Preparation and characterization of selected transition metallacyclohexa-2,5-dienes.

摘要

The goal of this research was to study the synthesis and chemistry of stable unsaturated six-membered transition metallacycles. The first examples of the new and novel class of metallacycles, metallacyclohexa-2,5-dienes, are reported. These metallacycles are also potential precursors to metallaaromatic complexes. Proton and/or hydride abstraction from the saturated methylene carbon concomitant with an electron redistribution of the organic moiety and a transition metal orbital of appropriate symmetry would lead to metallaaromatic complexes.;A titanacyclohexa-2,5-diene was prepared from the anionic alkylation and titanocene dichloride. Dibenzometallacyclohexa-2,5-dienes incorporating titanium, hafnium, cobalt, molybdenum, and platinum were obtained from the anionic alkylations of transition metal dihalides with 2,2;The reaction of titanocene dichloride with 1,5-dilithio-(1Z,4Z)-pentadiene gave bis(;An investigation aimed at isolating stable dibenzannelated metallacyclohexa-2,5-dienes prompted the reactions of 2,2;X-ray crystallographic analysis for bis(;Preliminary efforts aimed at conversion of dibenzometallacyclohexa-2,5-dienes into cationic or anionic metallaanthracene derivatives yielded unstable and/or intractable paramagnetic solids.