Computational investigation of ethene trimerisation catalysed by cyclopentadienyl chromium complexes

摘要: Abstract Intermediates and transition states of the reaction cycle for trimerisation ethene catalysed by initial catalyst precursor [η 5 -CpCrCl 2 ] have been characterised modeling, starting from species η -CpCrMe . This is a simplified model system actual catalytically active containing bulky cyclopentadienyls. The ground-state multiplicity configuration was determined to be that quartet, in case non-chlorinated Cr(III) species, triplet corresponding chlorinated Cr(IV) analogues. Geometry optimizations were performed on all intermediates, using their multiplicity, relevant located subsequently optimised. effect an additional chlorine ligand chromium centre (viz. form -CpCrClL n ) activation energy barriers also two key high transformations. It found are lowered significantly upon addition centre. rate determining step non-chlorinated, system, calculated as requiring free value 88 kJ mol −1 , with analogue at 56 kJ mol same step. process tetramerisation unfeasible barrier 162 kJ mol associated this transformation.