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Lindner E, Schreiber R, Schneller T, Wegner P, Mayer HA, Gopel W, Ziegler C: Synthesis of Polysiloxane-Bound (Ether-phosphine) palladium Complexes. Inorg Chem. 1996 Jan 17;35(2):514-525.
Stoichiometric and Catalytic Reactions in Interphases (1).. The reaction of two equiv of the monomeric ether-phosphine O,P ligand (MeO)(3) Si (CH (2))(3)(Ph) PCH (2)-Do [1a (T (0)()), 1b (T (0)())] {Do = CH (2) OCH (3) [1a (T (0)())], CHCH (2) CH (2) CH (2) O [1b (T (0)())]} with PdCl (2)(COD) yields the monomeric palladium (II) complexes Cl (2) Pd (P approximately 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 approximately 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]-SiO (n)()(/2)(OX)(3)(-)(n)()}(2)[SiO (k)()(/2)(OX)(4)(-)(k)()](y)(), [M] = (Cl (2) Pd)(1/2)(Ph) P (CH (2) Do)(CH (2))(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 (P&arcraise;O)(2)][SbF (6)](2) [3a (T (0)())(2)(), 3b (T (0)())(2)()] are formed by reacting Cl (2) Pd (P approximately O)(2) with 2 equiv of a silver salt {P&arcraise;O = eta (2)-O&arcraise;P-coordinated ether-phosphine ligand; 3a (T (0)())(2)(), 3b (T (0)())(2)() = [M]-SiOMe (3); [M] = {[Pd (2+)](1/)(2) P (Ph)(CH (2) CH (2) OCH (3))(CH (2))(3)-}{SbF (6)} (a), {[Pd (2+)](1/)(2) P (Ph)(CH (2) CHCH (2) CH (2) CH (2) O)(CH (2))(3)-}{SbF (6)} (b)}. Their polysiloxane-bound congeners 3a (T (n)())(2)(), 3b (T (n)())(2)() {[M]-SiO (n)()(/2)(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]-SiO (n)()(/)(2)(OX)(3)(-)(n)}(2)[SiO (k)()(/2)(OX)(4)(-)(k)](4), [M] = [(dba) Pd](1/)(2) P (Ph)(CH (2) Do)(CH (2))(3)-} undergo an oxidative addition reaction with iodobenzene in an interphase with formation of the complexes PhPd (I)(P approximately O)(2).4SiO (2) [6a (T (n)())(2)()(Q (k)())(4)(), 6b (T (n)())(2)()(Q (k)())(4)()] {[M]-SiO (n)()(/)(2)(OX)(3)(-)(n)](2)[SiO (k)()(/2)(OX)(4)(-)(k)](4), [M] = [PhPd (I)](1/2) P (Ph)(CH (2) Do)(CH (2))(3)-}, which insert carbon monoxide into the palladium-aryl bond even in the solid state. |
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