Decaisopropylstannocene 1 is the first decaisopropylmetallocene, where x-ray diffraction data could be successfully refined and the third example of a group 14 metallocene with a sym. sandwich structure. Due to the directionality of the iso-Pr substituents, 1 occurs as a mixt. of diastereomers in the cryst. state as well as in soln. The stereoisomers exhibit the expected signals in soln. (1H and 13C NMR) and in the crystal (CPMAS 119Sn NMR).