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The structure of the title compound, {(CH6N)[Co(CHO2)3]}n, consists of a three-dimensional net of central CoII ions connected via formate (methane­diolate) bridges. The negative charge is compensated by protonated methyl­amine cations. The CoO6 chromophores form slightly distorted octahedra, which are bridged by C atoms of formate groups. The central Co atom lies on an inversion center and most of the other atoms lie on an m plane.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270104025776/av1205sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270104025776/av1205Isup2.hkl
Contains datablock I

CCDC reference: 259018

Comment top

The initial aim of the present study was the preparation of single crystals of cobalt(II) complexes containing ligands with a Schiff base group and pyridine N-oxide fragments in order to compare these complexes with known copper(II), zinc(II) and iron(III) complexes (Boča, Baran et al., 2000). During the recrystallization of the starting complex from methyl formamide, decomposition of the complex occurred. The mechanism of this decomposition seems to be complicated. The following factors can play an important role: (i) the presence of water in the starting complex; (ii) the presence of a pyridine N-oxide fragment and its basic properties; (iii) the basic nature of methyl formamide; (iv) the acid properties of the remaining part of the ligand. Taking into account all these acid–base properties, the following processes can be expected: (i) decomposition of the ligand into the starting compounds; (ii) evolution of oxygen from the pyridine N-oxide fragment; (iii) evolution of methyl amine from methyl formamide; (iv) protonation of methyl amine; (v) formation of the formyl group. The Co atom is probably involved in some of these processes, which result in the formation of the title compound, (I). The evolution of methyl amine from methyl formamide is mentioned in the literature in basic environments of CoIII systems (Angus et al., 1993).

The structure of (I) consists of a three-dimensional net of cobalt(II) central atoms connected via formate (methanoldiolate), CHOO, bridges. The negative charge is compensated by protonated methylamine cations, CH3NH3+. The formula of the compound can therefore be written as [Co(CHOO)3]n·(CH3NH3)n. The electroneutral fragment surrounding the Co atom is shown in Fig. 1. The central Co atom lies on an inversion center and the majority of the other atoms lie on an m plane. The CoO6 chromophores form slightly distorted octahedra, which are bridged by C atoms of formate groups. Selected bond distances and angles are shown in Table 1. A l l three O—Co—O axes are perfectly linear, forming angles of 180°. However, these axes are not perpendicular to one another. Three different Co—O bonds distances are observed, in the range characteristic of coordination bond of CoII—O. The closest Co···Co distance is 5.840 Å, which is half the length of the diagonal of the ac plane. The second shortest Co···Co contact is only slightly longer, − 5.855 Å, which is the half the length of the b axis. In addition, the C—O bonds lengths in the formic group are normal, as are the values of the O—C—O angles for the bridging functionality. Three classical N—H···O hydrogen bonds are present (Table 2 and Fig. 2). Two C—H···O hydrogen contacts were also detected (not displayed).

The Cambridge Structural Database (CSD; Allen, 2002) contains 19 more examples of a formate group coordinated to CoII ions. The coordination behaviour of the formate group varies considerably. In some cases, it behaves as a bidentate ligand coordinated by both O atoms to the same central CoII ion [CSD refcodes NABHAZ (Sernau et al., 1996) and NABHAZ01 (Sernau et al., 1996)]; in other cases, the formate group behaves as a bridging species exclusively between Co atoms [OXCFOR (Cornils et al., 1976), ABOLOS (Saalfrank et al., 2001), COKCIO (Clegg & Sykes, 1984) and UFIQEF (Cadiou et al., 2002)] or between one Co atom and one other central metal atom (MOTQER; Arici et al., 2002). Structures with chain motives are also well documented. Chains containing only Co central atoms [COFORM01 (Kaufman et al., 1993), COFORM10 (Antsyshkina et al., 1967), PAKNIY (Fujino et al., 1992), PAKNIY01, PAKNIY10, PAKNIY11 and YAMKOM (Ridwan, 1992), DEJLEJ (Rettig et al., 1999), and DEJLEJ01 and CADFOD (Domasevitch et al., 2002)] and chains containing both Co and Cu central atoms [XIHDEX (Leyva et al., 2001) and OLEHUI (Baggio et al., 2003)] have been reported. In the majority of these chain structures, besides the formate group, aqua, urea and formamide groups are also coordinated to the central atoms. Consequently, structurally non-equivalent metal atoms can be identified in these structures, in contrast to the situation for the title compound.

A very similar structure to that of the title compound was reported for a complex with a central CuII atom (VINROZ; Nifontova et al., 1990). Both structures are isostructural, with close cell parameters and the same space group (the b and c vectors are transposed). In the copper analogue, the Cu—O bonds on one axis of the octahedron are significantly longer (2.389 Å) than the remaining metal–oxygen bonds (1.955 and 2.011 Å). Thus the copper complex exhibits a greater deviation from regular octahedral coordination, being elongated with D4 h symmetry. Both C—O—C angles are slightly larger in the copper complex than in the cobalt complex. The same system of hydrogen bonds was identified in the two complexes.

The formation of protonated methylamine is quite common and has been observed in many structures.

Experimental top

A solution of CoCl2·(H2O)6 (0.476 g, 2 mmol) in dry ethanol (5 ml) was added to a solution of the ligand L [0.356 g, 1 mmol, as a condensation product of 2-pyridinecarboxaldehyde N-oxide and triethylenetetramine (Boča, Valigura et al., 2000)] in dry ethanol (10 ml). The mixture was stirred for 2 h at room temperature. The resulting green solid was filtered off, washed with dry ethanol and dried for 3 h at 323 K. The resulting complex, Co2(L)Cl4·(H2O)2, was recrystallized isothermally from methyl formamide for two months until single crystals suitable for X-ray analysis were obtained. IR spectra were measured on single crystals. Antisymmetric N—H deformation (E) vibrations at 1563 cm−1 and symmetric N—H deformation (A1) vibrations at 1486 cm−1 were observed, as well as weak antisymmetric N—H valence (E) vibrations at 3097 cm−1 and symmetric N—H valence (A1) vibrations at 3014 cm−1. Lowering of the intensity of these vibrations can arise from the involvement of NH groups in the hydrogen-bonding network. Valence C—O vibrations (A') at 1102 cm−1 and deformation COO vibrations (A') at 669 cm−1 were observed. The lowering of the valence C—O frequency upon coordination in comparison with pure formic acid have been observed.

Refinement top

All C3—H distances for the methyl group were fixed at 0.96 Å, the mutual distances of all three H atoms of the methyl group were fixed at 1.46 Å and the N4—H distances for all three methyl H atoms were fixed at 1.87 Å. All N4—H distances of the aminium group were fixed at 0.86 Å. The H atoms on the formyl groups were included in the refinement at geometrically calculated positions and refined using a riding model, with Uiso(H) values constrained to 1.2Ueq of the parent C atom. [Distances don't match the distances listed in the cif, which all have s.u. values. Uiso treatment for other H atoms?]

Computing details top

Data collection: CrysAlis CCD (Oxford Diffraction, 2001); cell refinement: CrysAlis RED (Oxford Diffraction, 2001); data reduction: CrysAlis RED; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997) and PLATON (Spek, 2003); software used to prepare material for publication: reference?.

Figures top
[Figure 1] Fig. 1. The structure and atom-numbering of the title compound, showing 50% probability displacement ellipsoids. H atoms are shown as circles of arbitrary radius. [Symmetry codes: (i) − x + 1/2, − y, z + 1/2; (ii) − x, − y, − z; (iii) − x, y + 1/2, − z; (iv) x + 1/2, y, − z + 1/2; (v) x, − y + 1/2, z.]
[Figure 2] Fig. 2. A packing diagram illustrating the hydrogen-bonding network.
Poly[methylammonium [tris(µ2-formato-κ2O:O')cobalt(II)]] top
Crystal data top
(CH6N)[Co(CO2)3]F(000) = 460
Mr = 226.05Dx = 1.881 Mg m3
Orthorhombic, PnmaMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2nCell parameters from 899 reflections
a = 8.4069 (9) Åθ = 3.7–23.1°
b = 11.710 (1) ŵ = 2.14 mm1
c = 8.1075 (9) ÅT = 300 K
V = 798.14 (14) Å3Cube, brown
Z = 40.24 × 0.24 × 0.24 mm
Data collection top
Oxford Diffraction Xcalibur CCD
diffractometer
854 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.043
Graphite monochromatorθmax = 30.1°, θmin = 3.1°
Detector resolution: Sapphire CCD detector pixels mm-1h = 119
Rotation method data acquisition using ω scansk = 1615
5931 measured reflectionsl = 1111
1173 independent reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.049Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.160H-atom parameters constrained
S = 1.02 w = 1/[σ2(Fo2) + (0.1P)2]
where P = (Fo2 + 2Fc2)/3
1173 reflections(Δ/σ)max < 0.001
76 parametersΔρmax = 0.39 e Å3
10 restraintsΔρmin = 0.62 e Å3
Crystal data top
(CH6N)[Co(CO2)3]V = 798.14 (14) Å3
Mr = 226.05Z = 4
Orthorhombic, PnmaMo Kα radiation
a = 8.4069 (9) ŵ = 2.14 mm1
b = 11.710 (1) ÅT = 300 K
c = 8.1075 (9) Å0.24 × 0.24 × 0.24 mm
Data collection top
Oxford Diffraction Xcalibur CCD
diffractometer
854 reflections with I > 2σ(I)
5931 measured reflectionsRint = 0.043
1173 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.04910 restraints
wR(F2) = 0.160H-atom parameters constrained
S = 1.02Δρmax = 0.39 e Å3
1173 reflectionsΔρmin = 0.62 e Å3
76 parameters
Special details top

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 (Å2) top
xyzUiso*/Ueq
C10.2788 (5)0.5293 (4)0.2195 (5)0.0261 (8)
H10.235 (5)0.463 (4)0.272 (5)0.031*
C20.0122 (6)0.25000.0550 (8)0.0240 (11)
H20.009 (6)0.25000.064 (9)0.029*
C30.4218 (10)0.25000.0204 (9)0.0507 (19)
H3A0.3710 (17)0.1870 (4)0.022 (2)0.061*
H3B0.413 (3)0.25000.1329 (15)0.061*
O10.2231 (3)0.5606 (2)0.0834 (3)0.0256 (6)
O20.4025 (3)0.5676 (2)0.2835 (3)0.0287 (6)
O30.0283 (3)0.3440 (2)0.1260 (3)0.0277 (6)
N40.5835 (7)0.25000.0277 (6)0.0339 (12)
H4A0.636 (5)0.187 (3)0.001 (5)0.041*
H4B0.593 (7)0.25000.1368 (17)0.041*
Co10.00000.50000.00000.0179 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0262 (18)0.0253 (17)0.0268 (19)0.0031 (15)0.0010 (16)0.0021 (16)
C20.023 (3)0.027 (3)0.022 (3)0.0000.0028 (19)0.000
C30.045 (5)0.058 (5)0.049 (4)0.0000.001 (3)0.000
O10.0252 (12)0.0311 (14)0.0205 (12)0.0029 (11)0.0062 (10)0.0034 (11)
O20.0288 (13)0.0316 (14)0.0258 (13)0.0058 (11)0.0088 (11)0.0063 (12)
O30.0400 (15)0.0184 (13)0.0246 (13)0.0019 (11)0.0043 (11)0.0010 (11)
N40.039 (3)0.034 (3)0.029 (3)0.0000.012 (2)0.000
Co10.0190 (4)0.0182 (4)0.0165 (4)0.0019 (2)0.0002 (2)0.0001 (2)
Geometric parameters (Å, º) top
C1—O21.245 (4)C3—H3B0.915 (10)
C1—O11.253 (4)O1—Co12.117 (2)
C1—H10.95 (5)O2—Co1i2.093 (2)
C2—O31.249 (4)O3—Co12.107 (2)
C2—H20.98 (8)N4—H4A0.89 (1)
C3—N41.414 (11)N4—H4B0.89 (1)
C3—H3A0.920 (6)
O2—C1—O1125.0 (4)C3—N4—H4B111 (4)
O2—C1—H1116 (2)H4A—N4—H4B101 (4)
O1—C1—H1119 (2)O2iii—Co1—O2iv180.0
O3—C2—O3ii123.5 (6)O2iii—Co1—O388.03 (10)
O3—C2—H2118.2 (3)O2iv—Co1—O391.97 (10)
N4—C3—H3A110.0 (12)O3—Co1—O3v180.00 (7)
N4—C3—H3B110.9 (18)O2iii—Co1—O187.27 (10)
H3A—C3—H3B109.6 (12)O2iv—Co1—O192.73 (10)
C1—O1—Co1121.0 (2)O3—Co1—O192.07 (10)
C1—O2—Co1i122.7 (3)O3v—Co1—O187.93 (10)
C2—O3—Co1121.9 (3)O2iii—Co1—O1v92.73 (10)
C3—N4—H4A114 (3)O1—Co1—O1v180.0
O2—C1—O1—Co1174.0 (3)C2—O3—Co1—O1v52.3 (3)
O1—C1—O2—Co1i173.9 (3)C1—O1—Co1—O2iii57.8 (3)
O3ii—C2—O3—Co1180.0 (3)C1—O1—Co1—O2iv122.2 (3)
C2—O3—Co1—O2iii145.1 (3)C1—O1—Co1—O330.2 (3)
C2—O3—Co1—O2iv34.9 (3)C1—O1—Co1—O3v149.8 (3)
C2—O3—Co1—O1127.7 (3)
Symmetry codes: (i) x+1/2, y+1, z+1/2; (ii) x, y+1/2, z; (iii) x1/2, y, z+1/2; (iv) x+1/2, y+1, z1/2; (v) x, y+1, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N4—H4A···O1vi0.89 (1)2.01 (1)2.893 (4)170 (5)
N4—H4B···O3vii0.89 (1)2.28 (2)3.051 (5)145 (3)
N4—H4B···O3viii0.89 (1)2.28 (2)3.051 (5)145 (3)
Symmetry codes: (vi) x+1, y1/2, z; (vii) x+1/2, y, z+1/2; (viii) x+1/2, y+1/2, z+1/2.

Experimental details

Crystal data
Chemical formula(CH6N)[Co(CO2)3]
Mr226.05
Crystal system, space groupOrthorhombic, Pnma
Temperature (K)300
a, b, c (Å)8.4069 (9), 11.710 (1), 8.1075 (9)
V3)798.14 (14)
Z4
Radiation typeMo Kα
µ (mm1)2.14
Crystal size (mm)0.24 × 0.24 × 0.24
Data collection
DiffractometerOxford Diffraction Xcalibur CCD
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
5931, 1173, 854
Rint0.043
(sin θ/λ)max1)0.706
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.049, 0.160, 1.02
No. of reflections1173
No. of parameters76
No. of restraints10
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.39, 0.62

Computer programs: CrysAlis CCD (Oxford Diffraction, 2001), CrysAlis RED (Oxford Diffraction, 2001), CrysAlis RED, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEP-3 (Farrugia, 1997) and PLATON (Spek, 2003), reference?.

Selected geometric parameters (Å, º) top
C1—O21.245 (4)O1—Co12.117 (2)
C1—O11.253 (4)O2—Co1i2.093 (2)
C2—O31.249 (4)O3—Co12.107 (2)
C3—N41.414 (11)
O2—C1—O1125.0 (4)O3—Co1—O3v180.00 (7)
O3—C2—O3ii123.5 (6)O3—Co1—O192.07 (10)
O2iii—Co1—O2iv180.0O1—Co1—O1v180.0
Symmetry codes: (i) x+1/2, y+1, z+1/2; (ii) x, y+1/2, z; (iii) x1/2, y, z+1/2; (iv) x+1/2, y+1, z1/2; (v) x, y+1, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N4—H4A···O1vi0.89 (1)2.01 (1)2.893 (4)170 (5)
N4—H4B···O3vii0.89 (1)2.28 (2)3.051 (5)145 (3)
N4—H4B···O3viii0.89 (1)2.28 (2)3.051 (5)145 (3)
Symmetry codes: (vi) x+1, y1/2, z; (vii) x+1/2, y, z+1/2; (viii) x+1/2, y+1/2, z+1/2.
 

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