Complexes of Triamidoamines with the Early Actinides. Synthetic Routes to Monomeric Compounds of Tetravalent Uranium and Thorium Containing Halide and Amide Ligands

Abstract

The reaction of the lithiated triamidoamine [Li(3)(NN'(3))(THF)(3)] [NN'(3) = N(CH(2)CH(2)NSiMe(2)Bu(t))(3)] with AnCl(4) (An = U, Th) followed by sublimation gives monomeric [An(NN'(3))Cl]. Reaction of these complexes with SiMe(3)X (X = Br, I) gives [An(NN'(3))X]. The amido derivatives [An(NN'(3))(NEt(2))] are prepared from H(3)(NN'(3)) and [U(NEt(2))(4)] and from [Th(NN'(3))Cl] and [Li(NEt(2))]. In each case, the complexes [U(NN'(3))X] (X = Cl, Br, I, NEt(2)) are shown by X-ray crystallography to contain a triamidoamine ligand disposed with 3-fold symmetry about the metal center. The structures are distorted from trigonal bipyramidal by displacement of the uranium atoms out of the equatorial plane of the three amido nitrogen atoms by ca. 0.8 Å. The ligand backbone is distorted in such a manner as to cause the tert-butyldimethylsilyl groups to encircle the equatorial plane of the metal atom rather than surround the apical coordination site as is observed in the transition metal complexes of this type. Variation of the auxiliary ligand has little effect on the orientation, bond lengths, and angles within the (triamidoamine)uranium fragment. The tert-butydimethysilyl-substituted triamidoamine ligand is thus ideally suited for coordination to large metals since it stabilizes the formation of 3-fold symmetric structures while also allowing reactivity at the fifth coordination site.

The Nature of Unsupported Uranium–Ruthenium Bonds: A Combined Experimental and Theoretical Study

“…Deuterated benzene was distilled from potassium, degassed by three freeze-pump-thaw cycles, and stored under nitrogen. The compounds 1-4 [20,21,22] …”

“…Deuterated benzene was distilled from potassium, degassed by three freeze-pump-thaw cycles, and stored under nitrogen. The compounds 1-4 [20,21,22] and K[RuA C H T U N G T R E N N U N G (h 5 -C 5 H 5 )(CO) 2 ] [31b] were prepared according to published procedures. All other reagents were used as received.…”

“…Since those initial reports, a number of supported dative actinide-metal interactions have been reported, [14,15] and unsupported uranium-metal bonds have been reported in the p-block derivatives [{(Ar)A C H T U N G T R E N N U N G (tBu)N} 3 USi-A C H T U N G T R E N N U N G (SiMe 3 ) 3 ] (Ar= 3,5-Me 2 C 6 H 3 ), [16] [(h 5 -C 5 H 5 ) 3 USnPh 3 ], [17] and [(h 5 -C 5 H 4 SiMe 3 ) 3 UEA C H T U N G T R E N N U N G (h 5 -C 5 Me 5 )] (E = Al, Ga). [18] In the past three years we have been investigating the chemistry of uranium-metal bonds using tripodal triamido uranium groups [19] derived from the precursors [ (Tren TMS ) [21] [(Ts 3 ], [22] and [(Ts…”

“…Since those initial reports, a number of supported dative actinide-metal interactions have been reported, [14,15] and unsupported uranium-metal bonds have been reported in the p-block derivatives [{(Ar)A C H T U N G T R E N N U N G (tBu)N} 3 USi-A C H T U N G T R E N N U N G (SiMe 3 ) 3 ] (Ar= 3,5-Me 2 C 6 H 3 ), [16] [(h 5 -C 5 H 5 ) 3 USnPh 3 ], [17] and [(h 5 -C 5 H 4 SiMe 3 ) 3 UEA C H T U N G T R E N N U N G (h 5 -C 5 Me 5 )] (E = Al, Ga). [18] In the past three years we have been investigating the chemistry of uranium-metal bonds using tripodal triamido uranium groups [19] derived from the precursors [(Tren TMS )U(I)A C H T U N G T R E N N U N G (THF)] [1, Tren TMS = N(CH 2 CH 2 NSiMe 3 ) 3 ], [20] Scotts [(Tren DMSB )U(I)] [2, Tren DMSB = N(CH 2 CH 2 NSiMe 2 tBu) 3 ], [21] [(Ts Tolyl 3 ], [22] and [(Ts Xylyl )U(Cl)A C H T U N G T R E N N U N G (THF)] [4, Ts Xylyl = HC(SiMe 2 NC 6 H 3 -3,5-Me 2 ) 3 ]. [22] Some of these precursors have been successfully used to prepare the U-Ga complex [(Tren TMS )A C H T U N G T R E N N U N G (THF)UGa-A C H T U N G T R E N N U N G (NAr'CH) 2 ] [5, Ar' = 2,6-iPr 2 C 6 H 3 ], [23] and the U-Re complexes [(Tren R )UReA C H T U N G T R E N N U N G (h 5 -C 5 H 5 ) 2 ] (R= trimethylsilyl, 6 a; R= tert-butyldimethylsilyl, (7) and [(Ts Xylyl )UReA C H T U N G T R E N N U N G (h 5 -C 5 H 5 ) 2 ] (8), [24] and previously Gade and co-workers reported that the Ts Tolyl ligand can effectively stabilize Group 4-late metal bonds.…”

σ and π Donation in an Unsupported Uranium–Gallium Bond

“…[19] In some reactions, insertion of gallyl species into metal-halide bonds is followed by reductive elimination to afford gallium(II)-halide species. [20] Therefore, the tren ligand scaffold was chosen for uranium because it has been shown to be effective for supporting tetravalent uranium [21] and tetravalent cerium. [22] Reaction of 1 with [{Ga(NArCH) 2 }K(tmeda)] (2; Ar= 2,6-iPr 2 C 6 H 3 , tmeda = Me 2 NCH 2 CH 2 NMe 2 ) [23] affords, after workup and recrystallization, orange crystals of [(tren-TMS)U{Ga(NArCH) 2 }(thf)] (3) in high yield (Scheme 1).…”