Discrete neutral niobium cluster units in compounds of the type [Nb₆Cl₁₄L₄] with L = O or N donor ligand

Six new hexanuclear niobium cluster compounds of the general formula [Nb₆Cl₁₄L₄].x(solvent molecule) [L = neutral O or N donor ligand, x = 0-2.5; pyrimidine (1), 1-methyl imidazole (2), isobutyronitrile (3), isopropyl alcohol (4), triphenylphosphine oxide (5), dimethyl sulfoxide (6)] were prepared. The syntheses were carried out by dehydration of the precursor [Nb₆Cl₁₄(H₂O)₄].4H₂O with different water scavangers, like acetic anhydride, trimethyl acetic anhydride and diethylcarbonate in the presence of the corresponding neutral ligand. The structures are determined by single-crystal X-ray diffraction. The specific bonding situations of the ligands to the [Nb₆Cl₁₂]²⁺ cluster cores are compared and discussed. The phenomenon of the observed M₆ distortion is explained and interpreted based on the matrix effect and the terminal ligand effect. In addition, other interactions between the cluster units, such as hydrogen bonding and π-π stacking are discussed. (copyright 2019 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)