Separations of CO(2)/CH(4), CO(2)/N(2), and O(2)/N(2) mixtures were studied in three porous coordination polymers made of the same carborane ligand and Co(ii) nodes. High selectivities for CO(2) over CH(4) ( approximately 47) and CO(2) over N(2) ( approximately 95) were obtained, especially in the material with coordinated pyridine. Unusual selectivity for O(2) over N(2) (as high as 6.5) was demonstrated in the materials with open Co(ii) sites.