Some Novel Coordination Compounds of Group IV Metals

Abstract

In investigations to determine whether ligand groups can be added directly to the lower halides of zirconium and titanium it has been found that cyclopentadiene vapour reacts with these compounds at 200 – 300° to put a C₅H₅ ring in each of the vacant valency positions according to the reaction:

with the hydrogen apparently reacting with excess cyclopentadiene. From the appropriate lower halides the previously undescribed compounds C₅H₅ZrBr₃, C₅H₅ZrBr₃ and C₅H₅ZrI₃ and the known compounds (C₅H₅)₂ZrCl₂, (C₅H₅)₂ZrBr₂ and C₅H₅TiCl₃ were made. The known compounds had physical properties and X-ray powder patterns identical with samples made by other routes. The zirconium trihalogeno -compounds were also synthesized by the action of magnesium cyclopentadienide in xylene solution on zirconium tetrahalides, and these compounds were identical with those from the lower halides reactions. In all cases a single sharp proton magnetic resonance peak was obtained from the compounds in solution, showing them to contain π -bonded C₅H₅ rings. This was confirmed by the near infra-red reflectance spectra of the solids (1), which correspond closely with that of ferrocene.