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Medium Effects on 51 V NMR Chemical Shifts: A Density Functional Study
Author(s) -
Bühl Michael,
Parrinello Michele
Publication year - 2001
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20011015)7:20<4487::aid-chem4487>3.0.co;2-g
Subject(s) - solvation , molecular dynamics , molecule , chemical shift , vanadium , chemistry , aqueous solution , vanadate , solvent , chemical physics , density functional theory , computational chemistry , transition metal , inorganic chemistry , organic chemistry , catalysis
Car–Parrinello molecular dynamics simulations were performed for [H 2 VO 4 ] − , [VO 2 (OH 2 ) 4 ] + , and [VO(O 2 ) 2 (OH 2 )] − in periodic boxes with 30, 28, and 29 water molecules, respectively, employing the BLYP density functional. On the timescale of the simulations, up to 2 ps, well‐structured first solvation spheres are discernible for [H 2 VO 4 ] − and [VO(O 2 ) 2 (OH 2 )] − containing, on average, eight and ten water molecules, respectively. One of the four water molecules directly attached to the metal in [VO 2 (OH 2 ) 4 ] + is only loosely bound, and the average coordination number of vanadium in aqueous VO 2 + is between five and six. 51 V chemical shifts were evaluated at the B3LYP level for representative snapshots along the trajectories, including the water molecules of the solvent by means of point charges. The resulting averaged δ ( 51 V) values are proposed to model the combined effects of temperature (dynamic averaging) and solvent (charge polarization). Both effects are shown to be rather small, of the order of a few dozen ppm. The observed shielding of 51 V in the bis(peroxo) complex with respect to the vanadate species is not reproduced computationally.