Stereoelectronic effects in R–NSN–R systems. An MNDO and ab initio SCFMO study

Abstract

The syn,syn configurational preference of compounds of the type R–NSN–R, where the substituent R is SiMe₃, is rationalized in terms of anti-periplanar hyperconjugation between the in plane nitrogen lone pairs on the NSN fragment and the electropositive silicon-H/Me σ bonds. MNDO and ab initio calculated energies and geometries are reported for a range of electropositive and electronegative substituents R and discussed in terms of stereoelectronic interactions.