Cobalt Triflates [Co(H2O)6](CF3SO3)2 and Co(CF3SO3)2: Synthesis, Crystal Structures, Thermal Stability, and Magnetic Properties

Cobalt triflate hexahydrate [Co(H 2 O) 6 ](CF 3 SO 3 ) 2 ( I ) is crystallized from aquos solution. The dehydration of salt I at 200°C in an argon flow affords anhydrous salt Co(CF 3 SO 3 ) 2 ( II ). The crystal structures of compounds I and II are determined from single crystal and powder X-ray diffraction data, respectively. Compound I is isostructural to [Ni(H 2 O) 6 ](CF 3 SO 3 ) 2 and crystallizes in the space group P m 1, а = 7.3914(16), с = 8.704(2) Å, V = 411.8(2) Å 3 , Z = 1. The structure of compound II (space group R , а = 4.9996(1), с = 31.3137(8) Å, V = 677.86(3) Å 3 , Z = 3) belongs to the structural type M(CF 3 SO 3 ) 2 , where M = Mg, Ca, and Zn. In the structures of both compounds, the cobalt atoms are in the octahedral environment of the oxygen atoms belonging to the water molecules ( I ) or triflate groups ( II ). In compound I , the [Co(H 2 O) 6 ] 2+ cations localized in the nodes of a regular triangular network are linked with the (CF 3 -SO 3 ) – anions via hydrogen bonds to form layers parallel to the (001) plane. When compound I is dehydrated to form compound II , the [CoO 6 ] octahedra are coupled via the μ 3 -CF 3 SO 3 group with the retention of the layered structure. The synthesized compounds are characterized by IR spectroscopy, TG/DTA/MS. The results of studying the magnetic properties of compounds I and II indicate no magnetic ordering at low temperatures and correspond to the paramagnetic behavior of compounds I and II at high temperatures with a considerable contribution of the spin-orbital interaction to the effective magnetic moment of the cobalt atom.