Pentakis(methoxycarbonyl)cyclopentadiene chemistry. Part 4. Some silver(I) complexes: crystal and molecular structures of [{Ag[C5(CO2Me)5](OH2)}n]·1.5nH2O, [{Ag[C5(CO2Me)5](PPh3)}2], and [Ag{C5(CO2Me)5}(PPh3)2]

Abstract

A series of silver(I) derivatives of pentakis(methoxycarbonyl)cyclopentadiene has been prepared (from the diene and silver acetate), including [{Ag[C₅(CO₂Me)₅](OH₂)}_n]·1.5_nH₂O, [{Ag[C₅(CO₂Me)₅](PPh₃)}₂], [Ag{C₅(CO₂Me)₅}(PPh₃)₂], [Ag{C₅(CO₂Me)₅}(dppe)][dppe = 1,2-bis(diphenylphosphino)ethane], and [Ag{C₅(CO₂Me)₅}(tppme)][tppme = 1,1,1 -tris(diphenylphosphinomethyl)ethane]. In polar solvents, some of these complexes form conducting solutions. Structural studies by single-crystal X-ray diffraction have given the following results: [{Ag[C₅(CO₂Me)₅](OH₂)}_n]·1.5nH₂O forms a one-dimensional polymer, centrosymmetrically related silver atoms being bridged by a similarly related pair of water molecules [Ag–O 2.450(5), 2.437(5)Å], and also by a C₅(CO₂Me)₅ ligand, alternately bonded through a pair of carboxylate oxygen atoms [Ag–O 2.391 (5), 2.417(6)Å] and an interaction with two of the C₅(CO₂Me)₅ring carbons [2.586(7), 2.807(7)Å]; in [{Ag[C₅(CO₂Me)₅](PPh₃)}₂], the silver atom is essentially four-co-ordinated by a phosphine ligand [Ag–P 2.397(1)Å], a chelating C₅(CO₂Me)₅ ligand [Ag–O 2.415(3), 2.613(3)Å], and an interaction with one of the π bonds in the C₅ring of the C₅(CO₂Me)₅ligand [Ag–C 2.632(4), 2.472(4)Å], the whole species being bridged by C₅(CO₂Me)₅ligands to give a centrosymmetric dimer; [Ag{C₅(CO₂Me)₅}(PPh₃)₂] is monomeric, with silver four-co-ordinated by two phosphine ligands [Ag–P 2.428(2), 2.414(2)Å] and a chelating C₅(CO₂Me)₅ ligand [Ag–O 2.465(4), 2.594(5)Å].