Syntheses and properties of 2-D and 3-D Pb–Ag heterometallic iodides decorated with ethylene polyamines at the Pb(<scp>ii</scp>) center

Abstract

Hybrid organic-inorganic Pb-Ag heterometallic iodides [(en)2(PbAgI3)]2n·nH2O (1), [(pda)2(PbAgI3)]n (2), [(tmeda)(PbAgI3)]n (3), [(trien)(PbAgI3)]n (4), [(tepa)(PbAg2I4)]n (5), and [{(dien)3(CO3)}2(Pb6Ag8I15)]nIn (6) were prepared by the reactions of PbI2, AgI (or Ag2CO3) and KI with different polyamines in N,N'-dimethylformamide (DMF) solution. In 1-4, two AgI4 tetrahedra share a common edge to form the bimeric Ag2I6 unit. It coordinates to the Pb(II) ion of [PbL2](2+) or [PbL'](2+) (L = en, pda; L' = tmeda, trien) via iodine atoms to form hybrid organic-inorganic heterometallic iodides 1, 2, 3 and 4, respectively. Compounds 1, 3, 4 and contain 2-D layered backbones of [PbAgI3]n, whereas 2 contains a backbone of [PbAgI3]n with a 3-D structure. Steric hindrance and denticity of the ethylene polyamines influence the coordination modes and connection strength between the iodoargentate aggregates and Pb(II) ions. In 5 the AgI4 units are joined via sharing common edges to form a 1-D polymeric [Ag2I4]n(2n-) anion. It is connected with [Pb(tepa)](2+)via iodine atoms to form a 3-D network of [(tepa)(PbAg2I4)]n. In 6, the CO3(2-) ion binds three [Pb(dien)](2+) units to form the novel trinuclear [{Pb(dien)}3(μ3-CO3)](4+) complex ion. Eight AgI4 tetrahedra are connected via sharing common edges to give a novel Ag8I15 cluster with C3 symmetry. The Ag8I15 cluster and the [{Pb(dien)}3(CO3)](4+) unit are connected to form a novel layered heterometallic iodometallate cation [{(dien)3(CO3)}2(Pb6Ag8I15)]n(n+)via sharing iodine atoms. Compounds 1-6 represent a new type of hybrid organic-inorganic heterometallic iodide containing coordinative organic components. Optical absorption spectra show a blue shift of the absorption edges for 1-6 compared with those of the bulk PbI2 and AgI solids.