Abstract The catalytic properties of neodymium tris-phosphates with various diarylphosphate ligands in the stereoregular 1, 4-cis-polymerisation of butadiene and isoprene were studied. The considerable variability of the diaryl phosphate structure allowed for the systematic investigation of the dependence of the catalytic properties of neodymium tris- diarylphosphates on the electronic and steric properties of the ligand. Electron- ...