catena-Poly­[[tetra-μ-acetatodinickel(II)]μ-N,N′-hexa­methyl­enetetr­amine]

In the title compound, [Ni₂(C₂H₃O₂)₄(C₆H₁₂N₄)]_n, the hexa­methyl­enetetr­amine mol­ecules, occupying a special position of mm2 symmetry, link adjacent tetraacetatodinickel units, located in a special position of 2/m symmetry, into zigzag chains that run along the b axis of the unit cell. The Ni atom in the binuclear unit is five-coordinate and has a square-pyramidal geometry. It is displaced by 0.203 (3) Å out of the basal plane of the four O atoms towards the apical N atom of the adjacent hexa­methyl­enetetr­amine mol­ecule and away from the second Ni atom of the binuclear unit. The two Ni atoms are separated by 2.622 (1) Å.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.030
• wR factor = 0.076
• Data-to-parameter ratio = 12.8

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level C:



PLAT_703  Alert C Torsion Calc  -133.94(5), Rep -134.00(10), Dev.      1.20 Sigma
                     O2  -NI1 -N1  -C3     9.555   1.555   1.555   1.555

PLAT_703  Alert C Torsion Calc   133.94(5), Rep  134.00(10), Dev.      1.20 Sigma
                     O2  -NI1 -N1  -C3     4.555   1.555   1.555   1.555

General Notes



ABSTM_02  When printed, the submitted absorption T values will be replaced
          by the scaled T values. Since the ratio of scaled T's is
          identical to the ratio of reported T values, the scaling does
          not imply a change to the absorption corrections used in the
          study.
          Ratio of Tmax expected/reported      0.902
          Tmax scaled      0.462 Tmin scaled      0.364


 0 Alert Level A = Potentially serious problem

 0 Alert Level B = Potential problem

 2 Alert Level C = Please check

---

S1. Comment

Hexamethylenetetramine, a spacer molecule that has been extensively used in the crystal engineering of coordination polymers, can bridge through two (Zheng, Tong, Yu & Chen, 2001), three (Zheng, Tong, Zhu et al., 2001) or four (Tong et al., 1999) of its N atoms to furnish a variety of such polymers. To date, an enormous number of metal complexes of this kind have been reported (Zhang et al., 2000a,b); the title nickel acetate complex, (I), represents an exception, as only few acetate complexes have been studied.

The crystal structure of the title complex, which is isomorphous with its copper analog (Pickardt, 1981), is built of hexamethylenetetramine molecules and tetraacetatodinickel units, both of which occupy special positions. The hexamethylenetetramine molecule occupies the position of mm2 symmetry with one of the mirror planes passing through the N1, C3 and C5, and the other mirror plane passing through the N2, C3 and C5 atoms. The tetraacetatodinickel unit occupies the position of the 2/m symmetry with the mirror plane passing through both Ni atoms and bisecting two of the O—Ni—O angles in the coordination spheres of each of the Ni atoms; the twofold axis passes midway between the two Ni atoms but it does not pass through any of them.

The coordination geometry of the Ni atom may be described as a square pyramid, formed by four acetate O and the N atom of the adjacent hexamethylenetetramine, which is distorted towards an octahedron owing to the metal–metal interaction [2.622 (1) Å] (Fig. 1). The Ni atom is displaced out of the basal plane of the four O atoms by 0.203 (3) Å towards the apical hexamethylenetetramine N atom. The hexamethylenetetramine ligand uses only two of its four N atoms to link adjacent units to afford a zigzag chain running along the b axis of the unit cell (Fig. 2). The bonding pattern of the acetate groups in the title compound contrasts with that of tetraaquadiacetatonickel, a mononuclear compound with two monodetate acetate groups [Ni—O 2.067 (3) Å; Downie et al., 1971].

S2. Experimental

The title compound was synthesized by the reaction of nickel(II) acetate tetrahydrate (0.50 g, 2 mmol) and hexamethylenetetramine (0.14 g, 1 mmol) (2:1 molar ratio) in a small volume of ethanol. Water was added dropwise to dissolve the reactants. Green prismatic crystals deposited from solution in 80% yield after several weeks. Analysis calculated for C₁₄H₂₄N₄Ni₂O₈: C 34.05, H 4.86, N 11.15%; found: C 33.86, H 5.04, N 11.28%.

S3. Refinement

The H atoms of the hexamethylenetetramine entity were generated geometrically and allowed to ride on the parent C atom; U_iso(H) = 1.2U_eq(C). The methyl H atoms were positioned by using the HFIX 137 instruction in SHELXL97.

Computing details

Data collection: SMART (Bruker, 1999); cell refinement: SAINT (Bruker, 1999); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPII (Johnson, 1976); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. ORTEPII (Johnson, 1976) plot of (I) at the 50% probability level. H atoms are drawn as spheres of arbitrary radii.
	Fig. 2. ORTEPII (Johnson, 1976) plot showing the chain motif in the crystal packing of (I).

catena-µ-(N,N'-hexamethylenetetramine)[tetra-µ-acetatodinickel(II)]

Crystal data

[Ni2(C2H3O2)4(C6H12N4)]	Dx = 1.684 Mg m^−3
Mr = 493.79	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Cmma	Cell parameters from 1865 reflections
a = 15.480 (1) Å	θ = 2.5–25.0°
b = 15.638 (2) Å	µ = 1.98 mm^−1
c = 8.048 (1) Å	T = 298 K
V = 1948.2 (4) Å^3	Prism, green
Z = 4	0.56 × 0.48 × 0.39 mm
F(000) = 1024

Data collection

Bruker CCD area-detector diffractometer	937 independent reflections
Radiation source: fine-focus sealed tube	775 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.029
ω scans	θmax = 25.0°, θmin = 2.5°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −18→16
Tmin = 0.403, Tmax = 0.512	k = −18→18
3062 measured reflections	l = −5→9

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)] = 0.030	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.076	H-atom parameters constrained
S = 1.02	w = 1/[σ^2(Fo^2) + (0.0464P)^2 + 0.5367P] where P = (Fo^2 + 2Fc^2)/3
937 reflections	(Δ/σ)max < 0.001
73 parameters	Δρmax = 0.30 e Å^−3
0 restraints	Δρmin = −0.35 e Å^−3

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Ni1	0.0000	0.05907 (3)	0.11560 (5)	0.0277 (2)
O1	0.0920 (1)	0.1076 (1)	−0.0265 (2)	0.046 (1)
O2	0.0903 (1)	0.0092 (1)	−0.2250 (2)	0.049 (1)
N1	0.0000	0.1718 (2)	0.2823 (3)	0.029 (1)
N2	−0.0788 (2)	0.2500	0.4975 (4)	0.036 (1)
C1	0.1209 (2)	0.0742 (2)	−0.1568 (3)	0.035 (1)
C2	0.1992 (2)	0.1155 (2)	−0.2351 (4)	0.049 (1)
C3	0.0000	0.2500	0.1794 (6)	0.028 (1)
C4	−0.0774 (2)	0.1736 (2)	0.3915 (3)	0.034 (1)
C5	0.0000	0.2500	0.5988 (6)	0.041 (1)
H2a	0.2140	0.0857	−0.3354	0.074*
H2b	0.2469	0.1130	−0.1590	0.074*
H2c	0.1865	0.1742	−0.2607	0.074*
H3	0.0507	0.2500	0.1085	0.034*
H4a	−0.1290	0.1725	0.3234	0.041*
H4b	−0.0777	0.1229	0.4610	0.041*
H5	0.0000	0.1999	0.6698	0.049*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ni1	0.0280 (3)	0.0237 (3)	0.0314 (3)	0.000	0.000	−0.0038 (2)
O1	0.045 (1)	0.040 (1)	0.053 (1)	−0.011 (1)	0.015 (1)	−0.009 (1)
O2	0.054 (1)	0.047 (1)	0.047 (1)	−0.016 (1)	0.012 (1)	−0.008 (1)
N1	0.030 (1)	0.026 (2)	0.030 (2)	0.000	0.000	0.001 (1)
N2	0.041 (2)	0.029 (2)	0.039 (2)	0.000	0.010 (1)	0.000
C1	0.028 (1)	0.034 (2)	0.041 (2)	0.002 (1)	−0.001 (1)	0.010 (1)
C2	0.038 (1)	0.053 (2)	0.056 (2)	−0.005 (2)	0.005 (1)	0.01 (2)
C3	0.038 (3)	0.021 (3)	0.026 (2)	0.000	0.000	0.000
C4	0.032 (1)	0.032 (2)	0.040 (1)	−0.002 (1)	0.004 (1)	0.001 (1)
C5	0.062 (4)	0.037 (3)	0.024 (3)	0.000	0.000	0.000

Geometric parameters (Å, º)

Ni1—O1	1.978 (2)	N2—C4	1.469 (3)
Ni1—O1^i	1.978 (2)	N2—C4^iv	1.469 (3)
Ni1—O2^ii	1.967 (2)	C1—C2	1.511 (4)
Ni1—O2^iii	1.967 (2)	C3—N1^v	1.477 (4)
Ni1—N1	2.215 (3)	C5—N2^v	1.467 (4)
Ni1—Ni1^iii	2.622 (1)	C2—H2a	0.9600
O1—C1	1.254 (3)	C2—H2b	0.9600
O2—C1	1.248 (3)	C2—H2c	0.9600
N1—C3	1.477 (4)	C3—H3	0.9700
N1—C4^i	1.486 (3)	C4—H4a	0.9700
N1—C4	1.486 (3)	C4—H4b	0.9700
N2—C5	1.467 (4)	C5—H5	0.9700
O1—Ni1—O1^i	92.1 (1)	C5—N2—C4^iv	108.1 (2)
O1—Ni1—O2^ii	87.5 (1)	C4—N2—C4^iv	108.9 (3)
O1—Ni1—O2^iii	168.2 (1)	O2—C1—O1	124.9 (2)
O1—Ni1—N1	92.6 (1)	O2—C1—C2	118.0 (3)
O1—Ni1—Ni1^iii	82.0 (1)	O1—C1—C2	117.1 (3)
O1^i—Ni1—O2^ii	168.2 (1)	N1^v—C3—N1	111.8 (4)
O1^i—Ni1—O2^iii	87.5 (1)	N2—C4—N1	111.8 (2)
O1^i—Ni1—N1	92.6 (1)	N2—C5—N2^v	112.5 (4)
O1^i—Ni1—Ni1^iii	82.0 (1)	C1—C2—H2a	109.5
O2^ii—Ni1—O2^iii	90.6 (1)	C1—C2—H2b	109.5
O2^ii—Ni1—N1	99.3 (1)	H2a—C2—H2b	109.5
O2^ii—Ni1—Ni1^iii	86.3 (1)	C1—C2—H2c	109.5
O2^iii—Ni1—N1	99.3 (1)	H2a—C2—H2c	109.5
O2^iii—Ni1—Ni1^iii	86.3 (1)	H2b—C2—H2c	109.5
N1—Ni1—Ni1^iii	172.1 (1)	N1^v—C3—H3	109.2
C1—O1—Ni1	125.4 (2)	N1—C3—H3	109.2
C1—O2—Ni1^iii	121.0 (2)	N2—C4—H4a	109.3
C3—N1—C4^i	108.4 (2)	N1—C4—H4a	109.3
C3—N1—C4	108.4 (2)	N2—C4—H4b	109.3
C4^i—N1—C4	107.4 (3)	N1—C4—H4b	109.3
C3—N1—Ni1	108.6 (2)	H4a—C4—H4b	107.9
C4^i—N1—Ni1	111.9 (2)	N2—C5—H5	109.1
C4—N1—Ni1	111.9 (2)	N2^v—C5—H5	109.1
C5—N2—C4	108.1 (2)
O2^iii—Ni1—O1—C1	3.8 (5)	O1^i—Ni1—N1—C4	73.6 (2)
O2^ii—Ni1—O1—C1	84.4 (2)	Ni1^iii—O2—C1—O1	−8.5 (4)
O1^i—Ni1—O1—C1	−83.8 (2)	Ni1^iii—O2—C1—C2	170.7 (2)
N1—Ni1—O1—C1	−176.5 (2)	Ni1—O1—C1—O2	7.1 (4)
Ni1^iii—Ni1—O1—C1	−2.2 (2)	Ni1—O1—C1—C2	−172.1 (2)
O2^iii—Ni1—N1—C3	−134.0 (1)	C4^i—N1—C3—N1^v	−58.1 (2)
O2^ii—Ni1—N1—C3	134.0 (1)	C4—N1—C3—N1^v	58.1 (2)
O1—Ni1—N1—C3	46.1 (1)	Ni1—N1—C3—N1^v	180.0
O1^i—Ni1—N1—C3	−46.1 (1)	C5—N2—C4—N1	−58.9 (3)
O2^iii—Ni1—N1—C4^i	106.4 (2)	C4^iv—N2—C4—N1	58.4 (3)
O2^ii—Ni1—N1—C4^i	14.3 (2)	C3—N1—C4—N2	−58.1 (3)
O1—Ni1—N1—C4^i	−73.6 (2)	C4^i—N1—C4—N2	58.9 (3)
O1^i—Ni1—N1—C4^i	−165.8 (2)	Ni1—N1—C4—N2	−177.9 (2)
O2^iii—Ni1—N1—C4	−14.3 (2)	C4—N2—C5—N2^v	58.9 (2)
O2^ii—Ni1—N1—C4	−106.4 (2)	C4^iv—N2—C5—N2^v	−58.9 (2)
O1—Ni1—N1—C4	165.8 (2)

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