Expanding the Structural Motif Landscape of Heterometallic β-Diketonates: Congruently Melting Ionic Solids

The first example of ionic β-diketonates in which both the cation and anion are octahedral coordinatively saturated metal diketonate moieties are reported. Heterometallic tin-transition-metal heteroleptic diketonates were obtained through solid-state redox reactions and are formulated as {[Sn^IV(thd)₃]⁺[M^II(hfac)₃]^-} (M^II = Mn (1), Fe (2), Co (3); thd = 2,2,6,6-tetramethyl-3,5-heptanedionate, hfac = hexafluoroacetylacetonate). X-ray single-crystal structural investigations along with DART mass spectrometry, multinuclear NMR, and magnetic susceptibility measurements have been used to confirm an assignment of metal oxidation states in compounds 1-3. Ionic compounds were found to melt congruently at temperatures below the decomposition point. As such, they represent prospective materials that can be utilized as ionic liquids as well as reagents for the soft transfer of diketonate ligands. An unexpected volatility of ionic compounds 1-3 was proposed to occur through a transport reaction, in which the transport agent is one of the products of their partial decomposition in the gas or condensed phase.