Supported organometallic complexes. XXV [1] Accessibility and solid state NMR studies on sol-gel processed diphosphine ligands

摘要

Novel xerogels X1 a-d were obtained by sol-gel processing of the monomeric T-functionalized diphosphine ligand (MeO)(3)Si(CH2)(6)CH[CH2PPh2](2) [I(T-0)] with various amounts of the co-condensing agents MeSi(OMe)(2)-(CH2)(6)(OMe)(2)SiMe (D-0-C-6-D-0) and MeSi(OMe)(2)(CH2)(3)-(C6H4)(CH2)(3)(OMe)(2)SiMe [Ph(1,4-C3D0)(2)]. Si-29 CP/MAS NMR spectroscopic investigations were applied to probe the matrices and their degree of condensation. The integrity of the hydrocarbon backbone and diphosphine moiety was examined by means of solid state NMR spectroscopy (C-13, P-31). To study the dynamics of the matrices and the phosphorus centers detailed measurements of relaxation time (T-1pH) and cross polarization constants (T-SiH, T-PH) were carried out. The accessibility of the polysiloxane-supported diphosphines was scrutinized by some typical phosphine reactions. It was found that reagents such as H2O2, Mel as well as bulky molecules like (NBD)Mo(CO)(4) or (COD)PdCl2 are able to reach all phosphorus centers independent on the kind of the backbone of the matrix. SEM micrographs show the morphology of the hybrid materials and energy dispersive X-ray spectroscopy (EDX) suggest that the distribution of the elements agree with the applied composition. [References: 34]