The bonding properties and the potential energy surfaces for the chemical reactions of doubly bonded compounds that have the >E13═E15< pattern are studied using density functional theory (M06-2X/Def2-SVPD). Nine molecules, >E13═P< (E13 = B, Al, Ga, In, and Tl) and >B═E15< (E15 = N, P, As, Sb, and Bi), are used as model reactants in this work. Four types of chemical reactions, H2 addition, acetonitrile, benzophenone [2 + 2] cycloadditions, and dimethylbutadiene [4 + 2] cycloaddition, are used to study the chemical reactivity of these inorganic, ethylene-like molecules. The results of these theoretical analyses show that only the >B═P< molecule has a weak B═P double bond, while the >Al═P< , >Ga═P< , >In═P< , >Tl═P< , >B═N< , >B═As<, >B═Sb<, and >B═Bi< compounds are best described as having a strong single σ bond, instead of a traditional p-p π bond. The theoretical results also show that the singlet-triplet energy gap can be used to determine the relative reactivity of these doubly bonded molecules. According to these theoretical investigations, it is predicted that the order of reactivity is as follows: B═P > Al═P > Ga═P > In═P > Tl═P and B═N ≪ B═P < B═As < B═Sb < B═Bi. The conclusions drawn are consistent with the available experimental observations.

The bonding properties and the potential energy surfaces for the chemical reactions of heteroallenic compounds with a –P=C=E14< pattern are studied by using density functional theory (M06‐2X/Def2‐SVPD). Five Mes*P=C=E14(tBu)Tip species, for which E14 = C, Si, Ge, Sn, and Pb, were used as model reactants in this work. The theoretical evidence shows that Mes*P=C=E14(tBu)Tip molecules have both P=C and C=E14 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 (E14) in the heteroallenic –P=C=E14< 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=E14< increases in the order: –P=C=C<, –P=C=Si<, –P=C=Ge<, –P=C=Sn<, and –P=C=Pb<.

No abstract

A density functional study of singlet and triplet state fullerene carbenes is performed, using the M06-2X/CRENBL ECP, M06-2X/Def2-SV­(P), and M06-2X/LANL2DZ levels of theory. The structures of two model carbenes (C60–E–C60 and C70–E–C70; E = C, Si, Ge, Sn, and Pb) in their closed-shell singlet and open-shell triplet states are obtained. The theoretical computations suggest that the formation of C60–E–C60 should be energetically more feasible than that of C70-E-C70 (E = C, Si, and Ge). In particular, the C70–E–C70 species with tin and lead should be relatively difficult to produce, from the viewpoint of bonding dissociation energy. The theoretical evidence also suggests that the bulky substituents that occupy the inner side of C60–E–C60 and C70–E–C70 should make the triplet ground state easily achievable. These theoretical findings show that both the relativistic effect and steric effect play an essential role in determining the electronic states of fullerene carbenes.