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

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journal contribution
posted on 2006-10-04, 00:00 authored by Huajun Zhou, Abdessadek Lachgar
Reactions between solutions of [Me4N]4[Nb6Cl12(CN)6]·2MeOH and [Mn(L)]Cl (L = acacen2- = 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 14 are presented.