Patent GB-988442-A (GB)
Title: Preparation of alkali and alkaline earth metal etherate salts
IPC: C07F9/02
Filed: 1962-01-04
Abstract: Vanadium hexacarbonyl may be prepared from an alkali or alkaline earth metal etherate salt containing the hexacarbonyl vanadate anion by treatment with a substantially nonvolatile non-oxidizing acid, preferably phosphoric acid.  A large excess, generally 10 to 100 times the stoichiometric amount, of the acid is employed at about 25 DEG  C. and preferably in the presence of an inert atmosphere or under vacuum.  The ether present in the vanadium-containing salt should have a vapour pressure less than that of vanadium hexacarbonyl so that the latter may be sublimed off, under reduced pressure, in a highly pure state.  Vanadium hexacarbonyl may also be prepared by the electrolysis of an aqueous solution of said vanadium-containing salt or by oxidation of said salt with an aqueous solution of ammonium and mercuric chlorides. Vanadium hexacarbonyl may be further reacted with nitric oxide in petroleum ether to form nitrosyl vanadium carbonyl.ALSO:The invention comprises (a) a process for preparing alkali and alkaline earth metal etherate salts of vanadium, tantalum and niobium by mixing an alkali or alkaline earth metal in a highly reactive form with a metal salt of vanadium, tantalum or niobium, an ether which is a solvent for the reactants, and carbon monoxide under a pressure of 1000 to 10,000 p.s.i. at 60 DEG  to 150 DEG  C., and (b) alkali and alkaline earth metal salts of the formula [M1(Et)2]+[M(CO)6]-, wherein M1 is an alkali metal or alkaline earth metal equivalent, Et is a non-cyclic tridentate ether and M is vanadium, tantalum or niobium. The novel compounds (b) may be produced by the process of the invention (a).  The order of addition of the reactants in (a) is of importance when using tantalum or niobium salts and, hence, these metal salts should be added to the pressurized reaction vessel containing the reducing metal, ether and carbon monoxide. On the small scale it is convenient to add said salt by placing it in a vial of frangible material within the reaction vessel and braking this with the agitator after the vessel has been pressurized. The reducing metal, which may be employed in a fluidized suspension in an inert liquid, as an amalgam or as freshly prepared metal turnings, is preferably employed in at least a 50% excess over that theoretically required to reduce the Group V metal to a balance state of minus one.  The metal salt reactant is preferably a halide or oxyhalide and the ether, which may be cyclic or straight chain with one or a plurality of oxygen ether linkages, is preferably tridentate.  An excess of 100 to 1000 mols. of ether per gram atom equivalent of the reducing metal is generally employed. Inert gases may be employed to increase the reaction pressure without increasing the quantity of carbon monoxide in the reaction vessel. The etherate salts may be obtained from the liquid reaction mixture by filtering off the insoluble residue and precipitating said salts from the filtrate by addition of a hydrocarbon.  Alkali or alkaline earth metal etherate salts containing the hexacarbonyl vanadate anion may be converted into vanadium hexacarbonyl with a non-oxidizing acid, by electrolysis or by treatment with ammonium and mercuric chlorides (see Division C1).  Tetraalkyl ammonium hexacarbonyl vanadate, tantalate and niobate may be prepared by reacting the etherate salts with a tetraalkyl ammonium compound.  Tropenium vanadium tricarbonyl compounds may be prepared by reacting vanadium hexacarbonyl with cycloheptatriene or substituted cycloheptatriene.  Bis (arsine, phosphine or stibine) vanadium tetracarbonyl compounds may be prepared by reacting vanadium hexacarbonyl with trihydrocarbon, e.g. triphenyl, compounds of arsine, phosphine or stibine.  The triphenyl arsine, phosphine or stibine derivatives may be reacted further to form triphenyl (arsine, phosphine or stibine)-nitric oxide vanadium tetracarbonyl with nitric oxide and triphenyl (arsine, phosphine or stibine) pentacarbonyl vanadium (-1) anion on treatment with a reductant, e.g. sodium analgan.ALSO:A surface may be plated with a vanadium-, tantalum- or niobium-containing coating by the decomposition of a tetraalkylammonium salt of a vanadium, tantalum or niobium hexacarbonyl anion at said surface.  The plating may be accomplished by bringing a heated object, whose temperature is above the decomposition temperature of the tetraalkylammonium salt, into contact with said salt or by coating the surface of the object with said salt and heating said object to above the decomposition temperature.  A surface may also be plated with a vanadium containing coating by placing the object to be plated in a closed container with vanadium hexacarbonyl at about 400  DEG C., preferably in the presence of an inert gas.  In Example IV a glass cloth is coated with a tantalum-containing coating by the thermal decomposition of a coating of tetramethylammonium hexacarbonyl tantalate in the absence of air.