1983), with 1602 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.023 (16)

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
Cu1	0.68884 (4)	0.68029 (3)	1.00370 (4)	0.03090 (13)
Cl1	0.67218 (13)	1.05098 (10)	0.87564 (14)	0.0632 (4)
Cl2	0.21788 (12)	0.98168 (11)	0.68315 (12)	0.0607 (3)
S1	1.04785 (10)	0.81010 (9)	1.20265 (9)	0.0400 (3)
O1	0.6594 (3)	0.8214 (2)	0.9348 (3)	0.0398 (7)
N1	0.5457 (3)	0.6155 (2)	0.9228 (3)	0.0275 (6)
N2	0.7393 (3)	0.5206 (2)	1.0203 (3)	0.0317 (7)
N3	0.8350 (3)	0.7346 (3)	1.0873 (3)	0.0363 (8)
C1	0.4640 (4)	0.7809 (3)	0.8374 (3)	0.0298 (8)
C2	0.5631 (4)	0.8505 (3)	0.8759 (3)	0.0317 (8)
C3	0.5500 (4)	0.9622 (3)	0.8412 (3)	0.0372 (9)
C4	0.4472 (4)	1.0015 (3)	0.7833 (4)	0.0411 (10)
H4	0.4418	1.0753	0.7648	0.049*
C5	0.3509 (4)	0.9296 (3)	0.7527 (3)	0.0389 (9)
C6	0.3594 (4)	0.8219 (3)	0.7771 (4)	0.0380 (9)
H6	0.2953	0.7744	0.7538	0.046*
C7	0.4639 (4)	0.6659 (3)	0.8629 (3)	0.0327 (8)
H7	0.3979	0.6244	0.8329	0.039*
C8	0.5299 (4)	0.4984 (3)	0.9418 (4)	0.0366 (9)
H8A	0.5019	0.4632	0.8730	0.044*
H8B	0.4656	0.4862	0.9991	0.044*
C9	0.6533 (4)	0.4503 (3)	0.9788 (3)	0.0341 (9)
C10	0.6777 (5)	0.3389 (3)	0.9741 (4)	0.0505 (13)
H10	0.6180	0.2909	0.9439	0.061*
C11	0.7926 (5)	0.3004 (3)	1.0152 (6)	0.0554 (13)
H11	0.8104	0.2258	1.0142	0.066*
C12	0.8791 (5)	0.3722 (4)	1.0571 (4)	0.0505 (11)
H12	0.9568	0.3475	1.0849	0.061*
C13	0.8503 (4)	0.4820 (4)	1.0579 (4)	0.0414 (9)
H13	0.9103	0.5311	1.0856	0.050*
C14	0.9218 (4)	0.7661 (3)	1.1369 (3)	0.0284 (8)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu1	0.0296 (2)	0.0268 (2)	0.0362 (2)	−0.00162 (17)	−0.0056 (2)	0.0005 (2)
Cl1	0.0627 (8)	0.0332 (5)	0.0938 (10)	−0.0084 (5)	−0.0167 (7)	0.0070 (6)
Cl2	0.0580 (7)	0.0647 (8)	0.0595 (8)	0.0214 (6)	−0.0143 (6)	0.0148 (6)
S1	0.0315 (5)	0.0505 (6)	0.0379 (6)	−0.0056 (4)	−0.0028 (4)	−0.0088 (5)
O1	0.0394 (16)	0.0271 (14)	0.0530 (19)	−0.0017 (12)	−0.0104 (14)	0.0051 (12)
N1	0.0274 (16)	0.0256 (15)	0.0295 (15)	−0.0015 (12)	−0.0020 (12)	−0.0017 (13)
N2	0.0381 (17)	0.0289 (15)	0.0280 (17)	0.0022 (13)	0.0007 (13)	0.0011 (14)
N3	0.0311 (18)	0.0360 (18)	0.042 (2)	−0.0042 (15)	−0.0019 (15)	0.0003 (16)
C1	0.035 (2)	0.0285 (18)	0.0260 (19)	0.0030 (16)	0.0012 (15)	0.0029 (15)
C2	0.037 (2)	0.0293 (18)	0.0293 (19)	0.0042 (16)	0.0042 (16)	−0.0009 (16)
C3	0.046 (2)	0.0305 (19)	0.035 (2)	−0.0015 (17)	0.0011 (19)	0.0024 (17)
C4	0.051 (3)	0.035 (2)	0.037 (2)	0.0126 (19)	0.0063 (19)	0.0084 (18)
C5	0.042 (2)	0.044 (2)	0.031 (2)	0.0139 (19)	0.0005 (17)	0.0078 (18)
C6	0.039 (2)	0.040 (2)	0.034 (2)	0.0008 (18)	0.0003 (17)	0.0024 (18)
C7	0.035 (2)	0.0311 (19)	0.032 (2)	−0.0061 (16)	−0.0038 (16)	−0.0035 (16)
C8	0.040 (2)	0.0237 (18)	0.046 (2)	−0.0073 (16)	−0.0013 (18)	−0.0006 (17)
C9	0.042 (2)	0.0273 (18)	0.033 (2)	−0.0024 (16)	0.0011 (15)	0.0015 (15)
C10	0.061 (3)	0.029 (2)	0.062 (4)	0.0028 (19)	−0.013 (2)	−0.0018 (19)
C11	0.070 (3)	0.033 (2)	0.063 (3)	0.014 (2)	−0.011 (3)	0.001 (3)
C12	0.056 (3)	0.042 (2)	0.053 (3)	0.015 (2)	−0.013 (2)	0.003 (2)
C13	0.044 (2)	0.036 (2)	0.043 (2)	0.0028 (19)	−0.008 (2)	0.0003 (19)
C14	0.030 (2)	0.0238 (16)	0.0310 (19)	0.0029 (15)	0.0060 (16)	0.0020 (15)

Geometric parameters (Å, º)

Cu1—O1	1.932 (3)	C2—C3	1.431 (5)
Cu1—N3	1.944 (3)	C3—C4	1.367 (6)
Cu1—N1	1.952 (3)	C4—C5	1.387 (6)
Cu1—N2	2.030 (3)	C4—H4	0.9300
Cu1—S1^i	2.7923 (12)	C5—C6	1.350 (5)
Cl1—C3	1.728 (4)	C6—H6	0.9300
Cl2—C5	1.743 (4)	C7—H7	0.9300
S1—C14	1.628 (4)	C8—C9	1.488 (6)
S1—Cu1^ii	2.7923 (12)	C8—H8A	0.9700
O1—C2	1.280 (5)	C8—H8B	0.9700
N1—C7	1.274 (5)	C9—C10	1.385 (5)
N1—C8	1.456 (4)	C10—C11	1.384 (6)
N2—C13	1.334 (5)	C10—H10	0.9300
N2—C9	1.339 (5)	C11—C12	1.356 (7)
N3—C14	1.152 (5)	C11—H11	0.9300
C1—C6	1.404 (6)	C12—C13	1.374 (6)
C1—C2	1.419 (6)	C12—H12	0.9300
C1—C7	1.435 (5)	C13—H13	0.9300
O1—Cu1—N3	92.23 (14)	C6—C5—C4	120.8 (4)
O1—Cu1—N1	91.68 (12)	C6—C5—Cl2	120.7 (4)
N3—Cu1—N1	176.00 (14)	C4—C5—Cl2	118.6 (3)
O1—Cu1—N2	159.93 (13)	C5—C6—C1	120.6 (4)
N3—Cu1—N2	94.12 (14)	C5—C6—H6	119.7
N1—Cu1—N2	81.92 (13)	C1—C6—H6	119.7
O1—Cu1—S1^i	103.69 (10)	N1—C7—C1	126.2 (3)
N3—Cu1—S1^i	88.35 (10)	N1—C7—H7	116.9
N1—Cu1—S1^i	91.48 (9)	C1—C7—H7	116.9
N2—Cu1—S1^i	95.51 (9)	N1—C8—C9	109.5 (3)
C14—S1—Cu1^ii	92.19 (14)	N1—C8—H8A	109.8
C2—O1—Cu1	127.3 (3)	C9—C8—H8A	109.8
C7—N1—C8	119.0 (3)	N1—C8—H8B	109.8
C7—N1—Cu1	126.7 (3)	C9—C8—H8B	109.8
C8—N1—Cu1	114.1 (2)	H8A—C8—H8B	108.2
C13—N2—C9	119.1 (4)	N2—C9—C10	121.2 (4)
C13—N2—Cu1	126.8 (3)	N2—C9—C8	116.3 (3)
C9—N2—Cu1	113.8 (3)	C10—C9—C8	122.4 (4)
C14—N3—Cu1	179.6 (3)	C11—C10—C9	118.7 (4)
C6—C1—C2	121.6 (4)	C11—C10—H10	120.6
C6—C1—C7	117.1 (4)	C9—C10—H10	120.6
C2—C1—C7	121.2 (3)	C12—C11—C10	119.6 (4)
O1—C2—C1	126.1 (3)	C12—C11—H11	120.2
O1—C2—C3	119.9 (4)	C10—C11—H11	120.2
C1—C2—C3	114.0 (4)	C11—C12—C13	119.0 (4)
C4—C3—C2	123.7 (4)	C11—C12—H12	120.5
C4—C3—Cl1	119.0 (3)	C13—C12—H12	120.5
C2—C3—Cl1	117.2 (3)	N2—C13—C12	122.3 (4)
C3—C4—C5	119.1 (4)	N2—C13—H13	118.9
C3—C4—H4	120.5	C12—C13—H13	118.9
C5—C4—H4	120.5	N3—C14—S1	177.8 (3)
N3—Cu1—O1—C2	−170.7 (4)	C2—C3—C4—C5	−2.0 (6)
N1—Cu1—O1—C2	10.1 (4)	Cl1—C3—C4—C5	178.1 (3)
N2—Cu1—O1—C2	80.9 (5)	C3—C4—C5—C6	−1.5 (6)
S1^i—Cu1—O1—C2	−81.8 (3)	C3—C4—C5—Cl2	177.9 (3)
O1—Cu1—N1—C7	−8.0 (3)	C4—C5—C6—C1	2.1 (6)
N2—Cu1—N1—C7	−168.9 (3)	Cl2—C5—C6—C1	−177.2 (3)
S1^i—Cu1—N1—C7	95.7 (3)	C2—C1—C6—C5	0.8 (6)
O1—Cu1—N1—C8	176.4 (3)	C7—C1—C6—C5	178.1 (4)
N2—Cu1—N1—C8	15.5 (3)	C8—N1—C7—C1	179.0 (4)
S1^i—Cu1—N1—C8	−79.8 (3)	Cu1—N1—C7—C1	3.6 (6)
O1—Cu1—N2—C13	97.0 (5)	C6—C1—C7—N1	−175.1 (4)
N3—Cu1—N2—C13	−11.2 (4)	C2—C1—C7—N1	2.3 (6)
N1—Cu1—N2—C13	169.4 (4)	C7—N1—C8—C9	161.1 (4)
S1^i—Cu1—N2—C13	−99.9 (3)	Cu1—N1—C8—C9	−22.9 (4)
O1—Cu1—N2—C9	−76.7 (5)	C13—N2—C9—C10	0.0 (6)
N3—Cu1—N2—C9	175.2 (3)	Cu1—N2—C9—C10	174.2 (3)
N1—Cu1—N2—C9	−4.3 (3)	C13—N2—C9—C8	178.1 (4)
S1^i—Cu1—N2—C9	86.4 (3)	Cu1—N2—C9—C8	−7.7 (4)
Cu1—O1—C2—C1	−7.9 (6)	N1—C8—C9—N2	19.8 (5)
Cu1—O1—C2—C3	173.2 (3)	N1—C8—C9—C10	−162.2 (4)
C6—C1—C2—O1	177.2 (4)	N2—C9—C10—C11	1.1 (7)
C7—C1—C2—O1	0.0 (6)	C8—C9—C10—C11	−176.9 (5)
C6—C1—C2—C3	−3.9 (5)	C9—C10—C11—C12	−1.1 (8)
C7—C1—C2—C3	178.9 (3)	C10—C11—C12—C13	0.1 (8)
O1—C2—C3—C4	−176.4 (4)	C9—N2—C13—C12	−1.0 (7)
C1—C2—C3—C4	4.6 (6)	Cu1—N2—C13—C12	−174.4 (3)
O1—C2—C3—Cl1	3.5 (5)	C11—C12—C13—N2	1.0 (8)
C1—C2—C3—Cl1	−175.5 (3)

Symmetry codes: (i) x−1/2, −y+3/2, z; (ii) x+1/2, −y+3/2, z.