Synthesis, morphology, structure, and magnetic characterization of layered cobalt hydroxylsocyanates

New layered pink cobalt hydroxyisocyanates have been prepared by controlled hydrolysis of aqueous solutions of CoCl2 center dot 6H(2)O center dot Co(OH)(1.4)(NCO)(0.6) center dot 0.6H(2)O (1) is formed when urea is used as the hydrolysis agent and mannitol as the stabilizer, while Co(OH)(1.25)(NCO)(0.75) center dot 0.2H(0)O(2) is formed when the hydrolysis agent is changed to hexamethylenetetramine and NaOCN is added to the solution. IR spectroscopy of 1 and 2 indicates that the OCNis N-bonded to Co2+. The X-ray powder data for I could be indexed using an intergrowth model consisting of both rhombohedral (R (3) over barm (166); a 3.2031 (1) angstrom, c = 23.6876(1 1) angstrom, hydrotalcite-like, 3R(1)) and hexagonal (P 63/mmc (194); a = 3.2005(2) angstrom, c = 15.8303(5) angstrom, Manasseite-like, 2H(1)) polytypes. Rietveld refinement of the X-ray powder data was performed using a two polytype model and 30% random substitution of the OH- ions by OCN-. Although it is less crystalline, the XRD data for 2 can be indexed using a rhombohedral-symmetry cell with unit cell parameters, a = 3.158 angstrom and c = 21.57 angstrom. Both 1 and 2 exhibit magnetically ordered ground states with a saturation magnetization of ca. 2.0 mu B. The magnetization data is consistent with 3D ferromagnetic ordering of edge-share octahedral-Co2+ layers with effective spin S' = 1/2.