Spin uncoupling in ethylene activation by palladium and platinum atoms

Abstract

Spin-dependent effects in complex formation reactions of the ethylene molecule with palladium and platinum atoms were studied by electron correlation calculations with account of spin–orbit coupling. Simple correlation diagrams illustrating spin-uncoupling mechanisms were obtained, showing that the low spin state of the transition-metal atom or the transition-metal atom complex is always more reactive than are the high spin states because of the involvement of the triplet excited molecule in the chemical activation. Spin–orbit coupling calculations of the reaction between a platinum atom and ethylene explain the high-spin Pt(3D) reactivity as due to an effective spin flip at the stage of the weak triplet complex formation. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 72: 581–596, 1999