Discrete Neutral Niobium Cluster Units in Compounds of the Type [Nb₆Cl₁₄<i>L</i>₄] with <i>L</i> = O or N Donor Ligand

Abstract

Six new hexanuclear niobium cluster compounds of the general formula [Nb 6 Cl 14 L 4 ] · 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 [Nb 6 Cl 14 (H 2 O) 4 ] · 4H 2 O 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 [Nb 6 Cl 12 ] 2+ cluster cores are compared and discussed. The phenomenon of the observed M 6 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.