What molecule am I?
After the first organometallic “sandwich” compound, ferrocene1, was discovered and characterized in the 1950s, similar complexes containing other metal atoms followed. In the 1960s and 1970s, comparable complexes of cyclooctatetraene2 (COT) with the actinide metals uranium, thorium, neptunium, plutonium, and protactinium appeared.
After a long hiatus, a new actinide sandwich compound was reported this past February. Rebecca J. Abergel, Polly L. Arnold, and Stefan G. Minasian at Lawrence Berkeley National Laboratory (CA) and the University of California, Berkeley; Jochen Autschbach at the University of Buffalo; and 15 collaborators at these institutions synthesized a complex they called berkelocene that consists of a berkelium-249 (249Bk) atom sandwiched between two modified COT derivatives, hexahydrodicyclopenta[8]annulene3 (see images).
249Bk has a half-life of 327 days, making it convenient for use in chemistry experimentation. The researchers, however, had to handle it extremely carefully because its daughter particle, californium-249, is a strong α-particle emitter. The berkelium synthesis was performed with 0.3 mg of 249Bk.
Because of the limited amount of berkelocene that was made, no physical properties or hazard information for the molecule have been reported.
1. CAS Reg. No. 102-54-5.
2. CAS Reg. No. 629-20-9.
3. No CAS Reg. No. assigned.
Molecule in the News
1,4-Butanediol1 (1,4-BDO) is one of four possible butanediols and the only one with two primary hydroxyl groups. It was synthesized in 1890 when Dutch chemist Pieter Johannes Dekkers made it in five steps beginning with tetramethylenediamine2. A greatly improved synthesis was described in 1997, when Uwe Herrmann and Gerhard Emig at the University of Erlangen-Nuremberg (Erlangen, Germany) reported the hydrogenation of maleic anhydride3 or γ-butyrolactone4 to 1,4-BDO over a copper catalyst.
About half of the worldwide production (≈4.5 Mt) of 1,4-BDO is dehydrated to make tetrahydrofuran5, a solvent and poly(butylene terephthalate)6 (Spandex) fiber precursor. 1,4-BDO itself is also an industrial solvent as well as an ingredient used in plastics manufacture.
A July article by Michael McCoy at C&EN described the advent of biobased 1,4-BDO. Qore, a joint venture of food conglomerate Cargill (Minnetonka, MN) and chemical trader Helm AG (Hambug, Germany) built and operates a plant in Eddyville, IA, that uses genetically modified bacteria to convert corn-derived glucose7 to 1,4-BDO. The plant produces as much as 66 kt of 1,4-BDO annually.
1. CAS Reg. No. 110-63-4.
2. Aka 1,4-butanediamine, putrescine; CAS Reg. No. 110-60-1.
3. CAS Reg. No. 108-31-6.
4. CAS Reg. No. 96-48-0.
5. CAS Reg. No. 109-99-9.
6. CAS Reg. No. 24968-12-5.
7. CAS Reg. No. 50-99-7.
Molecules in the News
MOTW highlights molecules that appear in major news outlets. See this week's edition.
This molecule was suggested by a dear friend and colleague of your editor who passed away in July. We present almost all of the molecules suggested by our readers. If you have a molecule you would like us to consider, please send us a message. And thank you for your interest in Molecule of the Week! —Ed.
Berkelocene fast facts
| CAS Reg. No. | 3072829-86-5 |
| SciFinder name | Not yet assigned |
| Empirical formula | C28H32Bk |
| Molar mass | 617.63 g/mol |
| Appearance | Indigo crystals |
Learn more about this molecule from CAS, the most authoritative and comprehensive source for chemical information.
Molecule of the Week needs your suggestions!
If your favorite molecule is not in our archive, please send us a message. The molecule can be notable for its current or historical importance or for any quirky reason. Thank you!
Stay Ahead of the Chemistry Curve
Learn how ACS can help you stay ahead in the world of chemistry.
