Attachment and reactivity of tin-cobalt and tin-molybdenumcomplexes in Y zeolites and MCM-41

Novel attachment techniques for bimetallic organometallic species in large-pore zeolites are described. The intrazeolite surface chemistry and thermal stability of Me3SnCo(CO)₄ in NaY and H6Y zeolite (H₄₅Na₁₀Al₅₅Si₁₃₇O₃₈₄) were studied with X-ray absorption spectroscopy (Sn, Co edge EXAFS) and in-situ FTIRKPD-MS techniques. In the NaY host, the complex decomposes at about 160oc by loss of CO ligands and cleavage of the Sn-Co bond. Sn-Co bimetallic cluster species containing only a few atoms appear to form above that temperature. The acidic H6Y host can interact with the Me3Sn moiety of the bimetallic complex. IR and EXAFS data indicate attachment of the complex to the zeolite framework already at room temperature, while the Sn-Co bond seems to remain stable up to at least 90°c. These results are compared and contrasted with the reactions of Me₃SnMo(CO)₃Cp in the new mesoporous host MCM-41. Attachment of the latter complex to the MCM walls is observed, but due to the striking stability of this complex, cluster formation occurs after removal of the CO ligands only at very high temperature.