Synthesis, structure, and stereochemical non-rigidity of bis[(2,2-dimethyl-4-oxo-2H-benzo[e][1,3]oxazin-3(4H)-yl)methyl] dichlorosilane and -germane

Abstract

Bis[(2,2-dimethyl-4-oxo-2H-benzo[e][1,3]oxazin-3(4H)-yl)methyl]dichlorosilane (1) and -germane (2) were synthesized by the reaction of 2,2-dimethyl-3-(trimethylsilyl)-2H-benzo[e][1,3]oxazin-3(4H)-one with bis(chloromethyl)dichlorosilane and -germane, respectively, taken in a ratio of 2 : 1. The structures of these compounds were determined and their stereodynamic behavior in solution was studied by multinuclear (1H, 13C, and 29Si) and twodimensional (1H, 13C COSY, HETCOR) NMR spectroscopy. The 29Si NMR spectroscopic study of a solution of complex 1 provides evidence that the silicon atom in this complex is pentacoordinate. The X-ray diffraction study showed that the germanium atom in complex 2 in the solid state is hexacoordinate. The permutation isomerization in the coordination units of complexes 1 and 2 was found and investigated by dynamic 1H NMR spectroscopy. Different mechanisms of stereodynamic transformations are suggested and discussed.