| Abstrakt: |
Two new metastable polyoxovanadate-based cluster compounds have been isolated and crystallographically characterized with nuclearities of {V16} (1) and {V18} (2). The {V16} cluster represents a new framework type and incorporates two protons into the cluster framework whereas the {V18} framework has been previously characterised, and the oxidation states of the {V18} cluster can be assigned as {V15IVV3V}. Compound K10[H2V16O38]' ·13H2O (1) crystallizes in the monoclinic space group P21/c, a = 12.12820(10), b=38.2302(3), c = 12.35400(10) Å, β= 115.0470(10)°, V=5189.43(7) ų, Dc=2.624 g·cm-3. 10086 unique reflection and 702 refined parameters were used in structure refinement. R1=0.039, R2=0.109 (all data). From the same preparation the new compound K11[V18O42(SO4)]·20H2O (2) was also isolated and crystallographically characterized. Compound 2 crystallizes in the monoclinic space group P21/n, a= 12.7854(3), b=20.2812(5), c= 13.2386(4) Å, β=115.3400(10)°, V=3102.53(14) Å3, Dc = 2.650 g·cm-3. 7115 unique reflections and 462 refined parameters were used in structure refinement. R1 = 0.046, R2 = 0.121 (all data). KEY WORDS: Vanadium; vanadate; polyoxovanadate; polyoxometalate; x-ray crystal structure; mixed valence; cluster structure. [ABSTRACT FROM AUTHOR] |
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