The compounds germylcyclopentadiene (I), germyl(methyl)cyclopentadiene (II), methylgermylcyclopentadiene (III), bis(cyclopentadienyl)germane (IV), and germylindene (V) have been synthesised through reaction of halogenogermanes with appropriate hydrocarbon anions. Using variable-temperature 1H n.m.r. spectroscopy, it has been found that while compounds (I)–(IV) are fluxional at 35 °C, the onset of similar behaviour for (V) occurs only at 175 °C. For compounds (I) and (II), spin coupling between protons at Ge and on the C5 ring could be resolved (a) below –20 °C. establishing the identity of the species present at the slow-exchange limit in each case, and (b) above 50 °C, providing novel evidence for an intramolecular, metallotropic shift as the mechanism for rearrangement. I.r. and Raman spectra for compounds (I)–(V) have been partly assigned, with ν[Ge–C(ring)] near 370 cm–1; mass spectra show fragmentation patterns indicating extensive transfer of H from Ge to the organo-group. Heating compound (I) results in partial prototropic rearrangement to 2- and 3-germyl isomers; several reactions of (I), including those with HCl and Me3SnH, have been investigated.