Cobalt hydrogen selenite chloride dihydrate, Co(HSeO₃)Cl·2H₂O

Cobalt hydrogen selenite chloride dihydrate, Co(HSeO₃)Cl·2H₂O, is built up from a network of trans CoO₄Cl₂ octahedra, cis Co(H₂O)₄Cl₂ octahedra and HSeO₃ pyramids. These units [d_av(Co—O) = 2.075 (2) Å, d_av(Co—Cl) = 2.5370 (6) Å and d_av(Se—O) = 1.703 (2) Å] share vertices by way of Co—O—Se and Co—Cl—Co bonds to produce a three-dimensional structure. Co of the trans octahedron occupies an inversion centre; Co of the cis octahedron and two attached water O atoms lie on a mirror plane. The hydrogen-bonding scheme has been elucidated and involves O—H...O and O—H...Cl interactions. The title compound is isostructural with Cu(HSeO₃)Cl·2H₂O, although the metal polyhedra are distinctly different in the two phases.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](Co-O) = 0.002 Å
• R factor = 0.022
• wR factor = 0.062
• Data-to-parameter ratio = 27.5

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level B:



CHEMS_01  Alert B The sum formula contains elements in the wrong order.
          H  precedes Cl
          Sequence must be C, H, then alphabetical.

Author response: Sorry, don't know what we're doing wrong!

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      0.907
          Tmax scaled      0.471 Tmin scaled      0.124


 0 Alert Level A = Potentially serious problem

 1 Alert Level B = Potential problem

 0 Alert Level C = Please check

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S1. Comment

The title compound represents another example of a hydrogen selenite chloride hydrate, complementing Co(HSeO₃)Cl·3H₂O and Cu(HSeO₃)Cl·2H₂O (Johnston & Harrison, 2000). Co(HSeO₃)Cl·2H₂O (Figs. 1 and 2) is essentially isostructural with Cu(HSeO₃)Cl·2H₂O, although the metal coordinations are distinctly different in the two phases.

Co1 (site symmetry 1) has elongated octahedral coordination to four O and two Cl atoms. The cis bond angles lie between 88.09 (4) and 91.91 (4)°. The O atoms form bridges to adjacent Se atoms [θ_av(Co—O—Se) = 119.8 (8)°] and the Cl atoms link to Co2 cations. The average Co1—O distance of 2.049 (2) Å and the Co1—Cl separation of 2.5989 (6) Å correlate reasonably well with ionic radius (IR) sums for the species involved [d_IR(Co—O) = 2.09 Å and d_IR(Co—Cl) = 2.56 Å], assuming the presence of high-spin Co²⁺ (Shannon, 1976). In Cu(HSeO₃)Cl·2H₂O (Johnston & Harrison, 2000), the distinction between the equatorial Cu—O bonds [d_av = 1.976 (2) Å] and apical Cu—Cl [d = 2.8066 (5) Å] bonds is more extreme, and can be ascribed to a typical Jahn–Teller distortion for the d⁹ Cu²⁺ ion.

The pyramidal geometry of the [HSeO₃]^- moiety and the lengthened, protonated, Se—O3H bond in the title compound are typical for the hydrogen selenite group (Verma, 1999). The unobserved Se^IV lone pair of electrons is presumed to occupy the fourth vertex of a tetrahedron, and as such, is directed into empty space at an angle of about 35° with respect to a projection of the Se—E (E = lone pair) vector on to (010). These [Co(HSeO₃)₂Cl₂]^2- layers consist of polyhedral eight-rings (Fig. 3) and a pair of intra-sheet Se—O3—H1···O1 hydrogen bonds stabilizes each of these voids.

The four O and two Cl atoms around Co2 (site symmetry m) form a distorted cis Co(H₂O)₄Cl₂ octahedron [d_av(Co—O) = 2.100 (3) Å]. The cis and trans bond angles lie in the ranges 87.04 (8)–92.68 (7) and 173.00 (12)–179.19 (6)°, respectively. The [Co2(H₂O)₄Cl₂] octahedra are isolated from each other, and bridge the (010) [Co(HSeO₃)₂Cl₂]^2- sheets via Co1—Cl1—Co2—Cl1—Co1 bonds to produce a three-dimensional structure. The hydrogen bonds (Table 2 and Fig. 4) associated with the Co2-polyhedron water molecules include O—H···O and O—H···Cl links. In Cu(HSeO₃)Cl·2H₂O, a Jahn-T-eller distortion led to long bonds to two of the trans water-molecule O atoms [2.229 (3) and 2.634 (5) Å], two short symmetry-equivalent Cu—OH₂ links [2.0244 (16) Å] and a short Cu—Cl bond [d = 2.3127 (5) Å].

S2. Experimental

A mixture of 7 ml 0.5M `H₂SeO₃' solution (dissolved SeO₂), 8 ml 1 M LiCl solution and 0.714 g (3 mmol) CoCl₂·6H₂O were sealed in a 23 ml capacity Teflon-lined hydrothermal bomb, and heated to 473 K for 6 d. After cooling over a few hours and opening the bomb, there was no solid product. The resultant red liquor was placed in a Petri dish, and after 10 d, purple chunky crystals of the title compound were recovered by vacuum filtration. These were not rinsed, as the crystals redissolve very easily. Co(HSeO₃)Cl·2H₂O crystals appear to be stable when stored in a dry atmosphere.

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: SHELXS97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997) and ATOMS (Shape Software, 1999); software used to prepare material for publication: SHELXS97.

Figures

	Fig. 1. Fragment of Co(HSeO3)Cl·2H2O (50% displacement ellipsoids; arbitrary spheres for the H atoms). [Symmetry codes: (i) 1/2 + x, y, 1/2 - z; (ii) 1/2 - x, -y, 1/2 + z; (iii) 1 - x, -y, 1 - z; (iv) x, 1/2 - y, z.]
	Fig. 2. Polyhedral representation of Co(HSeO3)Cl·2H2O, viewed approximately normal to (001). Colour key: Co1O4Cl2 octahedra purple, Co2(H2O)4Cl2 octahedra blue, HSeO3E (E = dummy atom representing the lone pair of electrons placed 1.0 Å from Se) pseudo-tetrahedra yellow. The coloured spheres (radii arbitrary) represent O atoms (red), Cl atoms (green), and H atoms (grey).
	Fig. 3. Polyhedral representation of a sheet of Co1 and Se centred groups in Co(HSeO3)Cl·2H2O, viewed down [010] (-0.20 < y < 1/5), showing the squashed eight-ring voids bridged by pairs of hydrogen bonds (H···O portion coloured red). Otherwise, the colour key is as in Fig. 2.
	Fig. 4. Section of Co(HSeO3)Cl·2H2O (50% displacement ellipsoids; arbitrary spheres for the H atoms), showing the hydrogen bonds (dashed lines) associated with the water molecules bonded to Co2. Atom H1 has been omitted for clarity and the symmetry codes are as in Table 2.

(I)

Crystal data

Co(HSeO3)Cl·2H2O	F(000) = 984
Mr = 258.38	Dx = 2.895 Mg m^−3
Orthorhombic, Pnma	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2n	Cell parameters from 5736 reflections
a = 9.3384 (4) Å	θ = 3.5–32.5°
b = 17.3447 (7) Å	µ = 9.42 mm^−1
c = 7.3198 (3) Å	T = 293 K
V = 1185.60 (9) Å^3	Chunk, purple
Z = 8	0.35 × 0.16 × 0.08 mm

Data collection

Bruker SMART1000 CCD diffractometer	2199 independent reflections
Radiation source: fine-focus sealed tube	1923 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.025
ω scans	θmax = 32.5°, θmin = 2.4°
Absorption correction: multi-scan (SADABS; Bruker, 1999)	h = −13→14
Tmin = 0.137, Tmax = 0.519	k = −22→26
11031 measured reflections	l = −9→11

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.022	H-atom parameters constrained
wR(F^2) = 0.062	w = 1/[σ^2(Fo^2) + (0.0396P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.02	(Δ/σ)max = 0.001
2199 reflections	Δρmax = 0.92 e Å^−3
80 parameters	Δρmin = −0.94 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: 0.0007 (2)

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
Co1	0.5000	0.0000	0.5000	0.01431 (9)
Co2	0.34707 (4)	0.2500	0.44220 (6)	0.02110 (10)
Cl1	0.52299 (6)	0.14898 (3)	0.52387 (8)	0.02438 (12)
Se1	0.185092 (19)	−0.052173 (11)	0.34310 (2)	0.01417 (7)
O1	0.04599 (16)	0.00205 (9)	0.27245 (19)	0.0194 (3)
O2	0.28545 (15)	0.01510 (9)	0.4468 (2)	0.0190 (3)
O3	0.10764 (19)	−0.09922 (10)	0.5306 (2)	0.0248 (3)
H1	0.0548	−0.0635	0.5905	0.030*
O4	0.4115 (3)	0.2500	0.1698 (3)	0.0332 (6)
H2	0.4194	0.2907	0.1061	0.040*
O5	0.2540 (3)	0.2500	0.7117 (4)	0.0420 (7)
H3	0.2100	0.2097	0.7277	0.050*
O6	0.20069 (17)	0.16398 (10)	0.3759 (3)	0.0289 (3)
H4	0.2298	0.1197	0.3922	0.035*
H5	0.1539	0.1618	0.2721	0.035*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Co1	0.01159 (16)	0.01917 (19)	0.01216 (16)	0.00094 (13)	0.00081 (11)	0.00035 (12)
Co2	0.02045 (19)	0.0178 (2)	0.0250 (2)	0.000	0.00051 (14)	0.000
Cl1	0.0225 (2)	0.0177 (2)	0.0329 (3)	0.00136 (18)	−0.00375 (18)	0.00163 (19)
Se1	0.01389 (10)	0.01519 (10)	0.01344 (10)	0.00180 (6)	−0.00075 (6)	−0.00107 (6)
O1	0.0180 (6)	0.0260 (8)	0.0143 (6)	0.0075 (5)	−0.0035 (5)	−0.0022 (5)
O2	0.0139 (6)	0.0177 (7)	0.0254 (7)	0.0002 (5)	−0.0043 (5)	−0.0028 (5)
O3	0.0299 (8)	0.0204 (8)	0.0241 (7)	0.0032 (6)	0.0086 (6)	0.0065 (6)
O4	0.0501 (16)	0.0208 (12)	0.0287 (12)	0.000	0.0051 (11)	0.000
O5	0.0538 (18)	0.0298 (15)	0.0423 (14)	0.000	0.0195 (13)	0.000
O6	0.0253 (8)	0.0170 (8)	0.0444 (9)	−0.0004 (6)	−0.0076 (7)	−0.0001 (7)

Geometric parameters (Å, º)

Co1—O1^i	2.0403 (14)	Co2—Cl1^iv	2.4751 (6)
Co1—O1^ii	2.0403 (14)	Co2—Cl1	2.4751 (6)
Co1—O2	2.0578 (14)	Se1—O2	1.6779 (15)
Co1—O2^iii	2.0578 (14)	Se1—O1	1.6851 (14)
Co1—Cl1^iii	2.5989 (6)	Se1—O3	1.7530 (15)
Co1—Cl1	2.5989 (6)	O3—H1	0.9050
Co2—O6	2.0809 (17)	O4—H2	0.8493
Co2—O6^iv	2.0809 (17)	O5—H3	0.8200
Co2—O4	2.083 (2)	O6—H4	0.8227
Co2—O5	2.155 (3)	O6—H5	0.8776
O1^i—Co1—O1^ii	180.00 (9)	O6—Co2—Cl1^iv	179.19 (6)
O1^i—Co1—O2	91.01 (6)	O6^iv—Co2—Cl1^iv	89.13 (5)
O1^ii—Co1—O2	88.99 (6)	O4—Co2—Cl1^iv	92.27 (6)
O1^i—Co1—O2^iii	88.99 (6)	O5—Co2—Cl1^iv	92.68 (7)
O1^ii—Co1—O2^iii	91.01 (6)	O6—Co2—Cl1	89.13 (5)
O2—Co1—O2^iii	180.0	O6^iv—Co2—Cl1	179.19 (6)
O1^i—Co1—Cl1^iii	88.23 (5)	O4—Co2—Cl1	92.27 (6)
O1^ii—Co1—Cl1^iii	91.77 (5)	O5—Co2—Cl1	92.68 (7)
O2—Co1—Cl1^iii	91.91 (4)	Cl1^iv—Co2—Cl1	90.13 (3)
O2^iii—Co1—Cl1^iii	88.09 (4)	Co2—Cl1—Co1	129.26 (2)
O1^i—Co1—Cl1	91.77 (5)	O2—Se1—O1	100.44 (7)
O1^ii—Co1—Cl1	88.23 (5)	O2—Se1—O3	101.54 (8)
O2—Co1—Cl1	88.09 (4)	O1—Se1—O3	100.49 (8)
O2^iii—Co1—Cl1	91.91 (4)	Se1—O1—Co1^v	116.90 (8)
Cl1^iii—Co1—Cl1	180.0	Se1—O2—Co1	122.75 (8)
O6—Co2—O6^iv	91.62 (10)	Se1—O3—H1	106.6
O6—Co2—O4	88.08 (8)	Co2—O4—H2	123.4
O6^iv—Co2—O4	88.08 (8)	Co2—O5—H3	109.5
O6—Co2—O5	87.04 (8)	Co2—O6—H4	114.7
O6^iv—Co2—O5	87.04 (8)	Co2—O6—H5	124.0
O4—Co2—O5	173.00 (12)	H4—O6—H5	104.5

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O3—H1···O1^vi	0.90	1.74	2.641 (2)	173
O4—H2···O3^vii	0.85	2.00	2.8123 (18)	159
O5—H3···Cl1^viii	0.82	2.73	3.387 (2)	138
O6—H4···O2	0.82	1.93	2.750 (2)	175
O6—H5···Cl1^ix	0.88	2.50	3.3741 (18)	177

Symmetry codes: (vi) −x, −y, −z+1; (vii) −x+1/2, y+1/2, z−1/2; (viii) x−1/2, y, −z+3/2; (ix) x−1/2, y, −z+1/2.