Infrared Spectroscopic Studies of Mono-, Di-, and Trihydrido C−H Insertion Complexes Formed in Reaction of Ethylene with Laser-Ablated Hafnium Atoms and Isolated in a Solid Argon Matrix

Abstract

The C−H insertion reaction of laser-ablated Hf atoms with ethylene in excess argon has been carried out during codeposition at 7 K, and the reaction products have been investigated by means of infrared spectroscopy. Parallel to the case of Zr, mono-, di-, and trihydrido C−H insertion complexes are identified. Among them, the mono- and dihydrido C−H insertion complexes are reaction intermediates of hydrogen elimination from ethylene by second-row transition-metal atoms presumed in previous reaction dynamics studies. The higher Hf−H stretching frequencies and shorter Hf−H and C−Hf bond lengths of the hafnium C−H insertion products than those of the zirconium products are attributed to the shortened bonds of the heavier metal atom by relativistic effects.