每周分子 | Molecule of the Week

Original ACS 美国化学会 ACS美国化学会 2022-07-01

收录于合集 #每周分子 110个

每周分子：双环辛四烯合铀(铀烯)

Molecule of the Week: Uranocene

自从20世纪40年代发现二茂铁以来，人们合成了数百种“三明治”化合物：其中一个金属原子被夹在两个芳烃环之间。1968年，加州大学伯克利分校的Andrew Streitweiser, Jr.和Ulrich Mueller-Westerhoff通过制备夹在两个环状聚烯烃之间的锕系金属——双环辛四烯合铀，推进了这一领域的进展。

与具有环戊二烯(Cp)环的二茂铁不同，在双环辛四烯合铀中的配位分子是环辛四烯(COT)的二阴离子。Streitweiser和Mueller-Westerhoff加入元素钾到COT中，获得二价阴离子，然后在0ºC添加四氯化铀产生双环辛四烯合铀——绿色晶体。环辛四烯具有折叠结构；但是它的二价阴离子是平面的，使其看上去恰似一个三明治“面包”。

双环辛四烯合铀对水、酸、碱和适度的加热都是稳定的——但它在空气中会自燃。在二茂铁中，Cp环的6个π电子与铁中的3d轨道相互作用。在双环辛四烯合铀中，铀的6d轨道同样与COT的10π电子结合；但是铀5f轨道也参与其中，这有助于分子的稳定性。

2004年，麻省理工学院的Ditmar Seyferth写了一篇关于含有f轨道元素的有机金属化合物的综述。

双环辛四烯信息速览

CAS 登记号	11079-26-8
SciFinder命名	Uranium, bis(η⁸-1,3,5,7-cyclooctatetraene) coordination compound
分子式	C₁₆H₁₆U
摩尔质量	446.33 g/mol
外观	绿色晶体
熔点	180 ºC (subl)(4 Pa)
水溶性	不溶

双环辛四烯危害信息

GHS*分类：急性毒性，口服，分类1
H300-吞食致命
GHS分类：急性毒性，吸入，分类1
H330-吸入致命
GHS分类：特定靶器官毒性，反复暴露，分类2
H373-通过长时间或反复暴露对器官造成损害
GHS分类：对水环境有害，长期危害，分类2
H411-对水环境有害，长期危害

【关于每周分子】

自2001年以来，“每周分子”已成为广受欢迎的栏目。多数分子由读者推荐。每个结构都经由科学家审查，并以3-D和平面图像的形式显示，同时附有该分子简介。可以通过美国化学文摘社 (CAS) 提供的SciFinder中的CAS REGISTRY获取“每周分子”的更多信息。CAS REGISTRY中的每条物质信息都展示了物质的CAS登记号、索引名、通用名、商品名、书目信息等其他更多信息。发送邮件至motw@acs.org推荐您感兴趣的分子吧。

Ever since the discovery of ferrocene in the 1940s, hundreds of “sandwich” compounds, in which a metal atom is “sandwiched” between two arene rings, have been synthesized. In 1968, Andrew Streitweiser, Jr., and Ulrich Mueller-Westerhoff at the University of California, Berkeley, advanced the field by preparing uranocene, an actinide metal sandwiched between two cyclic polyolefins.

In contrast to ferrocene with its cyclopentadienide (Cp) rings, the coordinating molecule in uranocene is the dianion of cyclooctatetraene (COT). Streitweiser and Mueller-Westerhoff treated COT with elemental potassium to make the dianion and then added uranium tetrachloride at 0 ºC to produce uranocene, a green crystalline solid. COT has a folded structure; but its dianion is planar, making it a suitable “bread” for the sandwich.

Uranocene is stable to water, acids, bases, and moderate heating—but it ignites spontaneously in air. In ferrocene, the Cp rings’ six π electrons interact with the 3d orbitals in iron. In uranocene, uranium’s 6d orbitals similarly combine with the COT’s 10 π electrons; but uranium 5f orbitals are also involved, contributing to the molecule’s stability.

In 2004, Ditmar Seyferth at MIT wrote a comprehensive review of organometallic compounds that contain f-orbital elements.

Uranocenefast facts

CAS Reg. No.	11079-26-8
SciFinder nomenclature	Uranium, bis(η⁸-1,3,5,7-cyclooctatetraene) coordination compound
Empirical formula	C₁₆H₁₆U
Molar mass	446.33 g/mol
Appearance	Green crystals
Melting point	180 ºC (subl) (4 Pa)
Water solubility	Insoluble

Squalene hazard information

Hazard class: Acute toxicity, oral, category 1
H300 - Fatal if swallowed
Hazard class: Acute toxicity, inhalation, category 1
H330 - Fatal if inhaled
Hazard class: Specific target organ toxicity, repeated exposure, category 2
H373- Causes damage to organs through prolonged or repeated exposure
Hazard class: Hazardous to the aquatic environment, long-term hazard, category 2
H411 - Hazardous to the aquatic environment, long-term hazard

About Molecule of the Week

MOTW has been a popular feature on ACS website since 2001. Many molecules are suggested by our website visitors. Every structure is reviewed by a scientist and displayed in 3-D and flat images with a brief description. Each week’s molecule also links to a sample record from the CAS REGISTRY, which is searched using SciFinder. Each record displays the registry number, index name and synonyms, bibliographic information, and more. Send us a molecule suggestion at motw@acs.org.

往期精选：

每周分子Molecule of the Week：苯甲酸

每周分子Molecule of the Week：角鲨烯

每周分子Molecule of the Week：1H-1,2,3-三唑

每周分子Molecule of the Week：尿酸

每周分子Molecule of the Week：2-乙酰基呋喃、2-乙酰基吡咯

每周分子Molecule of the Week：硼烷-四氢呋喃

每周分子Molecule of the Week：硬脂酸钠

每周分子Molecule of the Week：4-甲氧基苯乙烯

每周分子Molecule of the Week：硫化锌

每周分子Molecule of the Week：螺旋内酯甾酮

每周分子Molecule of the Week：白磷