Trinuclear and polymeric cobalt(II or II/III) complexes with an arylhydrazone of acetoacetanilide and their application in cyanosilylation of aldehydes

Abstract

The new trinuclear [CoII(H2O)2(Me2NCHO)2{CoIII(1κNOO′:2κO″-μ-HL)}2(1κNOO′)]·2H2O (1) and polymeric [CoII(1κNOO′:2κO″-μ-HL)(MeOH)2]n (2) complexes were isolated by the reaction of (Z)-2-(2-(1,3-dioxo-1-(phenylamino)butan-2-ylidene)hydrazinyl)benzoic acid (H3L) with CoCl2·6H2O and Co(ClO4)2·6H2O, respectively, in a mixture of DMF/MeOH (1/10, v/v), in the presence of Et3N at room temperature, and characterized by IR and ESI-MS spectroscopies, elemental and X-ray crystal structural analyses. In both structures the cobalt centres display distorted octahedral geometries. The structural units in 1 and 2 are connected via intermolecular hydrogen bonds involving the coordinated HL2− and the bound and non-bound water molecules (in 1) or the methanol ligands (in 2) which provides supramolecular networks. 1 and 2 are catalyst precursors for the cyanosilylation reaction of a variety of both aromatic and aliphatic aldehydes with trimethylsilyl cyanide leading to the corresponding cyanohydrin trimethylsilyl ethers in high yields (up to 89%) in methanol and at room temperature.