Electronic Effects in the Catalytic Hydrosilylation with In‐Situ Generated Iron(II)‐Catalysts

Abstract

In combination with different aromatic N,N‐donors, iron acetate and octanoate are suitable catalyst precursors for the hydrosilylation of carbonyl compounds. Iron octanoate can be used to perform this catalytic transformation in cheap and non‐toxic petrol ether or heptane as the solvent and with versatile polymethylhydrosiloxane (PMHS) as the silane source. Investigation of the preformed catalyst (iron octanoate+N,N‐ligand+PMHS) by using Mössbauer spectroscopy suggests that the active species is a high‐spin iron(II) system.

Iron Catalysis in Organic Synthesis

“…1452 The reaction could be performed in alkane solution at 80°C using polymethylhydrosiloxane (PMHS) as reductant. Ligands with electron-donating substituents led to higher yields than those with electron-withdrawing groups.…”

Structure–Reactivity Relationships in the Hydrogenation of Carbon Dioxide with Ruthenium Complexes Bearing Pyridinylazolato Ligands

“…Synthesis and characterisation of the ruthenium catalysts : The pyrazole‐based ligands 1 a – f used for coordination to the ruthenium centre were accessed by established procedures following Claisen or Claisen‐type condensations and subsequent ring closing with hydrazine (Scheme ),23a,b,e whereas the triazolylpyridines 1 h – j were synthesised in a three‐step procedure starting from 2‐cyanopyridine 24. Unsubstituted 2‐(1,2,4‐triazol‐5‐yl)pyridine ( 1 g ) was obtained by heating the intermediate picolinimidohydrazide at reflux in concentrated formic acid 25…”

Iron(II) Complexes of Chiral Tridentate Nitrogen Donors and their Application in Catalytic Hydrosilylation Reactions

“…In the last decades different homogeneous catalysts often containing transition metal sites were found to catalyze hydrosilylation reactions. Frequently, these catalysts contain transition metal sites such as copper(I) or zinc(II) but lots of them are also based on iron(II) as the active species , . For hydrosilylation reactions several mechanisms were postulated, which differ in catalyst‐substrate interaction.…”

“…In previous studies we could show that triphenylphosphine ruthenium(II) complexes bearing N,N ‐diallyl‐2,6‐bis(pyrazol‐3‐yl)pyridine ligands are highly active catalysts for the transfer hydrogenation of ketones and aldehydes with either 2‐propanol or ethanol as the hydrogen source. [11a], [11b] In addition, we could demonstrate the catalytic activity of iron(II) 2,6‐bis(pyrazol‐3‐yl)pyridine and 2‐(pyrazol‐3‐yl)pyridine complexes in ethylene polymerization and in the hydrosilylation of ketones and aldehydes . In this paper we describe the synthesis of novel chiral N ‐functionalized C 2 ‐symmetric (2,6‐bis(pyrazol‐3‐yl)pyridine)iron(II) complexes based on (1 R ,4 R )‐(+)‐camphor and their application as catalysts for the hydrosilylation of ketones.…”

“…Another important class of iron catalysts based on bulky 2,6‐diiminopyridines was independently from each other published some years earlier by Gibson and Brookhart for ethylene polymerization . A particularly promising field for iron catalysis is catalytic hydrosilylation with either chiral or achiral iron(II) complexes.…”