The tetrapositive complex in which Th4+ is coordinated by three neutral tetramethyl-3-oxa-glutaramide ligands (L = TMOGA) was produced in gas phase by electrospray ionization.  This is a unique case of stabilization of a tetrapositive metal ion from solution to gas. DFT calculations reveal that Th(L)34+ possesses C3 symmetry, with thorium coordinated by nine oxygen atoms in a chiral twisted tricapped trigonal prismatic geometry.  The extensive oxygen coordination accounts for the stability of the tetrapositive metal ion complex. No Th(L)24+ was observed, suggesting that three TMOGA  ligands are necessary to stabilize Th4+. Calculations on Th(L)n4+ (n = 1-4) reveal a decrease in the Th-O binding energies and increase in the bond lengths as the number of TMOGA ligands increases. Formation of tetrapositive complexes should be favored by low fourth ionization energies of the metal, a feature exhibited by other actinides; we are pursuing the preparation and characterization of additional M(L)n4+ complexes in the gas phase.

Tetrapositive metal ion in the gas phase: Th<sup>4+</sup> coordinated by neutral tridentate ligands

246th National Meeting (2013)

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Tetrapositive metal ion in the gas phase: Th4+ coordinated by neutral tridentate ligands

Tetrapositive metal ion in the gas phase: Th⁴⁺ coordinated by neutral tridentate ligands