Self-Assembly of Cluster-Based Nanoscopic Supramolecules into One-Dimensional Coordination Polymers

Octahedral metal clusters [Nb6Cl12(CN)(6)](4-), (Mn(Salen))(+) (or (Mn(7-MeSalen))(+)) (Salen = N, N'-ethylene-bis-(salicylidene)iminate) and ditopic organic linkers (4, 4'-bpe (trans-1, 2-bis(4-pyridyl)-ethylene) or 4, 4'-dpyo (4, 4'-dipyridyl N, N'-dioxide)) self-assemble to form three cluster-based 1D coordination polymers: [Mn(Salen)(MeOH)(2)](2){(4, 4'-dpyo) [(Mn(Salen))(2)(Nb6Cl12(CN)(6))]} center dot 2MeOH (1), {(4, 4'-bpe)[(Mn(7-MeSalen))(2)(Mn(7-MeSalen)(H2O))(2)(Nb6Cl12(CN)(6))]} center dot 1.5MeCN center dot 8H(2)O (2), and [(4, 4'-bpe)(Mn(Salen)(H2O)(2)]{(4, 4'-bpe)(2)[(Mn(Salen)(MeOH))(2)(Mn(Salen))(2)(Nb6Cl12(CN)(6))] [(Mn(Salen))(2)(Nb6Cl12(CN)(6))]} center dot 16H(2)O (3). Single crystal X-ray diffraction analyses show that the frameworks of the three coordination polymers are built of heterotrimeric and/or heteropentameric supramolecular species linked by ditopic organic ligands. The framework of 1 consists of anionic chains built of heterotrimeric dianions [(Mn(Salen))(2)(Nb6Cl12(CN)(6))](2-) (T) linked by 4, 4'-dpyo. The chains run along two directions ([0 2 -2] and [0 3 3]) leading to the formation of channels along the crystallographic (a) direction where the cations [Mn(Salen)(S)(2)](+) and solvent molecules are located. Also, 2 was reported earlier, it possesses a neutral 1D chain built of neutral heterpentameric supramolecules: [(Mn(7-MeSalen))(2)(Mn(7-MeSalen)(S))(2)(Nb6Cl12(CN)(6))] (P) linked by 4, 4'-bpe ligands. Hydrogen bonds between non-bridging cyanide ligands and coordinated solvent molecules connect the chains into 2D hydrogen-bonded frameworks. Finally, 3 features an anionic chain, built of alternating heterotrimers [(Mn(Salen))(2)(Nb6Cl12(CN)(6))](2-) and heteropentamers [(Mn(Salen)(S))(2)(Mn(Salen))(2)(Nb6Cl12(CN)(6))] linked by the organic spacer 4, 4'-bpe. The anionic charge is compensated by the in situe-assembled [Mn(Salen)(S)(4, 4'-bpe)Mn(Salen)(S)](2+) dimers. Magnetic measurements reveal that the Mn(III) ions are well isolated and only weak magnetic interactions are observed. The thermal stability of the three compounds was investigated. Copyright (C) 2009 Jian-Jun Zhang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.