Dioxouranium(VI) complexes with 2,6-acetylpyridinebenzoylhydrazones and -semicarbazones
Symmetric and asymmetric benzoylhydrazones and semicarbazones derived from 2,6-diacetylpyridine react with common dioxouranium(VI) compounds to form air-stable complexes. The neutral compounds contain doubly deprotonated ligands and possess uranium atoms with distorted pentagonal-bipyramidal coordin...
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Published in | Inorganica Chimica Acta Vol. 357; no. 15; pp. 4405 - 4412 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
Elsevier B.V
01.12.2004
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Subjects | |
Online Access | Get full text |
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Summary: | Symmetric and asymmetric benzoylhydrazones and semicarbazones derived from 2,6-diacetylpyridine react with common dioxouranium(VI) compounds to form air-stable complexes. The neutral compounds contain doubly deprotonated ligands and possess uranium atoms with distorted pentagonal-bipyramidal coordination spheres. The equatorial coordination spheres of the metal atoms can be extended by the addition of a monodentate ligand such as pyridine or DMSO.
Benzoylhydrazones and semicarbazones derived from 2,6-diacetylpyridine react with common dioxouranium(VI) compounds such as uranyl nitrate or [NBu
4]
2[UO
2Cl
4] to form air-stable complexes. 2,6-Diacetylpyridinebis(benzoylhydrazone) (H
2L
1), 2,6-diacetylpyridinebis(N4-phenylsemicarbazone) (H
2L
2) and the asymmetric proligand 2,6-diacetylpyridine(benzoylhydrazone)(N4-phenylsemicarbazone) (H
2L
3) give yellow products of the composition [UO
2(L)]. The neutral compounds contain doubly deprotonated ligands and possess uranium atoms with distorted pentagonal-bipyramidal coordination spheres. The equatorial coordination spheres of the metal atoms can be extended by the addition of a monodentate ligand such as pyridine or DMSO. The uranium atoms in the resulting complexes have hexagonal-bipyramidal coordination environments with the oxo ligands in axial positions.
X-ray diffraction studies on [UO
2(L
1)(DMSO)], [UO
2(L
2)], [UO
2(L
2)(DMSO)] and [UO
2(L
3)] show relatively short U–O bonds to the benzoylic oxygen atoms between 2.273(6) and 2.368(5) Å. This suggests a preference of these donor sites of the ligands over their imino and amine functionalities (U–N bond lengths: 2.502(7)–2.671(7) Å). The addition of a sixth ligand to the equatorial coordination sphere results in a lengthening of the metal–pyridine bonds. |
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ISSN: | 0020-1693 1873-3255 |
DOI: | 10.1016/j.ica.2004.07.011 |