Syntheses and characterizations of polymeric silver iodoplumbates, and iodoplumbates with lanthanide complexes

Abstract

Novel heterometallic Ag–iodoplumbates [Ln(DMSO)8]Pb2Ag2I9 [Ln = La(1), Gd(2), Tm(3)] were prepared by reactions of LnCl3, PbI2, AgNO3 and KI in dimethyl sulfoxide (DMSO). The same reactions without reactant AgNO3 produced new iodoplumbates [Ln(DMSO)8][(DMSO)Pb4I11] [Ln = La(4), Pr(5), Nd(6)]. All Ln3+ ions are solvated with eight DMSO molecules in the reactions, forming [Ln(DMSO)8]3+ complex cations to act as counterions to the iodometallate anions. In compounds 1–3, two AgI4 tetrahedra and two PbI6 octahedra are connected into the 1D heterometallic Ag–Pb iodometallate [Ag2Pb2I9]n3n−via face-sharing. The [Ag2Pb2I9]n3n− anionic chains run parallel along the b axis in 1, and along the a axis in 2 and 3. The [Ln(DMSO)8]3+ cations are located between the chains. In compounds 4–6, two PbI6 and two PbI5O octahedra are interlinked end to end via sharing common faces to generate a 1D [(DMSO)Pb4I11]n3n− chain, which represents a new member of iodoplumbate aggregates. In the [(DMSO)Pb4I11]n3n− chain, the Pb2+ ions are joined not only via μ-I bridges, but also via μ-O bridges. The μ-O oxygen bridging has never been observed in iodoplumbates. Solid state optical absorption spectral analyses show optical band gaps in the range of 2.25–2.88 eV for compounds 1–6. Blue shift of the absorption edge caused by copolymerization of the AgI4 unit occurs on the iodoplumbates.