265ChemInform Abstract In research on the synthesis of Ta3Cl7(Et2PCH2CH2PEt2)3 the shown reaction leads to the isolation of two distinct crystalline forms of the complex (III) (no yield given). They can be distinguished optically and are revealed by X-ray analysis to be diastereomers. The difference between them lies in the conformations of the five-membered Ta-P-C-C-P chelate rings. One form (space group P1, Z=1) is the meso compound with one ring λ and the other δ, the other form (space group Pca21; Z=4) is chiral with both rings in the λ configuration.