Treatment of CoCl 2 •6H 2 O and tris(pyrazolyl-1-yl)borate tricyanoiron(III) anions at 55 °C afforded a series of new Fe-Co polynuclear clusters: {Co 2 Cl 2 (DMF) 4 [(Tp 4-Me )Fe(CN) 3 ] 2 } (1; Tp 4-Me = hydridotris(4methylpyrazol-1-yl)borate), (H 3 O + )@{Co 4 Cl 4 [(Tp 4-Me )Fe(CN) 3 ] 4 } (2), (MePh 3 P) 4 {Co 6 Cl 6 [(Tp 4-Me )Fe(CN) 3 ] 6 }•15CH 3 CN•3CH 3 OH•2H 2 O (3), and (BnEt 3 N) 4 {Co 5 Cl 8 [(Tp*)Fe(CN) 3 ] 4 }•4CH 3 CN•2H 2 O (4; Tp*= hydridotris(3,5dimethylpyrazol-1-yl)borate). They feature an asymmetric [Fe 2 Co 2 (CN) 4 ] square, a pseudocubic [Fe 4 Co 4 (CN) 12 ] cluster, a distorted-hexagonal-prism-shaped [Fe 6 Co 6 (CN) 18 ] cage, and a bis(trigonal-bipyramidal) cluster of [Fe 4 Co 5 (CN) 12 ] fused at one cobalt center, respectively. The Co(II) ions adopt a four-coordinate tetrahedral geometry except for half of 1 in an octahedral geometry. It should be mentioned that 3 and 4 provide two novel molecular skeletons in the cyanometalate family. Interestingly, 1 behaved as a single-molecule magnet with an effective energy barrier for spin reverse of 30.7 K at zero dc field. Our result demonstrated a possible self-assembly route toward high-nuclearity cyanide-bridged clusters by introducing four-coordinate cobalt(II) ions.

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Operation experiments were conducted to optimize the preparation of activated carbons from corn cob. The Cr(VI) adsorption capacity of the produced activated carbons was also evaluated. The impact of the adsorbent dosage, contact time, initial solution pH and temperature was studied. The results showed that the produced corn cob activated carbon had a good Cr(VI) adsorptive capacity; the theoretical maximum adsorption was 34.48 mg g(-1) at 298 K. The Brunauer-Emmett-Teller and iodine adsorption value of the produced activated carbon could be 924.9 m(2) g(-1) and 1,188 mg g(-1), respectively. Under the initial Cr(VI) concentration of 10 mg L(-1) and the original solution pH of 5.8, an adsorption equilibrium was reached after 4 h, and Cr(VI) removal rate was from 78.9 to 100% with an adsorbent's dosage increased from 0.5 to 0.7 g L(-1). The kinetics and equilibrium data agreed well with the pseudo-second-order kinetics model and the Langmuir isotherm model. The equilibrium adsorption capacity improved with the increment of the temperature.

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