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CoCl2 is trigonal omega-like structured and crystallizes in the trigonal R-3m space group. The structure is two-dimensional and consists of three CoCl2 sheets oriented in the (0, 0, 1) direction. Co2+ is bonded to six equivalent Cl1- atoms to form edge-sharing CoCl6 octahedra. All Co–Cl bond lengths are 2.43 Å. Cl1- is bonded in a distorted T-shaped geometry to three equivalent Co2+ atoms.
CoCl2 is trigonal omega structured and crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of one CoCl2 sheet oriented in the (0, 0, 1) direction. Co2+ is bonded to six equivalent Cl1- atoms to form edge-sharing CoCl6 octahedra. There are two shorter (2.40 Å) and four longer (2.46 Å) Co–Cl bond lengths. Cl1- is bonded in a distorted T-shaped geometry to three equivalent Co2+ atoms.
CoCl2 is trigonal omega structured and crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of one CoCl2 sheet oriented in the (0, 0, 1) direction. Co2+ is bonded to six equivalent Cl1- atoms to form edge-sharing CoCl6 octahedra. There are two shorter (2.42 Å) and four longer (2.44 Å) Co–Cl bond lengths. Cl1- is bonded in a distorted T-shaped geometry to three equivalent Co2+ atoms.
CoCl2 is trigonal omega-like structured and crystallizes in the trigonal P-3m1 space group. The structure is two-dimensional and consists of one CoCl2 sheet oriented in the (0, 0, 1) direction. Co2+ is bonded to six equivalent Cl1- atoms to form edge-sharing CoCl6 octahedra. All Co–Cl bond lengths are 2.44 Å. Cl1- is bonded in a distorted T-shaped geometry to three equivalent Co2+ atoms.
A heat-driven catch-and-release strategy for CoCl 2 capture is described. It is based on the use of an immobilized neutral dicyclohexylacetamide-based receptor L supported on polystyrene (PS-L). An X-ray diffraction analysis of a single crystal of L·CoCl 2 revealed an ion-pair complex comprising a hexacoordinated cobalt cation [L·Co] 2+ and a tetrachlorocobaltate anion [CoCl 4 ] 2– . Temperature dependent binding was seen, as inferred from UV–vis spectroscopic studies. Fits to the van’t Hoff equation yielded values of ΔH° = 12.4 kJ/mol and ΔS° = 56.0 J/K·mol for L + CoCl2, and ΔH° = 16.5 kJ/mol and ΔS° = 85.0 J/K·mol for PS-L + CoCl 2 in 95% ethanol. Consequently, cobalt capture and release are mediated by heating and cooling, respectively. The material PS-L exhibits a preference for binding cobalt over manganese and nickel as inferred from Langmuir–Freundlich isotherm analyses that revealed binding constants of KLF = 88.5 M –1 for CoCl 2 , 52.7 M –1 for MnCl 2 , and 49.7 M –1 for NiCl 2 . In a simulated ion mixture containing equimolar CoCl 2 , MnCl 2 , and NiCl 2 , ICP-MS analyses served to confirm that cobalt was selectively enriched to 52 mol % (from an initial level of ca. 32 mol %) after one catch-and-release cycle and 76.6% after three cycles. Our experimental results were validated by density functional theory calculations, which also show stronger binding of Co over Mn and Ni to L.