Insertion, Isomerization, and Cascade Reactivity of the Tethered Silylalkyl Uranium Metallocene (η5-C5Me4SiMe2CH2-κC)2U

Investigation of the insertion reactivity of the tethered silylalkyl complex (η5-C5Me4SiMe2CH2-κC)2U (1) has led to a series of new reactions for U−C bonds. Elemental sulfur reacts with 1 by inserting two sulfur atoms into each of the U−C bonds to form the bis(tethered alkyl disulfide) complex (η5:η2-C5Me4SiMe2CH2S2)2U (2). The bulky substrate N,N′-diisopropylcarbodiimide, iPrNCNiPr, inserts into only one of the U−C bonds of 1 to produce the mixed-tether complex (η5-C5Me4SiMe2CH2-κC)U[η5-C5Me4SiMe2CH2C(iPrN)2-κ2N,N′] (3). Carbon monoxide did not exclusively undergo a simple insertion into the U−C bond of 3 but instead formed {μ-[η5-C5Me4SiMe2CH2C(NiPr)O-κ2O,N]U[OC(C5Me4SiMe2CH2)CN(iPr)-κ2O,N]2 (4) in a cascade of reactions that formally includes U−C bond cleavage, C−N bond cleavage of the amidinate ligand, alkyl or silyl migration, U−O, C−C, and C−N bond formations, and CO insertion. The reaction of 3 with isoelectronic tert-butyl isocyanide led to insertion of the substrate into the U−C bond, but with a rearrangement of the amidinate ligand binding mode from κ2 to κ1 to form [η5:η2-C5Me4SiMe2CH2C(NtBu)]U[η5-C5Me4SiMe2CH2C(NiPr)N(iPr)-κN] (5). The product of double insertion of tBuNC into the U−C bonds of 1, namely [η5:η2-C5Me4SiMe2CH2C(NtBu)]2U (6), was found to undergo an unusual thermal rearrangement that formally involves C−H bond activation, C−C bond cleavage, and C−C bond coupling to form the first formimidoyl actinide complex, [η5:η5:η3-tBuNC(CH2SiMe2C5Me4)(CHSiMe2C5Me4)]U(η2-HCNtBu) (7).

对连接硅基烷基复合物（η5-C5Me4SiMe2CH2-κC）2U（1）的插入反应性进行研究，揭示了U-C键的一系列新反应。单质硫与1反应，将两个硫原子插入每个U-C键中，形成双连接烷基二硫化物复合物（η5:η2-C5Me4SiMe2CH2S2）2U（2）。庞大的底物N,N′-二异丙基脒基碳二亚胺，iPrNCNiPr，仅插入1中的一个U-C键，生成混合连接复合物（η5-C5Me4SiMe2CH2-κC）U[η5-C5Me4SiMe2CH2C(iPrN)2-κ2N,N′]（3）。一氧化碳并未仅限于简单插入3中的U-C键，而是在一系列反应中形成了{μ-[η5-C5Me4SiMe2CH2C(NiPr)O-κ2O,N]U[OC(C5Me4SiMe2CH2)CN(iPr)-κ2O,N]2（4），这些反应形式上包括U-C键断裂、脒基配体C-N键断裂、烷基或硅基迁移、U-O、C-C和C-N键的形成以及CO插入。3与等电子叔丁基异氰化物反应导致底物插入U-C键，但脒基配体结合模式从κ2转变为κ1，形成[η5:η2-C5Me4SiMe2CH2C(NtBu)]U[η5-C5Me4SiMe2CH2C(NiPr)N(iPr)-κN]（5）。将tBuNC的双插入1中的U-C键，即[η5:η2-C5Me4SiMe2CH2C(NtBu)]2U（6）的产物，发现经历了一种异常的热重排，形式上涉及C-H键活化、C-C键断裂以及C-C键偶联，形成了第一个亚甲基脒类锕系金属复合物，[η5:η5:η3-tBuNC(CH2SiMe2C5Me4)(CHSiMe2C5Me4)]U(η2-HCNtBu)（7）。