Molecules of the year

C&EN highlights some of the coolest compounds reported in 2016

Steve Ritter

First confirmed inorganic double helix


SnIP in 3-D
This short animation depicts a three-dimensional model of the inorganic double-helix compound SnIP, which consists of a tin iodide helix coiled with a phosphide helix.
Credit: Courtesy of Tom Nilges
Needlelike crystals of SnIP. Credit: Courtesy of Tom Nilges
Needlelike crystals of SnIP. Credit: Courtesy of Tom Nilges

Chemists led by Tom Nilges of the Technical University of Munich reported the first completely inorganic double-helix compound, SnIP, which is a semiconducting material featuring a twisted tin iodide (SnI+) chain intertwined with a twisted phosphide (P) chain. The chains are held together by weak interactions between tin and lone pairs of electrons on phosphorus, and each double helix is coordinated to neighboring ones by interactions that are stronger than hydrogen bonding in DNA (Adv. Mater. 2016, DOI: 10.1002/adma.201603135).

Chemists’ choice: Molecule of the Year

Researchers reported a lot of exciting new molecules in 2016. C&EN picked its favorites, listed on this page, then asked online viewers to vote on theirs.

Here are the results:

Molecule
Nitrido-imido-amido complex 31%
World’s most polar neutral molecule 28%
Ferrocene Ferris wheel 14%
World’s strongest chemical base 10%
16-Coordinate cesium-fluorine complex 8%
Inorganic double helix 7%
Compound with four group 15 elements 2%

Source: Results based on an online C&EN poll, held Dec. 6-14.


Presenting a ferrocene Ferris wheel

Credit: Nat. Chem.
Credit: Nat. Chem.

By directly fusing ferrocene molecules together, Michael S. Inkpen, Nicholas J. Long, and Tim Albrecht of Imperial College London and their colleagues prepared new iron-based macrocycles that resemble a Ferris wheel. The redox-active nanorings, with versions containing five to nine ferrocene units, offer possibilities for trapping ions or molecules to sense or control them, as well as for electronic and magnetic applications (Nat. Chem. 2016, DOI: 10.1038/nchem.2553).


Cesium hosts 16 fluorine atoms

Credit: Courtesy of Klaus-Richard Pörschke
Credit: Courtesy of Klaus-Richard Pörschke

Klaus-Richard Pörschke and coworkers of the Max Planck Institute for Kohlenforschung reported a new molecule in which a central cesium atom is coordinated by an unprecedented 16 fluorine atoms from five anion units. Matching the large, singly charged Cs+ cation with the weakly coordinating [H2NB2(C6F5)6] anion allowed the researchers to go beyond 12 bonds in a complex for the first time without using hydrogen as one of the coordinating ligands. It also was the first time scientists achieved 16 bonds to one metal, which is thought to be the maximum possible (J. Am. Chem. Soc. 2016, DOI: 10.1021/jacs.6b02590).


Chromium complex wins bonding triple crown09449-cover11-schrock-odom-350

In 1978, David N. Clark and Richard R. Schrock of Massachusetts Institute of Technology reported a tungsten alkyl-alkylidene-alkylidyne complex notable for being the first compound containing single, double, and triple metal-ligand carbon bonds in the same molecule. Fast-forward to this year, and Evan P. Beaumier and Aaron L. Odom of Michigan State University and their colleagues reported the first nitrogen analog, a chromium amido-imido-nitrido complex (Chem. Sci. 2016, DOI: 10.1039/c5sc04608d).


Pnictogens make chain-link progress
09449-cover11-fourelement-350

Alexander Hinz of Oxford University and Axel Schulz and Alexander Villinger of the University of Rostock thought it would be nice to make a heterocyclic ring containing four different pnictogens (group 15 elements, N to Bi). They ended up unable to close the linear precursor to make the ring, but the acyclic compound still included an unprecedented Sb–N–As=P chain. The researchers say that in principle it should be possible to include bismuth, which would be a periodic table first to incorporate all elements from one group in a molecular complex (Chem. Eur. J. 2016, DOI: 10.1002/chem.201601916).


New world champion base and polar molecule crowned
09449-cover11-strongest-molecule-350

By preparing the o-diethynylbenzene dianion in a gas-phase experiment, Berwyck Poad of Queensland University of Technology and coworkers set the record for the world’s strongest chemical base, as measured by the molecule’s proton affinity. The dianion is strong enough to deprotonate benzene in the gas phase, the researchers say, and its proton affinity record is unlikely to be broken (Chem. Sci. 2016, DOI: 10.1039/c6sc01726f). Meanwhile, a research team led by Klaus Müllen of the Max Planck Institute for Polymer Research made a hexasubstituted benzene in which electron-withdrawing cyano groups and electron-donating amino groups combine to pull and push the molecule’s electron density in the same direction. This compound is remarkable for being the most polar neutral molecule now known to exist (Angew. Chem. Int. Ed. 2016, DOI: 10.1002/anie.201508249).


Chemists’ choice: Molecule of the Year

Researchers reported a lot of exciting new molecules in 2016. C&EN picked its favorites, listed on this page, then asked online viewers to vote on theirs.

Here are the results:

Molecule
Nitrido-imido-amido complex 31%
World’s most polar neutral molecule 28%
Ferrocene Ferris wheel 14%
World’s strongest chemical base 10%
16-Coordinate cesium-fluorine complex 8%
Inorganic double helix 7%
Compound with four group 15 elements 2%

Source: Results based on an online C&EN poll, held Dec. 6-14.

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Comments (10)

  • ReplyTianqi sheng December 7, 2016

    Presenting a ferrocene Ferris wheel

  • ReplyDr Yogesh Ghalsasi December 7, 2016

    Great post. I think the world's strongest base is remarkable entity. It creates further opportunities in synthetic organic chemistry by making use of this strongest base.

  • ReplyDr Yau Yan Lim December 7, 2016

    I would choose the iron-based macrocycles as the molecule of the year as the unique structure has potential electronic and magnetic applications

    • ReplyEdward Abel December 31, 2016

      I too would like to commend this molecule. It not only has the very considerable physical and chemical novelty and significance to make it the front runner , but it is also of great , attractive and memorable elegance.

  • ReplyJ December 8, 2016

    The gif at the top of the page is quite off-putting. May we please have an off switch, make them smaller, or just not have them at all? I know they're cool and all, but I can't read the rest of the page while they keep changing. Thanks.

  • ReplyB M Reddy December 13, 2016

    I consider first completely inorganic double-helix compound, SnIP, as the molecule of the year.

  • ReplyJorge Cervantes December 13, 2016

    Very difficult decision but my vote for the first completely inorganic double-helix complex SnIP. Very beautiful chemistry but also the posibilities for several aplications in material science and technology

  • ReplyProf. Uwe Rosenthal December 14, 2016

    Klaus-Richard Pörschke and coworkers of the Max Planck Institute for Kohlenforschung reported a new molecule in which a central cesium atom is coordinated by an unprecedented 16 fluorine atoms from five anion units. This is my favorite! BR from Uwe Rosenthal

  • ReplyWagdy Sous December 15, 2016

    I would choose the Cesium hosts 16 fluorine atoms as the molecule of the year

  • ReplyZachariah George December 21, 2016

    I would consider the SniP Molecule as the most innovative creation of the year.