Synthesis, crystal structure and properties of a pentanuclear carboxylato-bridged complex containing a Cu3Y2 core

Preparation and isolation of a pentanuclear mixed metal complex having the formula [Cu3Y2(Cl-CH2COO)(12)(H2O)(8)]. 2H(2)O was accomplished by the reac tion of a mixture of copper(II) nitrate and yttrium nitrate with sodium chl oroacetate in aqueous solution. The structure of the complex was determined by X-ray crystallography. It consists of linear centrosymmetric pentanucle ar molecules with a four-coordinate copper atom at the inversion site and t he other two copper atoms having a 4 + 1 coordination geometry at both ends . Two yttrium atoms separate the three copper atoms. Each yttrium atom is b ridged to the neighbouring terminal copper atom by four carboxylato ligands in a syn-syn fashion forming a dimer with the Y ... Cu distance being 3.53 11(8)Angstrom. Each dimer is then linked to the central copper atom via a c arboxylato bridging ligand in a syn-anti fashion. Two other carboxylato lig ands coordinate to the central copper to complete its planar coordination. The apical site of each terminal copper atom is occupied by a water molecul e. The eight-coordinate geometry of each yttrium atom is completed by three water molecules. Bridging and the monodentate carboxylato ligands were cha racterized by IR analysis. TG studies confirmed the numbers of coordinated and lattice water molecules.