In this work new cluster compounds of the metal niobium with hexanuclear metal units were investigated.
In the first part, four new neutral cluster compounds of the general formula [Nb6Cli12Cla2(L)a4}] with L = dicyclohexylurea, pyridine, 1-methyl-imidazole, isobutylamine were synthesized, their crystal structures elucidated and physically, chemically characterized.
In the second part of this work, a new type of reaction and a first member of a new Nb6-cluster compound type were presented. By reaction of the compound [Nb6I11], in which the octahedron surfaces are ligand-bridged (6-8-type), a compound with edge-bridged metal atom octahedra (6-12-type) was used for the first time with NH2-(CH2)2-OH) in which intramolecular chelating ligands are present [Nb6(OCH2CH2NH2)i-a6(OCH2CH2NH2)i6]3+ 3[I]-. Within the hexanuclear cluster compounds of Group III-B, IV-B, and V-B metals, this is the first member of this class of compounds.
In the third part cluster compounds of the formula [A]4[Nb6Cli12(L)a6] with A = tetramethylguanidinium, tripropylammonium, pyridinium, 1-methyl-imidazolium and L = trifluoroacetate, pentafluoropropionate and heptafluorobutyrate were synthesized. Thus, 10 new cluster compounds were prepared and characterized structurally and spectroscopically. All contain perfluorinated carboxylates as ligands. The goal was to produce cluster compounds with weak intermolecular interactions and thus low melting points,to produce s. c. "cluster ionic liquids".
The starting compounds for these syntheses were in addition to [Nb6Cl14(H2O)4]. 4H2O, ionic liquids consisting of the perfluorinated carboxylate anions and the respective protonated N-based cations. From this class of compounds, 14 new representatives were prepared, characterized and their crystal structure elucidated.