Crystal and electronic structures of tris[4,4,4-Trifluoro-1-(2-X)-1,3-butanedionato]iron(III) isomers (X = thienyl or furyl): An X-ray and computational study

•Crystal structures of fac and mer isomers of tris(beta-diketonato)3 complexes.•DFT calculations showed that the mer isomers are energetically favoured for both complexes.•Molecular energy levels and orbitals of [Fe(acac)3].•DFT calculations showed that complex [Fe(acac)3] is high-spin.

DFT calculations showed that [Fe(acac)3] (where acac = acetylacetonato) is high-spin, with a negative D3 distortion from the octahedral ligand field. Calculations further showed that, although both the fac and mer isomers of complexes [Fe(CF3COCHCOR)3], where R = C4H3S or C4H3O, can exist, the mer isomers are energetically favoured in both complexes. The structure of the major mer isomer of [Fe(CF3COCHCOC4H3S)3] has been published previously, while the crystal structure of the minor fac isomer of [Fe(CF3COCHCOC4H3S)3] is presented in this study. The structure of the mer isomer of [Fe(CF3COCHCOC4H3O)3], in agreement with DFT calculations, showed that the furyl substituent pointed towards the CF3 group in a syn orientation.

Graphical abstractElectronic and crystal structures of selected fac and mer isomers of tris(beta-diketonato)3 complexes.Figure optionsDownload full-size imageDownload as PowerPoint slide