Pseudohalide Tectons within the Coordination Sphere of the Uranyl Ion: Experimental and Theoretical Study of C-H···O, C-H···S, and Chalcogenide Noncovalent Interactions.
Inorg Chem
; 57(7): 3699-3712, 2018 Apr 02.
Article
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| ID: mdl-29542918
ABSTRACT
A series of uranyl thiocyanate and selenocyanate of the type [R4N]3[UO2(NCS)5] (R4 = nBu4, Me3Bz, Et3Bz), [Ph4P][UO2(NCS)3(NO3)] and [R4N]3[UO2(NCSe)5] (R4 = Me4, nPr4, Et3Bz) have been prepared and structurally characterized. The resulting noncovalent interactions have been examined and compared to other examples in the literature. The nature of these interactions is determined by the cation so that when the alkyl groups are small, chalcogenide···chalcogenide interactions are present, but this "switches off" when R = nPr and charge assisted UâO···H-C and S(e)···H-C hydrogen bonding remain the dominant interaction. Increasing the size of the chain to nBu results in only S···H-C interactions. The spectroscopic implications of these chalcogenide interactions have been explored in the vibrational and photophysical properties of the series [R4N]3[UO2(NCS)5] (R4 = Me4, Et4, nPr4, nBu4, Me3Bz, Et3Bz), [R4N]3[UO2(NCSe)5] (R4 = Me4, nPr4, Et3Bz) and [Et4N]4[UO2(NCSe)5][NCSe]. The data suggest that UâO···H-C interactions are weak and do not perturb the uranyl moiety. While the chalcogenide interactions do not influence the photophysical properties, a coupling of the UâO and δ(NCS) or δ(NCSe) vibrational modes is observed in the 77 K solid state emission spectra. A theoretical examination of representative examples of Se···Se, C-H···Se, and C-H···OâU by molecular electrostatic potentials and NBO and AIM methodologies gives a deeper understanding of these weak interactions. C-H···Se are individually weak but C-H···OâU interactions are even weaker, supporting the idea that the -yl oxo's are weak Lewis bases. An Atoms in Molecules study suggests that the chalcogenide interaction is similar to lone pair···π or fluorine···fluorine interactions. An oxidation of the NCS ligands to form [(UO2)(SO4)2(H2O)4]·3H2O was also noted.
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Colección:
01-internacional
Banco de datos:
MEDLINE
Idioma:
En
Revista:
Inorg Chem
Año:
2018
Tipo del documento:
Article
País de afiliación:
Irlanda