Phenyl bismuth β-diketonate complexes: Synthesis and structural characterization

The first examples of arylbismuth diketonate complexes are reported. Phenylbismuth(III) bis(hexafluoroacetylacetonate), BiPh(hfac)2 (1) and its adducts [BiPh(hfac)2(L)] (Hhfac = 1,1,1,5,5,5-hexafluoro-2,4-pentanedione; L = H2O (1a), Me2CO (1b), THF (1c), DMA (N,N-dimethylacetamide) (1d), DMSO (1e), PhCN (1f), as well as a mixed hexafluoroacetylacetonate–trifluoroacetate complex, [BiPh(hfac)(O2CCF3)]2 (2), have been synthesized and characterized. Compound 1 is isolated from the reaction of BiPh3 with 2 equiv. of Hhfac in dry hexanes. Compound 2 can be synthesized using two different routes: one utilizes the reaction between stoichiometric amounts of 1 and CF3CO2H, while the second method involves the interaction of the previously described BiPh2(O2CCF3) (3) with Hhfac. Crystallographic analysis of the [BiPh(hfac)2(L)] adducts reveals a pentagonal pyramidal geometry around the metal center; similarly, the dinuclear [BiPh(hfac)(O2CCF3)]2 complex is composed of two distorted pentagonal pyramids connected into dimers by the bridging carboxylate groups. The effect of replacing the Lewis base in the coordination sphere of Bi(III) on the coordination polyhedron and crystal packing is discussed. The 1H and 19F NMR spectra of the title complexes at room temperature indicate single environments for the hfac group and suggest that they are fluxional in solutions on the NMR time scale. Compounds 1 and 2 are promising starting materials in the chemistry of bismuth(III) and as building blocks for the construction of heterometallic species.