Combined solid state NMR and ONIOM studies of reversible crystalline phase reaction for nickel coordination compounds

Ni(II) with bis(acetylacetone)ethylenediamine ligand forms complexes which crystallizes as semi-hydrate with C2/c space group in monoclinic system and anhydrous form with Pna2(1) space group in orthorhombic system. C-13 and N-15 CP/MAS experiments were employed for structural characterization of both forms and searching of process of reversible water exchange in the crystal lattice. Comparative analysis of C-13 and N-15 principal elements of chemical shift tensors for ligand and complexes showed the sensitivity of delta(ii) elements both for complexation and phase reaction processes. Theoretical C-13 and N-15 NMR shielding parameters sigma(ii) were computed employing ONIOM approach and correlated with experimental delta(ii) data. The applicability of ONIOM in structural analysis of coordination compounds (CC) is discussed. (C) 2009 Elsevier Inc. All rights reserved.