Experimental and Computational Studies of a Uranium Metallacyclocumulene
Experimental and Computational Studies of a Uranium Metallacyclocumulene
复制标题
铀金属环积烯的实验和计算研究
DOI：
10.1021/acs.organomet.6b00936
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发表时间：
2017
期刊：
影响因子：
2.8
通讯作者：
Walter Marc D
中科院分区：
文献类型：
--
作者：
Zhang Lei;Fang Bo;Hou Guohua;Zi Guofu;Ding Wanjian;Walter Marc D
研究了一种金属铀酰环枯烯的合成、电子结构和反应活性。[（η5-C5 Me 5）2UCl 2]（1）在1，4-二（三甲基硅基）丁二炔（Me3SiO_4C_4CSiMe 3）存在下用钾石墨（KC_8）还原，得到铀金属酰环枯烯[（η5-C5 Me 5）2U{η4-C_4（SiMe 3）_2}]（2），产率较高。磁化率数据证实了2的行为类似于U（IV）配合物，密度泛函理论（DFT）研究表明5 f轨道对金属环戊三烯U（η4-C C C）部分的成键有很大贡献，导致[（η5-C5 Me 5）2U]2+和[η4-C4（SiMe 3）2]2-片段之间的共价键比在相关Th（IV）化合物中发现的更多。因此，出现了非常不同的反应模式;例如，当与丁二炔、联吡啶和二氮杂丁二炔衍生物等共轭物质反应时，2可以作为（η5-C5 Me 5）2U（II）片段的合成等价物。另外，[（η4-Me 3 SiC <$C <$C <$CSiMe3）]2-部分在2中可以作为亲核试剂与各种简单的杂环饱和分子如醛、酮、腈、异硫氰酸酯、N-酰亚胺、吡啶和有机叠氮化物反应。DFT研究包括补充实验观察。
The synthesis, electronic structure, and reactivity of a uranium metallacyclocumulene were studied. Reduction of [(η5-C5Me5)2UCl2] (1) with potassium graphite (KC8) in the presence of 1,4-bis(trimethylsilyl)butadiyne (Me3SiCC–CCSiMe3) forms the uranium metallacyclocumulene [(η5-C5Me5)2U{η4-C4(SiMe3)2}] (2) in good yield. Magnetic susceptibility data confirm that2behaves as a U(IV) complex, and density functional theory (DFT) studies indicate a substantial 5f orbital contribution to the bonding of the metallacyclopentatriene U(η4-CCCC) moiety, leading to more covalent bonds between the [(η5-C5Me5)2U]2+and [η4-C4(SiMe3)2]2–fragments than those found in the related Th(IV) compound. Consequently, very different reactivity patterns emerge; e.g.,2can act as a synthetic equivalent for the (η5-C5Me5)2U(II) fragment when reacted with conjugated species such as butadiyne, bipy, and diazabutadiene derivatives. Alternatively, the [(η4-Me3SiCCCCSiMe3)]2–moiety in2may react as a nucleophile when exposed to a variety of simple heterounsaturated molecules such as aldehydes, ketones, nitriles, isothiocyanates, carbodiimides, pyridines, and organic azides. DFT studies are included to complement the experimental observations.