Novel organometallic reagents: geminal dianionic derivatives of the heavy group 14 elements

This Forum review describes the most recent achievements in the novel prospective field of highly reactive main-group organometallics, namely, geminal dianionic derivatives of the heavy group 14 elements (Si, Ge, Sn). A brief historical introduction to the topic is followed by discussion of the current state of affairs in the field of stable derivatives and prospects for future efforts, highlighting our own synthetic approach and recent results. The most important experimental contributions, including synthesis of 1,1-dilithiosilane, -germane, and -stannane derivatives; dilithio(halo)silanes (lithiosilylenoids); metallole 1,1-dianions; and heavy analogues of the cyclobutadiene dianion derivatives, are presented, along with a discussion of the synthetic applications of the above-mentioned organometallic compounds.     

Preparation of polysiloxanes from silicic acid. V. Condensation of silicic acid butyl esters and formation of silica fiber from the ester solutions

The condensation of silicic acid butyl esters was investigated by gel permeation chromatographic (GPC) analysis. The results revealed that the condensation was greatly dependent on a degree of esterification of the esters. The ester with the lowest degree of esterification underwent condensation to form a highly polymerized ester. It was found that fibers could be drawn from the ester solution before gelation.     

On the Manin-Mumford conjecture for abelian varieties with a prime of supersingular reduction

We give a short proof of the `` prime-to- version" of the Manin-Mumford conjecture for an abelian variety over a number field, when it has supersingular reduction at a prime dividing , by combining the methods of Bogomolov, Hrushovski, and Pink-Roessler. Our proof here is quite simple and short, and neither -adic Hodge theory nor model theory is used. The observation is that a power of a lift of the Frobenius element at a supersingular prime acts on the prime-to- torsion points via nontrivial homothety.