N
X
C
Hal
O
N
S
P Si
Natural
Products
Solvents
C
C
C
C C
C
331
7.9 Nitrogen Compounds
331
Typical Ranges (v ~ in cm -1 )
Assignment
Range
Comments
NH 2 st
3500–3300
Of variable intensity, generally 2 sharp bands,
Δν ~ = 65–75
At lower wavenumbers (<3200) and broader if
H-bonded. Free and H-bonded forms often
simultaneously observed
In primary aromatic amines, additional combination band at ≈3200
In the same range: OH st, – – – CH st
NH st
3450–3300
Of variable intensity, only one band
At lower wavenumbers (<3200) and broader if
H-bonded. Free and H-bonded forms often
simultaneously observed
In the same range: OH st, – – – CH st, H 2 O
NH 3
+ st
3000–2000
3000–2700
Medium, broad, highly structured, comb: ≈2000
Major maximum
NH 2
+ st
3000–2000
3000–2700
Medium, broad, highly structured
Major maximum
NH + st
3000–2000
2700–2250
Medium, broad, highly structured
Major maximum
In the same range: OH st, NH st, CH st, SH st, PH st, SiH st,
BH st, X=Y=Z st, X– – – – – Y st
NH 2 δ
1650–1590
Medium or weak
NH δ
1650–1550
Weak
NH 3
+ δ
1600–1460
Medium, often more than one band;
weak in aliphatic amines
NH 2
+ δ
1600–1460
Medium, often more than one band;
weak in aliphatic amines
NH + δ
1600–1460
Medium, often more than one band;
weak in aliphatic amines
C–N st
1400–1000
Medium, of no practical significance
NH 2 δ
850–700
Medium or weak; 2 bands in primary amines
NH δ
850–700
Medium or weak
P–N–C st
1110–930
770–680