Tris(1,2-dimethyl-3-hydroxy-4(1H)-pyridone)oxotantalum(v): a new water-soluble tantalum complex containing the [TaO]³⁺core

Abstract

The synthesis, the characterization and the X-ray crystal structure of a novel tantalum(v) complex tris(1,2-dimethyl-3-hydroxy-4(1H)-pyridone)oxotantalum(v) [TaO(C7H8O2N)3] 1 is reported. Starting from the tantalum pentaethoxide a two-step reaction was carried out observing rigorous anhydrous conditions in methanol in the first step, while the insertion of the oxo group was achieved using water as oxygen donor in the second step. X-Ray diffraction analysis of a crystal of 1 obtained upon evaporation of an aqueous solution shows a seven-coordinate monomeric complex containing the [Ta=O]3+ core in the triclinic space group P1, a = 7.282(3), b = 14.055(5), c = 16.987(6) A, alpha = 65.704(5), beta = 89.155(6), gamma = 75.270(6) degrees, V = 1525(1)A3, Z = 2. Spectroscopic investigation reveals that the complex is highly soluble and stable in water at physiological pH values; as a consequence the complex may represent a potential candidate for the development of new studies on aqueous tantalum(v) chemistry for radiopharmaceutical applications.

Rearrangement of Tridentate [OSO]-Type Ligands and Migratory Insertion Reaction Mechanisms in Cyclopentadienyl Tantalum Complexes

“…Geometrically this intermediate can be described as a pentagonal bipyramidal heptacoordinate complex, taking the centroid of the Cp* ring as an axial ligand. Tantalum complexes with pentagonal bipyramidal geometry have been experimentally reported …”

Vanadate complexes of 3-hydroxy-1,2-dimethyl-pyridinone: Speciation, structure and redox properties

“…The composition and the structure seems to be unique for vanadate, although, "naked", oxidooxygen free [V(dhp) 3 ] + tris-complexes were identified also in the VO(IV)-dhp system [30], and an X-ray structure of the tantalum(V) complex with similar composition (Ta(V)O(dhp) 3 ) was also published [35]. The most probable structure of this complex is depicted in Scheme 3.…”

Vanadium, niobium and tantalum

“…48 With biological applications in mind, tris(1,2-dimethyl-3-hydroxy-4(1H)-pyridone)oxotantalum(V) was synthesized and characterized as the octahydrate. 49…”