Supramolecular Assemblies Built of [Nb₆Cl₁₂(CN)₆]^4- Octahedral Metal Clusters and [Mn(acacen)]⁺ Complexes

Reactions between solutions of [Me₄N]₄[Nb₆Cl₁₂(CN)₆]·2MeOH and [Mn(L)]Cl (L = acacen^2- = bis(acetylacetonato)ethylenediamine at room temperature led to the formation of four compounds containing supramolecular assemblies formed of [Nb₆Cl₁₂(CN)₆]^4- and [Mn(L)]⁺ as building units. The four compounds were characterized by single-crystal X-ray diffraction, IR, elemental analysis, thermogravimetric analysis, and magnetic susceptibility measurements (for 3). In 1, each cluster is coordinated by one [Mn(L)(MeOH)]⁺ via a CN^- ligand to give an anionic dimeric unit {[Mn(L)(MeOH)][Nb₆Cl₁₂(CN)₆]}^3-, which connect to each other via hydrogen bonding between the CN^- ligand and MeOH from the cations [Mn(L)(MeOH)₂]⁺ to give anionic tubular-like chains. The structure of 2 comprises trimeric units {[Mn(L)(H₂O)]₂[Nb₆Cl₁₂(CN)₆]}^2- in which each cluster is trans-coordinated by two [Mn(L)(H₂O)]⁺ cations via the CN^- ligand. The trimeric units are connected to each other via hydrogen bonding between CN^- and the water of coordination to give anionic chains along the crystallographic a axis. The chains are connected to each other through further hydrogen bonding to give an overall three-dimensional hydrogen-bonded framework. In 3, each cluster is coordinated by two [Mn(L)(MeCN)]⁺ and two [Mn(L)(H₂O)]⁺ via CN^- ligand to give neutral pentameric units that are connected through hydrogen bonding between CN^- and aqua ligands to give hydrogen-bonded chains along the crystallographic b axis. 4 is based on two supramolecular ions; the cation consists of a heptameric unit {[Mn(L)(H₂O)]₄[Mn(L)]₂[Nb₆Cl₁₂(CN)₆]}²⁺ in which each cluster is coordinated by six [Mn(L)]⁺ via CN^- ligand, whereas the anion {[Mn(L)]₂[Nb₆Cl₁₂(CN)₆]}^2- is the same as that found in 2. Electrostatic interactions and hydrogen bonding between these two supramolecular species afford a 1D framework. Magnetic susceptibility shows that 3 is paramagnetic with four high-spin Mn(III) ions. Thermal behaviors of 1−4 are presented.