Dative and Electron‐Sharing Bonding in C 2 F 4

The reaction pathway for the rupture of the carbon–carbon double bond of C 2 F 4 has been calculated with ab initio methods at the CASSCF(8,8)+NEVPT2/aug‐cc‐pVTZ and CCSD(T)/aug‐cc‐pVTZ levels and with density functional theory using M06‐L and M06‐2X functionals in conjunction with aug‐cc‐pVTZ basis sets. The calculations suggest that the bond dissociation pathway proceeds by a nonlinear reaction course without an activation barrier yielding the CF 2 fragments in the ( 1 A 1 ) ground state. A bonding analysis indicates that there is a continuous change in the electronic structure of the CF 2 fragments during the elongation of the C–C distance from a ( 3 B 1 ) excited state at the equilibrium geometry of C 2 F 4 to the ( 1 A 1 ) ground state. EDA‐NOCV calculations suggest that the carbon–carbon interactions in C 2 F 4 at equilibrium distance and longer C–C values up to ≈1.60 Å are best described in terms of electron‐sharing bonding between the CF 2 fragments in the ( 3 B 1 ) excited state. At longer distances, the situation changes toward dative bonding between CF 2 fragments in the ( 1 A 1 ) ground state.