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Half‐Sandwich Nickel(II) NHC‐Picolyl Complexes as Catalysts for the Hydrosilylation of Carbonyl Compounds: Evidence for NHC‐Nickel Nanoparticles under Harsh Reaction Conditions
Author(s) -
Ulm Franck,
Shahane Saurabh,
TruongPhuoc Lai,
Romero Thierry,
Papaefthimiou Vasiliki,
Chessé Matthieu,
Chetcuti Michael J.,
PhamHuu Cuong,
Michon Christophe,
Ritleng Vincent
Publication year - 2021
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.202100371
Subject(s) - hydrosilylation , chemistry , carbene , catalysis , nickel , cationic polymerization , medicinal chemistry , denticity , metathesis , polymer chemistry , photochemistry , organic chemistry , polymerization , crystal structure , polymer
Abstract The cationic [NiCp(Mes‐NHC‐CH 2 py]Br complex 2 a was prepared directly by the reaction of nickelocene with 1‐(2‐picolyl)‐3‐mesityl‐imidazolium bromide ( 1 ), and its PF 6 − derivative 2 b , by subsequent salt metathesis. X‐ray diffraction studies and Variable Temperature 1 H NMR experiments run with 2 a and 2 b strongly suggest the bidentate coordination of the picolyl‐functionalized carbene to the nickel both in the solid state and in solution in both cases. These data suggest the absence of hemilabile behavior of the latter, even in the presence of a coordinating anion. Both complexes show similar activity in aldehyde hydrosilylation, further implying the absence of hemilability of the picolyl‐functionalized carbene, and effectively reduce a broad scope of aldehydes in the absence of additive under mild conditions. In the case of ketones, effective hydrosilylation is only observed in the presence of a catalytic amount of potassium t ‐butoxide at 100 °C. Dynamic light scattering, scanning transmission electron microscopy and X‐ray photoelectron spectroscopy show evidence for the involvement of NHC‐picolyl‐Ni nanoparticles under these conditions.