(Diphenylphosphanyl)tetramethylcyclopentadiene (1) reacts with TlOC2H5 to form Tl (2).In a transmetallation reaction 2 reacts with InCl to yield the corresponding In complex (3).The 1H-, 13C-NMR- and mass spectra as well as the single-crystal X-ray structure analysis of the monomeric 2 are reported and discussed. Key Words: Indium(I) complexes/Thallium(I) complexes/Cyclopentadiene, (diphenylphosphanyl)tetramethyl-