The synthesis and structure of new tin(II) complexes based on ferrocenyl-containing o-iminophenols

•Two new bis-o-iminophenolato tin(II) complexes Sn(FcCH = NArO)2 were prepared.•Complexes have a tetragonal-pyramidal geometry; tin(II) lone pair is in apical site.•DFT calculations were performed to evaluate the HOMO energy and delocalization.•According to NBO Sn(II) lone-pair energy increases in tert-butyl-containing compound.

The interaction of ferrocenyl-containing Schiff bases Fc-C(H) = N-(C6H4)-OH (1) and Fc-C(H) = N-(4,6-tBu-C6H2)-OH (2) with tin(II) chloride in THF solution in the presence of base leads to new tin(II) bis-o-iminophenolato complexes 3 and 4 of the type (Fc-CH = N-ArO)2SnII. Compounds were characterized in details by IR-, 1H and13C NMR spectroscopy. The molecular structures of 3·2THF and 4·0.5Et2O were determined by single-crystal X-ray crystallography to be a distorted tetragonal-pyramidal with tin(II) lone pair in the apical site. DFT (B3LYP/DZP) calculations of 3 and 4 have shown that the HOMO in 3 (− 5.17 eV) is located in energy lower than the HOMO in 4 (− 5.11 eV). In the accordance with NBO calculations, tin(II) lone-pair in 3 lies lower in energy (− 9.70 eV) than in 4 (− 9.61 eV) due to the presence of electron-donor tert-butyl groups in 4.

Graphical abstractTwo new tin(II) complexes based on ferrocene-containing Schiff base ligands of Fc-CH=N-Ar-OH type (Ar = C6H4,·4,6-tBu2C6H2) have been synthesized. Complexes are isostructural, the central tin(II) atom has a tetrahonal-pyramidal geometry. DFT calculations and NBO analysis have shown that electron-donor tert-butyl groups in increase the HOMO energy and the energy of a lone-pair of Sn(II) in these complexes.Figure optionsDownload full-size imageDownload as PowerPoint slide