The Mn(II)-2,2′-dipyridylamine-pseudohalide system:: Synthesis, crystal structure and luminescence behaviour of [Mn(dpa)2(X)2]•H2O and [Mn(dpa)2(X)(OH2)]ClO4 (dpa=2,2′-dipyridylamine;: X = N3-NCO-)

Four complexes of the type [Mn(dpa)(2)(X)(2)] (.) H2O (dpa = 2,2'-dipyridylamine; X = N-3(-) 1; X = NCO-, 2) and [Mn(dpa)(2)(X)-(OH2)]ClO4 (X = NCO-, 4) have been synthesized using single-pot reactions of manganese(II) salt, dpa and X in 1:2:2 and 1:2:1 molar ratios, respectively. The compounds have been characterized by microanalytical, physicochemical, spectroscopic and magnetic results. Room temperature magnetic moments (mu(eff)) are in the range 5.88-5.97 BM and are typical of high-spin manganese(II) complexes (t(2g)(5) idealized, S = 5/2). The complexes display a Mn(III)-Mn(II) couple at similar to 0.6 V versus SCE in DMF solutions. X-ray structure determinations show that in 1-4 the manganese(II) centres are in a distorted octahedral environment. Compounds I and 2 contain the MnN6 chromophore, completed by two bidentate dpa units and two terminal azido groups in I or N-coordinated cyanato ligands in 2, along with a water of crystallization. In 3 and 4, one water molecule acts as a coordinating ligand replacing one of the terminal pseudohalides in 1 and 2, respectively, resulting in a MnN5O chromophore. The amine H, terminal azido N or cyanato O, O and H's of the water molecule are engaged in extensive hydrogen bonding of the type N-(HN)-N-..., O-(HN)-N-... and N-(HO)-O-... in 1 and 2. Additionally O-(HO)-O-... bonding is observed in 3 and 4. Supramolecular 2D sheet structures are obtained arising from such weak intermolecular forces. All the complexes display high-energy intraligand (1)(pi-pi*) fluroscence and intraligand (3)(pi-pi) phosphorescence in glassy solutions (DMF at 77 K). (c) 2005 Elsevier Ltd. All rights reserved.