Molecular complexes of 4-NH2-benzophenone with bismuth(III) halides and with iodine

The following solid complexes of 4-NH₂-benzophenone (L) with bismuth (III) chloride, bromide and iodide and with iodine were prepared: BiCl₃·L (yellow), BiCl₃·2L (red), 3BiBr₃·2L (orange), BiBr₃·2L (red). 2BiI₃·3L (red), I·L (yellow), I·2L (orange), I·3L (red). The iodine complexes are obtained from ethanolic solutions of BiI₃ and the ligand, by precipitation with water or ligroin, the iodide ion being oxydized to iodine by the oxygen dissolved in the solvents. From an oxygen free ligroin-ethanolic solution only 2 BiI₃·3L is obtained. The i.r. spectra of the solids show that in the yellow or orange BiX₃ complexes the NH₂ group is involved into the coordination while in the red BiX₃ complexes and in the orange and red iodine complexes the v(NH) bands of the ligand remain unaltered. The carbonylic oxygen is not involved in the coordination. In DCM solution the red BiX₃ complexes and all the iodine complexes show a C.T. band at 440-420 nm, the energy of which gives a linear plot versus the electron affinity of the three halogens. The electronic spectra of the solids show a C.T. band in the region 470–500 nm.