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A Kumada Coupling Catalyst, [Ni{(Ph 2 P) 2 N(CH 2 ) 3 Si(OCH 3 ) 3 ‐ P,P′ }Cl 2 ], Bearing a Ligand for Direct Immobilization Onto Siliceous Mesoporous Molecular Sieves
Author(s) -
Stamatopoulos Ioannis,
Giannitsios Dimitrios,
Psycharis Vassilis,
Raptopoulou Catherine P.,
Balcar Hynek,
Zukal Arnošt,
Svoboda Jan,
Kyritsis Panayotis,
Vohlídal Jiří
Publication year - 2015
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.201500447
Subject(s) - chemistry , catalysis , reagent , nickel , ligand (biochemistry) , selectivity , crystallography , coordination sphere , medicinal chemistry , stereochemistry , inorganic chemistry , crystal structure , organic chemistry , biochemistry , receptor
The ligand‐exchange reaction between [Ni(PPh 3 ) 2 Cl 2 ] and (Ph 2 P) 2 N(CH 2 ) 3 Si(OCH 3 ) 3 afforded the novel Ni II complex [Ni{(Ph 2 P) 2 N(CH 2 ) 3 Si(OCH 3 ) 3 ‐ P , P′ }Cl 2 ] ( 1 ) in which the square‐planar NiP 2 Cl 2 coordination sphere contains a four‐membered Ni–P–N–P ring. Comparison of the structure of 1 and related Ni II square‐planar or Ni 0 tetrahedral complexes containing similar P–N–P ligands shows that the magnitude of the P–Ni–P angle is controlled by the presence of the Ni–P–N–P ring, irrespective of the geometry of the nickel coordination sphere. Direct anchoring of 1 onto SBA‐15 molecular sieves through the trimethoxysilyl end‐group of the ligand afforded heterogeneous catalyst 1 /SBA‐15. Both 1 and 1 /SBA‐15 catalyze Kumada cross‐coupling reactions, exhibiting similar activity and a slightly higher product selectivity than the [Ni{Ph 2 P(CH 2 ) 3 PPh 2 ‐ P , P′ }Cl 2 ] and [Ni{(Ph 2 P) 2 N‐( S )‐CHMePh‐ P , P ′}X 2 ] (X = Cl, Br) complexes described in the literature. The Grignard reagent employed is likely to induce leaching of the catalyst, which retains its activity in solution.