Modulated one-dimensional structure of [Cd(NH₃)₃Ni(CN)₄]

The crystal structure of [Cd(NH₃)₃Ni(CN)₄] has been solved and refined as an incommensurate structure in four-dimensional superspace. The Xcalibur point-detector diffractometer was used for data collection up to the third-order satellites. The structure was refined from 3496 observed reflections to a final R value of 0.0371. The modulation strongly affects all the atoms of the structure. The dominating feature of the modulation is the incommensurate alternation between octahedrally and tetrahedrally coordinated Cd atoms in the electroneutral chains [—Cd(NH₃)_n—NC—Ni(CN)₂—CN—]_∞ (n alternates between 2 and 4). The chain is propagated along the a axis, in which the [Cd(NH₃)_n]²⁺ cations are linked by square [Ni(CN)₄]²⁻ anions. The atomic positional modulations, having mainly a transversal character in the c-direction, exhibit a switching character that can be described by the crenel and sawtooth functions. The effectively pentagonal coordinated cadmium positions were detected in the intermediate regions.

Computing details

Data reduction: (Jana2000; Petricek and Dusek, 2000); program(s) used to solve structure: IR97 (Altomare et al., 1997); program(s) used to refine structure: Jana2000 (Petricek and Dusek, 2000); software used to prepare material for publication: (Jana2000; Petricek and Dusek, 2000).

Figures

(I)

Crystal data

C4H9CdN7NiO0	F(000) = 620
Mr = 326.3	Dx = 2.105 Mg m^−3
Monoclinic, C2/c(α0γ)0s†	Mo Kα radiation, λ = 0.71069 Å
q = 0.43650a* + 0.13070c*	Cell parameters from 30 reflections
a = 8.4867 (14) Å	θ = 9.1–16.3°
b = 15.951 (3) Å	µ = 3.86 mm^−1
c = 7.604 (3) Å	T = 260 K
β = 90.48 (2)°	Irregular, gold-yellow
V = 1029.3 (4) Å^3	0.35 × 0.09 × 0.07 mm
Z = 4

† Symmetry operations: (1) x₁, x₂, x₃, x₄; (2) −x₁, x₂, 1/2−x₃, 1/2−x₄; (3) −x₁, −x₂, −x₃, −x₄; (4) x₁, −x₂, 1/2+x₃, 1/2+x₄; (5) 1/2+x₁, 1/2+x₂, x₃, x₄; (6) 1/2−x₁, 1/2+x₂, 1/2−x₃, 1/2−x₄; (7) 1/2−x₁, 1/2−x₂, −x₃, −x₄; (8) 1/2+x₁, 1/2−x₂, 1/2+x₃, 1/2+x₄.

Data collection

Oxford Diffraction point detector diffractometer	Rint = 0.086
θ/2θ scans	θmax = 27.1°, θmin = 1.5°
Absorption correction: gaussian (Jana2000; Petricek, Dusek & Palatinus, 2000)	h = 0→12
Tmin = 0.660, Tmax = 0.807	k = −20→20
15484 measured reflections	l = −10→10
7894 independent reflections	3 standard reflections every 100 reflections
3496 reflections with I > 3σ(I)	intensity decay: 1.4%

Refinement

Refinement on F	Restrained
R[F^2 > 2σ(F^2)] = 0.037	Weighting scheme based on measured s.u.'s w = 1/[σ^2(F) + 0.0001F^2]
wR(F^2) = 0.043	(Δ/σ)max < 0.001
S = 1.78	Δρmax = 0.95 e Å^−3
3496 reflections	Δρmin = −0.99 e Å^−3
275 parameters

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

	x	y	z	Uiso*/Ueq
Cd1	1	0.20155 (4)	0.25	0.0247 (2)
Cd2	1	0.14519 (4)	0.25	0.0367 (2)
Ni	0.5	−0.01073 (3)	0.25	0.02530 (17)
C1	0.6550 (4)	0.07102 (18)	0.2481 (4)	0.0282 (9)
N1	0.7525 (3)	0.12053 (17)	0.2469 (4)	0.0371 (9)
C2	0.6550 (4)	−0.09278 (19)	0.2478 (4)	0.0311 (10)
N2	0.7485 (4)	−0.1440 (2)	0.2471 (4)	0.0455 (11)
N4	0.9962 (6)	0.0300 (3)	0.4583 (7)	0.0480 (16)
N3	0.9982 (4)	0.23658 (17)	−0.0019 (4)	0.0381 (9)
H31	0.921 (4)	0.209 (3)	−0.036 (7)	0.149 (16)*
H32	1.081 (4)	0.217 (3)	−0.046 (7)	0.149 (16)*
H33	0.987 (7)	0.2854 (14)	−0.032 (7)	0.149 (16)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cd1	0.0283 (6)	0.0237 (3)	0.0221 (3)	0	0.0006 (3)	0
Cd2	0.0253 (3)	0.0415 (4)	0.0434 (4)	0	−0.0008 (2)	0
Ni	0.0195 (3)	0.0215 (3)	0.0350 (3)	0	0.0007 (2)	0
C1	0.0249 (14)	0.0247 (15)	0.0350 (17)	0.0026 (12)	−0.0009 (13)	−0.0001 (12)
N1	0.0316 (14)	0.0337 (16)	0.0461 (18)	−0.0038 (12)	0.0002 (12)	0.0000 (12)
C2	0.0272 (17)	0.0325 (17)	0.0337 (18)	−0.0003 (13)	0.0004 (13)	−0.0006 (12)
N2	0.0404 (17)	0.045 (2)	0.0507 (19)	0.0115 (15)	0.0001 (14)	0.0012 (15)
N4	0.050 (3)	0.047 (2)	0.047 (3)	−0.0017 (19)	0.001 (2)	0.0165 (19)
N3	0.0392 (17)	0.0393 (15)	0.0358 (16)	0.0007 (12)	0.0003 (13)	0.0026 (12)

Geometric parameters (Å, º)

	Average	Minimum	Maximum
Cd1—N1	2.28 (3)	2.23 (3)	2.38 (2)
Cd1—N3	2.187 (19)	2.046 (19)	2.25 (2)
Cd1—N2^i	3.03 (3)	2.70 (3)	3.33 (3)
Cd2—N1	2.39 (2)	2.249 (15)	2.470 (17)
Cd2—N3	2.305 (18)	2.222 (17)	2.516 (17)
Cd2—N4	2.40 (2)	2.320 (18)	2.596 (18)
Ni—C1	1.85 (2)	1.78 (3)	1.89 (3)
Ni—C2	1.865 (19)	1.687 (19)	2.065 (19)
N1—C1	1.15 (3)	1.12 (2)	1.18 (4)
N2—C2	1.15 (3)	1.11 (3)	1.20 (3)
N3—N2^ii	3.22 (2)	3.11 (2)	3.38 (2)
N3—N2^iii	3.22 (2)	3.11 (2)	3.38 (2)
N1—Cd1—N1^iv	101.6 (12)	99.7 (15)	102.8 (12)
N1—Cd1—N3	98.6 (9)	95.0 (8)	102.3 (10)
N1—Cd1—N3^iv	99.4 (9)	92.1 (7)	106.0 (11)
N1—Cd1—N2^i	170.6 (11)	162.9 (8)	174.6 (10)
N1—Cd1—N2^v	87.5 (7)	80.4 (6)	93.4 (9)
N3—Cd1—N3^iv	150.3 (14)	148.8 (13)	152.6 (19)
N3—Cd1—N2^i	79.0 (8)	75.4 (7)	82.3 (8)
N3—Cd1—N2^v	79.4 (8)	76.7 (7)	81.6 (8)
N2^i—Cd1—N2^v	83.4 (8)	83.1 (7)	83.7 (10)
N1—Cd2—N1^iv	165.1 (10)	155.0 (10)	172.7 (12)
N1—Cd2—N3	93.7 (7)	91.4 (7)	96.1 (9)
N1—Cd2—N3^iv	95.2 (7)	85.7 (6)	109.0 (9)
N1—Cd2—N4	85.5 (9)	78.4 (7)	88.3 (9)
N1—Cd2—N4^iv	85.3 (8)	82.7 (8)	86.8 (8)
N3—Cd2—N3^iv	100.6 (8)	95.4 (10)	109.5 (7)
N3—Cd2—N4	169.3 (8)	152.7 (7)	175.6 (11)
N3—Cd2—N4^iv	90.2 (7)	82.5 (5)	96.0 (6)
N4—Cd2—N4^iv	83.0 (10)	77.8 (8)	86.4 (12)
Cd1—N1—C1	175 (2)	167.9 (14)	178 (2)
Cd2—N1—C1	140.8 (18)	135.9 (14)	145.4 (14)
Ni—C1—N1	178 (2)	177 (2)	179.4 (17)
Cd1^vi—N2—C2	98.9 (14)	90.3 (13)	108.9 (14)
Ni—C2—N2	176.1 (18)	168.5 (17)	179.9 (18)

Symmetry codes: (i) x₁+1/2, x₂+1/2, x₃, x₄; (ii) −x₁+2, −x₂, −x₃, −x₄; (iii) x₁, −x₂, x₃−1/2, x₁/2; (iv) −x₁+2, x₂, −x₃+1/2, −x₁/2; (v) −x₁+3/2, x₂+1/2, −x₃+1/2, −x₁/2; (vi) x₁−1/2, x₂−1/2, x₃, x₄.