Poly­[di­aqua­cobalt(II)-di-μ₄-benzene-1,2,4-tri­carboxyl­ato-bis­[1,10-phenanthrolinecobalt(II)]]

In the polymeric title compound, [Co₃(btc)₂(phen)₂(H₂O)₂]_n [btc is the benzene-1,2,4-tri­carboxyl­ate trianion (C₉H₃O₆) and phen is 1,10-phenanthroline (C₁₂H₈N₂)], there are two different Co centres, Co1 and Co2. The Co1 centre has a deformed trigonal–bipyramidal geometry, while the Co2 centre lies on an inversion centre and has distorted octahedral geometry. Moreover, the 1,2-di­carboxyl­ate groups of one btc ligand bridge the two adjacent Co2 centres, and each Co2 centre is coordinated by four carboxyl­ate O atoms from four different btc ligands, forming a novel kind of intersecting double-chain structure, with a Co...Co separation of 7.755 Å, along the a axis. On the other hand, the two Co1 centres are bridged by two btc ligands and chelated by phen mol­ecules, respectively, producing a binuclear unit with a Co...Co separation of 8.406 Å, and these binuclear units are linked by btc bridges and Co2 centres to extend hybrid chains of Co1 and Co2 along the [101] direction. Furthermore, each btc ligand acts as a pentadentate bridge, linking the Co2 double-chain structures and the hybrid chains of Co1 and Co2 to yield a two-dimensional network, and this leads to the formation of very different kinds of voids.

S1. Comment

In recent years, versatile benzene-polycarboxylate ligands, such as benzene-1,3,5-tricarboxylic acid and benzene-1,2,4,5-tetracarboxylic acid, have been widely applied in the rational design and syntheses of metal-organic coordination polymers, owing to their high symmetry and the intriguing coordination modes of the carboxylate groups (Eddaoudi et al., 2000; Hu et al., 2003; Yaghi et al., 1996). However, little attention has been paid so far to benzene-1,2,4-tricarboxylic. It is of great interest to us that the carboxylate groups of benzene-polycarboxylate anions are capable of rotating in different directions with respect to the aromatic rings (Pisareva et al., 2003), and the introduction of terminal ligands into the carboxylate system can result in the formation of low-dimensional frameworks (Plater et al., 1999). Thus, we have selected the phen-btc system in order to extend this research. In the present compound, Co₃(btc)₂(phen)₂(H₂O)₂, (I), two different kinds of independent Co^II centres are bridged by btc to form a novel two-dimensional network. \sch

In the structure of (I) (Fig. 1), there are two different Co centres. The Co1 centre has a deformed trigonal-bipyramidal geometry completed by three carboxylate O atoms belonging to two btc ligands and two N atoms from a terminal phen molecule. The Co2 centre possesses a distorted octahedral geometry. The basal plane consists of two aqua O atoms and two carboxylate O atoms from two btc ligands. The two apical positions are filled by two carboxylate O atoms from two other btc ligands, the corresponding axial Co—O bond distances [2.155 (3) Å] being longer than the equatorial Co—O bond distances [2.073 (3)–2.077 (3) Å]. The separation of the independent Co centres [5.097 Å] is in agreement with that reported for a cobalt-2,2'-bipyridine-btc analogue (Plater et al., 2001).

The neighbouring 1,2-dicarboxylate groups of one btc ligand bridge two adjacent Co2 centres, and each Co2 centre is coordinated by four carboxylate O atoms from four different btc ligands, forming a novel kind of intersecting double-chain structure, with a Co—Co separation of 7.755 Å along the a axis. This is comparable with what was found in [Co₂(C₁₀H₂O₈)(C₁₀H₈N₂)₂(H₂O)₂]_n (Xiao et al., 2004), in which the Co centres are also bridged by neighbouring 1,2-dicarboxylate groups and 4,5-dicarboxylate groups.

On the other hand, pairs of Co1 centres are bridged by two btc ligands to produce a binuclear unit, with a Co—Co separation of 8.406 Å, and these binuclear units are linked by btc bridges and Co2 centres to extend hybrid chains of Co1 and Co2 along the [101] direction.

Thus, as can be seen, three carboxylate groups of each btc ligand connect two Co1 centres and Co2 centres, respectively, by two different coordination modes, as a monodentate ligand with one Co centre and as a bidentate ligand with two Co centres. This is also comparable with what was found in a Fe—H₂O-btc analogue (Riou-Cavellec et al., 2003). In this way, each btc ligand acts as a pentadentate bridge, linking the Co2 double-chain structures and the hybrid chains of Co1 and Co2 to yield a two-dimensional network, and this leads to the formation of very different kinds of voids (Fig. 2). Please check rewording.

S2. Experimental

The title compound was synthesized by the hydrothermal method from a mixture of benzene-1,2,4-tricarboxylic acid (1 mmol, 0.21 g), CoCl₂·4H₂O (1 mmol, 0.20 g), 1,10-phenanthroline (4 mmol, 0.72 g) and water (20 ml) in a 30 ml Teflon-lined stainless steel reactor. The solution was heated to 438 K for 5 d. After slow cooling of the reaction system to room temperature, red prism crystals of (I) were collected and washed with distilled water.

S3. Refinement

The water H atoms were refined subject to the restraint O—H = 0.82 (1) Å. The other H atoms were positioned geometrically and allowed to ride on their parent atoms at C—H distances of 0.93 Å, with U_iso(H) = 1.2U_eq(C).

Computing details

Data collection: SMART (Bruker, 2002); cell refinement: SAINT (Bruker, 2002); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP (Bruker, 2002); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. The coordination environments of the two independent cations in (I), with the atom-numbering scheme, showing displacement ellipsoids at the 50% probability level.
	Fig. 2. The two-dimensional network of (I). H atoms, water molecules and 1,10-phenanthroline molecules have been omitted for clarity.

Poly[diaquacobalt(II)-di-µ₄-benzene-1,2,4-tricarboxylato-bis[1,10- phenanthrolinecobalt(II)]]

Crystal data

[Co3(C9H3O6)2(C12H8N2)2H2O)2]	Z = 1
Mr = 987.46	F(000) = 499
Triclinic, P1	Dx = 1.795 Mg m^−3
Hall symbol: -p1	Mo Kα radiation, λ = 0.71073 Å
a = 7.7548 (12) Å	Cell parameters from 824 reflections
b = 10.5687 (16) Å	θ = 2.3–21.4°
c = 12.1678 (19) Å	µ = 1.43 mm^−1
α = 88.238 (3)°	T = 273 K
β = 77.760 (2)°	Prism, red
γ = 69.813 (2)°	0.20 × 0.18 × 0.10 mm
V = 913.7 (2) Å^3

Data collection

Bruker APEX CCD area-detector diffractometer	3281 independent reflections
Radiation source: fine-focus sealed tube	3089 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.029
ϕ and ω scans	θmax = 25.2°, θmin = 1.7°
Absorption correction: multi-scan (SADABS; Bruker, 2002)	h = −9→9
Tmin = 0.763, Tmax = 0.870	k = −12→12
6767 measured reflections	l = −14→14

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.066	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.147	H atoms treated by a mixture of independent and constrained refinement
S = 1.22	w = 1/[σ^2(Fo^2) + (0.0524P)^2 + 2.7427P] where P = (Fo^2 + 2Fc^2)/3
3281 reflections	(Δ/σ)max < 0.001
287 parameters	Δρmax = 0.95 e Å^−3
0 restraints	Δρmin = −0.78 e Å^−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
Co1	0.18178 (9)	0.77024 (7)	0.78642 (5)	0.0230 (2)
Co2	−0.5000	1.0000	1.0000	0.0198 (2)
O1	0.3576 (5)	0.7775 (4)	0.8855 (3)	0.0301 (8)
O2	0.3791 (5)	0.8464 (3)	1.0513 (3)	0.0255 (8)
O3	−0.0393 (5)	0.8701 (4)	0.9137 (3)	0.0346 (9)
O4	−0.2674 (4)	0.8877 (3)	1.0634 (3)	0.0266 (8)
O5	−0.1972 (5)	0.4266 (4)	1.1925 (3)	0.0381 (9)
O6	0.0510 (6)	0.3142 (4)	1.2596 (4)	0.0463 (11)
O7	−0.3920 (5)	0.9036 (4)	0.8417 (3)	0.0281 (8)
H7A	−0.2831	0.8534	0.8379	0.042*
H7	−0.4486	0.8531	0.8334	0.042*
N1	0.4003 (6)	0.7110 (4)	0.6358 (4)	0.0292 (10)
N2	0.1144 (6)	0.9428 (4)	0.6922 (3)	0.0264 (9)
C1	0.5423 (8)	0.5953 (6)	0.6097 (5)	0.0417 (14)
H1	0.5558	0.5281	0.6617	0.050*
C2	0.6733 (9)	0.5704 (7)	0.5066 (6)	0.0539 (18)
H2	0.7740	0.4892	0.4920	0.065*
C3	0.6514 (9)	0.6661 (7)	0.4284 (6)	0.0517 (18)
H3	0.7351	0.6494	0.3589	0.062*
C4	0.5041 (9)	0.7891 (7)	0.4522 (5)	0.0423 (15)
C5	0.4700 (10)	0.8974 (8)	0.3765 (5)	0.0489 (17)
H5	0.5475	0.8857	0.3051	0.059*
C6	0.3279 (10)	1.0159 (7)	0.4065 (5)	0.0477 (16)
H6	0.3113	1.0851	0.3564	0.057*
C7	0.2034 (9)	1.0363 (6)	0.5136 (5)	0.0371 (13)
C8	0.0528 (9)	1.1576 (6)	0.5500 (5)	0.0447 (15)
H8	0.0297	1.2300	0.5032	0.054*
C9	−0.0572 (9)	1.1674 (6)	0.6533 (5)	0.0432 (15)
H9	−0.1555	1.2476	0.6786	0.052*
C10	−0.0246 (8)	1.0583 (6)	0.7224 (5)	0.0363 (13)
H10	−0.1041	1.0671	0.7929	0.044*
C11	0.2289 (8)	0.9318 (5)	0.5888 (4)	0.0291 (11)
C12	0.3819 (8)	0.8062 (6)	0.5578 (4)	0.0303 (12)
C13	0.3225 (6)	0.7818 (5)	0.9921 (4)	0.0220 (10)
C14	0.2160 (6)	0.6951 (5)	1.0539 (4)	0.0208 (10)
C15	0.0242 (6)	0.7190 (5)	1.0617 (4)	0.0218 (10)
C16	−0.0561 (7)	0.6300 (5)	1.1167 (4)	0.0228 (10)
H16	−0.1837	0.6472	1.1222	0.027*
C17	0.0479 (7)	0.5166 (5)	1.1635 (4)	0.0247 (11)
C18	0.2376 (7)	0.4946 (5)	1.1587 (4)	0.0280 (11)
H18	0.3093	0.4192	1.1909	0.034*
C19	0.3192 (7)	0.5841 (5)	1.1064 (4)	0.0260 (11)
H19	0.4444	0.5702	1.1062	0.031*
C20	−0.1014 (7)	0.8355 (5)	1.0094 (4)	0.0232 (10)
C21	−0.0376 (8)	0.4127 (5)	1.2095 (4)	0.0323 (13)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Co1	0.0208 (4)	0.0255 (4)	0.0232 (4)	−0.0108 (3)	−0.0016 (3)	0.0047 (3)
Co2	0.0144 (5)	0.0242 (5)	0.0207 (5)	−0.0082 (4)	−0.0016 (3)	0.0034 (4)
O1	0.0269 (19)	0.044 (2)	0.0243 (19)	−0.0199 (17)	−0.0032 (15)	0.0022 (16)
O2	0.0244 (18)	0.0288 (18)	0.0283 (19)	−0.0152 (15)	−0.0068 (15)	0.0042 (15)
O3	0.0232 (19)	0.041 (2)	0.028 (2)	−0.0033 (16)	0.0041 (15)	0.0144 (16)
O4	0.0139 (17)	0.034 (2)	0.0263 (18)	−0.0038 (15)	−0.0013 (14)	0.0060 (15)
O5	0.031 (2)	0.032 (2)	0.054 (3)	−0.0182 (17)	−0.0002 (18)	0.0019 (18)
O6	0.048 (3)	0.035 (2)	0.053 (3)	−0.015 (2)	−0.005 (2)	0.019 (2)
O7	0.0184 (17)	0.038 (2)	0.0250 (18)	−0.0106 (16)	0.0023 (14)	−0.0014 (15)
N1	0.025 (2)	0.034 (2)	0.028 (2)	−0.0099 (19)	−0.0022 (18)	−0.0035 (19)
N2	0.030 (2)	0.028 (2)	0.023 (2)	−0.0148 (19)	−0.0025 (18)	0.0061 (17)
C1	0.032 (3)	0.041 (3)	0.048 (4)	−0.010 (3)	−0.004 (3)	−0.003 (3)
C2	0.034 (4)	0.046 (4)	0.072 (5)	−0.005 (3)	−0.001 (3)	−0.015 (4)
C3	0.041 (4)	0.066 (5)	0.043 (4)	−0.025 (3)	0.015 (3)	−0.018 (3)
C4	0.043 (4)	0.060 (4)	0.028 (3)	−0.029 (3)	0.004 (3)	−0.007 (3)
C5	0.057 (4)	0.081 (5)	0.020 (3)	−0.044 (4)	0.001 (3)	0.003 (3)
C6	0.063 (4)	0.065 (4)	0.028 (3)	−0.039 (4)	−0.011 (3)	0.018 (3)
C7	0.048 (4)	0.049 (4)	0.027 (3)	−0.031 (3)	−0.012 (3)	0.013 (3)
C8	0.055 (4)	0.039 (3)	0.050 (4)	−0.022 (3)	−0.025 (3)	0.020 (3)
C9	0.043 (4)	0.035 (3)	0.049 (4)	−0.010 (3)	−0.011 (3)	0.010 (3)
C10	0.039 (3)	0.033 (3)	0.034 (3)	−0.010 (3)	−0.003 (2)	−0.001 (2)
C11	0.032 (3)	0.035 (3)	0.026 (3)	−0.019 (2)	−0.005 (2)	0.002 (2)
C12	0.032 (3)	0.044 (3)	0.023 (3)	−0.025 (3)	−0.004 (2)	−0.001 (2)
C13	0.013 (2)	0.023 (2)	0.029 (3)	−0.0047 (19)	−0.0039 (19)	0.003 (2)
C14	0.014 (2)	0.025 (2)	0.022 (2)	−0.0073 (19)	−0.0001 (18)	−0.0009 (19)
C15	0.017 (2)	0.026 (3)	0.022 (2)	−0.010 (2)	−0.0007 (19)	−0.0002 (19)
C16	0.017 (2)	0.024 (2)	0.027 (3)	−0.009 (2)	0.0003 (19)	0.000 (2)
C17	0.023 (3)	0.027 (3)	0.024 (3)	−0.012 (2)	0.002 (2)	−0.002 (2)
C18	0.026 (3)	0.022 (3)	0.035 (3)	−0.007 (2)	−0.008 (2)	0.004 (2)
C19	0.016 (2)	0.032 (3)	0.031 (3)	−0.010 (2)	−0.002 (2)	0.001 (2)
C20	0.022 (3)	0.026 (3)	0.024 (3)	−0.012 (2)	−0.005 (2)	0.001 (2)
C21	0.040 (3)	0.027 (3)	0.025 (3)	−0.015 (2)	0.007 (2)	−0.004 (2)

Geometric parameters (Å, º)

Co1—O1	2.024 (3)	C3—C4	1.391 (9)
Co1—O3	2.044 (4)	C3—H3	0.9300
Co1—O5^i	2.053 (4)	C4—C12	1.400 (7)
Co1—N2	2.093 (4)	C4—C5	1.435 (9)
Co1—N1	2.155 (4)	C5—C6	1.349 (10)
Co2—O7	2.073 (3)	C5—H5	0.9300
Co2—O7^ii	2.073 (3)	C6—C7	1.420 (8)
Co2—O4	2.077 (3)	C6—H6	0.9300
Co2—O4^ii	2.077 (3)	C7—C11	1.401 (8)
Co2—O2^iii	2.155 (3)	C7—C8	1.409 (9)
Co2—O2^iv	2.155 (3)	C8—C9	1.345 (9)
O1—C13	1.266 (6)	C8—H8	0.9300
O2—C13	1.245 (6)	C9—C10	1.389 (8)
O2—Co2^v	2.155 (3)	C9—H9	0.9300
O3—C20	1.257 (6)	C10—H10	0.9300
O4—C20	1.252 (6)	C11—C12	1.437 (8)
O5—C21	1.256 (7)	C13—C14	1.518 (6)
O5—Co1^i	2.053 (4)	C14—C19	1.396 (7)
O6—C21	1.253 (7)	C14—C15	1.403 (7)
O7—H7A	0.8200	C15—C16	1.382 (7)
O7—H7	0.8200	C15—C20	1.502 (7)
N1—C1	1.325 (7)	C16—C17	1.377 (7)
N1—C12	1.354 (7)	C16—H16	0.9300
N2—C10	1.319 (7)	C17—C18	1.396 (7)
N2—C11	1.360 (7)	C17—C21	1.505 (7)
C1—C2	1.404 (9)	C18—C19	1.380 (7)
C1—H1	0.9300	C18—H18	0.9300
C2—C3	1.360 (10)	C19—H19	0.9300
C2—H2	0.9300
O1—Co1—O3	88.42 (15)	C6—C5—C4	121.5 (6)
O1—Co1—O5^i	98.79 (16)	C6—C5—H5	119.3
O3—Co1—O5^i	102.01 (15)	C4—C5—H5	119.3
O1—Co1—N2	110.90 (16)	C5—C6—C7	120.9 (6)
O3—Co1—N2	89.05 (15)	C5—C6—H6	119.5
O5^i—Co1—N2	148.64 (17)	C7—C6—H6	119.5
O1—Co1—N1	94.23 (15)	C11—C7—C8	117.0 (5)
O3—Co1—N1	166.54 (16)	C11—C7—C6	119.4 (6)
O5^i—Co1—N1	90.65 (16)	C8—C7—C6	123.7 (6)
N2—Co1—N1	77.67 (17)	C9—C8—C7	119.3 (5)
O7—Co2—O7^ii	180	C9—C8—H8	120.4
O7—Co2—O4	93.96 (14)	C7—C8—H8	120.4
O7^ii—Co2—O4	86.04 (14)	C8—C9—C10	120.3 (6)
O7—Co2—O4^ii	86.04 (14)	C8—C9—H9	119.8
O7^ii—Co2—O4^ii	93.96 (14)	C10—C9—H9	119.8
O4—Co2—O4^ii	180	N2—C10—C9	122.7 (5)
O7—Co2—O2^iii	88.77 (13)	N2—C10—H10	118.6
O7^ii—Co2—O2^iii	91.23 (13)	C9—C10—H10	118.6
O4—Co2—O2^iii	88.54 (13)	N2—C11—C7	122.9 (5)
O4^ii—Co2—O2^iii	91.46 (13)	N2—C11—C12	117.2 (5)
O7—Co2—O2^iv	91.23 (13)	C7—C11—C12	119.8 (5)
O7^ii—Co2—O2^iv	88.77 (13)	N1—C12—C4	123.8 (5)
O4—Co2—O2^iv	91.46 (13)	N1—C12—C11	116.5 (5)
O4^ii—Co2—O2^iv	88.54 (13)	C4—C12—C11	119.7 (5)
O2^iii—Co2—O2^iv	180	O2—C13—O1	124.6 (4)
C13—O1—Co1	126.4 (3)	O2—C13—C14	116.4 (4)
C13—O2—Co2^v	127.8 (3)	O1—C13—C14	118.8 (4)
C20—O3—Co1	132.1 (3)	C19—C14—C15	118.6 (4)
C20—O4—Co2	127.1 (3)	C19—C14—C13	116.5 (4)
C21—O5—Co1^i	97.3 (3)	C15—C14—C13	124.8 (4)
Co2—O7—H7A	109.5	C16—C15—C14	119.7 (4)
Co2—O7—H7	109.5	C16—C15—C20	116.8 (4)
H7A—O7—H7	104.5	C14—C15—C20	123.5 (4)
C1—N1—C12	117.5 (5)	C17—C16—C15	121.7 (4)
C1—N1—Co1	128.9 (4)	C17—C16—H16	119.1
C12—N1—Co1	113.5 (3)	C15—C16—H16	119.1
C10—N2—C11	117.8 (5)	C16—C17—C18	118.7 (4)
C10—N2—Co1	127.2 (4)	C16—C17—C21	120.3 (5)
C11—N2—Co1	115.0 (3)	C18—C17—C21	120.8 (5)
N1—C1—C2	122.5 (6)	C19—C18—C17	120.4 (5)
N1—C1—H1	118.8	C19—C18—H18	119.8
C2—C1—H1	118.8	C17—C18—H18	119.8
C3—C2—C1	119.3 (6)	C18—C19—C14	120.8 (5)
C3—C2—H2	120.4	C18—C19—H19	119.6
C1—C2—H2	120.4	C14—C19—H19	119.6
C2—C3—C4	120.1 (6)	O4—C20—O3	124.1 (5)
C2—C3—H3	119.9	O4—C20—C15	116.4 (4)
C4—C3—H3	119.9	O3—C20—C15	119.4 (4)
C3—C4—C12	116.7 (6)	O6—C21—O5	121.9 (5)
C3—C4—C5	124.6 (6)	O6—C21—C17	120.7 (5)
C12—C4—C5	118.6 (6)	O5—C21—C17	117.4 (5)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O7—H7···O1^iii	0.82	1.92	2.671 (5)	152
O7—H7A···O3	0.82	2.33	2.950 (5)	133
O7—H7A···O6^i	0.82	2.19	2.899 (5)	144

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