D. Ramprasad, G. Pez, B. Toby
Nov 1, 1995
Citations
0
Influential Citations
67
Citations
Journal
Journal of the American Chemical Society
Abstract
Lithium pentacyanocobaltate coordination polymers with the formulas Li{sub 3}[Co(CN){sub 5}].4DMF (1, DMF = N, N-dimethylformamide) and Li{sub 3}[Co(CN){sub 5}].2DMF (2) have been synthesized and structurally characterized. Both compounds react reversibly with O{sub 2}, forming 1:1 superoxo complexes. Compound 2 reacts more rapidly and has the highest reported capacity for a solid O{sub 2} carrier (55 std cm{sup 3}/g). In contrast to previously reported dioxygen complexes of cyanocobaltates, the novel ability of 1 and 2 to react reversibly with O{sub 2} is made possible by the interaction of Li cations with the nucleophilic N atoms of the cyanide ligands. This interaction effectively reduces the basicity of the cyanide ligands, decreasing the net electron density on Co(2+) and hence weakening the charge-transfer interaction with O{sub 2}. The structure of 1 was determined from single-crystal X-ray diffraction measurements. Monocrystals of 2 suitable for X-ray structural analysis could not be grown, but the structure was solved ab initio from synchrotron powder diffraction data by using a simulated-annealing technique. 30 refs., 11 figs., 6 tabs.