engleski

Static ssNMR and NQR investigation of hexanuclear metallic clusters

Hexanuclear metallic clusters [(M6Li12)La6]n+ (n = 2, 3, 4) are worth studying due to their interesting physical properties which depend on oxidation states n as well as on dimensionality of structures they form. They consist of six metallic atoms M (Nb or Ta), twelve inner ligands Li (usually Cl or Br) and six apical ligands La (H2O, OH, CH3OH, Cl...). Especially interesting are paramagnetic clusters with n=3 which have one unpaired electron delocalised over whole cluster unit [1]. Here we present both theoretical NMR/NQR calculations and experimental results on two diamagnetic clusters [Nb6Br12(H2O)6][HgBr4]·12H2O, Nb6Cl12(H2O)4(OH)2·4H2O and paramagnetic one [Et4N][Ta6Br12(H2O)6]Br4·4H2O whose structures were previously determined [2]. Static 93Nb and 35Cl NMR spectra were obtained in 12 T field. Zero field NQR measurements on 93Nb, 79Br and 81Br were performed in order to fix EFG parameters for simulation of NMR spectra [3]. Independent GIPAW-DFT calculations of NMR/NQR parameters using CASTEP [4] are in good agreement with experimental results. This presentation is enabled by the European commission through FP7 project #229390 SOLeNeMaR.

ssNMR; niobium; clusters

nije evidentirano