Correlation Between Kinetic and Magnetic Properties of Itermetallic Compounds of Gd−In System in Paramagnetic Region

Russian Physics Journal - The paper presents the experimental results of the electrical resistance, magnetic susceptibility, and Hall effect of the intermetallic compounds of the Gd?In system...     

Molecular structure of cyclobutanones resulting from cycloaddition of Moore's ketene to styrene, 1-vinylnaphthalene andp-methoxystyrene

Styrene or 1-vinylnaphthalene react with Moore's ketene (t-butylcyanoketene) to give cyclobutanones1a and1b, respectively, withcis configuration of the vicinal bulkyt-butyl and aryl groups. Steric crowding is reduced by (i) nonplanarity distortion of the cyclobutanone ring (ca. 20°), (ii) elongation to ca. 1.6 Å of the C₂-C₃ bond (which is flanked by the bulky groups), (iii) deviation of the vicinal bulky groups by ca. 22° from the eclipsed conformation, and (iv) increased bond angles of thet-Bu-C₂-C₃ and Ar-C₃-C₂ groups.p-Methoxystyrene reacts with Moore's ketene to give cyclobutanone2a with the vicinal bulkyt-butyl and aryl groups in thetrans configuration. In contrast to1a and1b, (i) the cyclobutanone ring is planar, (ii) the C₂-C₃ bond is shorter (1.59 Å), and the bond angles (iii) and (iv) are each reduced by 12.5°. It is concluded that in the case of styrene and 1-vinylnaphthalene the cycloaddition reaction is seemingly concerted and occurs according to a_{2 s}+2 _a reaction mode, whereasp-methoxystyrene reacts stepwise with Moore's ketene, giving the thermodynamically more stable cyclobutanone isomer.