Surface study of organopalladium molecules on S‐terminated GaAs

Organopalladium species ({Pd}) immobilized on an Sterminated GaAs substrate (S/GaAs) effectively catalyzes C‐C bond formation in the Mizoroki‐Heck reaction with cycle durability. However, the immobilizing mechanism of {Pd} is unknown. In this study, we deposited Pd(OCOCH 3 ) 2 on S/GaAs in two different methods, namely dry‐physical vapor‐deposition and wetchemical deposition, and compared the catalytic activities in the Mizoroki‐Heck reaction. Also, S‐termination and {Pd}‐immobilization on GaAs grains were performed by the wet‐chemical method to monitor the change in the surface chemical structure during the preparation process with diffuse reflectance Fourier transform infrared spectroscopy (FT‐IR). FT‐IR measurements implied that the immobilization of catalytic active {Pd} was related to the OH groups on the S‐terminated surface. {Pd}‐S/GaAs prepared dryphysically showed poor catalytic activity, because {Pd} was not immobilized under absence of OH groups. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)