H + but not H ? : The reduction reaction of protochlorophyllide catalyzed by protochlorophyllide oxidoreductase features solvent‐slaved motions that control the proton‐ but not the hydride‐tunneling mechanism. These motions imply a long‐range dynamic network from the solvent to the enzyme active site that facilitate proton transfer (see picture, left). Motions for hydride transfer are more localized and are not slaved by the solvent (see picture, right).
Stuck on sulfur : The first transition‐metal complexes with S? Br units are surprisingly stable. Solid 3 is stable for at least six months and under vacuum solid 2 does not lose Br2. The formation of the first structurally characterized transition‐metal arenesulfenyl bromide complex 3 occurs with a change of the spin ground state from S=2 to S=0.
A spin‐crossover cluster with the {FeII4O4} core structure is presented by D. Y. Wu, O. Sato et al. in their Communication on page 1475 ff. The cluster is synthesized by self‐assembly and shows an abrupt spin transition, giving two high‐spin and two low‐spin states. It exhibits complete light‐induced excited spin‐state trapping effects. Importantly, synergy effects between the magnetic interaction and spin transition operate in the cluster.
Custom built : A promising new approach towards more efficient self‐assembled cage receptors through computer‐aided design is demonstrated. The resulting M4L6 tetrahedral cage, internally functionalized with accurately positioned urea hydrogen‐bonding groups (see structure; yellow: predicted, blue: experimental, space‐filling: SO42?), proved to be a remarkably strong sulfate receptor in water.
Don′t be square! A rare S42? rectangle bridging two M2Cp2(μ2‐CH2)2 (M=Rh, Ir) fragments is found to contain two “half‐bonds” with S? S distances of 2.70 or 2.90 Å. Computational studies explore the connection between these “half‐bonds” and a Jahn–Teller distortion, as well as possible intermediates that form M4S42+ clusters having the S42? rectangle rotated by 90°.
Y not? A unique, three‐coordinate Y‐shaped bis(silyl)platinum(II) complex was isolated and characterized (see structure; C light gray, N blue, Si pink, Pt dark gray). DFT studies on a model system shed light on the nature of this unusual coordination mode for platinum(II).
B‐hive? A family of crystalline materials analogous to porous AlPO4 but based on boron imidazolate frameworks (BIFs) can be formed by the crosslinking of various presynthesized boron imidazolates with monovalent cations (Li+ and Cu+, see picture). This synthetic method is capable of generating a large variety of open frameworks, ranging from the four‐connected zeolitic sodalite type to the three‐connected chiral (10,3)‐a type.
The true ground state of 1 is a matter of debate, but for clarity and convenience the allene resonance form 1 a , is the most appropriate. The arguments for aromaticity made by Christl and Engels are shown to be incorrect.
Nice coat! Organically modified silica (ormosil) is used for the ultrathin nanoprecise coating of individual multiwall carbon nanotubes using a soft‐chemistry approach. The coating layer has a uniform thickness of about 3 nm. The ormosil coating demonstrates the favorable electrical insulating properties of individual multiwall carbon nanotubes.
“My first experiment was the Wittig reaction to prepare chiral allenes. If I wasn′t a scientist, I would be a historian. …?” This and more about Yoshiaki Nishibayashi can be found on page 4276.
Ring any bells? The differential capacitance curve of Au(100) in neat [BMI]BF4 (BMI=1‐butyl‐3‐methylimidazolium) ionic liquid has a bell‐shaped feature (see picture). The adsorption of BMI+ shows a disorder–order transition and depends on the structure of the surface. Ordered adsorption in a micelle‐like structure stabilizes the underlying Au surface.
Hidden talent : Often perceived to be too thermodynamically and kinetically inert to be a useful chemical feedstock, carbon dioxide adds to allenes under exceptionally mild reductive conditions in the presence of a palladium pincer complex to give β,γ‐unsaturated carboxylic acids (see scheme). This transformation is discussed in the context of the requirements for CO2 fixation. DMF=N,N‐dimethylformamide, Tf=trifluoromethanesulfonyl.
A window of opportunity : A general copper‐catalyzed C? H bond‐activation path allows arylation of heterocycles with a wide range of aryl bromides (see scheme). The reaction shows excellent regioselectivity and exhibits good functional group tolerance. The 8‐aryl xanthines exhibit fluorescence in a variety of solvents and show promise as reagents for biological imaging.
A powerful fluoride trap : The extremely Lewis acidic silyl cation [Et3Si]+ is an active catalyst for the hydrodefluorination of fluoroalkyl groups at room temperature (see example). The carborane anion [CHB11H5Cl6]? plays an essential role in the catalytic cycle as a weakly coordinating anion that stabilizes cationic intermediates.
Taking shortcuts : A remarkably short and high‐yielding asymmetric total synthesis of (?)‐oseltamivir takes advantage of organocatalysis and single‐pot domino operations. The target, known as the drug Tamiflu, is prepared efficiently in a short time, and also its derivatives can be synthesized effectively.
Linked to the Pentagon : The addition of molybdate to [HBW11O39]8? ions leads to the formation of mixed pentagonal units {W(Mo5)} and {W(WMo4)} trapped as linkers in the resulting modular assemblies, thus establishing the first link between the conventional Keggin ion derivatives and the giant molybdenum oxide and keplerate ions.
