Syntheses,Structures And Properties Of New Type Polyoxoniobates

In this paper,seven novel polyoxoniobates?PONbs?were isolated through the reactions of hexaniobates K7HNb₆O₁₉·13H₂O,nitrogen-containing organic ligands and transition metals.The compounds were characterized by single-crystal X-ray diffraction,spectroscopy,mass spectrometry,magnetic study,and thermogravimetric analyses.1.A novel trinuclear nickel-containing PONb,Na8[Ni?Nien?₂Nb10O32]·28H₂O?1?,has been synthesized using the hydrothermal method.The {Ni[Ni?en?]₂Nb10O32} cluster is constructed by a{Ni[Ni?en?]₂} cluster sandwiched into the novel {Nb10O32} fragment and extends into a one-dimensional?1D?chain by high-nuclear sodium clusters.And the catalytic epoxidation of allylic alcohols has also been preliminary studied.Furthermore,magnetic measurements showed that the compound exhibits ferromagnetic interactions.2.A novel copper-containing polyoxoniobate Na,7K5H4[As₄Cu₁₆Nb28O109]·49.5H₂O?2?has been synthesized.The polyanion consists of one {As₄Cu₁₆} and four[Nb72O22]9-subunits.The {As₄Cu₁₆} subunit is composed of four {AsCu4} clusters,and further contect together by a ?4-O atom.Four[Nb2O22]9-anions are linked to the {As₄Cu₁₆} clusters via Cu-O-Nb bonds to form the polyanion.Magnetic measurements showed that compound 2 exhibits antiferromagnetic interactions.3.Two novel niobictellurate aggregates Cs3K[Cu?1,10-phen?]8[H₂Te6Nb24O83]·25H₂O?3?and{Cu?2,2'-bipy?}8[H6Te6Nb24O83]·28H₂O?4?have been successfully obtained by the conventional method?2,2'-bipy = 2,2'-bipydine,phen = 1,10-phenanthroline?.The polyoxoanion,[Te6Nb24O83]₂2-,consists of one[TeNb7023]8-?A?,[Nb?Te02?₃O6]7-?B?and[TeNb9O33]17-?C?clusters.Two A clusters contect together via one B subunit to form the {Te6Nb15} subunit and {Te6Nb15} subunit via Te-O and Nb-O bonds contects with C unit to form the polyanion.4.A novel niobictellurate aggregate[Cu?en?₂]6[H4Te8Nb18O69]·40H₂O?5?has been successfully obtained.The polyoxoanion[Te8Nb18O69]16-can be regarded as two[Te4Nb9O38]15-subunits connected together via three oxygen atoms.[Te4Nb9O36]11-is described as a trivacant lacunary Keggin type {TeNb9}which is connected to three Te atoms by oxygen atoms.5.A new polyoxoniobate[Ni?en?₃]3[Ni?en?₂?H₂O?₂]₂H[VNb₁₂O₄₀?VO?₂]·9H₂O?6?has been synthesized by the hydrothermal method.[VNb₁₂O₄₀?VO?₂]11-polyanion can be regarded as a decorated Keggin cluster with one vanadium atom as the heteroatom center and two vanadium atoms capping two opposite pits.6.A new polyoxoniobate[K?H₂O?]4[Cu?en?₂?H₂O?₂]₂[Cu?en?₂?H₂O?]11 {H6[SiNb18O54]₂[Nb₆O₁₉]}·36H₂O?7?has been synthesized by the hydrothermal method which contains two kinds of polyoxoanions...