HCSiF and HCSiCl: The First Detection of Molecules with Formal C≡Si Triple Bonds

Neutralization of [C,H,Si,X] radical cations (X=F, Cl) in conjunction with electronic structure calculations provides the first experimental evidence for the formation of the neutral silynes HC≡SiF and HC≡SiCl, which have nonlinear structures (see picture).     

On homomorphisms to acyclic local tournaments

A homomorphism of a digraph to another digraph is an edgepreserving vertex mapping. A local tournament is a digraph in which the inset as well as the outset of each vertex induces a tournament. Thus acyclic local tournaments generalize both directed paths and transitive tournaments. In both these cases there is a simple characterization of homomorphic preimages. Namely, if H is a directed path, or a transitive tournament, then G admits a homomorphism to H if and only if each oriented path which admits a homomorphism to G also admits a homomorphism to H. We prove that this result holds for all acyclic local tournaments. © 1995 John Wiley & Sons, Inc.     

Zur Erkennung terti?rer Alkohole

Ohne Zusammenfassung