Stereochemistry of nitrogen E lone pair in NH3E, NOFE, N2O3E2, AgNO2E, and NCl3E

We revisit nitrogen based simple fundamental molecules in their solid state structures, with the purpose of casting new light on the stereoactivity of valence lone pairs (LPs)-formally N(2s2)-in different crystal geometries. Based on coupled investigations of crystal chemistry and ab initio DFT calculations providing the electron localization function (ELF), LP behavior is analyzed precisely by finding its position E, orientation and “volume of influence” which consists in an electronic cloud generated around the so-called 'centroïd' Ec of the electronic doublet. The results show the paramount importance of the role of N(2s2) LP in the crystal network architecture through the different case studies pertaining to ammonia (NH3), nitrosyl fluoride (NOF), nitrosyl nitrite (N2O3), silver nitrite (AgNO2), and nitrogen trichloride (NCl3). An unexpected direct ionic interaction between [NO]+ or Ag+ and the centroïd Ec of the [NO2Ec]− nitrite group has been evidenced in N2O3E2 and AgNO2, respectively.