关键词：
Copper
Density functional theory
Ethylene
Organometallic
摘要：
A theoretical investigation at the density functional theory level (B3LYP) has been conducted to elucidate the impact of ligand basicity on the binding interactions between ethylene and copper(I) ions in [Cu( η-CH)] and a series of [Cu(L)( η-CH)] complexes, where L = substituted 1,10-phenanthroline ligands. Molecular orbital analysis shows that binding in [Cu( η-CH)] primarily involves interaction between the filled ethylene π-bonding orbital and the empty Cu(4 s) and Cu(4 p) orbitals, with less interaction observed between the low energy Cu(3 d) orbitals and the empty ethylene π*-orbital. The presence of electron-donating ligands in the [Cu(L)( η-CH)] complexes destabilizes the predominantly Cu(3 d)-character filled frontier orbital of the [Cu(L)] fragment, promoting better overlap with the vacant ethylene π*-orbital and increasing Cu → ethylene π-backbonding. Moreover, the energy of the filled [Cu(L)] frontier orbital and mixing with the ethylene π*-orbital increase with increasing p K of the 1,10-phenanthroline ligand. Natural bond orbital analysis reveals an increase in Cu → ethylene electron donation with addition of ligands to [Cu( η-CH)] and an increase in backbonding with increasing ligand p K in the [Cu(L)( η-CH)] complexes. Energy decomposition analysis (ALMO-EDA) calculations show that, while Cu → ethylene charge transfer (CT) increases with more basic ligands, ethylene → Cu CT and non-CT frozen density and polarization effects become less favorable, yielding little change in copper(I)-ethylene binding energy with ligand p K. ALMO-EDA calculations on related [Cu(L)(NCCH)] complexes and calculated free energy changes for the displacement of acetonitrile by ethylene reveal a direct correlation between increasing ligand p K and the favorability of ethylene binding, consistent with experimental observations. [ABSTRACT FROM AUTHOR]
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