Supported organometallic complexes. Part XX. Hydroformylation of olefins with rhodium(I) hybrid catalysts

The rhodium(I) complexes HRh(CO)[Ph2P(CH2)(x)Si(OMe)(3)](3), [1a,b(T-0),; a : x = 3, b: x = 6; T: T-type silicon atom, three oxygen neighbors] were sol -gel processed with the bifunctional cocondensation agent (MeO)(3)Si(CH2),S i(OMe)(3) (T-C-6-T) and in a separate reaction also with three additional e quivalents of the phosphine ligand Ph2P(CH2)(x)Si(OMe)(3) [2a,b(T-0)]. The resulting stationary phases 1a(T-n)(3)(T-n-C-6-T-n)(y), 1a(T-n),[2a(T-n)](3 )(T-n-C-6-T-n)(y), and 1b(T-n)(3)[2b(T-n)](3)(T-n-C-6-T-n)(y) (n=0-3, numbe r of Si-O-Si bonds; y: content of cocondensation agent) show a relatively n arrow particle size distribution. The structural integrity of the rhodium c omplex 1 after the polycondensation was established by an EXAFS structure e lucidation of the polysiloxane la(Tn),. The obtained stationary phases prov ed to be efficient catalysts for the hydroformylation of l-hexene in the pr esence of a wide variety of solvents in the interphase. Application of the materials containing non-coordinated ligands raised the selectivity toward hydroformylation up to 92% and the n/iso ratio to 14:1 with an average turn over number of 164 mol(sub)(-1)mo(cat)(-1) h(-1). Higher olefins than I-hex ene were also hydroformylated with catalyst D and similar turnover frequenc ies and selectivities were obtained. P-31 CP/MAS NMR relaxation time studie s (T-PH, T-1 rho H) were carried out in the presence (interphase) or absenc e (stationary phase) of a swelling solvent to investigate the dynamic behav ior of the catalytically active polymer 1a(T-n)(3)[2a(T-n)](3)(T-n-C-6-T-n) (y). The highest mobility of the nonpolar reactive centers was achieved in nonpolar solvents like toluene, while more polar solvents like ethanol affo rded the highest mobility of the overall polymer. (H-1,P-31) 2D WISE NMR ex periments performed on the same material revealed a substantial decrease of the line width for the swollen polymer. Si-29 CP/MAS NMR experiments revea led a high degree of cross-linking and a larger content of cocondensation a gent than introduced before condensation. (C) 2000 Elsevier Science. B.V. A ll rights reserved.