The Missing Link in Low Nuclearity Pure Polyoxovanadate Clusters: Preliminary Synthesis and Structural Analysis of a New {V16} Cluster and Related Products

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 {VIV 15VV 3}. 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) A, β=115.0470(10)°, V=5189.43(7) A3, D c=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) A, β=115.3400(10)°, V=3102.53(14) A3, D c=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).