U VI chemistry is dominated by the uranyl (UO 2 ) 2+ cation, in which the oxo group is essentially passivated by a triple bond to the metal center. Weak interactions between the oxo group Lewis acids or hydrogen-bond donors can be observed in extended solids, but there is little understanding of how the uranyl bond is affected by these additional forces. In the current study, the influence of charge-assisted hydrogen-bonding and crystallization effects on the uranyl oxo bond is explored through the synthesis and characterization of four uranyl compounds: [(UO 2 ) 3 (Gly) 2 (O) 2 (OH) 2 ](H 2 O) 1.5 (UG1b), [(UO 2 ) 4 (Gly) 3 -(For)(O) 3 (OH)](H 2 O) 6.5 (UGFA1a), [(UO 2 ) 8 (Gly) 6 (For) 2 (O) 6 (OH) 2 ]-(H 2 O) 10 (UGFA1b), and [(UO 2 ) 4 (Gly) 3 (O) 3 (OH) 2 ](HFor)(H 2 O) 9.45 [a]where S is representative of the bond valence or bond flux of each bond (expressed as valence units), R is the bond distance, R 0 is the Eur.