ic7b03080_si_001.pdf (8.45 MB)
How to Bend the Uranyl Cation via Crystal Engineering
journal contribution
posted on 2018-02-12, 21:32 authored by Korey P. Carter, Mark Kalaj, Andrew Kerridge, J. August Ridenour, Christopher L. CahillBending the linear uranyl (UO22+) cation represents both a significant challenge
and opportunity within the field of actinide hybrid materials. As
part of related efforts to engage the nominally terminal oxo atoms
of uranyl cation in noncovalent interactions, we synthesized a new
uranyl complex, [UO2(C12H8N2)2(C7H2Cl3O2)2]·2H2O (complex 2), that
featured both deviations from equatorial planarity and uranyl linearity
from simple hydrothermal conditions. Based on this complex, we developed
an approach to probe the nature and origin of uranyl bending within
a family of hybrid materials, which was done via the synthesis of
complexes 1–3 that display significant
deviations from equatorial planarity and uranyl linearity (O–U–O
bond angles between 162° and 164°) featuring 2,4,6-trihalobenzoic
acid ligands (where Hal = F, Cl, and Br) and 1,10-phenanthroline,
along with nine additional “nonbent” hybrid materials
that either coformed with the “bent” complexes (4–6) or were prepared as part of complementary
efforts to understand the mechanism(s) of uranyl bending (7–12). Complexes were characterized via single
crystal X-ray diffraction and Raman, infrared (IR), and luminescence
spectroscopy, as well as via quantum chemical calculations and density-based
quantum theory of atoms in molecules (QTAIM) analysis. Looking comprehensively,
these results are compared with the small library of bent uranyl complexes
in the literature, and herein we computationally demonstrate the origin
of uranyl bending and delineate the energetics behind this process.