Toward a General Strategy for the Synthesis of Heterobimetallic Coordination Complexes for Use as Precursors to Metal Oxide Materials:  Synthesis, Characterization, and Thermal Decomposition of Bi2(Hsal)6·M(Acac)3 (M = Al, Co, V, Fe, Cr)

Bismuth(III) salicylate, [Bi(Hsal)3]n, reacts readily with the trivalent metal β-diketonate compounds M(acac)3 (acac = acetylacetonate; M = Al, V, Cr, Fe, Co) to produce trinuclear coordination complexes of the general formula Bi2(Hsal)6·M(acac)3 (M = Al, V, Cr, Fe, Co) in 60−90% yields. Spectroscopic and single crystal X-ray diffraction experiments indicate that these complexes possess an unusual asymmetric nested structure in both solution and solid state. Upon standing in dichloromethane solution, Bi2(Hsal)6·Co(acac)3 eliminates Bi(Hsal)3 to give the 1:1 adduct Bi(Hsal)3·Co(acac)3. The 2:1 heterobimetallic molecular compounds undergo facile thermal decomposition on heating in air to 475 °C to produce heterometallic oxide materials, which upon annealing for 2 h at 700 °C form crystalline oxide materials. The synthetic approach detailed here represents a unique, general approach to the formation of heterobimetallic bismuth-based coordination complexes via the coordination of M(acac)3 complexes to bismuth(III) salicylate.