Carbon-nitrogen bond
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Carbon-nitrogen_bond".

A carbon-nitrogen bond is a covalent bond between carbon and nitrogen and one of the most abundant in organic chemistry and biochemistry [1].

Nitrogen has five valence electrons and in simple amines it is trivalent with two remaining electrons forming a lone pair. Through it, 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.

In common with carbon-carbon bonds, these bonds can be stable double bonds for instance 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]. The bond strength in a CN bond is higher (184 kcal/mol) than that of the CC bond (145 kcal/mol) [2]

A CN bond is strongly polarized towards nitrogen (electronegativity for C and N is 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.

Nitrogen functional groups

content
Chemical class Bond order Formula Structural Formula Example Avg. C–N bond length (Å)[3]
Amines 1 R2C-NH2 Primary amine methylamine
Methylamine
 1.469 (neutral amine)
1.499 (ammonium salt)
Aziridines 1 CH2NHCH2 Aziridine Phenyl azide
Mitomycin
 1.472
Azides 1 R2C-N3 Azide Phenyl azide
phenyl azide
Anilines 1 Ph-NH2 Aniline Ansidine
Anisidine
 1.355 (sp2 N)
1.395 (sp3 N)
1.465 (ammonium salt)
Pyrroles 1 amide Acetamide
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 Ansidine
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

See also


CH He
CLi CBe CB CC CN CO CF Ne
CNa CMg CAl CSi CP CS CCl Ar
CK CCa CSc CTi CV CCr CMn CFe CCo CNi CCu CZn CGa CGe CAs CSe CBr Kr
CRb CSr CY CZr CNb CMo CTc CRu CRh CPd CAg CCd CIn CSn CSb CTe CI Xe
CCs CBa CHf CTa CW CRe COs CIr CPt CAu CHg CTl CPb CBi CPo CAt Rn
Fr Ra Rf Db Sg Bh Hs Mt Ds Rg Uub Uut Uuq Uup Uuh Uus Uuo
↓
La CCe Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
Ac Th Pa CU Np Pu Am Cm Bk Cf Es Fm Md No Lr


Chemical bonds to carbon
Core organic chemistry many uses in chemistry.
Academic research, but no widespread use Bond unknown / not assessed.

References

  1. ^ Organic Chemistry John McMurry 2nd Ed.
  2. ^ a b CRC Handbook of Chemistry and Physics 65Th Ed.
  3. ^ 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.
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