The missing link in low nuclearity pure polyoxovanadate clusters: preliminary synthesis and structural analysis of a new {V₁₆} cluster and related products: dedicated to professor Achim Müller

Two new metastable polyoxovanadate-based cluster compounds have been isolated and crystallographically characterized with nuclearities of {V<SUB>16</SUB>} (<B>1</B>) and {V<SUB>18</SUB>} (<B>2</B>). The {V<SUB>16</SUB>} cluster represents a new framework type and incorporates two protons into the cluster framework whereas the {V<SUB>18</SUB>} framework has been previously characterised, and the oxidation states of the {V<SUB>18</SUB>} cluster can be assigned as {V<SUP>IV</SUP><SUB>15</SUB>V<SUP>V</SUP><SUB>3</SUB>}. Compound K<SUB>10</SUB>[H<SUB>2</SUB>V<SUB>16</SUB>O<SUB>38</SUB>]·13H<SUB>2</SUB>O (<B>1</B>) crystallizes in the monoclinic space group <I>P</I>2<SUB>1</SUB>/c, <I>a</I>=12.12820(10), <I>b</I>=38.2302(3), <I>c</I>=12.35400(10) Å, <I><I>β</I></I>=115.0470(10)°, <I>V</I>=5189.43(7) Å<SUP>3</SUP>, <I>D</I><SUB>c</SUB>=2.624 gβ. 10086 unique reflection and 702 refined parameters were used in structure refinement. <I>R</I>1=0.039, <I>R</I>2=0.109 (all data). From the same preparation the new compound K<SUB>11</SUB>[V<SUB>18</SUB>O<SUB>42</SUB>(SO<SUB>4</SUB>)]·20H<SUB>2</SUB>O (<B>2</B>) was also isolated and crystallographically characterized. Compound <B>2</B> crystallizes in the monoclinic space group <I>P</I>2<SUB>1</SUB>/<I>n</I>, <I>a</I>=12.7854(3), <I>b</I>=20.2812(5), <I>c</I>=13.2386(4) Å, <I>β</I>=115.3400(10)°, <I>V</I>=3102.53(14) Å<SUP>3</SUP>, <I>D</I><SUB>c</SUB>=2.650 g·cm<SUP>-3</SUP>. 7115 unique reflections and 462 refined parameters were used in structure refinement. <I>R</I>1=0.046, <I>R</I>2=0.121 (all data)