Potassium bis­(carbonato-O,O')(ethylenedi­amine-N,N')­cobaltate(III) monohydrate at 173 K

The title salt, K[Co(C₂H₈N₂)(CO₃)₂]·H₂O, consists of a distorted octahedral cobalt complex anion and a seven-coordinate potassium cation. Both metal atoms have crystallographic twofold symmetry, one C₂ axis passing through the Co atom and C-C bond, and another along a short K-O (water) bond of 2.600 Å (corrected for libration). The carbonate is bidentate to both cobalt and potassium and the water forms a hydrogen bond to a carbonate O atom.

S1. Comment

Carbonato complexes of cobalt(III) are important intermediates, allowing access to a wide range of cobalt complexes (Kitamura & Shibata, 1993; Shibata, 1983). There have been several reports of the structure of [CoCO₃(en)₂]⁺ with various anions (Bigoli et al., 1980; Healy et al., 1981; Bernal et al., 1993; Garcia-Granda et al., 1993; Hu et al., 1997) (en is ethylenediamine). Structures of other monocarbonato cobalt(III) complexes have also been reported. To our knowledge the only previous structure report of a cobalt(III) complex containing two coordinated carbonates on a single Co atom is the binuclear complex (NH₃)₄Co(µ –NH₂)(µ –OH)Co(CO₃)₂ (Churchill et al., 1979). \sch

The title salt, K[Co(CO₃)₂(NH₂CH₂CH₂NH₂)]·H₂O, (I), contains a distorted octahedral cobalt(III) anion (Fig. 1) with a crystallographic twofold axis passing through the Co and the C–C bond of the en ligand. The main distortions from octahedral geometry arise from the narrow 'bite' of the carbonato ligand, with a O1—Co—O2 angle of 69.12 (4)°. The C1≐O3 bond is slightly shorter (by about 0.07 Å) than C1≐O1 and C1≐O2, suggesting partial localization of the charge on the coordinated carbonate. Other distances and angles of the anion are as expected.

The potassium cation is seven-coordinate (Fig. 2). The carbonate is bidentate to Co through O1 and O2, and also bidentate to K through O2 and O3. The water oxygen O4 is bound to K along a crystallographic twofold axis, and carbonates from two neighboring anions bind in a monodentate fashion through O1. The two O1 carbonate O atoms and the O4 water oxygen form a trigonal plane with the K atom, having O—K—O angles of 124.28 (2), 124.28 (2) and 111.43 (5)°. The remaining O atoms from the bidentate carbonates form another approximate plane nearly perpendicular to the trigonal plane. Thus the K coordination might be described as a type of trigonal bipyramidal geometry where each axial ligand is split in two. This arrangement, which is facilitated by the small bite angle of carbonate [the O2—K—O3 angle is 46.68 (3)°], allows the O4 water oxygen to have less steric interaction with the other O atoms around the K atom. This partially accounts for the short O4—K distance of 2.583 (2) Å.

In addition the displacement ellipsoid of O4 is elongated along an axis perpendicular to the K—O bond indicating a librational shortening of the bond length. A libration calculation using the full Schomaker-Trueblood tensor analysis (Schomaker & Trueblood, 1968) yielded a corrected K—O4 bond length of 2.598 Å, while the `riding model' correction (Johnson, 1970) was similar, giving a corrected length of 2.600 Å with an upper limit of 2.638 Å. Use of the riding model was justified based on parallel and perpendicular RMS amplitudes of K and O4.

S2. Experimental

The compound was synthesized using literature methods (Kitamura & Shibata, 1993). Suitable crystals were obtained by evaporation of an aqueous solution of (I) containing excess KHCO₃.

S3. Refinement

H atoms were refined isotropically in observed positions. Final N—H distances were 0.80 (2) and 0.87 (2) Å; C—H distances were 0.95 (2) and 0.924 (18) Å; the O—H distance was 0.72 (2) Å.

Computing details

Data collection: SMART (Bruker, 1998); cell refinement: SAINT (Bruker, 1998); data reduction: SHELXTL (Bruker, 1998); 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. A view of the anion. Displacement ellipsoids are drawn at the 50% probability level.
	Fig. 2. A view of the potassium coordination sphere. Displacement ellipsoids are drawn at the 50% probability level. Symmetry operations; (i) 1/2 + x, 1 - y, 1/2 + z; (ii) -x, 1 - y, 1 - z; (iii) 1/2 - x, y, 3/2 - z; (iv) 1/2 - x, y, 3/2 - z.
	Fig. 3. The unit-cell packing viewed down b.

Potassium bis(carbonato-O,O')(ethylenediamine-N,N')cobaltate(III) monohydrate

Crystal data

K[Co(CO3)2(C2H8N2)]·H2O	F(000) = 300
Mr = 296.17	Dx = 2.005 Mg m^−3
Monoclinic, P2/n	Mo Kα radiation, λ = 0.71073 Å
a = 8.2527 (13) Å	Cell parameters from 4154 reflections
b = 7.3864 (12) Å	θ = 2.5–28.3°
c = 8.5085 (14) Å	µ = 2.19 mm^−1
β = 108.947 (2)°	T = 173 K
V = 490.56 (14) Å^3	Block, purple
Z = 2	0.24 × 0.20 × 0.20 mm

Data collection

Bruker SMART CCD area detector diffractometer	1193 independent reflections
Radiation source: normal-focus sealed tube	1139 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.022
ω scans	θmax = 28.3°, θmin = 2.8°
Absorption correction: multi-scan (SADABS; Blessing, 1995)	h = −10→10
Tmin = 0.538, Tmax = 0.645	k = −9→9
5227 measured reflections	l = −11→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)] = 0.021	All H-atom parameters refined
wR(F^2) = 0.057	w = 1/[σ^2(Fo^2) + (0.04P)^2 + 0.12P] where P = (Fo^2 + 2Fc^2)/3
S = 1.07	(Δ/σ)max < 0.001
1193 reflections	Δρmax = 0.44 e Å^−3
91 parameters	Δρmin = −0.52 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 1997), Fc^*=3DkFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.030 (3)

Special details

Experimental. An approximate sphere of data was collected to 0.75 Å resolution with 98% coverage and 4.3 average redundancy. Crystal stability was monitored by recollection of the first fifty frames after data collection was complete. No significant change was observed in the 87 reflections measured.

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.

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

	x	y	z	Uiso*/Ueq
Co	0.2500	0.49378 (3)	0.2500	0.01380 (11)
N	0.20522 (17)	0.30274 (17)	0.08522 (15)	0.0183 (2)
O1	0.02113 (13)	0.53391 (14)	0.24827 (13)	0.0189 (2)
O2	0.24457 (12)	0.67035 (13)	0.41367 (12)	0.0178 (2)
O3	−0.01352 (14)	0.72829 (16)	0.44064 (13)	0.0254 (2)
O4	0.2500	1.0228 (3)	0.7500	0.0466 (6)
C1	0.07802 (18)	0.65065 (18)	0.37111 (17)	0.0181 (3)
C2	0.1848 (2)	0.1283 (2)	0.16346 (19)	0.0230 (3)
K	0.2500	0.67304 (6)	0.7500	0.01818 (13)
H0A	0.113 (3)	0.331 (3)	0.005 (3)	0.026 (5)*
H0B	0.280 (3)	0.303 (3)	0.044 (3)	0.025 (5)*
H2A	0.205 (3)	0.029 (3)	0.102 (3)	0.034 (6)*
H2B	0.075 (2)	0.123 (2)	0.168 (2)	0.018 (4)*
H4A	0.181 (3)	1.080 (3)	0.702 (3)	0.041 (6)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Co	0.01435 (16)	0.01518 (16)	0.01043 (16)	0.000	0.00203 (10)	0.000
N	0.0191 (6)	0.0200 (6)	0.0141 (5)	0.0001 (5)	0.0030 (5)	−0.0017 (4)
O1	0.0157 (5)	0.0221 (5)	0.0175 (5)	−0.0011 (4)	0.0035 (4)	0.0005 (4)
O2	0.0187 (5)	0.0194 (5)	0.0145 (4)	−0.0011 (4)	0.0042 (4)	−0.0023 (4)
O3	0.0253 (5)	0.0315 (6)	0.0214 (5)	0.0094 (4)	0.0104 (4)	0.0034 (4)
O4	0.0483 (13)	0.0203 (9)	0.0467 (13)	0.000	−0.0185 (11)	0.000
C1	0.0197 (6)	0.0197 (6)	0.0141 (6)	0.0022 (5)	0.0046 (5)	0.0041 (5)
C2	0.0266 (7)	0.0177 (7)	0.0230 (7)	−0.0033 (5)	0.0060 (6)	−0.0025 (5)
K	0.0173 (2)	0.0207 (2)	0.0155 (2)	0.000	0.00406 (15)	0.000

Geometric parameters (Å, º)

Co—O1^i	1.9073 (11)	O2—K	2.8475 (10)
Co—O1	1.9073 (11)	O3—C1	1.2409 (17)
Co—O2	1.9190 (10)	O3—K	2.8473 (11)
Co—O2^i	1.9190 (10)	O4—K	2.583 (2)
Co—N	1.9383 (12)	O4—H4A	0.72 (2)
Co—N^i	1.9383 (12)	C2—C2^i	1.516 (3)
N—C2	1.4846 (19)	C2—H2A	0.95 (2)
N—H0A	0.87 (2)	C2—H2B	0.924 (18)
N—H0B	0.80 (2)	K—O1^ii	2.7138 (11)
O1—C1	1.3182 (18)	K—O1^iii	2.7138 (11)
O1—K^ii	2.7138 (11)	K—O3^iv	2.8473 (11)
O2—C1	1.3109 (17)	K—O2^iv	2.8475 (11)
O1^i—Co—O1	162.12 (7)	O3—C1—O1	124.41 (13)
O1^i—Co—O2	98.35 (4)	O2—C1—O1	111.30 (12)
O1—Co—O2	69.12 (4)	N—C2—C2^i	106.70 (9)
O1^i—Co—O2^i	69.12 (4)	N—C2—H2A	111.2 (14)
O1—Co—O2^i	98.35 (4)	C2^i—C2—H2A	109.8 (15)
O2—Co—O2^i	94.37 (6)	N—C2—H2B	108.2 (11)
O1^i—Co—N	94.27 (5)	C2^i—C2—H2B	110.8 (11)
O1—Co—N	98.73 (5)	H2A—C2—H2B	110.1 (18)
O2—Co—N	167.36 (5)	O4—K—O1^ii	124.28 (2)
O2^i—Co—N	90.79 (5)	O4—K—O1^iii	124.28 (2)
O1^i—Co—N^i	98.73 (5)	O1^ii—K—O1^iii	111.43 (5)
O1—Co—N^i	94.27 (5)	O4—K—O3^iv	81.76 (3)
O2—Co—N^i	90.79 (5)	O1^ii—K—O3^iv	117.34 (3)
O2^i—Co—N^i	167.36 (5)	O1^iii—K—O3^iv	72.67 (3)
N—Co—N^i	86.56 (8)	O4—K—O3	81.76 (3)
C2—N—Co	109.27 (9)	O1^ii—K—O3	72.67 (3)
C2—N—H0A	111.4 (13)	O1^iii—K—O3	117.34 (3)
Co—N—H0A	107.8 (13)	O3^iv—K—O3	163.52 (5)
C2—N—H0B	114.6 (14)	O4—K—O2^iv	90.40 (2)
Co—N—H0B	108.4 (14)	O1^ii—K—O2^iv	74.61 (3)
H0A—N—H0B	105.1 (19)	O1^iii—K—O2^iv	104.93 (3)
C1—O1—Co	89.92 (8)	O3^iv—K—O2^iv	46.68 (3)
C1—O1—K^ii	116.50 (8)	O3—K—O2^iv	133.48 (3)
Co—O1—K^ii	136.77 (5)	O4—K—O2	90.40 (2)
C1—O2—Co	89.63 (8)	O1^ii—K—O2	104.93 (3)
C1—O2—K	87.21 (7)	O1^iii—K—O2	74.61 (3)
Co—O2—K	137.52 (5)	O3^iv—K—O2	133.48 (3)
C1—O3—K	88.51 (8)	O3—K—O2	46.68 (3)
K—O4—H4A	126 (2)	O2^iv—K—O2	179.20 (4)
O3—C1—O2	124.27 (13)
O1^i—Co—N—C2	112.70 (10)	K—O3—C1—O2	−38.95 (13)
O1—Co—N—C2	−79.61 (10)	K—O3—C1—O1	139.00 (13)
O2—Co—N—C2	−64.0 (2)	K—O2—C1—O3	38.99 (13)
O2^i—Co—N—C2	−178.18 (10)	K—O2—C1—O1	−139.19 (10)
N^i—Co—N—C2	14.19 (7)	K^ii—O1—C1—O3	−32.16 (17)
O1^i—Co—O1—C1	−48.52 (18)	K^ii—O1—C1—O2	146.01 (8)
O2—Co—O1—C1	−1.07 (7)	Co—N—C2—C2^i	−38.67 (17)
O2^i—Co—O1—C1	−92.59 (8)	N—C2—C2^i—N^i	50.1 (2)
N—Co—O1—C1	175.31 (8)	C1—O3—K—O4	117.60 (9)
N^i—Co—O1—C1	88.14 (8)	C1—O3—K—O1^ii	−112.50 (9)
O1^i—Co—O1—K^ii	−179.06 (7)	C1—O3—K—O1^iii	−6.86 (10)
O2—Co—O1—K^ii	−131.62 (8)	C1—O3—K—O3^iv	117.60 (9)
O2^i—Co—O1—K^ii	136.86 (7)	C1—O3—K—O2^iv	−159.73 (8)
N—Co—O1—K^ii	44.77 (8)	C1—O3—K—O2	19.19 (8)
N^i—Co—O1—K^ii	−42.40 (8)	C1—O2—K—O4	−96.40 (7)
O1^i—Co—O2—C1	167.86 (7)	Co—O2—K—O4	177.20 (6)
O1—Co—O2—C1	1.08 (7)	C1—O2—K—O1^ii	29.39 (8)
O2^i—Co—O2—C1	98.36 (8)	Co—O2—K—O1^ii	−57.01 (7)
N—Co—O2—C1	−15.5 (2)	C1—O2—K—O1^iii	137.98 (8)
N^i—Co—O2—C1	−93.19 (8)	Co—O2—K—O1^iii	51.59 (6)
O1^i—Co—O2—K	−106.67 (7)	C1—O2—K—O3^iv	−175.40 (7)
O1—Co—O2—K	86.54 (7)	Co—O2—K—O3^iv	98.21 (7)
O2^i—Co—O2—K	−176.18 (9)	C1—O2—K—O3	−18.15 (7)
N—Co—O2—K	70.0 (2)	Co—O2—K—O3	−104.55 (8)
N^i—Co—O2—K	−7.73 (7)

Symmetry codes: (i) −x+1/2, y, −z+1/2; (ii) −x, −y+1, −z+1; (iii) x+1/2, −y+1, z+1/2; (iv) −x+1/2, y, −z+3/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N—H0A···O1^v	0.87 (2)	2.30 (2)	3.0910 (17)	150.8 (17)
N—H0B···O3^vi	0.80 (2)	2.17 (2)	2.9678 (17)	173.3 (19)
O4—H4A···O3^vii	0.72 (2)	2.07 (2)	2.7866 (17)	171 (3)

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