Reactivity of a Lewis base-supported uranium terminal imido metallocene towards small molecules.

The Lewis base-supported uranium terminal imido metallocene [η 5 -1,2,4-(Me 3 Si) 3 C 5 H 2 ] 2 UN( p -tolyl)(dmap) (1) readily reacts with various small molecules such as internal alkynes, isothiocyanates, thioketones, amidates, organic nitriles and imines, chlorosilanes, copper iodide, diphenyl disulfide, organic azides and diazoalkane derivatives. For example, treatment of 1 with PhCCCCPh and PhNCS forms metallaheterocycles originating from a [2 + 2] cycloaddition to yield [η 5 -1-( p -tolyl)NC(Ph)CHCC(Ph)CH 2 Si(Me) 2 -2,4-(Me 3 Si) 2 C 5 H 2 ][η 5 -1,2,4-(Me 3 Si) 3 C 5 H 2 ]U (2) and [η 5 -1,2,4-(Me 3 Si) 3 C 5 H 2 ] 2 U[N( p -tolyl)C(NPh)S](dmap) (3), respectively. The reaction of 1 with the thioketone Ph 2 CS forms the known uranium sulfido complex [η 5 -1,2,4-(Me 3 Si) 3 C 5 H 2 ] 2 US(dmap) (4), which reacts with a second molecule of Ph 2 CS to give the disulfido compound [η 5 -1,2,4-(Me 3 Si) 3 C 5 H 2 ] 2 U(S 2 CPh 2 ) (5). The imido moiety also promotes deprotonation reactions as illustrated in the reactions with the amide PhCONH( p -tolyl), the nitrile PhCH 2 CN and the imine ( p -tolyl) 2 CNH to form the bis-amidate [η 5 -1,2,4-(Me 3 Si) 3 C 5 H 2 ] 2 U[OC(Ph)N( p -tolyl)] 2 (7), and the iminato complexes [η 5 -1,2,4-(Me 3 Si) 3 C 5 H 2 ] 2 U[N( p -tolyl)C(CH 2 Ph)NH](NCCHPh) (8) and [η 5 -1,2,4-(Me 3 Si) 3 C 5 H 2 ] 2 U[NH( p -tolyl)][NC( p -tolyl) 2 ] (9), respectively. Addition of PhSiH 2 Cl to 1 yields [η 5 -1,2,4-(Me 3 Si) 3 C 5 H 2 ] 2 U(Cl)[N( p -tolyl)SiH 2 Ph] (10). In contrast, the uranium(V) imido complexes [η 5 -1,2,4-(Me 3 Si) 3 C 5 H 2 ] 2 UN( p -tolyl)(I) (11) and [η 5 -1,2,4-(Me 3 Si) 3 C 5 H 2 ] 2 UN( p -tolyl)(SPh) (12), may be isolated upon addition of CuI or Ph 2 S 2 to 1, respectively. Uranium(VI) bis-imido metallocenes [η 5 -1,2,4-(Me 3 Si) 3 C 5 H 2 ] 2 UN( p -tolyl)(NR) (R = p -tolyl (13), mesityl (14)) and [η 5 -1,2,4-(Me 3 Si) 3 C 5 H 2 ] 2 UN( p -tolyl)[NN(9-C 13 H 8 )] (15) are accessible from 1 on exposure to RN 3 (R = p -tolyl, mesityl) and 9-diazofluorene, respectively. Complexes 2, 3, 5, and 7-15 were characterized by various spectroscopic techniques and, in addition, compounds 2, 3, 5, and 7-13 were structurally authenticated by single-crystal X-ray diffraction analyses.