Five-membered saturated metallacarbocycles represent a large family of organometallic compounds, which are frequently postulated as reactive intermediates in catalysis or as precursors for the synthesis of a wide range of functionally substituted compounds, therefore, their NMR spectral data are incomplete and not systematized. Metallacarbocycles for Main III Group metals, which are spectroscopically characterized, are described in this article. Among these, of particular interest are 1-ethyl-3-substituted alumolanes, 3-spiro-substituted polycyclic alumolanes and nonbornen annelated alumolanes, which are supposed to be formed in alkene cycloalumination with AlEt₃ catalyzed by Cp₂ZrCl₂. Conformational analysis upon inversion of a five-membered ring for mono and polycyclic alumolanes is presented.