| 摘要 |
<p>A surface is coated with a Group Va metal e.g. V, Ta and Nb, by vaporizing a compound of formula QM(CO)4 wherein Q is a cyclopentadienyl radical of 6-13 C atoms and M is a Group Va metal, and contacting the vapour of said compound with the surface, the surface being maintained above the decomposition temperature of the compound. The surface plated may be of steel, brass, bronze, borosilicate glass, graphite, ceramic, porcelain, plastics, Fe, Cu, Cr, Ni, Be, Mo or Al. Whilst a carrier gas is not essential, H2, CO2,N2 or Ar may be used for flow coating technique. The surface to be plated may be heated to 200-600 DEG C. by resistance heating, I.R. heaters or an induction coil whilst the operating pressure may be 0.001-30 mm. Hg. The surface is preferably prepared by degreasing and sand-blasting. U.V. light or ultrasonic vibrations may also be used to aid thermal decomposition of the compound. In a specific example, a glass cloth is embedded in cyclopentadienyl tantalum tetracarbonyl in a tube devoid of air and heated to 400 DEG C. for 1 hour, to give a coating of Ta. The preparation of the compounds QM(CO)4 is described (see Division C2).ALSO:Cyclopentadienyl Group Va metal tetracarbonyls are made by the reaction of a compound of formula M1ExM(CO)6 with a compound of formula M1Q (where M1 is an alkali or alkaline earth metal including Mg; M is a Group Va metal, e.g. V, Ta and Nb; E is a bidentate or tridentate ether ligand and a is 3 or 2, respectively, and Q is a cyclopentadienyl radical or a hydrocarbon substituted radical having 6 to 13 carbon atoms) in the presence of an oxidizing agent at a temperature of 0 DEG to 150 DEG C. but preferably 25-100 DEG C. Oxidizing agents are listed and include permanganate, dichromate, air, oxygen, ozone and electrolytic oxidation, also numerous salts such as Group Ib and IIb halides, pseudohalides and hypohalites but the preferred oxidizing agent is mercuric chloride. An ether solvent such as diethyl and dibutyl ethers, dioxan, diethyleneglycol dimethyl and diethyl ethers, ethylenglycol dimethyl and diethyl ethers, the preferred solvent being dimethoxyethane. The cyclopentadienyl radicals specified are cyclopentadienyl, alkyl, alkaryl and aryl derivatives thereof, and indenyl and alkyl-indenyl, Na and Mg compounds being preferred. The preferred molar range of the reactants are 1.2: 1.2: 1.0 to 1.5 : 1.5 : 1.0 (metal halide: cyclopentadienyl metal :sodium-ether hexacarbonyl metal). Various pressures from 0.1 to 150 atmospheres may be used and the reaction time may be up to 40 hrs. An inert atmosphere may be used preferably nitrogen. The reactants may be mercuric chloride, cyclopentadienyl sodium and sodium bis-(diethylene glycol dimethyl ether), hexacarbonyl vanadium, tantalum or niobium (-1), or sodium tris-(dimethoxyethane) hexa-carbonyl tantalum (-1) or potassium bis-(di-ethyleneglycol dibutyl ether) hexacarbonyl vanadium (-1). Disclosed as new compounds are (C5H5)Ta(CO)4 and (C5H5)Nb(CO)4.</p> |
