The ring closure of 5-methylcyclopenta-1,3-dien-5-ylcarbene to 1-methylbenzvalene. An intramolecular 1,4 cheletropic carbene addition

The title carbene ($\text{7}$) is shown to produce the benzvalene skeleton by stereospecific intramolecular 1,4 addition and not by classic cyclopropanation.     

Study of electron-positron collisions at the highest PETRA energy

We report on the results of the study of e⁺e^? collisions at the highest PETRA energy of √s = 31.57 GeV, using the 4π sr, electromagnetic and calorimetric detector Mark J. Based on 88 hadron events, and an integrated luminosity of 243 nb^?1 we obtain R = σ(e⁺e^? → hadrons)/σ(e⁺e^? → μ⁺μ^?) = 4.0 ± 0.5 (statistical) ± 6 (systematic). The R value, the measured thrust distribution and average spherocity show no evidence for the production of new quark flavors.     

Bildung eines hochexplosiven Valenzisomeren des Indens aus Dilithiopentalen und Chlorcarben

Formation of a Highly Explosive Valence Isomer of Indene from Dilithiopentalene and Chlorocarbene The principal product of the reaction of dilithiopentalene ( 3 ) with methyllithium and methylene chloride is shown by difference-FT-NMR, spectroscopy to be tetracyclo[4.3.0.0^3,5.0^4,6]nona-1,7-diene ( 8 ). This laterally bridged benzvalene derivative explodes violently at temperatures as low as ?40° when concentrated. Controlled rearrangement in diluted solution gives indene ( 4 ). The key step in the formation of the tetracyclic C₉H₈-compound 8 is suggested to be an intramolecular 1,4-carbene addition.     

ESR in the Pd-Mn system: Some evidences of a bottlenecked relaxation for the Mn2+ ion

ESR experiments on Pd-Mn in the low Mn concentration region (200 ? c ? 5000 at. ppm) are reported. The results are consistent with the hypothesis of a bottlenecked resonance with different g-factors for the Mn²⁺ ions (2.055) and the electrons of Pd (2.25); besides, partial opening of this bottleneck can be achieved. A giant momentum for Mn²⁺ (9.15μ_B) is also confirmed.     

On the mechanism of the thermal naphthalene automerization,a comment

The title reaction is suggested to proceed by a reversible valence isomerization via a laterally bridge benzvalene (2). No analogous behaviour is expected for pyrene.