Aqua-nitrato complexes of palladium, rhodium and platinum: A comparative ¹⁵N NMR and DFT study.

The accurate prediction of 15N nuclear magnetic resonance (NMR) chemical shifts for three sets of nitrato and mixed-ligand aqua-nitrato rhodium (9 complexes), palladium (11 complexes) and platinum (11 complexes) systems was achieved using density functional theory (DFT) calculations employing the GIAO-PBE0/ADZP(M) 6-31+G(d)(E)/PCM (M = Rh, Pd or Pt, E = main group element) computational protocol. A comparison of δcalcd 15N NMR with δexptl 15N NMR chemical shifts reveals that the DFT calculations correctly predict the division of signals into two groups, the first one involving the Pd(II), Pt(II) and Rh(III) nitrato complexes, and the second the Pt(IV) and Pd(IV) nitrato complexes. Hydrogen bonds and the number of nitrato ligands and their coordination mode remarkably affect the δcalcd 15N chemical shift. Generally, the experimentally observed chemical shifts are found in a sufficiently narrower range for each metal centre in comparison to the calculated ones due to an averaging action of the outer-sphere interactions of complexes with external molecules of water and nitric acid.

from #MedicinebyAlexandrosSfakianakis via xlomafota13 on Inoreader http://ift.tt/2mRBVQH
via IFTTT