This PhD thesis focuses on diffusion NMR spectroscopy and the utilisation of the external calibration curve (ECC) diffusion-ordered spectroscopy (DOSY) technique on the estimation of molecular weights of organometallic compounds. The thesis is comprised of three parts. In the first part of this work, improvements of the ECC-DOSY methodology are the main focus. In particular, the limited applicability is adressed by introduction of ECCs for seven additional solvents. Furthermore, theoretical calculations on the limitations of the technique and molecule categorization are performed. Additionally, a software for the prediction of molecular weights is introduced. In the second part of this work, alkali metal cyclopentadienides are investigated with the ECC-DOSY technique in THF and DMSO. In THF they form mostly monomeric contact ion pairs, whereas in DMSO foremost solvent-separated ion pairs are observed. In the final part of this thesis, different ambiguities concerning various organometallic compounds were clarified using DOSY, e.g. for alkyl Grignard reagents.
