Even and odd: uranium(IV) complexes with two, four, and six salicylaldiminate ligands with an unusual κ1-coordination mode

Abstract

We report the synthesis and structural determination of three uranium(IV) complexes bearing two, four, and six salicylaldiminate ligands. Reaction of UI4(1,4-dioxane)2 with two, four, and six equivalents of K[OC6H4C(H)=N(2,6-iPr2C6H3)], 1, yielded [(2,6-iPr2C6H3)N=C(H)C6H4O-κ2(O,N)]2UI2(NCCH3), 2, [(2,6-iPr2C6H3)N=C(H)C6H4O-κ1(O)]2[(2,6-iPr2C6H3)N=C(H)C6H4O-κ2(O,N)]2U(THF), 3, and {[2,6-iPr2C6H3)N=C(H)C6H4O-κ1(O)]6U}2−, 4. While 2 shows normal κ2-coordination through both oxygen and nitrogen donors, 3 has two salicylaldiminate ligands bound only through oxygen and 4 has all six ligands bound only through oxygen. This is an exceedingly rare example of a chelating ligand not completing its chelation in f-element chemistry. In addition, 4 is the first report of a homoleptic octahedral actinide complex with a Schiff base ligand.