What molecule am I?
Ever since the discovery of ferrocene in the 1940s, hundreds of 鈥渟andwich鈥� compounds, in which a metal atom is 鈥渟andwiched鈥� 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 , 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 潞C to produce uranocene, a green crystalline solid. COT has a folded structure; but its dianion is planar, making it a suitable 鈥渂read鈥� for the sandwich.
Uranocene is stable to water, acids, bases, and moderate heating鈥攂ut it ignites spontaneously in air. In ferrocene, the Cp rings鈥� six 蟺 electrons interact with the 3d orbitals in iron. In uranocene, uranium鈥檚 6d orbitals similarly combine with the COT鈥檚 10 蟺 electrons; but uranium 5f orbitals are also involved, contributing to the molecule鈥檚 stability.
In 2004, Ditmar Seyferth at MIT wrote a of organometallic compounds that contain f-orbital elements.
Uranocene hazard information
| Hazard class* | Hazard statement | |
|---|---|---|
| Acute toxicity, oral, category 1 | H300鈥擣atal if swallowed |  |
| Acute toxicity, inhalation, category 1 | H330鈥擣atal if inhaled | |
| Specific target organ toxicity, repeated exposure, category 2 | H373鈥擟auses damage to organs through prolonged or repeated exposure |  |
| Hazardous to the aquatic environment, long-term hazard, category 2 | H411鈥擧azardous to the aquatic environment, long-term hazard |  |
*Globally Harmonized System of Classification and Labeling of Chemicals.聽聽
MOTW update
Ibogaine was the Molecule of the Week for June 16, 2014. It is a hallucinogenic, neurotoxic indole alkaloid that is successful in reducing withdrawal effects from abused drugs such as alcohol, nicotine, and methamphetamine. But ibogaine鈥檚 toxicity, especially its tendency to induce cardiac arrhythmia, led researchers to investigate safer efficacious analogues. David E. Olson and co-workers at the University of California, Davis, have synthesized that does not cause hallucinations in mice, nor does it inhibit the potassium channels linked to ibogaine鈥檚 cardiotoxicity. In rodent experiments, tabernanthalog reduced alcohol- and heroin-seeking behavior and had antidepressant effects.
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Uranocene聽fast facts
| CAS Reg. No. | 11079-26-8 |
nomenclature | Uranium, bis(畏8-1,3,5,7-cyclooctatetraene) coordination compound |
| Empirical formula | C16H16U |
| Molar mass | 446.33 g/mol |
| Appearance | Green crystals |
| Melting point | 180 潞C (subl) (4 Pa) |
| Water solubility | Insoluble |
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