Remarkably Large Geometry Dependence of57Fe NMR Chemical Shifts

Abstract

What's new about complexes 1 and 2, textbook examples of coordination compounds? Quantum‐chemical simulations reveal an exceptionally strong sensitivity of their 57Fe NMR spectroscopy chemical shifts to the FeC bond length, which, in turn, changes noticeably on going from the gas phase to aqueous solution.

Aqueous solutions: state of the art in ab initio molecular dynamics

“…In particular, these studies include a large variety of metallic oxides and complexes where the properties of the system strongly depend on both the pH and the concentration of the metallic species [154][155][156][157][158][159][160][161][162][163][164][165][166]. For example, in the case of molybdenum, these studies have unravelled the influence of pH on species such as MoO 2 (OH) 2 [161].…”

“…In addition, in a number of these works, AIMD simulations have been combined with an ab initio evaluation of the NMR parameters of the studied solutes to allow for a direct comparison with experimental measurements. For example, in the case of iron cyanide complexes, a large geometry dependence of the 57 Fe chemical shift has been proposed from AIMD [158,159]. In this context, Bühl and co-workers [158,159] proposed unusual temperature dependencies or isotope effects for the 57 Fe chemical shift of these complexes.…”

“…For example, in the case of iron cyanide complexes, a large geometry dependence of the 57 Fe chemical shift has been proposed from AIMD [158,159]. In this context, Bühl and co-workers [158,159] proposed unusual temperature dependencies or isotope effects for the 57 Fe chemical shift of these complexes. Although not directly verified experimentally, measurements on ferrocene seem to support their hypothesis [167].…”

Molecular Dynamics and NMR Parameter Calculations

“…In order to reduce the computational effort required, while allowing study of a sufficiently large system that boundary effects would be negligible could be studied, the BOMD simulations embedded a molecular mechanics calculation on the water molecules in a quantum mechanical treatment of the complex ion. This method enabled accurate determination of the 57 Fe chemical shift [8,9] in solution.…”

NMR, ESR, NQR and IR Studies of Paramagnetic Macrocyclic Complexes of 1st Transition Series Metal Ions Exhibiting MLCT Phenomenon: A DFT Application. Part: III. Tris (2, 2- bipyridine) Complexes

“…Accurate computations of their NMR, ESR and NQR (14)(15)(16)(17) parameters had become possible by DFT only recently (18)(19)(20).…”