Synthesis and spectroscopic characterization of actinyl(VI) tetrahalide coordination compounds containing 2, 2′-bipyridine

A novel symmetric pyrazine (pyz)-bridged uranyl dimer [UO2Cl3(H2O)(Pyz)0.5]22−: synthesis, structure and computational analysis

“…Typical compounds of this type pair the [UO 2 Cl 4 ] 2− with protonated organic cations via hydrogen bonding to one another. 3,8,13 The resultant phase from our current efforts, however, afforded a novel [UO 2 Cl 3 (H 2 O)(Pyz) 0.5 ] 2 2− dimer, which highlights an intriguing divergence from the oftenobserved tetrahalide monomer and expected protonation of the pyrazine. As such, we have been afforded a platform for probing bonding and electronic structure in a novel coordination geometry for the uranyl cation.…”

“…† These bands are typical for uranyl containing compounds, and represent lower energy axial O yl → U ligand to metal charge transfer (LMCT), along with a higher energy equatorial LMCT. 2,11,13 Luminescence. Solid state luminescence measurements were performed to serve as a secondary probe of the UO 2 2+ coordination environment on electronic structure and bonding.…”

“…The uranium oxygen bond within the UO 2 2+ unit is often probed via Raman spectroscopy, as it exhibits a strong, characteristic Raman-active symmetric stretching frequency (ν 1 ). 11,13,43,44 Changes in equatorial coordination, due to bonding or non-covalent interactions, are known to alter the frequency of this stretch, along with enhanced coordination to the uranyl oxygen. As the uranyl bond strengthens, we typically see a blue shift of ν 1 , meaning this value shifts to higher wavenumbers.…”

“…Directed assembly of reproducible inorganic anions with organic cations has proven useful for studying restricted speciation profiles in solution and, in turn, control over the solid products formed. [1][2][3][4][5][6][7][8][9] As such, we have a particular interest in the role of second-sphere interactions in the assembly process and the resultant effect on spectroscopic properties of uranyl containing solid-state materials. Our group [1][2][3][4]10 and others [5][6][7][8]11,12 have previously reported on the use of a robust synthetic strategy, using a combination of low pH and high anion media, as a means to offset uranyl hydrolysis and control assembly.…”

“…[1][2][3][4][5][6][7][8][9] As such, we have a particular interest in the role of second-sphere interactions in the assembly process and the resultant effect on spectroscopic properties of uranyl containing solid-state materials. Our group [1][2][3][4]10 and others [5][6][7][8]11,12 have previously reported on the use of a robust synthetic strategy, using a combination of low pH and high anion media, as a means to offset uranyl hydrolysis and control assembly. In this way, one may reliably produce the [UO 2 X 4 ] 2− (X = Cl, Br) building unit paired with a suite of organic cations.…”