Patent GB-797151-A (GB)
Title: Process for producing metal-cyclopentadiene derivatives
IPC: C07F17/00
Filed: 1956-02-02
Abstract: Organo - metallic compounds of formula R2MXz, wherein R is a cyclopentadiene radical, or an aliphatic- or aryl-substituted cyclopentadiene radical, M is a transition element, X is a halogen atom and z is 0, 1, 2 or 3, are prepared by reacting a transition element under substantially anhydrous conditions with a monomeric alicyclic cyclopentadiene in the presence of piperidine or an organic amine having a log Ka value of at least 9 (as defined in the Specification).  The term "transition element" covers those elements of the periodic system having an inner d level of electrons present but not filled to capacity, i.e. scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, yttrium, zirconium, niobium, molybdenum, technectium, ruthenium, rhodium, palladium, lanthanum, hafnium, tantalum, tungsten, rhenium, osmium, iridium, platinum and actinium as well as the lanthanide and actinide series of rare earths.  The term "alicyclic-cyclopentadiene" includes cyclopentadiene, and substituted cyclopentadienes in which the alicyclic character of the ring is preserved, e.g. indene but not fluorene.  The ring may be substituted by methyl, ethyl, propyl, butyl, vinyl or phenyl groups.  Specified amines include diethylamine, ethylamine, n-butylamine, methylamine, isobutylamine, N - ethyl - ethylenediamine, N - methylethylenediamine benzylamine, triethylamine, ethylenediamine and 1,6-hexane-diamine.  Such amines when liquid may be used as reaction media; other substances which may be used include alkylene and polyalkylene glycol ethers, benzene and alkyd ethers.  The reaction is preferably carried out between 10 DEG and 85 DEG  C., using a cyclopentadiene/metal halide molar ratio of at least 2:1.  The amine salts which form a by-product may be converted by heating with powdered metal element or its hydroxide or oxide back to the amine and the transition element halide.  In an example ferric chloride is converted to ferrous chloride by reaction with iron in anhydrous ethylene glycol dimethyl ether; diethylamine is added and then cyclopentadiene.  Solid diethylamine hydrochloride is filtered off, the filtrate vacuum stripped and the residue [bis-(cyclopentadienyl) iron] recrystallized from petroleum ether. Other examples describe the preparation of bis(cyclopentadienyl) - nickel, bis(cyclopentadienyl) - zirconium dichloride, bis(cyclopentadienyl)-titanium dichloride and bis(cyclopentadienyl)-cobalt.ALSO:Halides of transition metals may be prepared by heating piperidine hydrohalide or an amine hydrohalide with the metal. Amines specified are diethylamine, ethylamine, n-butylamine, methylamine, iso-butylamine, N-ethyl-ethylenediamine, N-methyl-ethylenediamine, benzylamine, triethylamine, ethylene diamine and 1.6-hexanediamine.  Specified metals are scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, yttrium, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, lanthanum, hafnium, tantalum, tungsten, rhenium, osmium, iridium, platinum, actinium and the lanthanide and actinide series of rare earths.  Example V describes the preparation of NiCl2 from diethylamine hydrochloride and nickel powder: and Example IX the preparation of FeCl2 from diethylamine hydrochloride and iron powder. The Specification also refers to the production of FeCl2 by reaction of FeCl3 with Fe powder in ethylene glycol dimethyl ether (Example I); of FeBr2 and CoBr2 by reaction of Br2 with Fe powder and Co powder respectively in ethylene glycol dimethyl ether (Examples III and VIII).  Technetium compounds of formula R2TcXz where R is a substituted or unsubstituted, cyclopentadiene or indene radical, X is halogen and z is 0, 1, 2 or 3 are prepared by reacting technetium under substantially anhydrous conditions with a monomeric alicyclic cyclopentadiene (alkyl- or aryl-substituted if desired), in the presence of piperidine or an organic amine having a log Ka value (as defined in the Specification) of at least 9.  Specified amines are listed above.