2-Nitrosopyridine, 1, 3-methyl-2-nitrosopyridine, 2, and 4-methyl-2-nitrosopyridine, 3, exist in org. solvents as monomer-azodioxy dimer equil. with the dimers predominating at ambient temps. In the case of compds. 1 and 3 only the Z-dimers co-exist with the monomers, whereas for compd. 2 both Z- (major) and E- (minor) dimers are present with the monomer. Variable temp. 1H NMR bandshape anal. and 2D-EXSY spectra of 1-3 provided thermodn. and kinetic data for the dissocn. equil. Z- (or E-) dimer .dblharw. 2 monomer, ΔH values being in the range 53-58 kJ mol-1 and ΔG ‡ (298.15 K) values in the range 70-82 kJ mol-1. An X-ray crystal structure of 1 identified the compd. as a Z-dimeric species with the two pyridine rings twisted by 62.7° and their heterocyclic N atoms pointing towards each other.

The solid-and the Solution-State Structures of 2-Nitrosopyridine and its 3- and 4- Methyl derivatives

MELE, Giuseppe Agostino;VASAPOLLO, Giuseppe;
2000

Abstract

2-Nitrosopyridine, 1, 3-methyl-2-nitrosopyridine, 2, and 4-methyl-2-nitrosopyridine, 3, exist in org. solvents as monomer-azodioxy dimer equil. with the dimers predominating at ambient temps. In the case of compds. 1 and 3 only the Z-dimers co-exist with the monomers, whereas for compd. 2 both Z- (major) and E- (minor) dimers are present with the monomer. Variable temp. 1H NMR bandshape anal. and 2D-EXSY spectra of 1-3 provided thermodn. and kinetic data for the dissocn. equil. Z- (or E-) dimer .dblharw. 2 monomer, ΔH values being in the range 53-58 kJ mol-1 and ΔG ‡ (298.15 K) values in the range 70-82 kJ mol-1. An X-ray crystal structure of 1 identified the compd. as a Z-dimeric species with the two pyridine rings twisted by 62.7° and their heterocyclic N atoms pointing towards each other.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11587/111794
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