Английская Википедия:Carbon–nitrogen bond
Шаблон:Short description A carbon–nitrogen bond is a covalent bond between carbon and nitrogen and is one of the most abundant bonds in organic chemistry and biochemistry.[1]
Nitrogen has five valence electrons and in simple amines it is trivalent, with the two remaining electrons forming a lone pair. Through that pair, nitrogen can form an additional bond to hydrogen making it tetravalent and with a positive charge in ammonium salts. Many nitrogen compounds can thus be potentially basic but its degree depends on the configuration: the nitrogen atom in amides is not basic due to delocalization of the lone pair into a double bond and in pyrrole the lone pair is part of an aromatic sextet.
Similar to carbon–carbon bonds, these bonds can form stable double bonds, as in imines; and triple bonds, such as nitriles. Bond lengths range from 147.9 pm for simple amines to 147.5 pm for C-N= compounds such as nitromethane to 135.2 pm for partial double bonds in pyridine to 115.8 pm for triple bonds as in nitriles.[2]
A CN bond is strongly polarized towards nitrogen (the electronegativities of C and N are 2.55 and 3.04, respectively) and subsequently molecular dipole moments can be high: cyanamide 4.27 D, diazomethane 1.5 D, methyl azide 2.17, pyridine 2.19. For this reason many compounds containing CN bonds are water-soluble. N-philes are group of radical molecules which are specifically attracted to the C=N bonds.[3]
Carbon-nitrogen bond can be analyzed by X-ray photoelectron spectroscopy (XPS). Depending on the bonding states the peak positions differ in N1s XPS spectra.[4][5][6]
Nitrogen functional groups
| Chemical class | Bond order | Formula | Structural Formula | Example | Avg. C–N bond length (Å)[7] |
|---|---|---|---|---|---|
| Amines | 1 | R2C-NH2 | Primary amine | methylamine Methylamine |
1.469 (neutral amine) 1.499 (ammonium salt) |
| Aziridines | 1 | CH2NHCH2 | Aziridine | Mitomycin Mitomycin |
1.472 |
| Azides | 1 | R2C-N3 | Azide | Phenyl azide Phenyl azide |
1.38–1.48[8] 1.47 (methyl azide)[9] 1.432 (phenyl azide)[10] |
| Anilines | 1 | Ph-NH2 | Aniline | Ansidine Anisidine |
1.355 (sp2 N) 1.395 (sp3 N) 1.465 (ammonium salt) |
| Pyrroles | 1 | amide | Porphyrin Porphyrin |
1.372 | |
| Amides | 1.2 | R-CO-NR2 | amide | Acetamide Acetamide |
1.325 (primary) 1.334 (secondary) 1.346 (tertiary) |
| Pyridines | 1.5 | pyr | pyridine | Nicotinamide Nicotinamide |
1.337 |
| Imines | 2 | R2C=NR | imine | DBN DBN |
1.279 (C=N bond) 1.465 (C–N bond) |
| Nitriles | 3 | R-CN | Nitrile | Benzonitrile Benzonitrile |
1.136 |
| Isonitriles | 3 | R-NC | isonitrile | TOSMIC TOSMIC |
1.154[11] |
See also
- Cyanide
- Other carbon bonds with group 15 elements: carbon–nitrogen bonds, carbon–phosphorus bonds
- Other carbon bonds with period 2 elements: carbon–lithium bonds, carbon–beryllium bonds, carbon–boron bonds, carbon–carbon bonds, carbon–nitrogen bonds, carbon–oxygen bonds, carbon–fluorine bonds
- Carbon–hydrogen bond
References
- ↑ Organic Chemistry John McMurry 2nd Ed.
- ↑ CRC Handbook of Chemistry and Physics 65Th Ed.
- ↑ Шаблон:Cite journal
- ↑ Шаблон:Cite journal
- ↑ Шаблон:Cite journal
- ↑ Шаблон:Cite journal
- ↑ F. H. Allen, O. Kennard, D. G. Watson, L. Brammer, A. G. Orpen. Tables of bond Lengths determined by X-Ray and Neutron Diffraction. Part 1. Bond Lengths in Organic Compounds. J. Chem. Soc. Perkin Trans. II 1987, S1-S19.
- ↑ Шаблон:Cite journal
- ↑ Шаблон:Cite journal
- ↑ Шаблон:Cite journal
- ↑ Шаблон:Cite journal
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