TY - JOUR
T1 - Perturbation of the O-U-O Angle in Uranyl by Coordination to a 12-Membered Macrocycle
AU - Pedrick, Elizabeth A.
AU - Schultz, Jason W.
AU - Wu, Guang
AU - Mirica, Liviu M.
AU - Hayton, Trevor W.
N1 - Publisher Copyright:
© 2016 American Chemical Society.
PY - 2016/6/6
Y1 - 2016/6/6
N2 - Reaction of [UO2Cl2(THF)2]2 (THF = tetrahydrofuran) with 2 equiv of HN4 (HN4 = 2,11-diaza[3,3](2,6) pyridinophane) or MeN4 (MeN4 = N,N′-dimethyl-2,11-diaza[3,3](2,6) pyridinophane), in MeCN, results in the formation of UO2Cl2(RN4) (R = H; 1; Me, 2), which were isolated as yellow-orange solids in good yields. Similarly, reaction of UO2(OTf)2(THF)3 with HN4 in MeCN results in the formation of UO2(OTf)2(HN4) (3), as an orange powder in 76% yield. Finally, reaction of UO2(OTf)2(THF)3 with MeN4 in THF results in the formation of [UO2(OTf)(THF)(HN4)][OTf] (4), as an orange powder in 73% yield. Complexes 1-4 were fully characterized, including characterization by X-ray crystallography. These complexes exhibit the smallest O-U-O bond angles measured to date, ranging from 168.2(3)° (for 2) to 161.7(5)° (for 4), a consequence of an unfavorable steric interaction between the oxo ligands and the macrocycle backbone. A Raman spectroscopic study of 1-4 reveals no correlation between O-U-O angle and the U=O νsym mode. However, complexes 1 and 2 do feature lower U=O νsym modes than complexes 3 and 4, which can be rationalized by the stronger donor strength of Cl- versus OTf-. This observation suggests that the identity of the equatorial ligands has a greater effect on the U=O νsym frequency than does a change in O-U-O angle, at least when the changes in the O-U-O angles are small.
AB - Reaction of [UO2Cl2(THF)2]2 (THF = tetrahydrofuran) with 2 equiv of HN4 (HN4 = 2,11-diaza[3,3](2,6) pyridinophane) or MeN4 (MeN4 = N,N′-dimethyl-2,11-diaza[3,3](2,6) pyridinophane), in MeCN, results in the formation of UO2Cl2(RN4) (R = H; 1; Me, 2), which were isolated as yellow-orange solids in good yields. Similarly, reaction of UO2(OTf)2(THF)3 with HN4 in MeCN results in the formation of UO2(OTf)2(HN4) (3), as an orange powder in 76% yield. Finally, reaction of UO2(OTf)2(THF)3 with MeN4 in THF results in the formation of [UO2(OTf)(THF)(HN4)][OTf] (4), as an orange powder in 73% yield. Complexes 1-4 were fully characterized, including characterization by X-ray crystallography. These complexes exhibit the smallest O-U-O bond angles measured to date, ranging from 168.2(3)° (for 2) to 161.7(5)° (for 4), a consequence of an unfavorable steric interaction between the oxo ligands and the macrocycle backbone. A Raman spectroscopic study of 1-4 reveals no correlation between O-U-O angle and the U=O νsym mode. However, complexes 1 and 2 do feature lower U=O νsym modes than complexes 3 and 4, which can be rationalized by the stronger donor strength of Cl- versus OTf-. This observation suggests that the identity of the equatorial ligands has a greater effect on the U=O νsym frequency than does a change in O-U-O angle, at least when the changes in the O-U-O angles are small.
UR - http://www.scopus.com/inward/record.url?scp=84973343839&partnerID=8YFLogxK
U2 - 10.1021/acs.inorgchem.6b00799
DO - 10.1021/acs.inorgchem.6b00799
M3 - Article
AN - SCOPUS:84973343839
SN - 0020-1669
VL - 55
SP - 5693
EP - 5701
JO - Inorganic Chemistry
JF - Inorganic Chemistry
IS - 11
ER -