Synthesis of polysiloxane-bound (ether phosphine)palladium complexes. Stoichiometric and catalytic reactions in interphases

The reaction of two equiv of the monomeric ether-phosphine O,P ligand (MeO)(3)Si(CH2)(3)(Ph)PCH2-Do [1a(T-0), 1b[(T-0)] {Do = CH2OCH3 [1a(T-0)], CHCH2CH2CH2O {1b(T-0)]} with PdCl2(COD) yields the monomeric palladium(II) complexes Cl2Pd(P similar to O)(2) [2a(T-0)(2), 2b(T-0)(2)]. The compounds 2a(T-0)(2) and 2b(T-0)(2) are sol-gel processed with variable amounts (y) of Si(OEt)(4) (Q(0)) to give the polysiloxane-bound complexes 2a(T-n)(2)(Q(k))(y), 2b(T-n)(2)(Q(k))(y) (Table 1) {P similar to O = eta(1)-P-coordinated ether-phosphine ligand; for T-n and Q(k), y = number of condensed T type (three oxygen neighbors), Q type (four oxygen neighbors) silicon atoms; n and k = number of Si-O-Si bonds; n = 0-3; k 0-4; 2a(T-n)(2)(Q(k))(y), 2b(T-n)(2)(Q(k))(y) = {[M]-SiOn/2(OX)(3-n)}(2)[SiOn/2 (OX)(4-k)](y), [M] (Cl2Pd)(1/2)(Ph)P(CH(2)Do)(CH2)(3)-, X = H, Me, Et}. The complexes 2b(T-n)(2)(Q(k))(y) (y = 4, 12, 36) show high activity and selectivity in the hydrogenation of 1-hexyne and tolan. The dicationic complexes [Pd((OP))(2)][SbF6](2) [3a(T-0)(2),3b(T-0)(2)] are formed by reacting Cl2Pd(P similar to O)(2) with 2 equiv of a silver salt {PO = eta(2)-OP-coordinated etherphosphine ligand; 3a(T-0)(2), 3b(T-0)(2) = [M] -SiOMe(3); [M] = {[Pd2+](1/2)Ph)(CH2CH2OCH3)(CH2)(3)-}{SbF6} (a), {[Pd2+]P-1/2(Ph)(CH2CHCH2CH2CH2O)(CH2)(3)-}{SbF6} (b)}. Their polysiloxane-bound congeners 3a(T-n)(2), 3b (T-n)(2){[M]-SiOn2(OX)(3-n)} are obtained if a volatile, reversible bound ligand like acetonitrile is employed during the sol-gel process. The bis(chelate)palladium(II) complexes 3a(T-n)(2), 3b(T-n)(2) are catalytic active in the solvent-free CO-ethene copolymerization, producing polyketones with chain lengths comparable to those obtained with chelating diphosphine ligands. The polysiloxane-bound palladium(0) complexes 5a(T-n)(2)(Q(k))(4), 5b(T-n)(2)(Q(k))(4) {[M] -SiOn/2(OX)(3-n)}(2)[SiOk/2(OX)(4-k)](4), [M] = [(dba)Pd]P-1/2(Ph)(CH(2)Do)(CH2)(3)-} undergo an oxidative addition reaction with iodobenzene in an interphase with formation of the complexes PhPd(I)(P similar to O)(2) . 4SiO(2) [6a(T-n)(2)(Q(k))(4), 6b(T-n)(2)(Q(k))(4)] {[M]-SiOn/2(OX)(3-n)](2)[SiOk/2(OX)(4-k)]4, [M] = [PhPd(I)/P-1/2(Ph)(CH(2)Do)(CH2)(3)-}, which insert carbon monoxide into the palladium-aryl bond even in the solid state.