Inclusion of the ligand field contribution in a polarizable molecular mechanics: SIBFA-LF.
To account for the distortion of the coordination sphere that takes place in complexes containing open-shell metal cations such as Cu(II), we implemented, in sum of interactions between fragments ab initio computed (SIBFA) molecular mechanics, an additional contribution to take into account the ligand field splitting of the metal d orbitals. This term, based on the angular overlap model, has been parameterized for Cu(II) coordinated to oxygen and nitrogen ligands. The comparison of the results obtained from density functional theory computations on the one hand and SIBFA or SIBFA-LF on the other shows that SIBFA-LF gives geometric arrangements similar to those obtained from quantum mechanical computations. Moreover, the geometric improvement takes place without downgrading the energetic agreement obtained from SIBFA. The systems considered are Cu(II) interacting with six water molecules, four ammonia or four imidazoles, and four water plus two formate anions.
Piquemal
Jean-Philip
JP
Laboratoire de Chimie Théorique, UMR 7616, Université P. & M. Curie, Case Courrier 137, 4, place Jussieu, 75252 Paris, Cedex 05, France.
Williams-Hubbard
Ben
B
Fey
Natalie
N
Deeth
Robert J
RJ
Gresh
Nohad
N
Giessner-Prettre
Claude
C