Double metal cyanide catalysts for the preparation of polyether polyols

A double metal cyanide (DMC) catalyst comprising:

• a) one or more double metal cyanide compounds of the formula
• M[M′(CN)4]
• wherein
• M is chosen from the metals Zn(II), Fe(II), Ni(II), Mn(II), Co(II), Sn(II), Pb(II), Sr(II), Cu(II), Cd(II), Hg(II), Pd(II), Pt(II), V(II), Mg(II), Ca(II) and Ba(II), and
• M′ is chosen from the metals Zn(II), Fe(II), Ni(II), Mn(II), Co(II), Sn(II), Pb(II), Sr(II), Cu(II), Cd(II), Hg(II), Pd(II), Pt(II), V(II), Mg(II), Ca(II) and Ba(II),
• b) one or more organic complexing ligands selected from the group consisting of alcohols, aldehydes, ketones, ethers, esters, amides, ureas, nitriles and sulfides,
• and optionally
• c) one or more complexing component(s) which differ from b) and are selected from the compound classes of polyethers, polyesters, polycarbonates, polyalkylene glycol sorbitan esters, polyalkylene glycol glycidyl ethers, polyacrylamide, poly(acrylamide-co-acrylic acid), polyacrylic acid, poly(acrylic acid-co-maleic acid), polyacrylonitrile, polyalkyl acrylates, polyalkyl methacrylates, polyvinyl methyl ether, polyvinyl ethyl ether, polyvinyl acetate, polyvinyl alcohol, poly-N-vinylpyrrolidone, poly(N-vinylpyrrolidone-co-acrylic acid), polyvinyl methyl ketone, poly(4-vinylphenol), poly(acrylic acid-co-styrene), oxazoline polymers, polyalkyleneimines, maleic acid and maleic anhydride copolymers, hydroxyethylcellulose, polyacetals, glycidyl ethers, glycosides, carboxylic acid esters of polyhydric alcohols, bile acids or salts, esters or amides thereof, cyclodextrins, phosphorus compounds, α,β-unsaturated carboxylic acid esters and ionic surface- or interface-active compounds.