Novel hexacoordinate organosilicon(IV) complexes of diethylenetriamine Schiff base with SiO2N3 skeleton

Abstract

Some novel hexacoordinate silicon(IV) complexes with a SiO2N3 skeleton were synthesized by using potentially pentadentate ligand N,N'-diethylenetriamine-bis(salicylideneimine). The aforesaid ligand, obtained by the condensation of diethylenetriamine and salicylaldehyde, contains two N of azomethine C=N group, two O of phenolic -OH group and one N of -NH- group capable of coordination. The ligand reacts with RSiCl3 (R = CH3, C6H5, C2H5, CH=CH2) in the presence of triethylamine to yield hexacoordinate silicon complexes 1-4. The resulting complexes were characterized by IR spectroscopy, 1 H, 13 C, 29 Si NMR spectroscopy and elemental analysis. The geometry and hexacoordination was confirmed by comparing the experimental results with computational studies by using GAUSSIAN 03 series of programs. The IR frequencies and 29 Si NMR shifts calculated for isomer B with Density Functional Theory (B3LYP-3-21+G* basis set) correlate with experimental values and suggested the geometry of synthesized complexes. Total energies, dipole moment and bond lengths were calculated from the geometries optimized with semi-empirical methods.