Amines, ligands

Coordination Compounds. Osmium in oxidation states from +2 to +8 forms a wide range of complexes with nitrogen ligands. Amine... 

Reduction of both nickel porphyrins and thiaporphyrins to Ni1 species has been studied by EPR and 2H NMR spectroscopy.179, 2 58 The Ni1 complex of 5,10,15,20-tetraphenyl-21-thiaporphyrin has been isolated and characterized. Reaction of this complex with sulfur dioxide produced a paramagnetic five-coordinated Ni1 S02 adduct, while reaction with nitrogenous base ligands (amines, pyridines, imidazoles) yielded five- and six-coordinate complexes. In addition, the crystal structure of Ni1 diphenyldi-p-tolyl-21-thiaporphyrin has been determined. The coordination geometry about the nickel center is essentially square planar with extremely short Ni—N and Ni—S bonds (Ni—N = 2.015(2) A, 2.014(12) A, and 1.910(14) A and Ni—S = 2.143(6) A).2359... 

The reaction can be performed in diethyl ether in the presence of iron(III) acetylaceto-nate, as reported by Nagano and Hayashi in 2004, or in the presence of FeCl(salen) or iron(III) chloride/triethylamine, as described by Bedford and coworkers (Scheme 39). The latter compared several ligands (amines , phosphines ) and the best results were obtained with triethylamine, TMEDA or DABCO. In all cases, the reactions have to be performed in refluxing diethyl ether and the Grignard reagent has to be added at once Unfortunately, these reaction conditions are only useable on a very small scale (1 mmol) but they cannot be used for large-scale applications. 

Nitrogen Ligands. Amine complexes are not particularly stable but there are cations like [Mn(bipy)3]2+ and tertiary amine complexes, e.g., [MnI3(NMe3)] and [MnI2(NEt3)]2.4... 

Me2CgH3 > Ph is accompanied by an increase of hyperconjugation from equatorial ligands (amine, F, pyrrole, Ph), resulting in an overall upheld shift. 

Perrhenates and related species Other oxygen ligands Amines and N-heterocycles Halides... 

Chiral Nitrogen Donor Ligands (Amines and Oxazolines). 1,2-Diphenyl-ethylenediamine (DPEN (56)) and its alkylated and tosylated derivatives, as well as 1,2-cyclohexane-diamine (CHDA (57)) based ligands proved to be applicable in a range of asymmetric reactions (Fig. 7), especially in enantioselective transfer hydrogenations providing ees more than 90% for acetophenone as substrate. Crucial steps of this reaction are the irreversible deprotonation of the ligand... 

While the pyridyl-1,2,3-triazoles are the most abundant class of bidentate click ligands, amine-1,2,3-triazole, phosphine-1,2,3-triazole, cyclometallated phenyl-1,2,3-triazole, and bi-1,2,3-triazole scaffolds have all been reported and are discussed in the following sections. 

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