catena-Poly[[(nitrito-κ²O,O′)silver(I)]-μ-1,2-bis­­[1-(pyridin-4-yl)ethyl­­idene]hydrazine-κ²N:N′]

The asymmetric unit of the title compound, [Ag(NO₂)(C₁₄H₁₄N₄)]_n, contains half of the repeating formula unit (Z′ = 1/2). The Ag^I ion lies on a twofold rotation axis. The primary structure consists of a one-dimensional coordination polymer formed by the Ag^I ions and the bipyridyl azine ligand in which there is an inversion center at the mid-point of the N—N bond. The nitrite anion inter­acts with the Ag^I ion through a chelating μ² inter­action involving both O atoms. In the crystal, the coordination chains are parallel and inter­act through Ag⋯π [3.220 (2) Å] and π–π [3.489 (3) Å] inter­actions.

Related literature

For a review of Ag(I) bipyridyl coordination behaviour, see: Khlobystov et al. (2001). For the synthesis and structure of related coordination polymers with azine linkers, see: Kennedy et al. (2005). For nitrite-containing examples, see: Chen & Mak (2005); Blake et al. (1999); Cingolani et al. (1999); Flörke et al. (1998); Tong et al. (2002).

Experimental

Crystal data

• [Ag(NO₂)(C₁₄H₁₄N₄)]

• M_r = 392.17

• Monoclinic, P 2/n

• a = 4.8645 (2) Å

• b = 7.3283 (2) Å

• c = 20.7228 (6) Å

• β = 93.710 (2)°

• V = 737.19 (4) ų

• Z = 2

• Mo Kα radiation

• μ = 1.38 mm⁻¹

• T = 123 K

• 0.30 × 0.30 × 0.28 mm

Data collection

• Nonius Kappa CCD diffractometer

• Absorption correction: multi-scan (SORTAV; Blessing, 1997) T_min = 0.667, T_max = 0.687

• 3223 measured reflections

• 1693 independent reflections

• 1487 reflections with I > 2σ(I)

• R_int = 0.027

Refinement

• R[F² > 2σ(F²)] = 0.023

• wR(F²) = 0.048

• S = 1.05

• 1693 reflections

• 102 parameters

• H-atom parameters constrained

• Δρ_max = 0.44 e Å⁻³

• Δρ_min = −0.44 e Å⁻³

Data collection: DENZO (Otwinowski & Minor, 1997) and COLLECT (Hooft, 1998); cell refinement: DENZO and COLLECT; data reduction: DENZO; program(s) used to solve structure: SIR92 (Burla et al., 2005); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997) and X-SEED (Barbour, 2001); software used to prepare material for publication: SHELXL97.

Supporting information

S1. Comment

The formation of Ag(I) complexes of "off-axis rod" type bipyridyl ligands has attracted much interest. Partly this is due to the relative ease of crystal formation, as compared to similar systems with other metals, and partly because aggregation of the one-dimensional polymeric chains typically formed is thought to give insight into the formation of more complicated two-dimensional or three-dimensional networks (Khlobystov et al., 2001). Previous work on such bipyridyl ligands containing azine chromophores showed that all displayed simple one-dimensional chains based on the coordination of two ligands to each Ag(I) centre in a trans manner (Kennedy et al., 2005). However, the stacking of these chains is not simple - with much variation seen in the interaction types observed. With better coordinating anions Ag···anion interactions were important but Ag···Ag, Ag···solvent, Ag···azine and Ag···π contacts were also observed with little apparent systematic variation. Here we utilize the nitrite anion to limit the number of interchain Ag···anion interactions possible.

[Ag(pyC(Me)N—NC(Me)py)(NO₂)]_n (I) has the expected primary chain structure with each Ag(I) centre forming two dative bonds to pyridyl fragments from two seperate ligands, see Fig 1. However, the nitrite anion also interacts with the Ag(I) centre. Its O,O' chelating geometry appears to be more sterically demanding than that of other anions used with such systems (e.g. NO₃, ClO₄, BF₄ and SbF₆) and thus the NAgN angle of 142.18 (8) ° is considerably more bent than previously seen (range 167.0 to 180 °, Kennedy et al., 2005).

Whilst the observed chelating nitrite bonding mode is the commonest found in related Ag(I) complexes (see for example Blake et al., 1999; Chen & Mak, 2005; Tong et al., 2002) nitrite can also bridge between Ag(I) centres either through O atom coordination only (Cingolani et al., 1999) or more rarely by also using the central N atom to bind (Flörke et al., 1998). However, in (I) no further interactions are formed by the nitrite anion. Instead the intermolecular network expands through Ag···π interactions. Pyridyl rings lie equidistant above and below the plane of primary coordination (Ag1···C1ⁱⁱⁱ and Ag1···C1^iv are both 3.220 (2) Å, where iii is 1 + x, y, z and iv is 0.5 - x, y, 0.5 - z). Additionally the coordination chains also form π–π contacts that are within the range normally treated as significant (C3···C5^v = 3.489 (3) Å where v is x - 1, y, z) (see Fig. 2 for the crystal packing).

Related literature

For a review of Ag(I) bipyridyl coordination behaviour, see: Khlobystov et al. (2001). For the synthesis and structure of related coordination polymers with azine linkers, see: Kennedy et al. (2005). For nitrite-containing examples, see: Chen & Mak (2005); Blake et al. (1999); Cingolani et al. (1999); Flörke et al. (1998); Tong et al. (2002).

S2. Experimental

The azine ligand and complex (I) were synthesized as described in Kennedy et al. (2005), and crystals were grown by the solvent layering method also described therein.

S3. Refinement

H atoms were placed in calculated positions and refined in riding modes with C—H = 0.98 or 0.95 Å for the CH₃ and CH groups respectively. For the methyl group U_iso(H) = 1.5U_eq and for CH groups U_iso(H) = 1.2U_eq of the parent C atoms.

Computing details

Data collection: DENZO (Otwinowski & Minor, 1997) and COLLECT (Hooft, 1988); cell refinement: DENZO (Otwinowski & Minor, 1997) and COLLECT (Hooft, 1988); data reduction: DENZO (Otwinowski & Minor, 1997); program(s) used to solve structure: SIR92 (Burla et al., 2005); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997) and X-SEED (Barbour, 2001); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures

	Fig. 1. The molecular structure of (I) extended to show coordination geometry about Ag1. Non-H atoms are drawn as 50% probability displacement ellipsoids. i = 1.5 - x, y, 0.5 - z, ii = -1 - x, -y, -z.
	Fig. 2. Packing diagram of (I) viewed along the crystallographic a direction.

catena-Poly[[(nitrito-κ²O,O')silver(I)]- µ-1,2-bis[1-(pyridin-4-yl)ethylidene]hydrazine-κ²N:N']

Crystal data

[Ag(NO2)(C14H14N4)]	F(000) = 392
Mr = 392.17	Dx = 1.767 Mg m^−3
Monoclinic, P2/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yac	Cell parameters from 7462 reflections
a = 4.8645 (2) Å	θ = 1.0–27.5°
b = 7.3283 (2) Å	µ = 1.38 mm^−1
c = 20.7228 (6) Å	T = 123 K
β = 93.710 (2)°	Prism, orange
V = 737.19 (4) Å^3	0.30 × 0.30 × 0.28 mm
Z = 2

Data collection

Nonius Kappa CCD diffractometer	1693 independent reflections
Radiation source: fine-focus sealed tube	1487 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.027
ϕ and ω scans	θmax = 27.5°, θmin = 2.0°
Absorption correction: multi-scan (SORTAV; Blessing, 1997)	h = −6→6
Tmin = 0.667, Tmax = 0.687	k = −9→9
3223 measured reflections	l = −26→26

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)] = 0.023	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.048	H-atom parameters constrained
S = 1.05	w = 1/[σ^2(Fo^2) + (0.0235P)^2 + 0.063P] where P = (Fo^2 + 2Fc^2)/3
1693 reflections	(Δ/σ)max < 0.001
102 parameters	Δρmax = 0.44 e Å^−3
0 restraints	Δρmin = −0.44 e Å^−3

Special details

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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
Ag1	0.7500	0.19621 (3)	0.2500	0.01866 (8)
O1	0.7224 (4)	0.5063 (2)	0.19907 (7)	0.0362 (4)
N1	0.4040 (3)	0.0979 (2)	0.18357 (7)	0.0172 (4)
N2	−0.3966 (3)	0.0334 (2)	0.02212 (7)	0.0177 (4)
N3	0.7500	0.5978 (3)	0.2500	0.0307 (6)
C1	0.2330 (4)	0.2146 (3)	0.15100 (9)	0.0178 (4)
H1	0.2628	0.3418	0.1570	0.021*
C2	0.0163 (4)	0.1591 (3)	0.10933 (9)	0.0184 (4)
H2	−0.1003	0.2471	0.0879	0.022*
C3	−0.0314 (4)	−0.0271 (3)	0.09871 (8)	0.0155 (4)
C4	0.1426 (4)	−0.1477 (3)	0.13369 (9)	0.0178 (4)
H4	0.1156	−0.2756	0.1293	0.021*
C5	0.3544 (4)	−0.0809 (3)	0.17470 (9)	0.0180 (4)
H5	0.4708	−0.1659	0.1978	0.022*
C6	−0.2540 (4)	−0.0928 (3)	0.05205 (9)	0.0168 (4)
C7	−0.2886 (5)	−0.2950 (3)	0.04252 (10)	0.0252 (5)
H7A	−0.4465	−0.3183	0.0118	0.038*
H7B	−0.3202	−0.3528	0.0840	0.038*
H7C	−0.1216	−0.3458	0.0255	0.038*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ag1	0.01728 (12)	0.01806 (13)	0.01952 (12)	0.000	−0.00753 (8)	0.000
O1	0.0545 (11)	0.0246 (9)	0.0279 (9)	−0.0056 (8)	−0.0108 (8)	0.0019 (7)
N1	0.0160 (9)	0.0178 (9)	0.0173 (8)	0.0010 (7)	−0.0022 (7)	0.0006 (7)
N2	0.0139 (8)	0.0228 (9)	0.0156 (8)	−0.0017 (7)	−0.0040 (6)	−0.0011 (7)
N3	0.0342 (16)	0.0185 (14)	0.0373 (16)	0.000	−0.0143 (12)	0.000
C1	0.0162 (10)	0.0163 (10)	0.0204 (10)	0.0007 (8)	−0.0026 (8)	−0.0008 (8)
C2	0.0165 (10)	0.0183 (10)	0.0198 (10)	0.0023 (8)	−0.0032 (8)	0.0014 (8)
C3	0.0130 (10)	0.0204 (10)	0.0131 (9)	0.0005 (8)	0.0003 (7)	0.0004 (8)
C4	0.0194 (10)	0.0142 (10)	0.0196 (10)	−0.0010 (8)	−0.0008 (8)	−0.0004 (8)
C5	0.0168 (10)	0.0174 (11)	0.0194 (10)	0.0030 (8)	−0.0023 (8)	0.0017 (8)
C6	0.0157 (10)	0.0193 (11)	0.0153 (9)	−0.0012 (8)	0.0007 (8)	−0.0015 (8)
C7	0.0265 (11)	0.0214 (11)	0.0262 (11)	−0.0012 (9)	−0.0105 (9)	−0.0013 (9)

Geometric parameters (Å, º)

Ag1—N1	2.2242 (16)	C2—C3	1.399 (3)
Ag1—N1^i	2.2242 (16)	C2—H2	0.9500
Ag1—O1^i	2.5058 (15)	C3—C4	1.394 (3)
Ag1—O1	2.5058 (15)	C3—C6	1.485 (3)
O1—N3	1.2501 (19)	C4—C5	1.382 (3)
N1—C5	1.343 (2)	C4—H4	0.9500
N1—C1	1.344 (2)	C5—H5	0.9500
N2—C6	1.291 (3)	C6—C7	1.503 (3)
N2—N2^ii	1.405 (3)	C7—H7A	0.9800
N3—O1^i	1.2501 (19)	C7—H7B	0.9800
C1—C2	1.380 (3)	C7—H7C	0.9800
C1—H1	0.9500
N1—Ag1—N1^i	142.18 (8)	C4—C3—C2	116.58 (18)
N1—Ag1—O1^i	124.92 (6)	C4—C3—C6	121.75 (18)
N1^i—Ag1—O1^i	90.89 (5)	C2—C3—C6	121.67 (17)
N1—Ag1—O1	90.89 (5)	C5—C4—C3	119.94 (18)
N1^i—Ag1—O1	124.92 (6)	C5—C4—H4	120.0
O1^i—Ag1—O1	49.81 (7)	C3—C4—H4	120.0
N3—O1—Ag1	97.52 (13)	N1—C5—C4	123.36 (18)
C5—N1—C1	116.89 (17)	N1—C5—H5	118.3
C5—N1—Ag1	121.54 (13)	C4—C5—H5	118.3
C1—N1—Ag1	121.56 (13)	N2—C6—C3	115.29 (17)
C6—N2—N2^ii	113.8 (2)	N2—C6—C7	126.27 (17)
O1—N3—O1^i	115.2 (2)	C3—C6—C7	118.41 (17)
N1—C1—C2	123.34 (18)	C6—C7—H7A	109.5
N1—C1—H1	118.3	C6—C7—H7B	109.5
C2—C1—H1	118.3	H7A—C7—H7B	109.5
C1—C2—C3	119.86 (18)	C6—C7—H7C	109.5
C1—C2—H2	120.1	H7A—C7—H7C	109.5
C3—C2—H2	120.1	H7B—C7—H7C	109.5
N1—Ag1—O1—N3	137.41 (9)	C1—C2—C3—C4	2.2 (3)
N1^i—Ag1—O1—N3	−55.60 (11)	C1—C2—C3—C6	−177.15 (18)
O1^i—Ag1—O1—N3	0.0	C2—C3—C4—C5	−2.0 (3)
N1^i—Ag1—N1—C5	0.55 (13)	C6—C3—C4—C5	177.38 (17)
O1^i—Ag1—N1—C5	−157.90 (13)	C1—N1—C5—C4	1.0 (3)
O1—Ag1—N1—C5	163.02 (15)	Ag1—N1—C5—C4	−179.70 (14)
N1^i—Ag1—N1—C1	179.78 (15)	C3—C4—C5—N1	0.4 (3)
O1^i—Ag1—N1—C1	21.33 (17)	N2^ii—N2—C6—C3	179.36 (17)
O1—Ag1—N1—C1	−17.75 (15)	N2^ii—N2—C6—C7	1.1 (3)
Ag1—O1—N3—O1^i	0.0	C4—C3—C6—N2	−178.81 (18)
C5—N1—C1—C2	−0.8 (3)	C2—C3—C6—N2	0.5 (3)
Ag1—N1—C1—C2	179.94 (15)	C4—C3—C6—C7	−0.4 (3)
N1—C1—C2—C3	−0.9 (3)	C2—C3—C6—C7	178.89 (18)

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