Pyridyl ring

A, and fl = 90.48°. The 2-pyridyl ring and p-tolyl group make dihedral angles of 29.7° and 55.3° respectively with the double bond plane. The inter-aryl dihedral angle is 106.5°. The data was obtained on crystals grown from a solution of the compound in anisole. A Picker FACS-1 diffractometer with CuK radiation was used for the measurements, or... 

From a mechanistic standpoint, ammonia serves two functions 1) it behaves as a base to catalyze an aldol reaction between 2 equivalents of 31 to generate the corresponding enal 33, and 2) it is the source of nitrogen for the resultant pyridyl ring. This occurs through formation of enamine 34 with a third equivalent of 31. The Michael addition of 34 to 33 followed by cyclization gives rise to 32. 

Compound 13a can been obtained via two different routes firstly in the reaction of 11 with dimethyl aluminum chloride where LiCl is eliminated and secondly by the reaction of di(pyridyl) phosphane 12 (Py2PH) with trimethyl aluminum where methane is formed, (Scheme 5). The X-ray structure determination of [Me2AlPy2P] 13a, (Fig. 3) elucidates the aluminum atom to be coordinated by the two nitrogen atoms of the pyridyl rings in addition to the two remaining methyl groups leaving the aluminum four... 

In solution, [Co(terpy)2]2+ is also in a high-spin/low-spin equilibrium. Ultrasonic absorption measurements determined the spin equilibrium relaxation time in both water and MeOH solution to be less than 2 ns.249 Electron-donating functional groups such as methoxyl appended to the terpy ring result in a shift towards the high-spin form of the complex,250 as does replacement of one pyridyl ring with a pyrazole.251... 

Racemic amino acids have been resolved via stereoselective coordination to the square planar chiral matrix complex (178).584 The bisamidobispyridyl ligand (179) forms a square planar Ni11 complex with considerable tetrahedral twist due to repulsion of the ortho protons of the pyridyl rings.585... 

The complex trans-[Cun(hfac)2(TTF—CH=CH—py)2](BF4)2-2CH2Cl2 was obtained after 1 week of galvanostatic oxidation of Cun(hfac)2(TTF CH=CH py)2 [61]. The molecular structure of the copper complex is identical to its neutral form. There is one TTF CH=CH py molecule per BF4 and one dichloromethane solvent molecule. The copper is located at the center of a centrosymetric-distorted octahedron two TTF CH=CH py ligands in trans- conformation are bonded to Cun by the nitrogen atoms of the pyridyl rings. From the stoichiometry, the charge distribution corresponds to fully oxidized TTF CH=CH—py+" radical units. 

Bipyridine (44-BP) is a bifunctional, non-chelating molecule, which consists of two planar pyridyl rings connected by a C-C bond in 4 and 4 positions. It has been extensively employed as a bridging ligand in coordination chemistry [291]. 

The rotation angle between the two planar pyridyl-rings was found to vary between 18.2 (solid-state [293]) and 37.2 (gas-phase [294]). H-NMR experiments in several solvents of different dielectric constants revealed that 4,4 -BP appears either highly twisted, or as a free rotor. The barrier to internal rotation has been estimated to be 17.0 kJ mol-1. The two rings are rotating almost freely in most liquid environments [295-297]. 

N-(4-nitrophenyl)-amino acids N-(2,4-dinitrophenyl)-amino acids 8) and 3-nitro-2-pyridyl amino acids have been of considerable interest. A generally applicable mechanistic scheme does not exist so far, and except for 3-nitrophenyl acetate in ortho and/or -para position of the phenyl (pyridyl) ring seems to be a prerequisite for efficient decarboxylation. 

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