Synthesis and Characterization of New Phenylbis(salicylato)bismuth(III) Complexes

Compounds with the compositions [BiPh(Hsal)₂] (1a) and [BiPh(Hsal^4Me)₂] (1b) were prepared by the reactions of triphenylbismuth with 2-hydroxybenzoic acid (H₂sal) and 4-methyl-2-hydroxybenzoic acid (H₂sal^4Me), respectively, in a 1:2 ratio. The reactions of 1a,b with the bidentate nitrogen donor ligands 1,10-phenanthroline (phen) and 2,2‘-bipyridine (bipy) led to the isolation of the corresponding adducts [BiPh(Hsal)₂(phen)] (2a), [BiPh(Hsal^4Me)₂(phen)] (2b), [BiPh(Hsal)₂(bipy)] (2c), and [BiPh(Hsal^4Me)₂(bipy)] (2d). Crystallographic analyses of the adducts showed the solids to have monomeric structures with six-coordinate Bi(III). One salicylato ligand is coordinated in a monodentate fashion and the other in a bidentate, chelating manner. The phenol oxygen atoms remain uncoordinated in both cases. The coordination geometry around Bi(III) in 2a, 2b·Me₂CO, 2c, and 2d·DMF can be described as distorted pentagonal pyramidal with an apical C atom, while the free space trans to the ipso carbon atom of the phenyl group is believed to accommodate a stereochemically active pair of electrons. The ¹H data demonstrate that the salicylate ligands are fluxional in solution. It was shown that under different reaction conditions a number of bismuth(III) oligomeric, dimeric, and monomeric complexes are produced, including [Bi₃₈O₄₄(Hsal)₂₆(Me₂CO)₁₆(H₂O)₂]·4Me₂CO, [Bi(Hsal^4Me)(sal^4Me)(phen)]₂·2Me₂CO ([3]₂·2Me₂CO), [Bi(Hsal^4Me)₃(bipy)]₂·4Me₂CO ([4]₂·4Me₂CO), and [Bi(Hsal^4Me)₃(phen)(MeOH)] (5), which attest to a rich chemistry in this system.