3-Aminopyridine

Chao, M.; Schemp, E.; Rosenstein, R. D.

doi:10.1107/s0567740875009284

Cited by 46 publications

(21 citation statements)

References 2 publications

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“…Examination of the CÀC and CÀN bond lengths in the PYE moiety indicates that the valence-bond structure A is the accurate representation in which C(1) À C(2) and C(2) À C(3), for example, are 1.4496(16) and 1.3527 (16) , respectively, and the exocyclic C=N bond C(1) À N(1) is 1.2960 (15) . In contrast, the single-crystal X-ray structure of 2-amino pyridine exhibits all of the C À C and C À N bond lengths as approximately 1.36 , [54,55] including the exocyclic C À NH 2 bond (which is shorter than 1.38 that is typical of a single CA C H T U N G T R E N N U N G (sp 2 )ÀN bond). [56] For 7, the atoms about the C(1)ÀN(1) bond are also essentially planar with planes defined by C(2)-C(1)-N(2) and C(7)-N(1)-C(1), which is twisted by approximately 6.58.…”

Section: Resultsmentioning

confidence: 84%

Synthesis, Coordination Chemistry and Bonding of Strong N‐Donor Ligands Incorporating the 1H‐Pyridin‐(2E)‐Ylidene (PYE) Motif

Qiu

Thatcher

Slattery

et al. 2009

Chemistry A European J

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A range of N-donor ligands based on the 1H-pyridin-(2E)-ylidene (PYE) motif have been prepared, including achiral and chiral examples. The ligands incorporate one to three PYE groups that coordinate to a metal through the exocyclic nitrogen atom of each PYE moiety, and the resulting metal complexes have been characterised by methods including single-crystal X-ray diffraction and NMR spectroscopy to examine metal-ligand bonding and ligand dynamics. Upon coordination of a PYE ligand to a proton or metal-complex fragment, the solid-state structures, NMR spectroscopy and DFT studies indicate that charge redistribution occurs within the PYE heterocyclic ring to give a contribution from a pyridinium-amido-type resonance structure. Additional IR spectroscopy and computational studies suggest that PYE ligands are strong donor ligands. NMR spectroscopy shows that for metal complexes there is restricted motion about the exocyclic C-N bond, which projects the heterocyclic N-substituent in the vicinity of the metal atom causing restricted motion in chelating-ligand derivatives. Solid-state structures and DFT calculations also show significant steric congestion and secondary metal-ligand interactions between the metal and ligand C-H bonds.

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Section: Resultsmentioning

confidence: 84%

Synthesis, Coordination Chemistry and Bonding of Strong N‐Donor Ligands Incorporating the 1H‐Pyridin‐(2E)‐Ylidene (PYE) Motif

Qiu

Thatcher

Slattery

et al. 2009

Chemistry A European J

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“…C (2) The decreased acidity of the NH 2 groups, as compared to 2,4-dinitroaniline (Weber & Sheldrick, 1981), is reflected in C(12)-N(19) and C(13)--N(20) bonds of 1.378 (4) and 1.367 (3) A, respectively, comparable to C-NH 2 distances in non-complexing o-nitroaniline (Dhaneshwar, Tavale & Pant, 1978) and 3-aminopyridine (Chao, Schempp & Rosenstein, 1975) but slightly shorter than in 1,2-diaminobenzene and its hydrochloride (Sfftlhandske, 1976). Accordingly, a systematic distribution of bond lengths in the benzene ring is less distinct; but the lengthened C(12)-C(13) bond of 1.420 (3)/k (between the two amine functions) may give some evidence for a contribution of quinonoid canonical forms to the overall resonance state.…”

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confidence: 84%

A 2:1 complex of 4-nitro-1,2-benzenediamine and 1,4,7,10,13,16-hexaoxacyclooctadecane (18-crown-6)

Weber¹

1982

Acta Crystallogr B Struct Crystallogr Cryst Chem

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“…The title compound, however, has two such amino groups; and each group experiences less demand for n electrons, less constraint on hybridization, and a longer bond to the ring. In 3-aminopyridine the amino group is more isolated from the heterocyclic N atom, and so less sp 2 character is expected, resulting in a similar lengthening of the C-NH 2 bond to 1.384 (4)/~ (Chao, Schempp & Rosenstein, 1975b. A comparable trend is manifested by the sum of bond angles, ~, at the amino N atom, which should be 360 ° for perfect sp 2 hybridization and trigonal geometry but which should decrease upon pyramidalization.…”

Section: H2~ Nh2mentioning

confidence: 99%