title: Insight into the local environment of magnesium and calcium in low-coordination-number organo-complexes using25Mg and43Ca solid-state NMR: a DFT study.
abstract: With the increasing number of organocalcium and organomagnesium complexes under development, there is a real need to be able to characterize in detail their local environment in order to fully rationalize their reactivity. For crystalline structures, in cases when diffraction techniques are insufficient, additional local spectroscopies like25Mg and43Ca solid-state NMR may provide valuable information to help fully establish the local environment of the metal ions. In this current work, a prospective DFT investigation on crystalline magnesium and calcium complexes involving low-coordination numbers and N-bearing organic ligands was carried out, in which the25Mg and43Ca NMR parameters [isotropic chemical shift, chemical shift anisotropy (CSA) and quadrupolar parameters] were calculated for each structure. The analysis of the calculated parameters in relation to the local environment of the metal ions revealed that they are highly sensitive to very small changes in geometry/distances, and hence that they could be used to assist in the refinement of crystal structures. Moreover, such calculations provide a guideline as to how the NMR measurements will need to be performed, revealing that these will be very challenging.
authors.affiliation: Sorbonne Universités, UPMC - Paris 06, Collège de France, UMR CNRS 7574, Laboratoire de Chimie de la Matière Condensée de Paris, 4 place Jussieu, 75252 Paris Cedex 05, France.
authors.forename: Christel
authors.initials: C
authors.lastname: Gervais
authors.affiliation: School of Chemistry, Monash University, PO Box 23, Victoria 3800, Australia.
authors.forename: Cameron
authors.initials: C
authors.lastname: Jones
authors.affiliation: Sorbonne Universités, UPMC - Paris 06, Collège de France, UMR CNRS 7574, Laboratoire de Chimie de la Matière Condensée de Paris, 4 place Jussieu, 75252 Paris Cedex 05, France.
authors.forename: Christian
authors.initials: C
authors.lastname: Bonhomme
authors.affiliation: Institut Charles Gerhardt de Montpellier, UMR5253, CNRS UM ENSCM, CC1701, Pl. E. Bataillon, 34095 Montpellier Cedex 05, France.
authors.forename: Danielle
authors.initials: D
authors.lastname: Laurencin
keywords: 25Mg; 43Ca; DFT; GIPAW; NMR crystallography; computational chemistry; organo-complexes; solid-state NMR