Synthesis and crystal structures of silver(I) bridged tetra-phenyl-pyrylium complexes from tetraphenyl-cyclopentadiene

Reactions of silver(I) perchlorate with tetraphenyl-cyclopentadiene (Ph4H2C5) have isolated two novel silver(I) bridged tetraphenyl-pyrylium complexes: [Ag(ClO4)(Ph4HC5O+)](ClO4)− (1) and View the MathML source[Ag(ClO4)(H2O)(Ph4HC5O+)](ClO4-) (2), depending on moisture-content of the reactants. Structure studies using single-crystal X-ray diffraction have showed that complex 1 contains a distorted tetrahedral metal center bridging two neighboring peripheral phenyl rings of one pyrylium cation and two perchlorate anions, whereas 2 involves a three-coordinate metal ion interacting with a pair of phenyl rings and one water molecule, leaving two perchlorate anions free from coordination. For both complexes, the precursor ligand Ph4H2C5 undergoes a ring-enlargement reaction, forming a six-membered pyrylium cation. The fundamentals of the synthesis, structure characterization and some properties are discussed.