ABSTRACT
The interplay of bond strength and covalency are examined in AnO2Cl2(OPcy3)2 (An = Pu, U) complexes. The synthesis of trans-PuO2Cl2(OPcy3)2, 1-Pu, has been carried out and confirmed by single crystal X-ray diffraction along with UV-vis-NIR, and 31P NMR spectroscopies. Theoretical analysis finds that despite a higher calculated covalency for the Pu-Cl interaction, the Pu-OPcy3 interaction is stronger due to the accumulation of electron density in the interatomic region. The coordination of equatorial ligands slightly decreases the strength of the PuîOyl interactions relative to the free gas phase (PuO2)2+ ion.
ABSTRACT
The synthesis, characterization, and theoretical analysis of meridional americium tribromide tris(tricyclohexylphosphine oxide), mer-AmBr3(OPcy3)3, has been achieved and is compared with its early lanthanide (La to Nd) analogs. The data show that homo trans ligands display significantly shorter bonds than the cis or hetero trans ligands. This is particularly pronounced in the americium compound. DFT along with multiconfigurational CASSCF calculations show that the contraction of the bonds relates qualitatively with overall covalency, i.e. americium shows the most covalent interactions compared to lanthanides. However, the involvement of the 5p and 6p shells in bonding follows a different order, namely cerium > neodymium â¼ americium. This study provides further insight into the mechanisms by which ITI operates in low-valent f-block complexes.
