Uranyl Complexes with Selenium or Tellurium Containing Chelate Ligands

The syntheses and characterization of uranyl complexes containing the OP(Se)(OEt) 2 − or OP(Te)(OEt) 2 − ligands are described. The U(VI) complexes UO 2 (OP(Se)(OEt) 2 ) 2 (OP(NMe 2 ) 3 ) 2 (1) and UO 2 (OP(Te)(OEt) 2 ) 2 (OP(NMe 2 ) 3 ) 2 (4) were prepared by the reaction of UO 2 (NO 3 ) 2 (OP(NMe 2 ) 3 ) 2 with the corresponding NaOP(E)(OEt) 2 salt in THF (E=Se, Te). The complexes UO 2 (OP(Se)(OEt) 2 ) 2 (OPPh 3 ) 2 (2 ) and UO 2 (OP(Se)(OEt) 2 ) 2( (OAsPh 3 )(HOMe) (3) were prepared by the reaction of [UO 2 Cl 2 (THF) 2 ] 2 with NaOP(Se)(OEt) 2 in THF solution in the presence of OPPh 3 (2) or OAsPh 3 (3) and recrystallised from THF (2) and HOMe (3) respectively. Although the OP(E)(OEt) 2 − (E=Se, Te) ligands may be able to act as bidentate chelate ligands, evidence for the weak coordination of the Se atom to the uranium(VI) centre was only observed in complexes 2 and 3 . No coordination of the Te atom to the U(VI) centre in complex 4 was observed. Complexes 2 – 3 were characterized using vibrational (IR, Raman) spectroscopy. In addition, the structures of compounds 1 – 4 were determined using single crystal X‐ray diffraction techniques: Compounds 2 and 3 are examples of structurally characterized compounds containing significant U(VI)−Se interactions.