INTRAMOLECULAR NITROGEN LIGAND STABILIZATION OF PHENYL-IMIDAZOLIDINE DERIVED SILICON SPECIES

The synthesis of some new functional aminoarylsilanes with the aromati c ring substituted in the ortho-position by a 2-(1,3-dimethyl)imidazol idine ligand is presented. The donating properties of the imidazolidin e fragment, in which the two coordinating nitrogen atoms are located o n the same side of the silicon center induce a specific chemical behav ior of the organosilicon species. Thus, only one Si-H bond of ArSiH3 w as found to react with an excess of organic acids and heterocumulenes. NMR studies showed that, if in imidazolidinylphenyldihydrosilanes con taining a strong electronegative substituent, the silicon center is pe ntacoordinated by forming one additional N-->Si bond, only a small act ivation energy is sufficient to exchange the two donating nitrogen ato ms. The reason for this easy exchange is probably the small distance b etween the two donor centers and the rigidity caused by the bridging e thylene unit. (C) 1998 Elsevier Science S.A. All rights reserved.