A Model Study on Molecular Properties and Mechanistic Investigations of P=C=E 14 Molecules

The bonding properties and the potential energy surfaces for the chemical reactions of heteroallenic compounds with a –P=C=E 14 < pattern are studied by using density functional theory (M06‐2X/Def2‐SVPD). Five Mes*P=C=E 14 ( t Bu)Tip species, for which E 14 = C, Si, Ge, Sn, and Pb, were used as model reactants in this work. The theoretical evidence shows that Mes*P=C=E 14 ( t Bu)Tip molecules have both P=C and C=E 14 double bonds. Four types of chemical reaction – water addition, acetylene [3+2] cycloaddition, ketone [2+2] cycloaddition, and selenium [1+2] cycloaddition – have been used to study the reactive activity of these group 14 heteroallenic molecules. This theoretical work predicts that the heavier the group 14 element (E 14 ) in the heteroallenic –P=C=E 14 < compounds, the smaller is its singlet–triplet energy splitting, the lower is its activation barrier, and the more rapid are its chemical reactions with various chemical species. As a result, this theoretical investigation shows that the relative reactivity of –P=C=E 14 < increases in the order: –P=C=C<, –P=C=Si<, –P=C=Ge<, –P=C=Sn<, and –P=C=Pb<.