Structural Diversity in 2,2′-[Naphthalene-1,8:4,5-bis(dicarboximide)-N,N'-diyl]-bis(ethylammonium) Iodoplumbates

Abstract

Crystallization from solutions containing 2,2'-[naphthalene-1,8:4,5-bis(dicarboximide)-N,N'-diyl]-bis(ethylammonium) diiodide ((NDIC2)I-2) and PbI2 has been investigated. Eight different materials are obtained, either by variation of crystallization conditions or by subsequent thermal or solvent-induced transformations. Crystal structures have been determined for five materials. [(NDIC2)(2)Pb5I14(DMF)(2)]center dot 4DMF (DMF = N,N-dimethylformamide) (1), [(NDIC2)Pb4I10]center dot 4DMF (3), [(NDIC2)Pb2I6]center dot 4NMP (NMP = N-methyl-2-pyrrolidone) (4), and [(NDIC2)Pb2I6]center dot 2H(2)O (5) form 1-dimensional (1D) chains consisting of PbI6 (and, in the case of 1, PbI5(DMF)) octahedra, either solely face-sharing or a mixture of face-sharing and vertex-sharing. The structure of [(NDIC2)(3)Pb5I16]center dot 6NMP (2) contains 0D clusters; these consist of three PbI6 octahedra and two unusually coordinated lead centers that exhibit three relatively short Pb-I bonds, two very long Pb-I contacts, and eta(2)-coordination of an aromatic ring of NDIC2 to the lead. Close contacts between iodide ions and the imide rings of NDIC2 in four of the structures suggest that an iodide-to-NDIC2 charge-transfer interaction may be responsible for the observed red coloration of the materials. The optical and electrical properties of 1 have been studied; its onset of absorption is at 2.0 eV, and its conductivity was measured as 5.4 x 10(-5 )+/- 1.1 x 10(-5 )S m(-1).