Shine your light : Recent work in photocrystallography demonstrates a large photoinduced increase in the magnetic susceptibility of a solid, which is accompanied by significant changes in the bond lengths of the Nd? NC? Fe moiety (see picture; black are ground‐state bond lengths in Å, red are photoinduced bond lengths).
Six combinations of oxidation states are conceivable for the paramagnetic title complex. Single‐crystal X‐ray diffraction, spectroscopic analysis (IR, EPR at conventional and high frequency), and DFT calculations establish that it is the iminosemiquinone radical structure that is formed: [Ruk(NOm)(Qn)(terpy)]2+ (k=2+, m=1+, n=1?).
“The biggest challenge facing chemists is being creative. When I was eighteen I wanted to be an astrophysicist…︁.” This and more about Sandro Gambarotta can be found on page 2449.
Komplett fluoriert : Vollständig fluoriertes Pentaphenylborol (siehe Struktur) wurde durch aufeinander folgende Transmetallierungsreaktionen unter Beteiligung von Zr‐ und Sn‐Heterocyclen synthetisiert. Das hoch feuchtigkeitsempfindliche Borol ist ein neues Mitglied der Familie der Perfluorarylborane, einer Klasse von antiaromatischen Verbindungen mit grundlegender Bedeutung für Aromatizitätskonzepte.
Bridging or pendant? Palladium and rhodium complexes deriving from an ambiphilic phosphine–borane ligand are shown to adopt a bridging P→M? Cl→B coordination mode in the solid state. DFT calculations provide more insight into the Cl→B interaction and suggest the possible interconversion of the bridging and B‐pendant forms in solution.
Mixed doubles : The dimeric complex [{Fe(tim)}2] (see structure, tim=2,3,9,10‐tetramethyl‐1,4,8,11‐tetraazacyclotetradeca‐1,3,8,10‐tetraene) represents an unprecedented complex containing an unsupported Fe? Fe bond. The crystal structure confirms the presence of reduced tim units, thus indicating ligand redox activity. Spectroscopic and computational studies establish a triplet ground state for [{Fe(tim)}2] and suggest a mixed‐valence compound with respect to both the Fe ions and the ligands.
Discriminating elimination : A new method for the synthesis of methyl‐branched trisubstituted Z olefins, a structural motif in many polyketides with anticancer activity, relies on an ?OH‐induced decarboxylative Grob‐type fragmentation (see scheme; Ms=mesyl). The starting materials are β‐mesyloxy lactones with a quaternary α center, which are prepared by aldol reactions in a diastereo‐ and enantioselective manner.
Heads or tails? The evolution of structural and electronic properties of tin–phthalocyanine films has been analyzed for sub‐monolayer to multilayer coverage using low‐temperature scanning tunneling microscopy. Two molecular conformations are observed: randomly dispersed for the first layer, and islands with a single conformation in subsequent layers.
SiSe matters : Diselenadisiletane 2 , formed from direct reaction of a racemic silylene 1 with elemental selenium, gives the first bis(silaselenone) upon hydrolysis with water ( 3 ; see picture, C gray, H white, N blue, O red, Se purple, Si green; d(Si?Se)=215 pm). The reaction is stereoconvergent: only racemic forms of 3 are obtained from a mixture of racemic and meso forms of 2 .
(?)‐Dysibetaine has been synthesized in 11 steps from readily available L ‐malic acid (see scheme). The key step is a unique Ugi 4‐center‐3‐component cyclization reaction, where an ester group acts as the carboxylic acid component. The use of 1,1,1,3,3,3‐hexamethyldisilazane as an ammonia equivalent and a specially designed isocyanide leads to an expeditious synthesis.
Funky discotics : Photoconductivity is measured in newly synthesized cyclopalladated metallomesogens exhibiting hexagonal columnar mesophases at room temperature. The tuning of the HOMO/LUMO energy levels by modification of the chain/core linkage (ester 1 vs ether 2 ) makes compound 2 photoconductive across the whole UV/Vis/NIR range.
?My most exciting discovery to date has been always the last one (or better still, the next one). The biggest challenge facing scientists is the responsible use of knowledge and scientific power for the betterment of humanity. …?“ This and more about P. Melchiorre can be found on page 3389.
The structural changes of the polymers having the following structures: at high temperatures were studied by the spectroscopic and thermal analysis. When the polymers were heated in air, they were oxidized predominantly to polymers having the structure: The rate of oxidation was fast and the reaction was almost completed within 2 hr at 180°C. In the case of polymer 3, an intramolecular cyclization to form acridone was detected as a minor reaction. 相似文献
