A novel two-dimensional nickel(II) coordination polymer with 1,4-bis­(1,2,4-triazol-1-ylmeth­yl)benzene and azide ligands

The coordination geometry of the Ni^II atom in the title complex, poly[diazido­bis[μ-1,4-bis­(1,2,4-triazol-1-ylmethyl)­benzene-κ²N⁴:N^4′]nickel(II)], [Ni(N₃)₂(C₁₂H₁₂N₆)₂]_n, is a distorted octa­hedron, in which the Ni^II atom lies on an inversion centre and is coordinated by four N atoms from the triazole rings of two symmetry-related pairs of 1,4-bis­(1,2,4-triazol-1-ylmeth­yl)benzene (bbtz) ligands and two N atoms from two symmetry-related monodentate azide ligands. The Ni^II atoms are bridged by four bbtz ligands to form a two-dimensional (4,4)-network.

S1. Comment

Recently, considerable attention has been paid to transition metal coordination polymers, due to their intriguing structures and potential application as functional materials (Batten & Robson, 1998; Blake et al., 1999; Kitagawa et al., 2004). 1,2,4-Triazole and its derivatives are very interesting ligands because they combine the coordination geometry of both pyrazole and imidazole with regard to the arrangement of their three heteroatoms. Some novel coordination polymers with the flexible bis(triazole) ligands have already been synthesized (Haasnoot, 2000; Albada et al., 2000; Zhao et al., 2002; Meng et al., 2004; Li et al., 2005).

In our previous studies, we synthesized several coordination polymers with the flexible ligands 1,2-bis(1,2,4-triazol-1-yl)ethane (bte) (Wang et al., 2005; Zhu et al., 2006) and 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene (bbtz; Li et al., 2005). In the present paper, we report the synthesis and crystal structure of the title novel two-dimensional coordination polymer, [Ni(bbtz)₂(N₃)₂]_n, (I).

As shown in Fig. 1, the Ni^II atom of (I) occupies an inversion centre. The coordination geometry of the Ni^II atom is distorted octahedral. It is coordinated equatorially by four N atoms from the triazole rings of two symmetry-related pairs of bbtz molecules, in which two methylene groups link the benzene ring and two triazole rings [Ni1—N3 = 2.1162 (16) Å and Ni1—N6ⁱ = 2.1012 (16) Å; symmetry code: (i) x + 1, -y + 3/2, z - 1/2], and axially by two N atoms from two symmetry-related azido ligands [Ni1—N7 = 2.1112 (17) Å]. This coordination environment is similar to those in [Ni(bte)₂(NCO)₂]_n and [Ni(bte)₂(N₃)₂]_n (Zhu et al., 2006). The Ni—N(triazole) bond lengths in (I) are in the range 2.1012 (16)–2.1162 (16) Å, corresponding to the values [in the range 2.095 (2)–2.1185 (13) Å] in [Ni(bte)₂(NCO)₂]_n and [Ni(bte)₂(N₃)₂]_n (Zhu et al., 2006), and in [Ni(trzppo)₄Cl₂]·6H₂O [trzppo is beta-(1,2,4-triazol-1-yl)proiophenone; Jian et al., 2003].

The N—Ni—N bond angles are in the range 86.11 (6)–93.89 (6)°, close to 90°. The Ni—N(azido) bond lengths are 2.1112 (17) Å, similar to the Ni—N(triazole) bond lengths, compared with the Ni—N(azido) bond lengths of 2.100 (3) and 2.108 (3) Å in the monodentate coordination azido complex [Ni(bte)₂(N₃)₂]_n (Zhu et al., 2006). The azido ligand is almost linear [bond angle N7—N8—N9 = 177.2 (3)°], in good agreement with the results usually obtained for monodentate azido complexes. The Ni1—N7—N8 bond angle is 129.58 (14)°.

Because the methyl C atom of bbtz can rotate freely to adjust itself to the coordination environment, bbtz can exhibit trans–gauche and gauche–gauche conformations (Li et al., 2005). The bbtz ligands of (I) exhibit the trans–gauche conformation, similar to the free bbtz molecule (Peng et al., 2004). The three rings (two triazole rings and one benzene ring) of one bbtz ligand are not coplanar. The dihedral angle between the two triazole planes is 63.70 (9)° in (I), but 0° in free bbtz due to symmetry. The dihedral angles between the benzene ring plane and the N1–N3/C9/C10 and N4–N6/C11/C12 triazole planes in (I) are 66.46 (9) and 66.10 (7)°, respectively, compared with 77.81 (9)° in free bbtz (Peng et al., 2004).

As illustrated in Fig. 2, each bbtz ligand in (I) coordinates to Ni^II atoms through its two 4-position triazole N atoms, thus acting as a bridging bidentate ligand to form a two-dimensional neutral (4,4) network. The networks contain nearly square grids (52-membered rings), with an Ni^II atom at each corner and a bbtz ligand at each edge connecting two Ni^II atoms. As a consequence of the crystal structure symmetry, the edge lengths are equal, with a value of 14.3646 (15) Å. The diagonal lengths of the nearly square grid are 20.542 (2) and 20.084 (2) Å, and the angles of the square are 88.7 (1) and 91.3 (1)°.

The nearly square grid sheets are stacked in an offset fashion parallel to the c direction. The offset half-cell superpositions of each pair of adjacent networks divide the voids into smaller rectangles whereby the azide anions of one sheet project into the holes of the next sheet. In the superposition structure, the sheets are arranged in the sequence ···A–B–A–B··· (Fig. 3).

Complex (I) has a two-dimensional (4,4) network, while [Ni(bte)₂(NCO)₂]_n and [Ni(bte)₂(N₃)₂]_n (Zhu et al., 2006) form one-dimensional double chains. The reason may be that bte is more flexible than bbtz.

Related literature

For related literature, see: Albada et al. (2000); Batten & Robson (1998); Blake et al. (1999); Haasnoot (2000); Jian et al. (2003); Kitagawa et al. (2004); Li et al. (2005); Meng et al. (2004); Peng et al. (2004); Wang et al. (2005); Zhao et al. (2002); Zhu et al. (2006).

S2. Experimental

An H₂O–MeOH solution (20 ml, 1:1 v/v) of Ni(NO₃)₂·6H₂O (0.145 g, 0.50 mm mol) was added to one leg of an H-shaped tube, and an H₂O–MeOH solution (20 ml, 1:1 v/v) of bbtz (0.240 g, 1.00 mmol) and NaN₃ (0.065 g, 1.00 mmol) was added to the other leg of the tube. After several weeks, well shaped blue single crystals of (I) were obtained. Analysis, found: C 46.21, H 3.83, N 40.38%; calculated for C₂₄H₂₄N₁₈Ni: C 46.25, H 3.88, N 40.46%.

S3. Refinement

H atoms were placed in idealized positions and refined as riding, with C—H distances of 0.95 (triazole and benzene) and 0.99 Å (methyl), and with U_iso(H) = 1.2U_eq(C).

Computing details

Data collection: CrystalClear (Rigaku, 2000); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1998); software used to prepare material for publication: SHELXTL.

Figures

	Fig. 1. The coordination environment of the Ni^II atom of (I), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. [Symmetry codes: (i) x + 1, -y + 3/2, z - 1/2; (ii) -x, y - 1/2, -z + 1/2; (iii) -x + 1, -y + 1, -z.]
	Fig. 2. A view of the two-dimensional (4,4) network of (I), along the c direction.
	Fig. 3. The cell packing of (I).

poly[diazidobis[µ-1,4-bis(1,2,4-triazol-1-ylmethyl)benzene- κ²N⁴:N^4']nickel(II)]

Crystal data

[Ni(N3)2(C12H12N6)2]	F(000) = 644
Mr = 623.32	Dx = 1.502 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 5721 reflections
a = 8.2566 (14) Å	θ = 3.1–27.5°
b = 20.542 (3) Å	µ = 0.76 mm^−1
c = 8.3351 (14) Å	T = 193 K
β = 102.850 (4)°	Block, blue
V = 1378.3 (4) Å^3	0.40 × 0.30 × 0.18 mm
Z = 2

Data collection

Rigaku Mercury CCD area-detector diffractometer	3157 independent reflections
Radiation source: fine-focus sealed tube	2850 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.028
ω scans	θmax = 27.5°, θmin = 3.2°
Absorption correction: multi-scan (Jacobson, 1998)	h = −10→9
Tmin = 0.752, Tmax = 0.876	k = −26→26
15202 measured reflections	l = −10→10

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.040	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.102	H-atom parameters constrained
S = 1.08	w = 1/[σ^2(Fo^2) + (0.051P)^2 + 0.6816P] where P = (Fo^2 + 2Fc^2)/3
3157 reflections	(Δ/σ)max < 0.001
196 parameters	Δρmax = 0.29 e Å^−3
0 restraints	Δρmin = −0.44 e Å^−3

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
Ni1	0.5000	0.5000	0.0000	0.02364 (12)
N1	0.4010 (2)	0.58666 (8)	0.4290 (2)	0.0300 (4)
N2	0.5687 (2)	0.58553 (10)	0.4833 (2)	0.0415 (5)
N3	0.49401 (19)	0.54219 (8)	0.2302 (2)	0.0265 (3)
N4	−0.2445 (2)	0.84711 (8)	0.3265 (2)	0.0338 (4)
N5	−0.3632 (2)	0.81002 (9)	0.3721 (3)	0.0406 (4)
N6	−0.38380 (19)	0.91472 (8)	0.4432 (2)	0.0282 (3)
N7	0.2689 (2)	0.54614 (8)	−0.0887 (2)	0.0314 (4)
N8	0.1444 (2)	0.52474 (9)	−0.1686 (2)	0.0320 (4)
N9	0.0209 (3)	0.50582 (11)	−0.2519 (4)	0.0600 (7)
C1	0.1824 (3)	0.66610 (10)	0.4565 (2)	0.0316 (4)
C2	0.2283 (3)	0.73001 (12)	0.4889 (3)	0.0460 (6)
H2	0.3309	0.7399	0.5622	0.055*
C3	0.1256 (3)	0.78012 (11)	0.4149 (4)	0.0472 (6)
H3	0.1592	0.8240	0.4372	0.057*
C4	−0.0249 (3)	0.76687 (11)	0.3092 (3)	0.0354 (5)
C5	−0.0719 (3)	0.70296 (12)	0.2793 (3)	0.0445 (6)
H5	−0.1753	0.6931	0.2075	0.053*
C6	0.0306 (3)	0.65288 (11)	0.3532 (3)	0.0421 (5)
H6	−0.0040	0.6090	0.3325	0.051*
C7	0.2922 (3)	0.61042 (12)	0.5336 (3)	0.0430 (6)
H7A	0.3614	0.6249	0.6402	0.052*
H7B	0.2213	0.5741	0.5558	0.052*
C8	−0.1356 (3)	0.82084 (13)	0.2248 (3)	0.0469 (6)
H8A	−0.0656	0.8564	0.1973	0.056*
H8B	−0.2049	0.8041	0.1205	0.056*
C9	0.6176 (3)	0.55832 (11)	0.3595 (3)	0.0358 (5)
H9	0.7313	0.5506	0.3609	0.043*
C10	0.3593 (3)	0.56110 (11)	0.2796 (3)	0.0340 (5)
H10	0.2487	0.5569	0.2168	0.041*
C11	−0.4425 (3)	0.85332 (10)	0.4424 (3)	0.0357 (5)
H11	−0.5340	0.8422	0.4888	0.043*
C12	−0.2592 (2)	0.90857 (10)	0.3687 (3)	0.0324 (4)
H12	−0.1901	0.9432	0.3485	0.039*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ni1	0.01983 (19)	0.02525 (19)	0.02808 (19)	−0.00137 (12)	0.01011 (14)	−0.00126 (13)
N1	0.0320 (9)	0.0317 (9)	0.0278 (8)	0.0079 (7)	0.0094 (7)	0.0001 (7)
N2	0.0325 (10)	0.0503 (12)	0.0404 (10)	0.0057 (8)	0.0051 (8)	−0.0112 (9)
N3	0.0242 (8)	0.0280 (8)	0.0296 (8)	−0.0006 (6)	0.0112 (6)	−0.0031 (6)
N4	0.0342 (9)	0.0341 (9)	0.0363 (9)	0.0116 (7)	0.0149 (7)	0.0064 (7)
N5	0.0379 (10)	0.0318 (9)	0.0545 (12)	0.0046 (8)	0.0154 (9)	0.0012 (8)
N6	0.0244 (8)	0.0296 (8)	0.0324 (8)	0.0033 (6)	0.0103 (7)	0.0016 (7)
N7	0.0249 (8)	0.0323 (9)	0.0367 (9)	0.0013 (7)	0.0062 (7)	−0.0024 (7)
N8	0.0255 (9)	0.0295 (8)	0.0443 (10)	0.0027 (7)	0.0149 (8)	−0.0057 (8)
N9	0.0243 (11)	0.0628 (15)	0.0903 (18)	−0.0023 (9)	0.0073 (11)	−0.0371 (13)
C1	0.0331 (10)	0.0340 (10)	0.0320 (10)	0.0068 (8)	0.0167 (8)	−0.0010 (8)
C2	0.0321 (11)	0.0411 (12)	0.0617 (15)	0.0019 (9)	0.0039 (11)	−0.0097 (11)
C3	0.0405 (13)	0.0283 (11)	0.0739 (17)	−0.0010 (9)	0.0152 (12)	−0.0064 (11)
C4	0.0376 (11)	0.0357 (11)	0.0385 (11)	0.0113 (9)	0.0205 (9)	0.0007 (9)
C5	0.0322 (11)	0.0451 (13)	0.0522 (14)	0.0069 (10)	0.0008 (10)	−0.0102 (11)
C6	0.0397 (12)	0.0289 (11)	0.0580 (14)	0.0006 (9)	0.0112 (11)	−0.0079 (10)
C7	0.0494 (14)	0.0506 (14)	0.0342 (11)	0.0196 (11)	0.0202 (10)	0.0029 (10)
C8	0.0561 (15)	0.0510 (14)	0.0416 (12)	0.0243 (11)	0.0280 (11)	0.0095 (11)
C9	0.0250 (10)	0.0422 (12)	0.0405 (11)	0.0028 (8)	0.0077 (9)	−0.0080 (9)
C10	0.0271 (10)	0.0445 (12)	0.0318 (10)	0.0016 (8)	0.0097 (8)	−0.0051 (9)
C11	0.0286 (10)	0.0308 (10)	0.0508 (13)	0.0020 (8)	0.0157 (9)	0.0047 (9)
C12	0.0271 (10)	0.0330 (10)	0.0401 (11)	0.0043 (8)	0.0143 (9)	0.0051 (9)

Geometric parameters (Å, º)

Ni1—N6^i	2.1012 (16)	C1—C2	1.377 (3)
Ni1—N6^ii	2.1012 (16)	C1—C6	1.380 (3)
Ni1—N7^iii	2.1112 (17)	C1—C7	1.511 (3)
Ni1—N7	2.1112 (17)	C2—C3	1.388 (3)
Ni1—N3^iii	2.1162 (16)	C2—H2	0.9500
Ni1—N3	2.1162 (16)	C3—C4	1.381 (3)
N1—C10	1.325 (3)	C3—H3	0.9500
N1—N2	1.358 (3)	C4—C5	1.376 (3)
N1—C7	1.467 (3)	C4—C8	1.508 (3)
N2—C9	1.313 (3)	C5—C6	1.386 (3)
N3—C10	1.327 (2)	C5—H5	0.9500
N3—C9	1.350 (3)	C6—H6	0.9500
N4—C12	1.324 (3)	C7—H7A	0.9900
N4—N5	1.361 (3)	C7—H7B	0.9900
N4—C8	1.468 (3)	C8—H8A	0.9900
N5—C11	1.317 (3)	C8—H8B	0.9900
N6—C12	1.321 (2)	C9—H9	0.9500
N6—C11	1.351 (3)	C10—H10	0.9500
N6—Ni1^iv	2.1012 (16)	C11—H11	0.9500
N7—N8	1.179 (2)	C12—H12	0.9500
N8—N9	1.165 (3)
N6^i—Ni1—N6^ii	180.0	C4—C3—C2	120.8 (2)
N6^i—Ni1—N7^iii	91.77 (6)	C4—C3—H3	119.6
N6^ii—Ni1—N7^iii	88.23 (6)	C2—C3—H3	119.6
N6^i—Ni1—N7	88.23 (6)	C5—C4—C3	118.7 (2)
N6^ii—Ni1—N7	91.77 (6)	C5—C4—C8	120.0 (2)
N7^iii—Ni1—N7	180.0	C3—C4—C8	121.2 (2)
N6^i—Ni1—N3^iii	91.91 (6)	C4—C5—C6	120.5 (2)
N6^ii—Ni1—N3^iii	88.09 (6)	C4—C5—H5	119.7
N7^iii—Ni1—N3^iii	86.11 (6)	C6—C5—H5	119.7
N7—Ni1—N3^iii	93.89 (6)	C1—C6—C5	120.7 (2)
N6^i—Ni1—N3	88.09 (6)	C1—C6—H6	119.6
N6^ii—Ni1—N3	91.91 (6)	C5—C6—H6	119.6
N7^iii—Ni1—N3	93.89 (6)	N1—C7—C1	112.84 (17)
N7—Ni1—N3	86.11 (6)	N1—C7—H7A	109.0
N3^iii—Ni1—N3	180.00 (8)	C1—C7—H7A	109.0
C10—N1—N2	109.79 (17)	N1—C7—H7B	109.0
C10—N1—C7	128.68 (19)	C1—C7—H7B	109.0
N2—N1—C7	121.45 (17)	H7A—C7—H7B	107.8
C9—N2—N1	102.41 (17)	N4—C8—C4	112.72 (18)
C10—N3—C9	102.56 (16)	N4—C8—H8A	109.0
C10—N3—Ni1	126.26 (14)	C4—C8—H8A	109.0
C9—N3—Ni1	131.17 (13)	N4—C8—H8B	109.0
C12—N4—N5	110.23 (17)	C4—C8—H8B	109.0
C12—N4—C8	127.44 (19)	H8A—C8—H8B	107.8
N5—N4—C8	121.80 (19)	N2—C9—N3	114.92 (18)
C11—N5—N4	101.91 (17)	N2—C9—H9	122.5
C12—N6—C11	102.96 (17)	N3—C9—H9	122.5
C12—N6—Ni1^iv	128.90 (14)	N1—C10—N3	110.32 (18)
C11—N6—Ni1^iv	126.77 (13)	N1—C10—H10	124.8
N8—N7—Ni1	129.58 (14)	N3—C10—H10	124.8
N9—N8—N7	177.2 (3)	N5—C11—N6	114.83 (18)
C2—C1—C6	118.8 (2)	N5—C11—H11	122.6
C2—C1—C7	121.7 (2)	N6—C11—H11	122.6
C6—C1—C7	119.5 (2)	N6—C12—N4	110.07 (18)
C1—C2—C3	120.4 (2)	N6—C12—H12	125.0
C1—C2—H2	119.8	N4—C12—H12	125.0
C3—C2—H2	119.8
C10—N1—N2—C9	−0.3 (2)	C7—C1—C6—C5	−179.3 (2)
C7—N1—N2—C9	176.7 (2)	C4—C5—C6—C1	−0.8 (4)
N6^i—Ni1—N3—C10	111.99 (18)	C10—N1—C7—C1	−61.1 (3)
N6^ii—Ni1—N3—C10	−68.01 (18)	N2—N1—C7—C1	122.5 (2)
N7^iii—Ni1—N3—C10	−156.36 (17)	C2—C1—C7—N1	−93.7 (3)
N7—Ni1—N3—C10	23.64 (17)	C6—C1—C7—N1	87.4 (3)
N6^i—Ni1—N3—C9	−66.11 (19)	C12—N4—C8—C4	125.4 (2)
N6^ii—Ni1—N3—C9	113.89 (19)	N5—N4—C8—C4	−63.8 (3)
N7^iii—Ni1—N3—C9	25.54 (19)	C5—C4—C8—N4	95.6 (3)
N7—Ni1—N3—C9	−154.46 (19)	C3—C4—C8—N4	−85.5 (3)
C12—N4—N5—C11	−0.6 (2)	N1—N2—C9—N3	0.2 (3)
C8—N4—N5—C11	−172.8 (2)	C10—N3—C9—N2	−0.1 (3)
N6^i—Ni1—N7—N8	139.76 (19)	Ni1—N3—C9—N2	178.38 (15)
N6^ii—Ni1—N7—N8	−40.24 (19)	N2—N1—C10—N3	0.3 (3)
N3^iii—Ni1—N7—N8	47.96 (19)	C7—N1—C10—N3	−176.44 (19)
N3—Ni1—N7—N8	−132.04 (19)	C9—N3—C10—N1	−0.1 (2)
C6—C1—C2—C3	−1.8 (4)	Ni1—N3—C10—N1	−178.67 (13)
C7—C1—C2—C3	179.3 (2)	N4—N5—C11—N6	0.5 (3)
C1—C2—C3—C4	0.7 (4)	C12—N6—C11—N5	−0.2 (3)
C2—C3—C4—C5	0.4 (4)	Ni1^iv—N6—C11—N5	167.28 (15)
C2—C3—C4—C8	−178.4 (2)	C11—N6—C12—N4	−0.1 (2)
C3—C4—C5—C6	−0.4 (4)	Ni1^iv—N6—C12—N4	−167.30 (14)
C8—C4—C5—C6	178.5 (2)	N5—N4—C12—N6	0.5 (2)
C2—C1—C6—C5	1.8 (4)	C8—N4—C12—N6	172.2 (2)

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