Two new polyoxovanadate clusters templated through cysteamine

Abstract

Two new fully oxidized polyoxovanadate cluster-based solids (C 4 N 2 S 2 H 14) 2 [H 2 V 10 O 28 ]⋅4H 2 O, 1 and (C 4 N 2 S 2 H 14) 5 [H 4 V 15 O 42 ] 2 ⋅10H 2 O, 2 are crystallized under self-assembly process in the presence of cysteamine. In both 1 and 2, cysteamines are oxidized forming disulphide linkages and occur as counter cations. The organic cations assemble around V 10 O 28 cluster anions in 1 whereas they aggregate around V 15 O 42 clusters in 2. pH appears to be the structure determinant in the occurrence of decavanadate cluster in 1 and pentadecavanadate in 2, with the same counter cation.

A New Dicationic Ring [(Water)6–(Ammonium)2] Acts as a Building Block for a Supramolecular 3D Assembly of Decavanadate Clusters and 4-(N,N-dimethylamino)pyridinium Ions

“…The total weight loss for the compound was 40.5 %, which is in good agreement with the calculated value (40.26 %). The profiles of the thermal decomposition obtained for this compound is comparable with that reported for other decavanadate molecules containing organic cations and carried out in similar conditions [47,48].…”

Formation of high nuclearity mixed-valent polyoxovanadates in the presence of copper amine complexes

“…We intentionally did not employ any vanadium metal or lower valent vanadium precursors in our reactions. On the basis of the present work and past experience, 5,6,[25][26][27] we infer that in many cases pH and concentration of lower-valent vanadium are the primary factors responsible for the occurrence of a particular POV cluster-based solid; in many cases the organic cations occur as spectator counter-cations. Hydrothermal conditions assist the reduction of vanadates by organic amines to the lower-valent state.…”

“…Another interesting observation that emerges out of this work is that whenever crystallisation is carried out under slow evaporation conditions, bi-capped Keggin clusters are favoured if the solution does not contain sufficient concentration of lower-valent vanadium. 5,13,25 Formation of V 15 and V 18 under our reaction conditions was due to the reduction of vanadium species by the organic amines such as en and pn under hydrothermal condition. We intentionally did not employ any vanadium metal or lower valent vanadium precursors in our reactions.…”

Cystamindi-ium tetrachlorocuprate [NH3(CH2)2SS(CH2)2NH3][CuCl4]: synthesis, crystal structure, and thermal decomposition

“…The lack of coordination between the metal and sulfur atoms was detected on the example of CystaH 2 [HgCl 4 ] and described in detail in (Bharara et al , 2005b). Saving S–S bonding was observed with the coordination centers as Pb, Bi, and V atoms (Pavani et al , 2006; Bi et al , 2007; Louvain et al , 2007). The coordination sphere around the central atoms in such compounds is formed by oxygen or halogen atoms.…”

“…The CystaH 2 [HgCl 4 ] was obtained under neutral conditions in a nitrogen stream (Bharara et al , 2005a). There are other ionic compounds containing cystamindi-ium cation, for example, with bismuth CystaH 2 [Bi I 5 ], (CystaH 2 ) 2 I 3 [Bi I 6 ] (Bi et al , 2007, 2008) and with vanadium (CystaH 2 ) 2 H 2 [V 10 O 28 ] * 4H 2 O, (CystaH 2 ) 5 H 4 [V 15 O 42 ] 2 * 10H 2 O (Pavani et al , 2006). As a rule, cystamindi-ium cations occupy crystalline space by individual particles linking with an anionic part by the Coulomb forces and hydrogen bonds.…”