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Trialkoxysilyl‐Functionalized Silver( I ) Carboxylates: New Building Blocks for the Synthesis of Immobilizable and Immobilized Homogeneous Catalysts
Author(s) -
Vehlow Kati,
Köhler Katrin,
Blechert Siegfried,
Dechert Sebastian,
Meyer Franc
Publication year - 2005
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200500082
Subject(s) - chemistry , carboxylate , catalysis , silylation , amide , intramolecular force , ligand (biochemistry) , transition metal , polymer chemistry , metal , crystallography , stereochemistry , organic chemistry , biochemistry , receptor
Partly fluorinated trialkoxysilyl‐substituted carboxylic acids (RO) 3 Si(CH 2 ) 3 N(R')C(O)(CF 2 ) 3 COOH ( 3a : R = Et, R' = H; 3b : R = R' = Me) have been prepared in a straightforward synthesis from the respective trialkoxysilyl‐substituted primary and secondary amines and hexafluoroglutaric anhydride. Treatment with silver( I ) oxide yields the corresponding silver carboxylates 4a , b which have been thoroughly characterized in solution and in the solid state, including an X‐ray crystallographic analysis of 4a . The molecular structure of 4a consists of archetypal carboxylate‐bridged disilver( I ) pairs with a strong closed‐shell Ag–Ag (d 10 –d 10 ) interaction and a unique intramolecular bond between a silyl ether group and the metal ion. In addition the amide oxygen atoms are involved in H‐bonding and in intermolecular silver coordination, giving rise to an unusual two‐dimensional network structure. Silyl‐free acid i Pr 2 NC(O)(CF 2 ) 3 COOH ( 5 ) and its silver salt 6 have been prepared and structurally characterized for comparison. It is shown that the trialkoxysilyl tail in 4a , b allows for convenient attachment of these silver complexes to silica surfaces, as is corroborated by DRIFT measurements. The immobilized silver carboxylates 7a , b exhibit remarkable stability and are expected to open an easy access to a wide variety of SiO 2 ‐grafted transition metal catalysts via transfer of the carboxylate ligand in simple exchange reactions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)