in ethanol metal:ligand ratio=1:2, reflux for 8 h on steambath with stirring; filtered, washed with ethanol and ether, dried in an evacuated desiccator over CaCl2;

in ethanol metal:ligand ratio=1:2, reflux for 8 h on steambath with stirring; filtered, washed with ethanol and ether, dried in an evacuated desiccator over CaCl2;

in ethanol metal:ligand ratio=1:2, reflux for 8 h on steambath with stirring; filtered, washed with ethanol and ether, dried in an evacuated desiccator over CaCl2;