Chemistry is the science of change. But why do chemical reactions take place? Why do chemicals react with each other? The answer is in thermodynamics and kinetics.In a document type is Article, the author is Fuss, Martin and a compound is mentioned, 1125-80-0, 3-Methylisoquinoline, introducing its new discovery. 1125-80-0
Dynamics of noncovalent supramolecular complexes. NMR study of the rotational barriers in chiral BINAP palladium(II) and platinum(II) bis(phosphane) complexes that resemble the minimal subunits of chiral polygons and polyhedra
In the reaction between 3-picoline, 2-bromo-5-methylpyridine, 2-methylquinoline, 3-methylisoquinoline, and [MCR-(+)-BINAP)][OTf]2 (M = Pd, Pt; BINAP = 2,2?-bis(diphenylphosphino)-1,1?-binaphthyl), the nature and the distribution of the products were investigated by various physical and spectroscopic methods. The alpha-substituents on the heteroaryl ring, such as the bromine atom in 2-bromo-5-methylpyridine or the methyl group in 2-methylquinoline, tend to promote the simultaneous formation of mono(heteroaryl)- and bis-(heteroaryl)-containing products. The reaction of the most sterically demanding 2-methylquinoline favors the formation of mono(heteroaryl) complexes exclusively within the limits of NMR detection. Reaction of 3-picoline with the chiral Pd(II) and Pt(II) bis(triflates) results in the formation of diastereomeric, square-planar, cationic complexes, due to the hindered rotation about the metal-nitrogen heteroaryl bond. 1H NMR variable-temperature studies of [M(R-(+)-BINAP)(3-picoline)2][OTf]2 were performed. The activation barriers for the rotation of the beta-picoline ligands around the M-N linkage axis were determined for [Pd-(R-(+)-BINAP)(3-picoline)2][OTf]2 and [Pt(R-(+)-BINAP)(3-picoline)2][OTf]2 by a kinetic line shape analysis of the methyl signals. The Gibbs free energy of activation was found to be 12(¡À0.5) kcal/mol for the Pd complex 15 and 14(¡À0.5) kcal/mol for the Pt complex 16. Ab initio calculations (HF/lanl2dz) of model complexes [dpe]Pd(HN=CH2)22+ and [dpe]Pt(HN= CH2)22+ (dpe = diphosphinoethylene) provided insights into the observed results. The nitrogen-metal pi-sigma-interaction is found to be stronger for the Pt complex, resulting in a higher energy barrier for the rotation around the Pt-N bond compared to the rotation around the Pd-N bond. A comparison is made between the covalent and coordinated Pt(II) complexes, and the similarities and differences of their dynamic behavior are discussed.
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Reference£º
Isoquinoline – Wikipedia,
Isoquinoline | C9H7N – PubChem