Interaction between zeolites and cluster compounds. Part 1.—Adsorption of iron pentacarbonyl on zeolites

Abstract

The adsorption isotherms of Fe(CO)₅ on NaY, HY and Linde L zeolites obtained in McBain balances show micropore adsorption, whereas additional capillary condensation is found with zeolite omega and Na-mordenite. The pores and/or cages of the zeolites studied are completely filled with the complex upon saturation, with the exception of Na-mordenite. Their behaviour is explained, respectively, by pore blocking and the occurrence of channel openings that are too narrow. The silicalite channel system also is too narrow to accept Fe(CO)₅ molecules.

Infrared results show that an increasing interaction of the complex with faujasites exists in the sequence: dealuminated Y < CsY < HY < NaY. This is derived from the increasing band half-width of the adsorbed complex in the CO stretching region and from the increasing intensity of the v₁ vibration, which upon adsorption becomes i.r. active. The interaction is assumed to be influenced mainly by electrostatic fields in the cages or pores, which can lead to a very restricted mobility for the encaged complex. The complex seems to remain intact upon adsorption at 293 K in all the zeolites studied.