Uranium(VI) bis(imido) disulfonamide and dihalide complexes: Synthesis density functional theory analysis

Novel cis- and trans-bis(imido) uranium disulfonamide derivatives have been prepared from iodide metathesis reactions between two equivalents of K[N(Me)(SO2Ar’)] (Ar’ = 4-Me-C6H4) and U(NtBu)2(I)2(L)x (L = OPPh3, x = 2; Me2bpy, x = 1; Me2bpy = 4,4’-dimethyl-2,2’-bipyridyl). These bis(amide) derivatives serve as useful precursors for the synthesis of the trans-diphenolate complex U(NtBu)2(O-2-tBuC6H4)2(OPPh3)2 (5), cis- and trans-dithiolate complexes U(NtBu)2(SPh)2(L)x (L = OPPh3 (6); Me2bpy (7)), and cis- and trans-dihalide complexes with the general formulas U(NtBu)2(X)2(L)x (X = Cl, L = OPPh3 (8), L = Me2bpy (10); X = Br, L = OPPh3 (9), L = Me2bpy (11)). DFT calculations performed on the trans-dihalide series U(NtBu)2(X)2(L)2 and the UO22+ analogues UO2X2(OPPh3)2 suggest that the uranium centers in the [U(NtBu)2]2+ ions possess more covalent character than analogous UO22+ derivatives but that the U-X bonds in the U(NtBu)2X2L2 complexes possess a more ionic nature.