A new look at the essence of the formation of trigonal planar coordination of the central N and O atoms

Abstract

In this paper, we argued that the classical explanation to the formation of trigonal planar coordination of the center N and O atoms in N(SiR3)3 and [O(SiR3)3]+ by forming 4-center 2-electron conjugated d-pπ bond was questionable, since it could not correctly predict the configurations of P(SiR3)3 and [S(SiR3)3]+. We found that the trigonal planar configuration of the center N and O atoms was strongly correlated to the greater difference between the electronic negativities of the center atom N/O, and the around Si atoms. We proposed that repulsive interactions among the three positive charged YR3 (Y=Si) moieties resulted in the trigonal planar configuration of the center N and O atoms. This proposal was supported by the predicted trigonal planar configurations of model species [F(BH3)3]− and [O(BH3)3]2−, in which the formation of 4-center 2-electron conjugated d-pπ bond was impossible.