Study of cloverite molecular sieves modified by grafting organometallic complexes inside the pores -: I.: Synthesis and characterization of cloverite modified by grafting -SnR3 fragments (R = Me, Et, n-Bu, Cy)

The reaction of various alkyltin compounds [HSnBu3 and SnR4, R=Me, Et, cyclohexyl (Cy)] with cloverite dehydroxylated at 450 degrees C was studied by various methods such as H-1, P-31 and Sn-119 MAS NMR, C-13 CP-MAS NMR, infrared spectroscopy, analysis of evolved gases, thermolysis and chemical analysis. All techniques showed that there was a formation of grafted -SnR3 fragments. However, depending on the size of the organometallic fragment, the grafting reaction did not occur in the same manner: while -SnR3 (R=Me, Et, n-Bu) fragments were grafted homogeneously over the entire crystal volume, -SnCy3 fragments were grafted only on the external surface, as previously observed on mordenite. In addition, depending on the size of the R alkyl group, different grafted complex loadings were achieved: for R=Me, up to four -SnMe3 could be grafted per window aperture, while for R=Et and n-Bu, only one complex could be grafted per window aperture. (C) 1998 Elsevier Science B.V. All rights reserved.