Di-2-pyridyl ketone in actinide chemistry: Dinuclear uranyl complexes

Treatment of UO2X2 (X = OAc, Cl, NO3) with 1 mol equiv of (py)2CO in THF afforded the adducts [UO2X2{(py)2CO}] in almost quantitative yields. The same reactions in MeOH, in the presence of NEt3 for X = Cl and NO3, gave yellow crystals of [(UO2X)2{μ-(py)2C(OMe)O}2]·MeOH (X = OAc, 1·MeOH and X = Cl, 2·MeOH) and [{UO2(NO3)}2{μ-(py)2C(OMe)O}2] (3). Reactions of UO2X2 (X = OAc, Cl) with 2 mol equiv of (py)2CO and NEt3 in MeOH or further treatment of 1 and 2 with 1 mol equiv of (py)2CO and NEt3 afforded the methoxide derivative [{UO2(OMe)}2{μ-(py)2C(OMe)O}2] (4), while UO2(NO3)2 was transformed into [{UO2(NO3)}{UO2(OH)}{μ-(py)2C(OMe)O}2] (5). In these first structurally characterized actinide compounds with a (py)2CO-based ligand, the uranium atoms are located at the center of pentagonal (X = Cl and OMe) or hexagonal (X = OAc and NO3) bipyramids sharing one edge defined by the μ-alkoxo oxygen atoms. Crystals of [{UO2(OMe)}2{μ-(py)2C(OMe)O}2]·[(UO2)4{μ2-(py)2C(OMe)O}2(μ2-OAc)2(μ3-O)2(MeOH)2]·H2O (6·H2O) were serendipitously obtained in one experiment with [UO2(OAc)2(H2O)2] and (py)2CO.

The first structurally characterized actinide compounds with a (py)2CO-based ligand, [(UO2X)2{μ-(py)2C(OMe)O}2] (X = OAc, Cl, NO3, OMe) were isolated from reactions of UO2X2 (X = OAc, Cl, NO3) with (py)2CO and NEt3 in MeOH. The uranium atoms are located at the center of pentagonal (X = Cl and OMe) or hexagonal (X = OAc and NO3) bipyramids sharing one edge defined by the μ-alkoxo oxygen atoms.Figure optionsDownload as PowerPoint slide