Two　isomeric　forms　of　the　octamolybdate　cluster,　(NH4)(2)(HbPY)(2)[Mo8O26](bpy)(3)　1　(bpy　=　bipydine),　and　[Cu-2(imi)(4)](2)[Mo8O26]　2　(imi　=　imidazole),　were　synthesized　by　hydrothermal　method　and　characterized　by　X-ray　single　analysis,　one-dimensional　(113)　infrared　spectroscopy　and　two-dimensional　(2D)　correlation　infrared　spectroscopy　under　thermal　perturbation.　In　compound　1,　the　[Mo8O26]　units　are　beta-structure,　and　octamolybdate　anion　is　zeta-structure　in　compound　2.　The　2D　IR　correlation　spectroscopy　study　indicates　that　the　intensity　changes　of　Mo=0　band　are　more　sensitive　to　the　temperature　variation　than　that　of　the　Mo-O　bond.　The　mu-Mo-O　bond　and　framework　vibrations　in　compound　I1are　more　sensitive　to　the　temperature　variation　than　that　for　compound　2.　As　the　vibrations　of　mu-Mo-O　bond　accompanied　by　the　transfer　of　an　oxygen　atom,　the　catalysis　ability　of　compound　1　may　be　higher　than　that　of　compound　2.　(c)　2006　Elsevier　Inc.　All　rights　reserved.