A three-dimensional porous framework complex, poly[[bis(ethylenediamine)copper(II)] [potassium hexacyanocobalt(III)]]

The crystal structure of the title compound, {[Cu(en)₂][KCo(CN)₆]}_n (en is ethyl­enedi­amine, C₂H₈N₂), reveals a novel three-dimensional porous framework in which [Cu(en)₂]²⁺ acts as a template and K⁺ as a connecting unit. The Cu atom lies on an inversion centre and the Co and K atoms are on twofold axes.

S1. Comment

The design and synthesis of well characterized molecular-based magnets remains a challenge (Kahn, 1995). It is well known that hexacyanometallate ions, [M(CN)₆]^3-, acting as good building blocks, play an important role in realising bimetallic assemblies. Although a series of bimetallic assemblies derived from a hexacyanometallate ion and a four-coordinate bis(diamine)-metal complex have been synthesized (Ohba et al., 1994; Fukita et al., 1998; Yuan et al., 2000), the most commonly employed building blocks are [Fe(CN)₆]^3-, [Cr(CN)₆]^3- and [Co(CN)₆]^3- (Ferbinteanu et al., 1999). We have previously reported the three-dimensional porous framework complex {[Cu(en)₂][KCr(CN)₆]}_n (Yuan et al., 2000), and we report here the crystal structure of the title complex, {[Cu(en)₂][KCo(CN)₆]}_n, (I). \sch

The structure of (I) is shown in Fig. 1, 2 and 3. The Co³⁺ ion is coordinated by six C atoms of the cyanide groups to form a slightly distorted octahedral geometry, and the Co—C bond lengths are 1.9001 (19), 1.9004 (19) and 1.9056 (18) Å, which are similar to the values found in K₃[Co(CN)₆] [1.876 (11), 1.896 (11) and 1.916 (11) Å; Vannerberg, 1972] and less than the Cr—C bond lengths in the similar complex {[Cu(en)₂][KCr(CN)₆]}_n [2.065 (3), 2.080 (2) and 2.085 (2) Å]. The C3—Co—C4, C4—Co—C5 and C5—Co—C3 bond angles are 92.71 (8), 87.95 (7) and 89.05 (8)°, respectively. The K⁺ cation is unusually coordinated by six cyanide groups of neighbouring cyanometallates, which act as bridging ligands to link the Co³⁺ and K⁺ ions.

All the cyanide groups in (I) can be divided into two groups according to the K···N distances and C—N···K angles. One is with a linear Co—C—N—K linkage, using the σ electrons of the N atom coordinating to the K⁺ cation, the K···N distances of which are 2.8158 (18) and 2.8746 (16) Å; the C—N···K angles are 179.28 (17) and 172.46 (17)°. The other is with a non-linear Co—C—N—K linkage, using the π electrons of the CN group coordinating to the K⁺ cation (Guo & Mak, 1998). Here, the K···N and K···C distances are 3.183 (2) and 3.326 (2) Å, respectively; the K···N distance is much longer than that of the above linear span. The C—N···K and N—C···K angles are 86.88 (14) and 72.85 (13)°, respectively.

The three-dimensional framework of (I) is composed of two kinds of linkage, CN—Co—CN—K and Co—CN—K—CN, with σ- and π-coordination forming a distorted cube-like void space, as shown in Fig. 2, with sides of about 9.0 × 8.9 Å. There are two small squares in both the upper and lower planes of the cube, which are composed of KOC, CoD and two CN with a π-coordination mode. Three other squares are as follows: KOD, CoE and two CN, KOG, CoF and two CN, and KOH, CoJ and two CN (atom labels as in Fig. 2). The sides of the square are about 3.2 × 3.1 Å. The complex [Cu(en)2]²⁺ ions occupy the centre of the cube with two positions of occupancies 0.535 and 0.465.

The Cu—N bond lengths within [Cu(en)₂]²⁺ are 1.9929 (18) and 1.9895 (19) Å, which are similar to those found in [Cu(en)₂X₂] (where X is NCS^-, BF₄^-, ClO₄^-, NO₃^- or Cl^-, Br^-; Procter et al., 1968). The distance between Cu and the nearest cyano N atom is 2.891 (4) Å. The Cu²⁺ ion is coordinated by four N atoms from two en ligands and two cyano N atoms, forming an elongated octahedron geometry.

Related literature

For related literature, see: Ferbinteanu et al. (1999); Fukita et al. (1998); Guo & Mak (1998); Kahn (1995); Ohba et al. (1994); Procter et al. (1968); Vannerberg (1972); Yuan et al. (2000).

S2. Experimental

Caution! Perchlorate salts are potentially explosive and should be handled in small quantities.

Ethylenediamine (en; 2 mmol) was added to an aqueous solution (20 ml) of Cu(ClO4)₂·6H₂O (1 mmol) with stirring. The colour of the solution turned to blue-violet. After stirring for 20 min, the solution was then mixed with an aqueous solution (20 ml) of K₃[Co(CN)₆] (1 mmol). The resulting solution was filtered and the filtrate was left for one week in the dark at room temperature. Violet-red crystals of {[Cu(en)₂][KCo(CN)₆]}_n, (I), suitable for X-ray diffraction analysis, were obtained. The product is stable under ambient conditions, and is insoluble in most common inorganic and organic solvents. Analysis, found: C 27.14, H 3.58, N 31.32%; calculated for C₁₀H₁₆CoCuKN₁₀: C 27.43, H 3.68, N 32.00%.

S3. Refinement

H atoms were treated as riding, with C—H = 0.97 and N—H = 0.90 Å, and with U_iso(H) equal to 1.2 times U_eq of the parent atom. Query.

Computing details

Data collection: XSCANS (Siemens, 1996); cell refinement: XSCANS; data reduction: SHELXTL (Sheldrick, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Figures

	Fig. 1. The coordination geometry of the K^+, Co^3+ and [Cu(en)2]^2+ ions of (I), with displacement ellipsoids at the 30% probability level. H atoms have been omitted for clarity.
	Fig. 2. A view of (I) parallel to the b axis.
	Fig. 3. The unit-cell contents of (I).

Poly{[bis(ethylenediamine)copper(II)] [potassium hexacyanocobalt(III)]}

Crystal data

[Cu(C2H8N2)2][KCo(CN)6]	F(000) = 884
Mr = 437.90	Dx = 1.764 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
a = 8.391 (2) Å	Cell parameters from 26 reflections
b = 16.866 (3) Å	θ = 3.0–17.5°
c = 11.791 (2) Å	µ = 2.56 mm^−1
β = 98.91 (2)°	T = 295 K
V = 1648.6 (6) Å^3	Block, violet-red
Z = 4	0.44 × 0.41 × 0.20 mm

Data collection

Siemens P4 diffractometer	1606 reflections with I > 2σ(I)
Radiation source: normal-focus sealed tube	Rint = 0.013
Graphite monochromator	θmax = 27°, θmin = 2.4°
ω scans	h = 0→10
Absorption correction: ψ-scan (North et al., 1968)	k = −1→21
Tmin = 0.333, Tmax = 0.599	l = −15→14
2172 measured reflections	3 standard reflections every 97 reflections
1797 independent reflections	intensity decay: 3.6%

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)] = 0.024	H-atom parameters constrained
wR(F^2) = 0.062	w = 1/[σ^2(Fo^2) + (0.0355P)^2 + 0.0854P] where P = (Fo^2 + 2Fc^2)/3
S = 1.05	(Δ/σ)max = 0.001
1797 reflections	Δρmax = 0.43 e Å^−3
127 parameters	Δρmin = −0.28 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 1997), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0044 (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	Occ. (<1)
Cu	0	0	0	0.03702 (13)
Co	−1/2	−0.11561 (2)	−1/4	0.01809 (11)
K	−1/2	0.14220 (4)	−1/4	0.02579 (14)
N1	0.1150 (2)	0.08553 (11)	−0.07137 (15)	0.0381 (5)
H1A	0.2174	0.0898	−0.0355	0.046*	0.535 (4)
H1B	0.1164	0.0748	−0.1460	0.046*	0.535 (4)
N2	−0.1205 (2)	0.08848 (12)	0.05931 (17)	0.0472 (6)
H2A	−0.2240	0.0876	0.0247	0.057*	0.535 (4)
H2B	−0.1192	0.0824	0.1353	0.057*	0.535 (4)
C1	0.0287 (10)	0.1575 (5)	−0.0597 (9)	0.055 (2)	0.535 (4)
H1C	0.1037	0.2015	−0.0559	0.066*	0.535 (4)
H1D	−0.0509	0.1647	−0.1279	0.066*	0.535 (4)
C2	−0.0510 (12)	0.1605 (6)	0.0384 (7)	0.056 (2)	0.535 (4)
H2C	0.0261	0.1754	0.1050	0.068*	0.535 (4)
H2D	−0.1341	0.2010	0.0268	0.068*	0.535 (4)
H1A'	0.2219	0.0765	−0.0563	0.046*	0.465 (4)
H1B'	0.0853	0.0840	−0.1480	0.046*	0.465 (4)
H2A'	−0.2265	0.0769	0.0496	0.057*	0.465 (4)
H2B'	−0.0861	0.0951	0.1349	0.057*	0.465 (4)
C1'	0.0804 (10)	0.1669 (7)	−0.0284 (9)	0.044 (2)	0.465 (4)
H1'1	0.0912	0.2067	−0.0860	0.053*	0.465 (4)
H1'2	0.1542	0.1795	0.0409	0.053*	0.465 (4)
C2'	−0.0944 (12)	0.1636 (7)	−0.0039 (7)	0.0413 (18)	0.465 (4)
H2'1	−0.1154	0.2090	0.0420	0.050*	0.465 (4)
H2'2	−0.1686	0.1655	−0.0756	0.050*	0.465 (4)
N3	−0.2401 (2)	−0.24183 (11)	−0.24466 (15)	0.0451 (5)
N4	−0.49330 (19)	−0.11768 (12)	0.00952 (13)	0.0366 (4)
N5	−0.2312 (2)	0.00773 (11)	−0.20865 (17)	0.0384 (4)
C3	−0.3384 (2)	−0.19515 (11)	−0.24350 (15)	0.0267 (4)
C4	−0.4945 (2)	−0.11660 (11)	−0.08784 (15)	0.0241 (4)
C5	−0.3349 (2)	−0.03750 (11)	−0.22782 (14)	0.0234 (4)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu	0.0317 (2)	0.0334 (2)	0.0518 (2)	0.00252 (15)	0.02479 (17)	0.00547 (16)
Co	0.01755 (18)	0.01938 (18)	0.01787 (17)	0	0.00438 (12)	0
K	0.0281 (3)	0.0260 (3)	0.0241 (3)	0	0.0067 (2)	0
N1	0.0324 (10)	0.0466 (12)	0.0372 (9)	−0.0069 (8)	0.0115 (7)	0.0009 (8)
N2	0.0463 (12)	0.0492 (13)	0.0516 (12)	0.0145 (10)	0.0249 (9)	0.0086 (10)
C1	0.053 (5)	0.030 (4)	0.086 (6)	−0.005 (3)	0.023 (4)	0.014 (4)
C2	0.066 (6)	0.044 (4)	0.063 (6)	−0.003 (4)	0.022 (4)	−0.011 (5)
C1'	0.035 (5)	0.039 (4)	0.061 (5)	−0.018 (3)	0.012 (3)	−0.007 (3)
C2'	0.047 (5)	0.034 (3)	0.043 (5)	0.012 (3)	0.008 (3)	0.011 (4)
N3	0.0456 (11)	0.0461 (11)	0.0437 (11)	0.0194 (10)	0.0077 (9)	−0.0019 (10)
N4	0.0382 (10)	0.0498 (12)	0.0227 (9)	0.0014 (8)	0.0072 (7)	0.0024 (7)
N5	0.0351 (10)	0.0367 (10)	0.0448 (11)	−0.0108 (8)	0.0112 (8)	−0.0062 (8)
C3	0.0270 (9)	0.0283 (10)	0.0248 (9)	0.0028 (8)	0.0042 (7)	−0.0005 (8)
C4	0.0200 (8)	0.0262 (9)	0.0262 (10)	0.0020 (7)	0.0042 (7)	0.0004 (7)
C5	0.0249 (9)	0.0248 (9)	0.0215 (8)	0.0013 (8)	0.0068 (7)	−0.0013 (7)

Geometric parameters (Å, º)

Cu—N2^i	1.9895 (19)	N1—H1B	0.9000
Cu—N2	1.9895 (19)	N2—C2	1.386 (11)
Cu—N1	1.9928 (18)	N2—H2A	0.9000
Cu—N1^i	1.9928 (18)	N2—H2B	0.9000
Co—C5^ii	1.9001 (19)	C1—C2	1.424 (15)
Co—C5	1.9001 (19)	C1—H1C	0.9700
Co—C3	1.9004 (19)	C1—H1D	0.9700
Co—C3^ii	1.9004 (19)	C2—H2C	0.9700
Co—C4	1.9056 (18)	C2—H2D	0.9700
Co—C4^ii	1.9056 (18)	C1'—C2'	1.539 (15)
K—N3^iii	2.8158 (18)	C1'—H1'1	0.9700
K—N3^iv	2.8158 (18)	C1'—H1'2	0.9700
K—N4^v	2.8746 (16)	C2'—H2'1	0.9700
K—N4^vi	2.8746 (16)	C2'—H2'2	0.9700
K—N5^ii	3.183 (2)	N3—C3	1.142 (2)
K—N5	3.183 (2)	N3—K^vii	2.8158 (18)
K—C5	3.326 (2)	N4—C4	1.147 (2)
K—C5^ii	3.326 (2)	N4—K^vi	2.8746 (16)
N1—C1	1.431 (10)	N5—C5	1.153 (2)
N1—H1A	0.9000
N2^i—Cu—N2	180.00 (14)	C2—N2—Cu	110.1 (4)
N2^i—Cu—N1	95.10 (9)	C2—N2—H2A	109.6
N2—Cu—N1	84.90 (9)	Cu—N2—H2A	109.6
N2^i—Cu—N1^i	84.90 (9)	C2—N2—H2B	109.6
N2—Cu—N1^i	95.10 (9)	Cu—N2—H2B	109.6
N1—Cu—N1^i	180.00 (12)	H2A—N2—H2B	108.1
C5^ii—Co—C5	92.21 (11)	C2—C1—N1	114.6 (8)
C5^ii—Co—C3	174.44 (7)	C2—C1—H1C	108.6
C5—Co—C3	89.05 (8)	N1—C1—H1C	108.6
C5^ii—Co—C3^ii	89.05 (8)	C2—C1—H1D	108.6
C5—Co—C3^ii	174.44 (7)	N1—C1—H1D	108.6
C3—Co—C3^ii	90.20 (12)	H1C—C1—H1D	107.6
C5^ii—Co—C4	92.74 (7)	N2—C2—C1	112.1 (7)
C5—Co—C4	87.95 (7)	N2—C2—H2C	109.2
C3—Co—C4	92.71 (8)	C1—C2—H2C	109.2
C3^ii—Co—C4	86.58 (8)	N2—C2—H2D	109.2
C5^ii—Co—C4^ii	87.95 (7)	C1—C2—H2D	109.2
C5—Co—C4^ii	92.74 (7)	H2C—C2—H2D	107.9
C3—Co—C4^ii	86.58 (8)	C2'—C1'—H1'1	110.6
C3^ii—Co—C4^ii	92.71 (8)	C2'—C1'—H1'2	110.6
C4—Co—C4^ii	179.00 (11)	H1'1—C1'—H1'2	108.7
C1—N1—Cu	106.8 (4)	C1'—C2'—H2'1	109.7
C1—N1—H1A	110.4	C1'—C2'—H2'2	109.7
Cu—N1—H1A	110.4	H2'1—C2'—H2'2	108.2
C1—N1—H1B	110.4	N3—C3—Co	176.75 (18)
Cu—N1—H1B	110.4	N4—C4—Co	179.06 (18)
H1A—N1—H1B	108.6	N5—C5—Co	176.10 (17)
N2^i—Cu—N1—C1	169.2 (4)	Cu—N2—C2—C1	27.7 (9)
N2—Cu—N1—C1	−10.8 (4)	N1—C1—C2—N2	−39.4 (11)
N1—Cu—N2—C2	−9.1 (4)	C3—Co—C5—K	174.59 (7)
N1^i—Cu—N2—C2	170.9 (4)	C4—Co—C5—K	−92.67 (7)
Cu—N1—C1—C2	29.7 (8)	C4^ii—Co—C5—K	88.06 (7)

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