Insertion of Isonitriles into the Zr–CH 3 Bond of Cp* 2 Zr(CH 3 ) 2 and Electrophilic Cleavage of the Remaining Methyl Group
Insertion of Isonitriles into the Zr–CH 3 Bond of Cp* 2 Zr(CH 3 ) 2 and Electrophilic Cleavage of the Remaining Methyl Group
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异腈插入 Cp* 2 Zr(CH 3 ) 2 的 Zr–CH 3 键和剩余甲基的亲电裂解
DOI：
10.1021/acs.organomet.8b00690
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发表时间：
2018
期刊：
影响因子：
2.8
通讯作者：
Rauch, Michael
中科院分区：
文献类型：
--
作者：
Chen, Jiawei;Chen, Tao;Norton, Jack R.;Rauch, Michael
将叔丁基异腈 (tBuNC) 插入 Cp*2Zr(CH3)2(1) 的 M-C 键中，形成单亚氨基酰基产物 Cp*2Zr(亚氨基酰基)CH3(2)。 SC-XRD分析表明，η2配位的亚氨基酰基配体具有“N-外侧”取向。化合物 2 与布朗斯台德酸 CpCr(CO)3H 或路易斯酸 B(C6F5)3 发生快速 Zr-C 键断裂，产生 Zr 阳离子 4 或 5 以及相应的阴离子 [MeB(C6F5)3]− 或 [CpCo(CO)3]−。在 4 的固态结构中，Zr 阳离子的亚氨基酰基具有 η2“N-inside”几何形状，并通过 CO 配体之一的氧原子与 [CpCo(CO)3]− 相互作用。用 CpCr(CO)3H 从 Zr of1 上裂解甲基配体的二阶速率常数 k1 为 2.11(4) × 10–3M–1s–1，而从 Zr of2 上裂解甲基配体的速度明显更快，估计 k2 大于 104M–1s–1。根据观察到的“N-outside”到“N-inside”从2到4的变化，我们认为2的速率增强是由于其氮的初始质子化、随后的从外到内的旋转以及最终质子转移到Zr-C键上。
The insertion oftert-butyl isonitrile (tBuNC) into the M–C bond of Cp*2Zr(CH3)2(1) leads to the formation of a monoiminoacyl product Cp*2Zr(iminoacyl)CH3(2). SC-XRD analysis has revealed that the η2coordinated iminoacyl ligand has an “N-outside” orientation. Compound2undergoes rapid Zr–C bond cleavage with the Brønsted acid CpCr(CO)3H or the Lewis acid B(C6F5)3, yielding Zr cation4or5with the corresponding anion [MeB(C6F5)3]−or [CpCo(CO)3]−. In the solid-state structure of4, the Zr cation features an η2“N-inside” geometry for the iminoacyl group and interacts with the [CpCo(CO)3]−via the oxygen atom of one of the CO ligands. Cleavage of the methyl ligand from the Zr of1with CpCr(CO)3H proceeds with a second-order rate constantk1of 2.11(4) × 10–3M–1s–1, whereas cleavage of the methyl ligand from the Zr of2is significantly faster, with an estimatedk2greater than 104M–1s–1. In light of the observed “N-outside” to “N-inside” change from2to4, we propose that the enhanced rate with2is due to initial protonation of its nitrogen, subsequent outside-to-inside rotation, and eventual transfer of the proton onto the Zr–C bond.