Solvothermal syntheses and crystal structures of one 1D and two 3D [PbxIy]-based coordination polymers

Abstract

Reactions of PbI2 with KI, I2 and 1,2-bis(diphenylphosphino)ethane (dppe) (molar ratio = 1:5:3:4) in MeCN/EtOH under solvothermal conditions afforded a one-dimensional (1D) coordination polymer [(EP)(Pb2I6)]n (EP2 + = ethane-1,2-diylbis(ethyldiphenylphosphonium)) (1) and a three-dimensional (3D) coordination polymer [{(Pb3(μ-I)6)(dppeo)3}·EtOH]n (2) (by-product). Treatment of the same components with H2O2 under similar conditions produced another 3D coordination polymer [{Pb2(μ-I)2(μ3-I)2}(dppeo)]n (dppeo = ethane-1,2-diylbis(diphenylphosphine oxide)) (3). Compound 2 could also be prepared in a medium yield from solvothermal reactions of PbI2 with KI, I2 and dppeo (molar ratio = 1:5:3:4). Compounds 1–3 were characterized by elemental analysis, IR and single crystal X-ray diffraction. Compound 1 contains one 1D anionic [PbI3]nn − chain with EP2 + dications being embedded between chains. The EP2 + dication was in situ generated via the cleavage of CO bond of EtOH followed by alkylation of dppe. Compound 2 consists of trinuclear [Pb3(μ-I)6] fragments that are interlinked via dppeo bridges to form a 3D 6-connected net (a 41263 Schläfli symbol). Compound 3 has a 3D net (with a 66 Schläfli symbol) constructed from 1D [Pb2(μ-I)2(μ3-I)2]n chains linked by dppeo ligands. The dppeo ligand in 3 was formed in situ from the oxidation of dppe by H2O2. The optoelectronic properties of 1–3 were also investigated.