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Cu ii in Liquid Ammonia: An Approach by Hybrid Quantum‐Mechanical/Molecular‐Mechanical Molecular Dynamics Simulation
Author(s) -
Schwenk Christian F.,
Rode Bernd M.
Publication year - 2004
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200300972
Subject(s) - chemistry , molecular dynamics , ligand (biochemistry) , solvation , molecule , density functional theory , ion , solvation shell , ab initio , picosecond , chemical physics , computational chemistry , crystallography , organic chemistry , biochemistry , receptor , laser , physics , optics
To investigate the solvation structure of the Cu ii ion in liquid ammonia, ab initio quantum‐mechanical/molecular‐mechanical (QM/MM) molecular dynamics (MD) simulations were carried out at Hartree Fock (HF) and hybrid density functional theory (B3 LYP) levels. A sixfold‐coordinated species was found to be predominant in the HF case whereas five‐ and sixfold‐coordinated complexes were obtained in a ratio 2:1 from the B3 LYP simulation. In contrast to hydrated Cu ii , which exhibits a typical Jahn–Teller distortion, the geometrical arrangement of ligand molecules in the case of ammonia can be described as a [2+4] ([2+3]) configuration with 4 (3) elongated copper–nitrogen bonds. First shell solvent exchange reactions at picosecond rate took place in both HF and B3 LYP simulations, again in contrast to the more stable sixfold‐coordinated hydrate. NH 3 ligands apparently lead to strongly accelerated dynamics of the Cu ii solvate due to the “inverse” [2+4] structure with its larger number of elongated copper–ligand bonds. Several dynamical properties, such as mean ligand residence times or ion–ligand stretching frequencies, prove the high lability of the solvated complex.