Towards the accurate computation of properties of transition metal compounds: the binding energy of ferrocene

Recently published ab initio computations on ferrocene in the framework of coupled-cluster as well as multireference perturbation theory are exploited to obtain a theoretical best estimate of 655 ± 15 kcal/mol for the heterolytic bond disruption enthalpy. This best estimate was obtained by establishing the complete atomic orbitals basis set limit at the level of single-reference second-order perturbation theory, and computing corrections for relativistic effects, semicore (3s/3p) electron correlation effects, vibrational zero-point energy corrections, and structural relaxation energies of the fragments. Agreement with the experimental value of 635 ± 6 kcal/mol is unsatisfactory.