Metal-organic supramolecular assemblies generated from bismuth(III) bromide and polyimine ligands

Three new BiBr3 supramolecular complexes, [Bi-2(3-bpdb)(2)Br-8]center dot(3-H(2)bpdb) (1), [Bi-2(3-Hbpdh)(2)Br-8](2) and [Bi-2(4-bpdh)Br-9]center dot 3(4-Hbpdh) (3) {3-bpdb = 1,4-bis(3-pyridyl)-2,3-diaza-1,3-butadiene, 3-bpdh = 2,5-bis(3-pyridyl)-3,4-diaza-2,4-hexadiene and 4-bpdh = 2,5-bis(4-pyridyl)-3,4-diaza-2,4-hexadiene} were prepared by the reaction of bismuth(III) bromide with three organic nitrogen donor based ligands under thermal gradient conditions using the branched tube method. All three compounds were structurally characterized by single-crystal X-ray diffraction. In complex 1 the bismuth atoms are coordinated by one pyridyl nitrogen atom of the 3-bpdb ligand and are bridged by two bromide atoms to produce a dimeric complex. Compound 2 consists of dimeric units and the bismuth atoms are linked by one nitrogen atom of the 3-Hbpdh ligand and by five bromide atoms, and can be considered to be six-coordinate with a Br5N array of donor atoms. The single-crystal X-ray data of compounds I and 3 show that the compounds contain two anionic and cationic 1D chains, [3-H(2)bpdb](2+)[Bi-2(3-bpdb)(2)Br-8](2-) and 3[4-Hbpdh](+)[Bi-2(4-bpdh)Br-9](3-). In all three compounds extensive hydrogen-bonding interactions produce supramolecular networks. The thermal stabilities of compounds 1-3 were studied by thermal gravimetric (TG) and differential thermal analyses (DTA). (C) 2009 Elsevier Ltd. All rights reserved.