Competing metal-ligand interactions in tris(cyclopentadienyl)-cyclohexylisonitrile complexes of trivalent actinides and lanthanides

The structure and bonding properties of 16 complexes formed by trivalent f-elements (M = U, Np, Pu and lanthanides except for Pm and Pr) with cyclopentadienyl (Cp) and cyclohexylisonitrile (C≡NCy) ligands, (Cp)3M(C≡NCy), have been studied by a joint experimental (XRD, NMR) and theoretical (DFT) analysis. For the large La(III) ion the bis-adduct (Cp)3La(C≡NCy)2 could also by synthesized and characterized. The metal-ligand interactions have been assessed using the Quantum Theory of Atoms in Molecules (QTAIM) and Natural Bond Orbital (NBO) models. The results point to interactions of comparable strengths with the anionic Cp and neutral C≡NCy lig-ands in the complexes. The structural and bonding properties of the actinide complexes reflect small but characteristic differences with respect to the lanthanide analogues. They include larger ligand-to-metal charge transfers as well as metal-ligand electron sharing interactions. The most significant experimental marker of these covalent interactions is the C≡N stretching frequency.

KOVACS Attila;  APOSTOLIDIS C.;  WALTER Olaf; 

2022-06-15

MDPI

JRC129486

1420-3049 (online),   

https://www.mdpi.com/1420-3049/27/12/3811,    https://publications.jrc.ec.europa.eu/repository/handle/JRC129486,   

10.3390/molecules27123811 (online),