Metathesis of a UV imido complex: a route to a terminal UV sulfide

The metathesis reaction of a U^V imido complex supported by sterically demanding tris(tert-butoxy)siloxide ligands with CS₂ afforded a terminal U^V thiocarbonate but metathesis with H₂S afforded the first example of a terminal U^V sulfide.

Herein, we report the synthesis and characterisation of the first terminal uranium(v) sulfide and a related U^V trithiocarbonate complex supported by sterically demanding tris(tert-butoxy)siloxide ligands. The reaction of the potassium-bound U^V imido complex, [U(NAd){OSi(OtBu)₃}₄K] (4), with CS₂ led to the isolation of perthiodicarbonate [K(18c6)]₂[C₂S₆] (6), with concomitant formation of the U^IV complex, [U{OSi(OtBu)₃}₄], and S Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> CNAd. In contrast, the reaction of the U^V imido complex, [K(2.2.2-cryptand)][U(NAd){OSi(OtBu)₃}₄] (5), with one or two equivalents of CS₂ afforded the trithiocarbonate complex, [K(2.2.2-cryptand)][U(CS₃){OSi(OtBu)₃}₄] (7), which was isolated in 57% yield, with concomitant elimination of the admantyl thiocyanate product, SCNAd. Complex 7 is likely formed by fast nucleophilic addition of a U^V terminal sulfide intermediate, resulting from the slow metathesis reaction of the imido complex with CS₂, to a second CS₂ molecule. The addition of a solution of H₂S in thf (1.3 eq.) to 4 afforded the first isolable U^V terminal sulfide complex, [K(2.2.2-cryptand)][US{OSi(OtBu)₃}₄] (8), in 41% yield. Based on DFT calculations, triple-bond character with a strong covalent interaction is suggested for the U–S bond in complex 7.

Complexes with S-Donor Ligands. 6. Synthesis of the First Family of (Trithiocarbonato)gold Complexes. Crystal Structure of [(PPh(3))(2)N][AuCl(2)(CS(3))]

[(PPh(3))(2)N][Au(SH)(2)] reacts with CS(2) in acetone to give [(PPh(3))(2)N](2)[Au(2)(CS(3))(2)] (1) which reacts with iodine (1:1) or PhICl(2) (1:1) to give 2 or 2', which is an equimolar mixture of the gold(III) complex [(PPh(3))(2)N][Au(CS(3))(2)] (3) and [(PPh(3))(2)N][AuX(2)] (X = I, Cl). These mixtures decompose in dichloromethane or acetone solutions giving an insoluble dark-red solid analyzing as the mixed-valence complex [(PPh(3))(2)N][Au(I)(n)(){Au(III)(CS(3))(2)}(n)()(+1)] (4) with an average n value of 6. The best method to prepare 3 is by reacting 2 with PTo(3) (To = C(6)H(4)Me-4). The reaction of 4 with [Et(2)NC(S)S](2) gives [Au(S(2)CCNEt(2))(2)][Au(CS(3))(2)] (5), which can also be obtained by reacting 3 with [Au(S(2)CNEt(2))(2)]ClO(4). The complex [(PPh(3))(2)N][AuCl(2)(CS(3))] (6) can be obtained by reacting 3 with PhICl(2) (1:1) or 1 with PhICl(2) (1:2). By reaction of 6 with an excess of NaBr, the complex [(PPh(3))(2)N][AuBr(2)(CS(3))] (7) can be isolated. Iodine reacts with 3 (1:1) to give [(PPh(3))(2)N][AuI(2)(CS(3))] (8). Cationic complexes [Au(CS(3))(LL)]CF(3)SO(3) [LL = 1,10-phenanthroline (phen) (9), 2,2'-bipyridyl (bipy) (10)] can be obtained by reacting 6 with TlO(3)SCF(3) and the corresponding bidentate ligand (1:2:1). Complex 6 crystallizes in the triclinic system, space group P&onemacr;, with a = 9.482(2) Å, b = 11.888(2) Å, c = 17.303(2) Å, alpha = 108.236(6) degrees, beta = 93.340(10) degrees, gamma = 95.605(10) degrees, V = 1835.5 Å(3), and Z = 2. The structure was refined to values of R1 = 0.0393 [I > 2sigma(I)] and wR2 = 0.0970 (all data). The planar coordination at the gold atom is distorted by the bite of the CS(3) ligand [the S(2)-Au-S(1) angle is only 74.49(7) degrees ]. The CS(Au) bond distances are 1.743(7) and 1.748(7) Å, whereas the CS(exo) bond is much shorter at 1.608(7) Å.