Synthesis,structure and magnetism of a novel Cu_4~ⅡTi_5~Ⅳ heterometallic cluster

A nonanuclear Cu_4~ⅡTi_5~Ⅳ heterometallic cluster,Ti_5 Cu_4 O_6(ba)_(16)](1,Hba=benzoic acid) was synthesized in one-pot reaction under the solvothermal condition.The metallic skeleton 1 contains a Ti_5 core constructed from two vertex-shared Ti_3 triangles and four separated Cu atoms outside which are connected together by μ_3-O~2 ions.Total 16 ba ligands adopt μ_2-η~1:η~1 coordination mode to protect the overall hetero metallic co re.Due to the unique d-d transitions of Cu~Ⅱ ion,the reflectance spectrum of 1 displays broad and strong absorption towards visible light extending to the near-infrared region.Moreover,1 shows almost purely paramagnetic behavior with the presence of weak antiferromagnetic interactions at low temperatures.