Acid Anion - The Synthesis Of Transition Metal Cations To Form The Functional Compounds, Crystal Structure And Nature Of The Study

Combining with molecular design and self-assembly, seven crystals of polyoxometalates were prepared by means of hydrothermal techniques and conventional methods on the basis of organic amine molecules, carboxyl acids and polyoxometalate anions. They were determined structurally by X-ray single crystal diffraction and characterized by elemental analysis, IR, TG-DTA, XRD and CV.1. Three new polyoxometalate crystals, {[Co(dpaH)₂]₂V₄O₁₂}·H₂O (1), {[Ni(dpaH)₂]₂V₄O₁₂}·H₂O (2) and [Cu(dpaH)]V₂O₆·H₂O (3) were synthesized. The former two are the discrete structure and the latter is the two-dimension structure. The crystals (1) and (2) are chair-like configurations. Every M metal ion (M = Co Ni) is coordinated by two dpaH ligands and two bridging-oxygen atoms from [V₄O₁₂]^4- unit. The crystal (3) consists of a two-dimensional bimetallic oxide of {Cu₂V₄O₁₂ }, which is formed by one-dimension [Cu₂V₃O₈] chains through VO₄.2. Two new discreate structure polyoxometalate compounds of [Co₄O₄(dpaH)₄(CH₃COO)₂]₂V₄O₁₂·5H₂O (4) and [Co(phen)₃]₂·V₄O₁₂₁6.5H₂O-C₈H₆O₄ (5) were synthesized. The crystal (4) consists of two [Co₄O₄(dpaH)₄(CH₃COO)₂]²⁺ moieties and an isolated molecular unit [V₄O₁₂]^4-, with a cyclic eight-membered {V₄O₄} core. The crystal is the first Co₄O₄ cubane synthesized by hydrothermal techniques. The Co(phen)₃²⁺ cation and [V₄O₁₂]^4- anion are stably connected by electrostatic interaction, and C₈H₆O₄ molecules exist in crystal (5) dissociatively.3. Two microporous crystals of the saturated Wells-Dawson K₄[Cr₃O(H₂O)₃(OOCH)₆][P₂W₁₈O₆₂]·9.5H₂O (6) and cobalt atom monosubstituted Wells-Dawson K₄[Cr₃O(H₂O)₃(OOCH)₆][H₃P₂W₁₇Co(H₂O)O₆₁]·14H₂O (7) were synthesized. It is found that the polyoxometalate anions maintain the Wells-Dawson structure for crystal 6 and the substituted Wells-Dawson structure for crystal 7. The crystal 6 can reversibly desorb and absorb water molecules and its crystal structure can...