Volume 3 Issue 7, July 2011

Volume 3 Issue 7

Despite the broad appeal of carbenes as ligands for metal complexes and as catalysts in their own right — typically in the form of N-heterocyclic carbenes — the isoelectronic nitrenium analogues have received much less attention. Now, Mark Gandelman and co-workers have prepared several N-heterocyclic nitrenium ions (one of which is shown conceptually on the cover) and examined their ligand properties. It is found that relatively strong metal–nitrenium bonds are formed and the ligands are shown to be poor σ donors and good π acceptors.

Cover design by Alex Wing, Nature Chemistry

Article p525

Thesis

  • Thesis |

    Could short, non-traditional sabbaticals help scientists better organize their research groups and make improvements to their laboratory's IT infrastructure? Bruce Gibb ponders this question.

    • Bruce C. Gibb

Books and Arts

Research Highlights

Blogroll

News and Views

  • News & Views |

    The search for efficient oxygen reduction catalysts made from perovskite oxides rather than expensive precious metals is hindered by the sheer range of these oxides — where should the search begin? Developing design rules that can identify the best candidates is the first step towards a more targeted strategy.

    • Robert F. Savinell
  • News & Views |

    The discoveries of ruthenium– and iron–nitrido complexes that can be transformed to release ammonia could be important steps towards realizing the catalytic reduction of nitrogen under mild reaction conditions.

    • Yoshiaki Nishibayashi
  • News & Views |

    The mechanism of NO and O2 production through the photolysis of the nitrate radical has long proved elusive. Now, theoretical studies help to explain previous experiments, suggesting that two distinct pathways are responsible that both involve 'roaming dynamics' on the 'dark' excited electronic state.

    • Simon W. North
  • News & Views |

    A catalyst has been developed that enables poly(propylene carbonate) chains to be made in which the configuration of the repeat units changes gradually from exclusively S at one end of the chain to exclusively R at the other. The improved physical properties of this 'stereogradient' polymer may help its adoption as an environmentally friendly material.

    • Bun Yeoul Lee
    •  & Anish Cyriac
  • News & Views |

    Do unusual geometries always come from the force exerted by a protein, a solid-state lattice or bulky ligands? In a new iron(II) complex, simple ligands stabilize a square-planar high-spin complex through finesse rather than force.

    • Patrick L. Holland

Review

  • Review Article |

    Peptide macrocycles have a number of important applications. Among other things, the reduced conformational freedom of the cyclic structure enables strong binding to the extended contact regions of protein–protein complexes. Here, emerging methods directed towards the synthesis of these valuable molecules are reviewed.

    • Christopher J. White
    •  & Andrei K. Yudin

Articles

  • Article |

    Nitrenium salts have been known for more than 100 years. Despite being isoelectronic and isostructural to the ubiquitous N-heterocyclic carbene ligands and other main-group analogues, their coordination to metals has remained elusive. Here, the first examples of nitrenium ions as ligands for transition metals are described, along with investigations of their electronic properties.

    • Yuri Tulchinsky
    • , Mark A. Iron
    • , Mark Botoshansky
    •  & Mark Gandelman
  • Article |

    One of the hurdles facing the development of effective catalysts to produce ammonia from nitrogen is the stability of the metal nitrides that form during the reaction. Now, the hydrogenolysis of nitride ligands with hydrogen is reported and attributed to PNP pincer ligand cooperativity.

    • Bjorn Askevold
    • , Jorge Torres Nieto
    • , Samat Tussupbayev
    • , Martin Diefenbach
    • , Eberhardt Herdtweck
    • , Max C. Holthausen
    •  & Sven Schneider
  • Article |

    Single-molecule magnets hold great promise for device miniaturization but the blocking temperatures at which they perform must first reach practical values. Now, the electronically diffuse N23− radical bridge has been shown to endow two di-lanthanide complexes with good magnetic properties — a di-gadolinium complex displays a strong magnetic coupling and its di-dysprosium analogue a high blocking temperature.

    • Jeffrey D. Rinehart
    • , Ming Fang
    • , William J. Evans
    •  & Jeffrey R. Long
  • Article |

    Loline is a small alkaloid with a deceptively simple-looking structure. Here, a remarkably short synthesis is reported, the key step of which is a transannular aminobromination. The synthesis provides access to loline and to several other members of the loline family in sufficient yield to support a programme investigating the complex biological interactions of these compounds.

    • Mesut Cakmak
    • , Peter Mayer
    •  & Dirk Trauner
  • Article |

    With the cost of noble metal oxygen-reduction catalysts rendering some fuel cells and batteries prohibitively expensive, the search for effective and cheaper catalysts is underway and would be speeded up by ‘design principles’. Now, the catalytic activity of oxide materials has been correlated to σ*-orbital occupation and the extent of metal–oxygen covalency.

    • Jin Suntivich
    • , Hubert A. Gasteiger
    • , Naoaki Yabuuchi
    • , Haruyuki Nakanishi
    • , John B. Goodenough
    •  & Yang Shao-Horn
  • Article |

    Small nanoparticles with controlled morphologies can be prepared for catalysis applications by colloidal methods using stabilizing ligands. A solvent-extraction method has now been described that removes the ligands without affecting the morphology of the nanoparticles, or their catalytic activity over a range of reactions.

    • Jose A. Lopez-Sanchez
    • , Nikolaos Dimitratos
    • , Ceri Hammond
    • , Gemma L. Brett
    • , Lokesh Kesavan
    • , Saul White
    • , Peter Miedziak
    • , Ramchandra Tiruvalam
    • , Robert L. Jenkins
    • , Albert F. Carley
    • , David Knight
    • , Christopher J. Kiely
    •  & Graham J. Hutchings
  • Article |

    Oligosaccharides displayed at cell surfaces have important biological functions — such as controlling the entry of viruses — but a full understanding of this behaviour requires the synthesis of such compounds, which remains challenging. Here, two synthetic octasaccharides were shown to have remarkably similar inhibition of herpes simplex virus type 1 infection of cell cultures to the natural oligosaccharide identified in enzymatic studies.

    • Yu-Peng Hu
    • , Shu-Yi Lin
    • , Cheng-Yen Huang
    • , Medel Manuel L. Zulueta
    • , Jing-Yuan Liu
    • , Wen Chang
    •  & Shang-Cheng Hung
  • Article |

    In extended networks, light-induced magnetic ordering through spin change typically involves a charge-transfer mechanism, and thus a valence change of the magnetic metal centres. Now, such long-range ordering has been achieved in a three-dimensional metal–organic framework through the low-spin to high-spin transition of iron(II) centres, leading to a pronounced spontaneous magnetization.

    • Shin-ichi Ohkoshi
    • , Kenta Imoto
    • , Yoshihide Tsunobuchi
    • , Shinjiro Takano
    •  & Hiroko Tokoro

In Your Element

  • In Your Element |

    Russell Boyd ponders on how selenium — despite close similarities with its neighbours of the chalcogen family, sulfur and tellurium — continues to reveal chemical and biological activities of its own.

    • Russell Boyd