Abstract. Lewis bases like bis (dimethy1amide) phosphoryl compounds (2, 5-7), N- heterocycles (8 and 9) and N, N-dial-kylamino-3-propylsilanes bearing alkoxy groups are grafted via siloxane bonds onto silica carriers. The preparation and characterisation of 5-9 are reported. The grafted bis (dimethy1-amide) phosphoryl compounds (2, 5-7) and N- heterocycles (8, 9) are efficient catalysts for the disproportionation of ...