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Volume 70 
Part 2 
Pages 198-201  
February 2014  

Received 30 August 2013
Accepted 15 January 2014
Online 31 January 2014

A two-dimensional hydrogen-bonded water layer in the structure of a cobalt(III) cubane complex

aCenter of Applied Solid State Chemistry Research, Ningbo University, Ningbo, Zhejiang 315211, People's Republic of China
Correspondence e-mail: linjianli@nbu.edu.cn

A tetranuclear CoIII oxide complex with cubane topology, tetra­kis­(2,2'-bi­pyridine-[kappa]2N,N')di-[mu]2-carbonato-[kappa]4O:O'-tetra-[mu]3-oxido-tetra­cobalt(III) penta­deca­hydrate, [Co4(CO3)2O4(C10H8N2)4]·15H2O, with an unbounded hydrogen-bonded water layer, has been synthesized by reaction of CoCO3 and 2,2'-bi­pyridine. The solvent water mol­ecules form a hydrogen-bonded net with tetra­meric and penta­meric water clusters as subunits. The Co4O4 cubane-like cores are sandwiched between the water layers, which are further stacked into a three-dimensional metallo-supra­molecular network.

1. Introduction

In the past few years, metal complexes containing hydrogen-bonded water clusters have attracted a great deal of attention in the fields of supra­molecular chemistry and crystal engineering, because studying the behaviour of water clusters can provide insight into the mutual inter­action of unusual properties which are of importance in many physical, chemical and biological processes (Yang et al., 2008[Yang, A.-H., Zhang, H., Gao, H.-L., Zhang, W.-Q., He, L. & Cui, J.-Z. (2008). Cryst. Growth Des. 8, 3354-3359.]; Moorthy et al., 2002[Moorthy, J. N., Natarajan, R. & Venugopalan, P. (2002). Angew. Chem. Int. Ed. 41, 3417-3420.]; Wu & Lin, 2005[Wu, C.-D. & Lin, W.-B. (2005). Angew. Chem. Int. Ed. 44, 1958-1961.]; Liu et al., 2007[Liu, J.-Q., Wang, Y.-Y., Liu, P. & Wu, W.-P. (2007). Inorg. Chem. Commun. 10, 343-347.]; Cheng et al., 2006[Cheng, L., Lin, J. B., Gong, J. Z. & Sun, A. P. (2006). Cryst. Growth Des. 12, 2739-2746.]; Jin & Che, 2007[Jin, Y. & Che, Y.-X. (2007). Inorg. Chem. Commun. 10, 514-516.]). The theoretical and experimental study of flexible hydrogen-bonded water clusters can provide direct information on how the clusters are formed and how they inter­link in various geometries under diverse environments (Ghosh & Bharadwaj, 2004[Ghosh, S. K. & Bharadwaj, P. K. (2004). Angew. Chem. Int. Ed. 43, 3577-3580.]; Atwood et al., 2001[Atwood, J. L., Barbour, L. J., Ness, T. J., Raston, C. L. & Raston, P. L. (2001). J. Am. Chem. Soc. 123, 7192-7193.]; Müller et al., 2003[Müller, A., Krickemeyer, E., Bögge, H., Schmidtmann, M., Botar, B. & Talismanova, M. O. (2003). Angew. Chem. Int. Ed. 42, 2085-2090.]; Meng et al., 2010[Meng, Q.-G., Yan, S.-T., Kong, G.-Q., Yang, X.-L. & Wu, C.-D. (2010). CrystEngComm, 12, 688-690.]). During the past decade, a variety of water clusters, such as trimers (Ghosh & Bharadwaj, 2005[Ghosh, S. K. & Bharadwaj, P. K. (2005). Inorg. Chem. 44, 5553-5555.]), tetra­mers (Zuhayra et al., 2006[Zuhayra, M., Kampen, W. U., Henze, E., Soti, Z., Zsolnai, L., Huttner, G. & Oberdorfer, F. (2006). J. Am. Chem. Soc. 128, 424-425.]), penta­mers (Zabel et al., 1986[Zabel, V., Saenger, W. & Mason, S. A. (1986). J. Am. Chem. Soc. 108, 3664-3673.]), hexa­mers (Saha & Nangia, 2006[Saha, B. K. & Nangia, A. (2006). Chem. Commun. pp. 1825-1827.]), octa­mers (Khatua et al., 2010[Khatua, S., Kang, J., Huh, J. O., Hong, C. S. & Churchill, D. G. (2010). Cryst. Growth Des. 10, 327-334.]), deca­mers (Yoshizawa et al., 2005[Yoshizawa, M., Kusukawa, T., Kawano, M., Ohhara, T., Tanaka, I., Kurihara, K., Niimura, N. & Fujita, M. (2005). J. Am. Chem. Soc. 127, 2798-2799.]), dodeca­mers (Song & Ma, 2007[Song, H.-H. & Ma, B.-Q. (2007). CrystEngComm, 9, 625-627.]), tetra­deca­mers (Ghosh et al., 2005[Ghosh, S. K., Ribas, J., Fallah, M. S. E. & Bharadwaj, P. K. (2005). Inorg. Chem. 44, 3856-3862.]), hexa­deca­mers (Bi et al., 2009[Bi, Y., Liao, W., Zhang, H. & Li, D. (2009). CrystEngComm, 11, 1213-1216.]) and octa­deca­mers (Luan et al., 2006[Luan, X., Chu, Y., Wang, Y., Li, D., Liu, P. & Shi, Q. Z. (2006). Cryst. Growth Des. 6, 812-814.]), and one-dimensional chains (Saha & Nangia, 2005[Saha, B. K. & Nangia, A. (2005). Chem. Commun. pp. 3024-3026.]), one-dimensional tapes (Cheng et al., 2006[Cheng, L., Lin, J. B., Gong, J. Z. & Sun, A. P. (2006). Cryst. Growth Des. 12, 2739-2746.]), two-dimensional layers (Zhang et al., 2005[Zhang, J.-P., Huang, X.-C., Lin, Y.-Y. & Chen, X.-M. (2005). Inorg. Chem. 44, 3146-3150.]) and three-dimensional structures (Carballo et al., 2005[Carballo, R., Covelo, B., Lodeiro, C. & Vázquez-López, E. M. (2005). CrystEngComm, 7, 294-296.]) have been reported. However, detailed studies of the aggregation patterns of smaller subunits within larger water clusters are less numerous (Yang et al., 2008[Yang, A.-H., Zhang, H., Gao, H.-L., Zhang, W.-Q., He, L. & Cui, J.-Z. (2008). Cryst. Growth Des. 8, 3354-3359.]; Li et al., 2008[Li, C.-H., Huang, K.-L., Dou, J.-M., Chi, Y.-N., Xu, Y.-Q., Shen, L., Wang, D.-Q. & Hu, C.-W. (2008). Cryst. Growth Des. 8, 3141-3143.]). In this paper, we present the structure of a cubane-like tetra­nuclear oxide-bridged cobalt(III) complex, namely [Co4(CO3)2([mu]3-O)4(bpy)4]·15H2O (bpy is 2,2'-bi­pyridine), (I)[link], including isolated two-dimensional water cluster layers.

[Scheme 1]
[Figure 1]
Figure 1
The mol­ecular structure of the cubane-like tetra­nuclear oxide-bridged cobalt(III) cluster of (I)[link], showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 45% probability level. [Symmetry code: (i) x, -y + [{1\over 2}], z.]
[Figure 2]
Figure 2
The structure and hydrogen-bond connectivity of the (H2O)14 cluster of (I)[link]. Green dashed lines indicate hydrogen-bonding interactions within tetrameric and pentameric water cluster units, and purple dashed lines represent hydrogen bonds between the pendent water molecules and the tetrameric and pentameric units in the (H2O)14 cluster. [Symmetry code: (i) x, -y + [{1\over 2}], z.]
[Figure 3]
Figure 3
The hydrogen-bonded network of the supra­molecular water layer of (I)[link]. Dashed lines indicate hydrogen bonds. [Symmetry codes: (i) x, -y + [{1\over 2}], z; (ii) x, y, z + 1; (iv) -x, -y + 1, -z + 1.]
[Figure 4]
Figure 4
The three-dimensional supra­molecular structure of (I)[link]. Green dashed lines indicate hydrogen-bonding interactions within the two-dimensional water cluster layers and purple dashed lines represent hydrogen bonds between the Co4O4 cores and the water clusters.

2. Experimental

2.1. Synthesis and crystallization

All chemicals and solvents were commercially available and were used without further purification. A purple precipitate resulted from the addition of Na2CO3 (1.0 ml, 1.0 M) to an aqueous solution of CoCl2·6H2O (0.1594 g, 0.67 mmol) in H2O (5 ml); it was separated by centrifugation and washed with distilled water four times, then transferred into a solution of 2,2'-bi­pyridine (0.1062 g, 0.67 mmol) in methanol (10 ml) and water (10 ml). To the resulting red solution (pH = 11.24), Na2CO3 (1.0 ml, 1.0 M) was added dropwise to adjust the pH to 12.21. The mixture obtained was allowed to stand at room temperature for 12 d to afford dark-red needle-shaped crystals of (I)[link].

2.2. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1[link]. H atoms bonded to C atoms were placed in geometrically calculated positions and refined using a riding model, with C-H = 0.93 Å and Uiso(H) = 1.2Ueq(C). H atoms attached to O atoms were found in a difference Fourier synthesis and refined with the O-H and intramolecular H...H distances restrained to 0.85 (1) and 1.35 (1) Å, respectively, and with Uiso(H) = 1.5Ueq(O), while the H atoms of the multiply split O19 atom could not be positioned reliably and were omitted from the structure model. Finally, all non-H atoms, except O19, were refined with anisotropic displacement parameters. Atom O19 was found to be split over four sites, which were assigned fractional occupancies summing to 0.5 and a common variable isotropic displacement parameter.

3. Results and discussion

Hydrated complex (I)[link] crystallizes in the ortho­rhom­bic space group Pnma, with a hydrogen-bonded water layer separating molecules of the cluster, which has a Co4O4 cubane core (Fig. 1[link]). The CoIII cations and O atoms are located at alternating corners of a distorted cube. Each CoIII cation is coordinated by two bpy N atoms, one carbonate O atom and three oxide O atoms, forming an octa­hedral CoN2O4 coordination geometry. Atom Co1 lies in a general posiiton (Wyckoff site 8d), while atoms Co2 and Co3 are halved by a mirror plane (Wyckoff sites 4c). The Co1-N/O bond lengths span the range 1.876 (2)-1.950 (2) Å, and the cisoid and transoid N/O-Co1-N/O angles span the ranges 81.68 (10)-97.73 (10) and 172.79 (9)-177.04 (10)°, respectively. For atom Co2, the corresponding ranges are 1.876 (2)-1.943 (3) Å, 81.61 (16)-96.77 (10) and 173.63 (12)-176.58 (10)°, and for atom Co3 they are 1.878 (2)-1.947 (2) Å, 81.05 (15)-98.05 (10) and 172.21 (13)-176.77 (10)°. All of these parameters are normal and confirm a slightly distorted octa­hedral coordination for the cations.

The cuboidal core of the cluster is distorted, with all the O-Co-O angles being smaller than 90° and all the Co-O-Co angles being larger than 90°. The Co...Co distances within the cubane vary from 2.6645 (9) to 2.8582 (7) Å (Table 2[link]). The resulting Co4O4 cubane-like cores are capped by two crystallographically distinct carbonate ligands, both of them bis­ected by a mirror plane.

It is inter­esting to note that ten symmetry-independent solvent water mol­ecules, by co-operative hydrogen-bonding inter­actions, form a two-dimensional water network comprised of tetra­meric and penta­meric water clusters as subunits (Fig. 2[link]). The water mol­ecules at O10, O14, O14i and O17 [symmetry code: (i) x, -y + [{1\over 2}], z] form a cyclic tetra­meric cluster through hydrogen bonds. The water mol­ecules containing O10 and O17 form pairs of mirror-symmetric hydrogen bonds, viz. O10-H10A...O14 and O17-H17A...O14, respectively (see Fig. 2[link] and Table 3[link] for details). With the inclusion of water atoms O11, O12, O16 and O16i, a cyclic tetra­meric water cluster is formed. In these tetra­meric clusters, the average O...O separation (2.84 Å) is comparable with the value of 2.85 Å in liquid water, where the O...O...O angles are in the range 73.6-98.4° (Eisenberg & Kauzmann, 1969[Eisenberg, K. D. & Kauzmann, W. (1969). In The Structure and Properties of Water. Oxford University Press.]). The hydrogen bonds within the penta­meric core involve atoms O10, O12, O14, O15 and O16, and their associated H atoms. As far as the penta­mer is concerned, the O...O...O angles are in the range 95.8 (2)-112.8 (3)° and the O...O distances range from 2.756 (5) to 2.840 (6) Å (average 2.796 Å), slightly longer than those observed in ice Ih (2.759 Å at 200 K; Eisenberg & Kauzmann, 1969[Eisenberg, K. D. & Kauzmann, W. (1969). In The Structure and Properties of Water. Oxford University Press.]).

The tetra­meric water clusters and the two crystallographically equivalent penta­meric water clusters are edge-shared into (H2O)14 clusters (Fig. 2[link]), in which the penta­meric clusters form hydrogen-bonding inter­actions with solvent water mol­ecule O13, and the crystallographically independent tetra­meric water cluster is a hydrogen-bond acceptor in an interaction with O9 and is a donor to O18. Neighbouring (H2O)14 clusters are joined together by hydrogen-bonding inter­actions through two independent six-membered water rings [one formed by atoms O13, O14, O15, O13iv, O14iv and O15iv, and the other formed by atoms 09ii, O10ii, O11, O14ii, O17ii and O18; symmetry codes: (ii) x, y, z + 1; (iv) -x, -y + 1, -z + 1], extending into a two-dimensional layer of water clusters (Fig. 3[link]). Inter­estingly, the Co4O4 cubane-like cores are sandwiched between these two-dimensional water cluster layers. Solvent mol­ecules O9, O12, O13 and O15 donate H atoms to carbon­ate atoms O1, O2, O3 and O5 (Table 3[link]). Due to this connection between the Co4O4 cubane-like core and the two-dimensional water cluster layers, the overall structure of (I)[link] can be considered as a three-dimensional metallo-supra­molecular network (Fig. 4[link]).

Table 1
Experimental details

Crystal data
Chemical formula [Co4(CO3)2O4(C10H8N2)4]·15H2O
Mr 1314.71
Crystal system, space group Orthorhombic, Pnma
Temperature (K) 293
a, b, c (Å) 30.712 (6), 16.820 (3), 10.588 (2)
V3) 5469.5 (19)
Z 4
Radiation type Mo K[alpha]
[mu] (mm-1) 1.28
Crystal size (mm) 0.27 × 0.20 × 0.08
 
Data collection
Diffractometer Rigaku R-AXIS RAPID diffrac­tometer
Absorption correction Multi-scan (ABSCOR; Higashi, 1995[Higashi, T. (1995). ABSCOR. Rigaku Corporation, Tokyo, Japan.])
Tmin, Tmax 0.742, 0.902
No. of measured, independent and observed [I > 2[sigma](I)] reflections 49124, 6456, 4752
Rint 0.077
(sin [theta]/[lambda])max-1) 0.649
 
Refinement
R[F2 > 2[sigma](F2)], wR(F2), S 0.042, 0.119, 0.99
No. of reflections 6455
No. of parameters 435
No. of restraints 30
H-atom treatment H atoms treated by a mixture of independent and constrained refinement
[Delta][rho]max, [Delta][rho]min (e Å-3) 0.69, -0.41
Computer programs: RAPID-AUTO (Rigaku, 1998[Rigaku (1998). RAPID-AUTO. Rigaku Corporation, Tokyo, Japan.]), CrystalStructure (Rigaku/MSC, 2004[Rigaku/MSC (2004). Crystal Structure. Rigaku/MSC Inc., The Woodllands, Texas, USA.]), SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]), SHELXL2013 (Sheldrick, 2008)[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.] and SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]).

Table 2
Selected bond lengths (Å)

Co1-O7 1.876 (2) Co2-O3 1.943 (3)
Co1-O8 1.879 (2) Co3-O6 1.878 (2)
Co1-O6 1.900 (2) Co3-O7 1.902 (3)
Co1-N1 1.940 (2) Co3-O4 1.940 (3)
Co1-N2 1.943 (2) Co3-N4 1.947 (2)
Co1-O1 1.950 (2) Co1...Co1i 2.6645 (9)
Co2-O6 1.876 (2) Co1...Co2 2.8547 (8)
Co2-O8 1.897 (3) Co1...Co3 2.8582 (7)
Co2-N3 1.943 (3) Co2...Co3 2.6689 (9)
Symmetry code: (i) [x, -y+{\script{1\over 2}}, z].

Table 3
Hydrogen-bond geometry (Å, °)

D-H...A D-H H...A D...A D-H...A
O9-H9A...O10 0.85 (1) 1.87 (1) 2.720 (6) 176 (5)
O9-H9B...O5 0.85 (1) 1.82 (2) 2.650 (5) 164 (5)
O10-H10A...O14 0.85 (1) 1.95 (2) 2.781 (4) 168 (9)
O11-H11A...O18 0.85 (1) 1.83 (1) 2.680 (7) 179 (6)
O11-H11B...O9ii 0.85 (1) 1.93 (1) 2.774 (5) 171 (6)
O12-H12A...O3 0.85 (1) 1.87 (2) 2.701 (5) 166 (5)
O12-H12B...O10 0.85 (1) 2.00 (1) 2.840 (6) 175 (5)
O13-H13A...O15 0.84 (1) 1.99 (2) 2.822 (4) 167 (4)
O13-H13B...O1iii 0.85 (1) 1.99 (2) 2.823 (3) 165 (4)
O14-H14A...O15 0.85 (1) 1.91 (1) 2.756 (5) 174 (5)
O14-H14B...O13iv 0.85 (1) 1.94 (2) 2.772 (4) 164 (5)
O15-H15A...O16 0.85 (1) 1.95 (1) 2.791 (5) 170 (5)
O15-H15B...O2v 0.84 (1) 1.90 (2) 2.722 (4) 163 (4)
O16-H16A...O11 0.85 (1) 2.03 (2) 2.862 (4) 169 (5)
O16-H16B...O12 0.85 (1) 1.99 (2) 2.811 (4) 161 (5)
O17-H17A...O14 0.85 (1) 2.05 (1) 2.891 (4) 171 (4)
O18-H18A...O17ii 0.85 (1) 1.96 (2) 2.791 (8) 164 (8)
O18-H18B...O2v 0.85 (1) 2.38 (4) 3.163 (7) 152 (7)
Symmetry codes: (ii) x, y, z+1; (iii) [x-{\script{1\over 2}}, -y+{\script{1\over 2}}, -z+{\script{3\over 2}}]; (iv) -x, -y+1, -z+1; (v) [x-{\script{1\over 2}}, y, -z+{\script{3\over 2}}].

Supporting information for this paper is available from the IUCr electronic archives (Reference: BG3165 ).


Acknowledgements

This project was supported by the K. C. Wong Magna Fund of Ningbo University.

References

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Acta Cryst (2014). C70, 198-201   [ doi:10.1107/S2053229614001107 ]