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J. Appl. Cryst.の発刊に際して

Global energy consumption is projected to increase, even in the face of substantial declines in energy intensity, at least 2-fold by midcentury relative to the present because of population and economic growth. This demand could be met, in principle, from fossil energy resources, particularly coal. However, the cumulative nature of CO2 emissions in the atmosphere demands that holding atmospheric CO2 levels to even twice their preanthropogenic values by midcentury will require invention, development, and deployment of schemes for carbon-neutral energy production on a scale commensurate with, or larger than, the entire present-day energy supply from all sources combined. Among renewable energy resources, solar energy is by far the largest exploitable resource, providing more energy in 1 hour to the earth than all of the energy consumed by humans in an entire year. In view of the intermittency of insolation, if solar energy is to be a major primary energy source, it must be stored and dispatched on demand to the end user. An especially attractive approach is to store solar-converted energy in the form of chemical bonds, i.e., in a photosynthetic process at a year-round average efficiency significantly higher than current plants or algae, to reduce land-area requirements. Scientific challenges involved with this process include schemes to capture and convert solar energy and then store the energy in the form of chemical bonds, producing oxygen from water and a reduced fuel such as hydrogen, methane, methanol, or other hydrocarbon species.

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Powering the planet: Chemical challenges in solar energy utilization

N-Heterocyclic Carbenes in Late Transition Metal Catalysis

1. Organometallic Pincer Type Complexes: Recent Applications in Synthesis and Catalysis (J. Dupont et al.). 2. Synthesis and Transformation of Allyl- and Allenyl-Metal Species by Pincer-Complex Catalysis(K.J. Szabo). 3. Chiral Pincer Complexes and their Application to Asymmetric Synthesis (C.J. Richards, J.S. Fossey). 4. Desulfurization Catalyzed by Nickel PCP-Pincer Compounds (J. Torres-Nieto, J.J. Garcia). 5. Pincer Systems as Models for the Activation of Strong Bonds: Scope and Mechanism (B. Rybtchinski, David Milstein). 6. 'Pincer'-Carbene Complexes (E. Peris, R.H. Crabtree). 7. Pincer Complexes Derived from Benzimidazolin-2-ylidene Ligands (F. Ekkehardt Hahn, M.C. Jahnke). 8. Pincer Complexes of N-Heterocyclic Carbenes. Potential Uses as Pharmaceuticals (M.J. Panzner et al.). 9. The Chemistry of PCP-Pincer Phosphinite Transition Metal Complexes (D. Morales-Morales). 10. Nitrogen-Based Pincers: a Versatile Platform for Organometallic Chemistry (P. Chase, G. van Koten). 11. S-P-S and S-C-S Pincer Ligands in Coordination Chemistry and Catalysis (N. Mazailles, P. Le Floch). 12. Pincer Ligand Complexes with Unusual Atoms and Molecular Backbones (H.A. Mayera et al.). 13. Rigid PNP Pincer Ligands and their Transition Metal Complexes (O.V. Ozerov). 14. Pincer, Chelate and Spirocyclic Metal Carbene Complexes from Bis(iminophosphorane)methane Ligands (R.G. Cavell). 15. Pincer and Chelate Carbodiphosphorane Complexes of Noble Metals (R.G. Cavell). 16. Hypervalent Organotin, Aluminum, Antimony and Bismuth Y,C,Y-Chelate Complexes (R. Jambor, P. Libor Dostal). 17. Stability of Supported Pincer Complexes-Based Catalysts in Heck Catalysis (W.J. Sommer, M. Weck). 18. Dendrimers Incorporating Metallopincer Functionalities: Synthesis and Applications (P. Chase, G. van Koten). 19. Future Trends and Perspectives in the Chemistry of Pincer Complexes (W.D. Jones).

The chemistry of pincer compounds

High yield olefination of a wide scope of aryl chlorides catalyzed by the phosphinito palladium PCP pincer complex: [PdCl{C6H3(OPPri2)2-2,6}]

Pincer ligands have become ubiquitous in organometallic chemistry and homogeneous catalysis. Recently, new varieties of pincer ligands with non-symmetrical backbones and/or ligating groups have been reported and their application in transition metal complexes has been exploited in a variety of catalytic transformations. This non-symmetric approach vastly increases the structural and electronic diversity of this class of ligand. This approach has proven beneficial in a variety of ways, such as the use of a single weakly coordinating moiety, which can dissociate and thereby create a vacant coordination site to increase the catalyst activity. Additionally, this provides further access to chiral ligands and complexes for asymmetric induction. This perspective highlights recent, important examples of non-symmetric pincer ligands, which feature aryl or pyridine backbones, and the synthesis and use of subsequent complexes in catalytic transformations, and discusses the future potential of this type of ligand system.

Non-symmetric pincer ligands: complexes and applications in catalysis

Highly efficient and regioselective production of trisubstituted alkenes through heck couplings catalyzed by a palladium phosphinito PCP pincer complex

David Morales-Morales

Papers

The chemistry of pincer compounds

High yield olefination of a wide scope of aryl chlorides catalyzed by the phosphinito palladium PCP pincer complex: [PdCl{C6H3(OPPri2)2-2,6}]

Non-symmetric pincer ligands: complexes and applications in catalysis

Highly efficient and regioselective production of trisubstituted alkenes through heck couplings catalyzed by a palladium phosphinito PCP pincer complex

Synthesis and catalytic activity of pincer-type bis(benzimidazolin-2-ylidene) palladium complexes