Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Putting the squeeze on rare earth metals

18.04.2011
‘Pincer’ molecules trap reactive rare earth elements into previously unseen hydrogen-infused structures

Rare-earth metals are a series of elements that represent one of the final frontiers of chemical exploration. The vigorous reactivity of these substances, however, has made it difficult for researchers to transform them into stable materials with well-defined structures. But when they succeed, the payoff can be enormous—rare-earth compounds have important applications in areas ranging from catalysis to clean energy.

Now, Zhaomin Hou and colleagues from the RIKEN Advanced Science Institute in Wako have discovered a new way to isolate rare-earth metals as hydrogen-infused crystals by using wedge-shaped bis(phosphinophenyl)amido (PNP) ligands to ‘pinch’ them in place[1]. These ligands squeeze rare-earth yttrium atoms together tighter than any previous material, and can even stabilize highly volatile charged complexes.

Metallic compounds that incorporate multiple hydrogen atoms, or polyhydrides, into their frameworks are useful to chemists because they provide some of the purest understandings of bonding and reactivity available. Previously, Hou’s team isolated an yttrium polyhydride containing a hydrogen ligand that simultaneously bonds to four metals[2]. This compound sparked remarkable chemical curiosity because of its structural novelty.

According to Hou, the trick to producing rare-earth polyhydrides is to surround them with large, cumbersome molecules that easily pack together to form crystals. The distinct structure of PNP ligands—two phosphorus atoms, linked together by a rigid aromatic–amino core that can bind to metals with a pincer-like grip—made this ligand a promising candidate for the researchers’ investigation.

By first substituting extra methyl units onto the aromatic backbone of PNP to increase its bulkiness, and then mixing the ligand with an yttrium alkyl precursor and hydrogen gas, the team synthesized pale yellow crystals of a new yttrium polyhydride complex. X-ray structural analysis revealed that three yttrium atoms, held in place by PNP ‘pincers’, were interlinked by a set of double- and triple-bridged hydrogen ligands (Fig. 1). This intricate network of bonds produced the shortest yttrium–yttrium distance ever recorded—an extraordinary packing density that may be critical for future hydrogen-storage applications.

The researchers found that an ammonium proton could remove a hydride from the complex without disrupting crystallization, yielding the first-ever cationic tri- and di-yttrium polyhydrides. The charged nature of these materials should impart potent chemical activity, attributes which Hou and his team are currently investigating. “Our results clearly demonstrate the vital importance of ligand-tuning in the isolation and characterization of rare earth polyhydrides, and should encourage further explorations in this burgeoning area,” he says.

The corresponding author for this highlight is based at the Organometallic Chemistry Laboratory, RIKEN Advanced Science Institute

Journal information

[1] Cheng, J., Shima, T. & Hou, Z. Rare-earth polyhydride complexes bearing bis(phosphinophenyl)amido pincer ligands. Angewandte Chemie International Edition 50, 1857–1860 (2011).

[2] Hou, Z., Nishiura, M. & Shima, T. Synthesis and reactions of polynuclear polyhydrido rare earth metal complexes containing “(C5Me4SiMe3)LnH2” units: A new frontier in rare earth metal hydride chemistry. European Journal of Inorganic Chemistry 18, 2535–2545 (2007).

gro-pr | Research asia research news
Further information:
http://www.rikenresearch.riken.jp/eng/research/6567
http://www.researchsea.com

More articles from Life Sciences:

nachricht 'Y' a protein unicorn might matter in glaucoma
23.10.2017 | Georgia Institute of Technology

nachricht Microfluidics probe 'cholesterol' of the oil industry
23.10.2017 | Rice University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Salmonella as a tumour medication

HZI researchers developed a bacterial strain that can be used in cancer therapy

Salmonellae are dangerous pathogens that enter the body via contaminated food and can cause severe infections. But these bacteria are also known to target...

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

3rd Symposium on Driving Simulation

23.10.2017 | Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

 
Latest News

Microfluidics probe 'cholesterol' of the oil industry

23.10.2017 | Life Sciences

Gamma rays will reach beyond the limits of light

23.10.2017 | Physics and Astronomy

The end of pneumonia? New vaccine offers hope

23.10.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>