Muhammad D. Bala

Synthesis and characterization of a large bite angle iridium nixantphos complex

The complex (nixantphos)Ir(cod)Cl·CH2Cl2(0.5C7H8) 3 has been synthesized and structurally characterized by NMR, IR, and single crystal X-ray diffraction. The coordination around Ir is trigonal bipyramidal with both P groups of the nixantphos bound in a bis-equatorial mode. The bis-chelating cod (C8H12) occupies the remaining equatorial position and an axial position. This mode of bonding resulted in a large bite angle (P1—Ir—P2) of 106.49° (3) for 3. The IR and NMR data support the elucidated structure. Thermal analyses of 3 indicate that it is thermally stable up to decomposition greater than 400°C.

Solvent-free Substitution Reactions of Solid Phosphines with (η5-RC5H4)Fe(CO)2I (R = H, Me) Complexes

Reactions of (η5-RC5H4)Fe(CO)2I (R = H, Me) complexes with phosphine ligands PR′3 (R′ = Ph, m-Tol, p-C6H4OMe, p-C6H4Cl, p-C6H4F) have been performed under solvent-free conditions in the melt phase and generally yielded the ionic products [(η5-RC5H4)Fe(CO)2PR′3]I rather than the CO substituted products (η5-RC5H4)Fe(CO)(PR′3)I. The complexes have been characterised by IR, NMR and MS techniques. By contrast, the same reactions studied in benzene solution have yielded mainly the CO substitution products. Factors that affect the solvent-free reaction include variation in R and R′ , reaction temperature and the addition of [CpFe(CO)2]2 as a catalyst. The mechanism of the reaction for the formation of the ionic complex is proposed to go via a 19 electron intermediate. This is in contrast to the reaction in bezene that occurs via a 17 electron intermediate, clearly indicating the role of the melt phase in the reaction.

Earth abundant metal complexes of donor functionalised N-heterocyclic carbene ligands: synthesis, characterisation and application as amination catalysts

Six new imidazolium salts of the form 3-R-1-picolylimidazolium bromide (1a: R = 4-nitrophenyl, 1b: R = 4-acetylphenyl, 1c: R = 4-cyanophenyl, 1d: R = allyl, 1e: R = butenyl, 1f: R = pentenyl) were synthesised and isolated in high yields. The corresponding Ag–NHC intermediate complexes 2a, 2d, and 2e were transmetalated to yield [M(NHC)2Cl2 M = Co, Ni] complexes in good to excellent yields. The Co–NHC (3a, 3d, 3e) and Ni–NHC (3a′, 3d′, 3e′) complexes were relatively stable in air, insoluble in chlorinated solvents but very soluble in methanol and DMSO. Poorly resolved NMR spectra and magnetic susceptibility values of 2.53 and 2.73 μB for 3d and 3e respectively suggest both to be paramagnetic cobalt complexes. All the imidazolium salts, isolated Ag–NHC complexes and the corresponding Co and Ni–NHC complexes were characterised by spectroscopic and analytical techniques. The complexes were found to be active at low catalyst loading (1 mol%) for the C–N coupling of aniline with phenyl bromide under mild reaction conditions. In addition, the in situ generated catalyst obtained from a mixture of NiCl2/1a (1 : 2 molar ratio) initiated the C–N coupling of several aryl amines with substituted aryl bromides bearing a wide variety of functional groups. Good to excellent yields of the desired diaryl amine products were obtained. The yields are comparable to data obtained with palladium catalysts or to data obtained under harsher temperature conditions of Cu mediated Ullman reactions.

2,6-Bis(tosyloxymethyl)pyridine.

The title compound, C21H21NO6S2, is organized around a twofold axis parallel to the crystallographic c axis and containing the N atom and a C atom of the pyridine ring. The tosyl moiety and the pyridine ring are both essentially planar [maximum deviations 0.028 (2) and 0.020 (3) Å, respectively]; their mean planes form a dihedral angle of 33.0 (2)°.

Homogeneous oxidation reactions catalysed by in situ-generated triazolylidene copper(I) complexes

Four new Cu complexes bearing triazolylidene ligands 1-(R)-3-methyl-4-phenyl-1H-1,2,3-triazol-3-ium-5-yl: R = phenyl (2a), mesitylenyl (2b), propyl (2c), hexyl (2d) (NHC) were synthesised in high yields. Characterisation by spectroscopic and analytical methods confirmed the molecular composition of the complexes as NHC–Cu-I. The complexes 2(a–d) bearing NHC wingtip variations were tested as in situ-generated catalysts for homogeneous oxidation catalysis with H2O2 as oxidant. The in situ technique was adopted for ease of application and to circumvent the poor stability of the complexes in solution. The results showed that the NHC–Cu-I complexes are capable of initiating oxidation reactions, yielding ketones/aldehydes as dominant products for the oxidation of alkanes under optimised reaction conditions, with complexes bearing aliphatic N-substituents showing the highest catalytic activities. Oxidation of toluene with 2c resulted in a mixture of benzaldehyde and benzyl alcohol as the main products. Also, 2c catalysed the oxidation of n-octane, yielding a mixture of mainly C-8 oxidation products with over 75% selectivity for the isomeric octanones. Analysis of regioselectivity indicated that the internal

CCDC 1522045: Experimental Crystal Structure Determination

{\text{C}}_{{sp^{3} }}

Synthesis and characterization of a large bite angle xantphos iridium complex

Csp3–H bonds of n-octane [especially C(2)] are more reactive than the terminal ones.Graphical abstract

(2,4,6-Trimethyl­phen­yl){2-[N-(2,4,6-trimethyl­phen­yl)formamido]­eth­yl}ammonium chloride

Abstract New air stable N-heterocyclic carbene functionalized Schiff base ligands (L) of the type 2-[-2-[3-(R)imidazol-1-yl]ethyliminomethyl]phenol [R = methyl (2), 2-pyridylmethyl (3)] were synthesized and characterized by NMR, IR, MS, and CHN analysis. Single crystal X-ray structural analysis of their Ni(II) complexes revealed square planar arrangement of the chelating ligands coordinated in tridentate (2, C^N^O) and tetradentate (3, N^C^N^O) modes around the metal. The three new isolated and fully characterized complexes were utilized as catalysts for the catalytic transfer hydrogenation of aliphatic ketones in 2-propanol as solvent and source of hydrogen. Based on 0.2 mol% catalyst concentration, the complexes showed activity for aliphatic ketones and 100% conversion (turnover number of 500) for cyclohexanone and all the aromatic ketones tested. Graphical Abstract