Redetermination of [Ni(NH₃)₆]Cl₂ at 173 K

The structure of hexaamminenickel(II) dichloride determined previously by Eßmann et al. [Eßmann, Kreiner, Niemann, Rechenbach, Schmieding, Sichla, Zachwieja & Jacobs (1996). Z. Anorg. Allg. Chem. 622, 1161-1166] was redetermined at 173 K. There are no significant differences between these two structures.

S1. Comment

In an attempt to obtain a polymer of Ni²⁺ and 2,5-bis(1-pyrazolyl)hydrochinon via a new route, crystals of the title compound, (I), were obtained. After structure determination it turned out that the crystals contained [Ni(NH₃)₆]Cl₂, whose structure was determined previously by E\&smann et al. (1996). The cell axes are a little bit shorter at 173 K and the anisotropic displacement parameters are, as expected, smaller. However, there are no significant differences between the structures at different temperatures. The difference in the Ni—N bond lengths in both structures is 0.016 Å and the difference between the two N—H bond lengths (0.1 Å) is less than their standard deviation (0.2 Å).

S2. Experimental

A solution of 2,5-bis(1-pyrazolyl)hydrochinon (0.063 g; 0.260 mmol) in 10 ml CH₂Cl₂ was layered with a solution of 5 ml concentrated aqueous ammonia and 0.161 g (0.677 mmol) of NiCl₂^.6H₂O. Formation of purple crystals was observed after one week. The liquid was removed from the crystals by filtration. The remaining crystalline compound was washed with 5 ml CH₂Cl₂ (yield: 0.034 g, 0.147 mmol; 22%).

S3. Refinement

The H atom was refined freely with a site-occupation facter of 0.75.

Computing details

Data collection: SMART (Siemens, 1995); cell refinement: SMART; data reduction: SAINT (Siemens, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997).

(I)

Crystal data

[Ni(NH3)6]Cl2	Mo Kα radiation, λ = 0.71073 Å
Mr = 231.81	Cell parameters from 339 reflections
Cubic, Fm3m	θ = 1–20°
a = 10.029 (2) Å	µ = 2.40 mm^−1
V = 1008.7 (3) Å^3	T = 173 K
Z = 4	Octahedron, purple
F(000) = 488	0.60 × 0.50 × 0.50 mm
Dx = 1.526 Mg m^−3

Data collection

Siemens CCD three-circle diffractometer	116 independent reflections
Radiation source: fine-focus sealed tube	115 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.042
ω scans	θmax = 31.4°, θmin = 3.5°
Absorption correction: numerical numerical	h = −14→14
Tmin = 0.327, Tmax = 0.380	k = −14→14
4406 measured reflections	l = −14→12

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)] = 0.013	All H-atom parameters refined
wR(F^2) = 0.033	w = 1/[σ^2(Fo^2) + (0.0135P)^2 + 0.5364P] where P = (Fo^2 + 2Fc^2)/3
S = 1.32	(Δ/σ)max < 0.001
116 reflections	Δρmax = 0.25 e Å^−3
10 parameters	Δρmin = −0.30 e Å^−3
0 restraints	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0173 (12)

Special details

Experimental. The data collection nominally covered a sphere of reciprocal space, by a combination of seven sets of exposures; each set had a different ϕ angle for the crystal and each exposure covered 0.3° in ω. The crystal-to-detector distance was 5.5 cm. Coverage of the unique set is 100% complete to at least 30° in θ. Crystal decay was monitored by repeating the initial frames at the end of data collection and analyzing the duplicate reflections.

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	Occ. (<1)
Ni1	0	0	0	0.0164 (2)
Cl1	0.25	0.25	0.25	0.0237 (2)
N1	0.21195 (16)	0	0	0.0314 (3)
H1	0.244 (2)	0.0561 (11)	0.0561 (11)	0.060 (6)*	0.75

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ni1	0.0164 (2)	0.0164 (2)	0.0164 (2)	0.000	0.000	0.000
Cl1	0.0237 (2)	0.0237 (2)	0.0237 (2)	0.000	0.000	0.000
N1	0.0206 (8)	0.0367 (6)	0.0367 (6)	0.000	0.000	0.000

Geometric parameters (Å, º)

Ni1—N1	2.1256 (17)	Ni1—N1^iv	2.1257 (17)
Ni1—N1^i	2.1257 (17)	Ni1—N1^v	2.1257 (17)
Ni1—N1^ii	2.1257 (17)	N1—H1	0.859 (16)
Ni1—N1^iii	2.1257 (17)
N1—Ni1—N1^i	90.0	N1^ii—Ni1—N1^iv	90.0
N1—Ni1—N1^ii	180.0	N1^iii—Ni1—N1^iv	180.0
N1^i—Ni1—N1^ii	90.0	N1—Ni1—N1^v	90.0
N1—Ni1—N1^iii	90.0	N1^i—Ni1—N1^v	180.0
N1^i—Ni1—N1^iii	90.0	N1^ii—Ni1—N1^v	90.0
N1^ii—Ni1—N1^iii	90.0	N1^iii—Ni1—N1^v	90.0
N1—Ni1—N1^iv	90.0	N1^iv—Ni1—N1^v	90.0
N1^i—Ni1—N1^iv	90.0

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···Cl1	0.86 (2)	2.75 (2)	3.5663 (7)	159 (2)
Ni1—N1···H1				112 (2)