Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

The new kid on the block

06.06.2011
The first cubic-shaped complexes of rare-earth metals and organic carbenes present chemists with a unique structure motif for carbene chemistry study

In synthetic chemistry, ‘carbene’ species—compounds bearing a carbon atom with two unpaired electrons—have a ferocious reputation. Left uncontrolled, they will react with almost any molecule they meet.

But by harnessing this vigor with transition metals, chemists can turn carbenes into powerful chemical transformation reagents. Now, Zhaomin Hou and colleagues from the RIKEN Advanced Science Institute in Wako report a new class of compounds that contain multiple carbene units in one extraordinary structure: a cube-shaped molecule stabilized by ligand-protected rare-earth metals[1].

Rare-earth metals hold more electrons within their atomic radii than most other elements, making them essential in high-tech devices such as superconductors and hybrid vehicle batteries. Combining these metals with carbenes could lead to breakthrough procedures in synthetic chemistry. However, rare-earth metal–carbene complexes are usually unstable because the bonds they form are lopsided electronically, and therefore extremely reactive.

To overcome this problem, Hou and colleagues turned to a bulky ligand, based on a five-membered aromatic ring called cyclopentadiene (Cp´), which can trap rare-earth metal–carbene complexes into ordered solids. By mixing Cp´-protected lutetium (Lu) and thulium (Tm) rare-earth metal precursors with a carbon-donating aluminum reagent, they isolated a unique set of hybrid polyhedral crystals. X-ray analysis showed that these materials had a core of three rare-earth metals interconnected by six bridging methyl (CH3) groups.

An unexpected twist occurred when the researchers tested the thermal stability of the Lu– and Tm–methyl complexes. Heating to 90 °C caused the methyl groups to lose one of their hydrogen atoms, transforming them into carbenes. Then, after the elimination of a methane molecule, the crystal structure rearranged into a perfectly shaped cube featuring four Cp´-protected rare-earth metals and four carbene units (Fig. 1).

The team’s experiments revealed that the cubes spontaneously turned benzene–carbonyl molecules into alkenes by swapping their carbene groups for oxygen atoms, yielding a new oxygenated cube in the process. The researchers are now examining the reactivity of the cubes toward other molecules and plan to fine-tune the structure and reactivity of carbene compounds by investigating differently sized rare-earth metals together with different supporting ligands.

“This work demonstrates for the first time that methane can be eliminated rather easily from rare earth complexes containing methyl groups, affording structurally stable but highly reactive multi-carbene species,” says Hou. “Further studies along this line should open up a completely new frontier in rare-earth carbene chemistry.”

The corresponding author for this highlight is based at the Advanced Catalyst Research Team, RIKEN Advanced Science Institute

Journal information

[1] Zhang, W.-X., Wang, Z., Nishiura, M., Xi, Z. & Hou, Z. Ln4(CH2)4 cubane-type rare-earth methylidene complexes consisting of “(C5Me4SiMe3)LnCH2” units (Ln = Tm, Lu). Journal of the American Chemical Society 133, 5712–5715 (2011).

gro-pr | Research asia research news
Further information:
http://www.riken.jp
http://www.researchsea.com

More articles from Life Sciences:

nachricht Complete skin regeneration system of fish unraveled
24.04.2018 | Tokyo Institute of Technology

nachricht Scientists generate an atlas of the human genome using stem cells
24.04.2018 | The Hebrew University of Jerusalem

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: BAM@Hannover Messe: innovative 3D printing method for space flight

At the Hannover Messe 2018, the Bundesanstalt für Materialforschung und-prüfung (BAM) will show how, in the future, astronauts could produce their own tools or spare parts in zero gravity using 3D printing. This will reduce, weight and transport costs for space missions. Visitors can experience the innovative additive manufacturing process live at the fair.

Powder-based additive manufacturing in zero gravity is the name of the project in which a component is produced by applying metallic powder layers and then...

Im Focus: Molecules Brilliantly Illuminated

Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.

Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Quantum Technology for Advanced Imaging – QUILT

24.04.2018 | Information Technology

AWI researchers measure a record concentration of microplastic in arctic sea ice

24.04.2018 | Earth Sciences

Complete skin regeneration system of fish unraveled

24.04.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>