Cobalt aminodiphosphine complexes as catalysts in the oxidation of n-octane

Abstract

Two types of cobalt aminodiphosphine complexes have been synthesized and characterized by IR spectroscopy, elemental analyses and single crystal X-ray diffraction. These are [Ph 2 PN(R)PPh 2 ]CoCl 2 , 1 and [Ph 2 P(CH 2 ) 2 N(R)(CH 2 ) 2 PPh 2 ]CoCl 2 , 2 where R ¼ C 6 H 11 (a); C 5 H 11 (b); C 3 H 7 (c). The functional groups on the nitrogen atom (R) were varied from a cyclohexyl ring, to n-pentyl alkyl chain, to an iso-propyl branched substituent. Complexes 2a and 2c were analyzed using single crystal X-ray diffraction. The geometry around the metal centers in 2a and 2c were distorted tetrahedral. All the complexes showed good activity as catalysts for the oxidation of n-octane using tert-butyl hydroperoxide (TBHP) as the oxidant. The complex bearing the flexible ligand backbone with the cyclohexyl substituent on the nitrogen atom was the most active and showed high selectivity towards ketones with 2-octanone being the dominant product.R 1 ¼ 0.0301, wR 2 ¼ 0.0534 Largest diff. peak and hole (eÅ À3 ) 1.035 and À0.804 0.364 and À0.268This journal is

Stereoselective Alkane Oxidation with meta-Chloroperoxybenzoic Acid (MCPBA) Catalyzed by Organometallic Cobalt Complexes

“…We must emphasize that, although treatment with PPh 3 can be used in order to only remove from the reaction mixtures peroxides (starting H 2 O 2 , tert -BuOOH, produced ROOH etc.) [84,85,86,87,88,89,90,91], the main aim of the method under discussion is estimation of real concentrations of ROOH, alcohol and ketone formed in the reaction. Chromatograms obtained only after reduction of the reaction mixture cannot be used for determination of real concentration of each oxygenate.…”

Crystal structure of N,N-bis(diphenylphosphanyl)cyclohexylamine, C30H31NP2

“…The modular structure of the ligands enables "tuning" of the catalyst activity and selectivity through systematic variation of the donor atoms, their substituents, and the ligand backbone framework. There are numerous examples of crystal structures of such PNP-pincer ligands [1][2][3][4][5][6] and metal complexes [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. Diphosphinoamine (PNP) and other P donor ligands [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] with various substituents on both the P and N atoms have been applied to several catalytic reactions such as methoxycarbonylation [17], metathesis [18], hydroformylation [19] and C-H activation [24].…”

The effects of metals and ligands on the oxidation of n-octane using iridium and rhodium “PNP” aminodiphosphine complexes

“…Considering the worldwide increase in gas to liquid plants, there is an increase in the production of medium- to long-chain paraffins, which increases the need to functionalize these hydrocarbons. 70–72 In continuation of our previous work on metal complexes containing aminodiphosphine ligands for n -octane oxidation, 73 this study focuses on the application of iridium ( 1 ) and rhodium ( 2 ) aminodiphosphine “PNP” complexes (Figure 1) for the oxidation of n -octane. Optimization of the solvent, the temperature, and the oxidant was carried out.…”