Volatile β-diketonate complexes of Rb-Co: effect of incorporation a neutral ligand 18-crown-6 ether

Heterometallic β-diketonate complexes MI[M(L)n] containing alkali metal cations MI are of great interest from the point of view of their use in the preparation of halide perovskites. However, such compounds are poorly studied for MI = Rb and there is no information on their crystal structure. In this work, two types of such complexes are presented: Rb[Co(hfac)3] 1 and novel [Rb(18C6)][Co(hfac)3] 2 (hfac = CF3COCHCOCF3–, hexafluoroacetylacetonate ion, 18C6 = 18-crown-6 ester). The compounds were characterized by elemental analysis, IR spectroscopy, single-crystal and powder XRD, and TGA. Both complexes have a chain polymeric structure, whereas the inclusion of the neutral 18C6-ligand effectively reduces the number of contacts between the cation and the complex anion [Co(hfac)3]–. Both heterometallic complexes are more thermally stable than Rb(hfac), with 1 partially transitioning into the gas phase at atmospheric pressure.