Natural orbitals for chemical valence as descriptors of chemical bonding in transition metal complexes
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Natural orbitals for chemical valence (NOCV) are defined as the eigenvectors of the chemical valence operator defined by Nalewajski et al.; they decompose the deformation density (differential density, Δρ) into diagonal contributions. NOCV were used in a description of the chemical bond between the organometallic fragment and the ligand in example transition–metal complexes: heme–CO ([FeN5C20H15]–CO), [Ni–diimine hydride]–ethylene ([N^N–Ni–H]–C2H4, N^N = –NH–CH–CH–NH–), and [Ni(NH3)3]–CO. DFT calculations were performed using gradient-corrected density functional theory (DFT) in the fragments resolution, using the fragment/ligand Kohn–Sham orbitals as a basis set in calculations for the whole fragment–ligand complex. It has been found that NOCV lead to a very compact description of the fragment–ligand bond, with only a few orbitals exhibiting non-zero eigenvalues. Results of NOCV analysis, compared with Mulliken populations analysis and Zigler–Rauk interaction–energy decomposition, demonstrate that the use of the natural valence orbitals allows for a separation of the σ-donation and π-back-donation contributions to the ligand–fragment bond. They can be also useful in comparison of these contributions in different complexes.
KeywordsNatural orbitals for chemical valence Chemical bond—bonding in transition Metal complexes σ-donation/π-back-donation Dewar–Chatt–Duncanson model
This work was supported by a research grant from the Ministry of Education and Science in Poland (1130-T09-2005-28).
- 4.Dewar MJS (1951) Bull Soc Chim 18:C71–C79Google Scholar
- 6.Cotton FA, Wilkinson G (1988) Advanced Inorganic Chemistry. Wiley, New YorkGoogle Scholar
- 12.Nalewajski RF, Mrozek J, Michalak A (1998) Polish J Chem 72:1779–1791Google Scholar
- 13.Stryer L (1995) Biochemistry. In: Freeman WH (ed) San FranciscoGoogle Scholar
- 24.Fonesca Geurra C, Visser O, Snijders JG, te Velde G, Baerends EJ (1995) In: Clementi E, Corongiu G (eds) Methods and Techniques in Computational Chemistry METACC-9. STEF: Cagliari, pp 303–395Google Scholar
- 26.Ziegler T, Rauk A (1978) Theor Chim Acta 46:1–9Google Scholar