The microwave spectra of seven isotopic species of propylene have been studied in order to obtain an accurate molecular structure. The complete rs (substitution) structure has been calculated. The more important parameters are: r(C=C)=1.336±0.004 A,r(CC)=1.501±0.004 A, ≰CCC=124.3±0.3. The structure is compared with those of related molecules. It is concluded that no difference can be detected in the double‐bond lengths in ethylene, propylene, and the vinyl halides. The CC single‐bond length in propylene is indistinguishable from that in acetaldehyde and other acetyl compounds, and is 0.025 A shorter than the CC distance in saturated hydrocarbons. In the =CH2 group in propylene, the CH bond trans to the methyl group appears slightly shorter than the cis CH bond; a similar effect occurs in the vinyl halides.

1.
D. R.
Lide
and
D. E.
Mann
,
J. Chem. Phys.
27
,
868
(
1957
).
2.
M. J. S.
Dewar
and
A. N.
Schmeising
,
Tetrahedron
5
,
166
(
1959
).
3.
R. S.
Mulliken
,
Tetrahedron
5
,
253
(
1959
);
R. S.
Mulliken
,
6
,
68
(
1959
).,
Tetrahedron
4.
B.
Bak
and
L.
Hansen‐Nygaard
,
J. Chem. Phys.
33
,
418
(
1960
).
5.
D. R.
Herschbach
and
L. C.
Krisher
,
J. Chem. Phys.
28
,
728
(
1958
).
6.
J.
Kraitchman
,
Am. J. Phys.
21
,
17
(
1953
).
7.
C. C.
Costain
,
J. Chem. Phys.
29
,
864
(
1958
).
8.
D. R.
Lide
,
J. Chem. Phys.
33
,
1514
(
1960
).
9.
D. R.
Lide
,
J. Chem. Phys.
33
,
1519
(
1960
).
10.
L. S.
Bartell
and
R. A.
Bonham
,
J. Chem. Phys.
27
,
1414
(
1957
).
11.
J. M.
Dowling
and
B. P.
Stoicheff
,
Can. J. Phys.
37
,
703
(
1959
).
12.
H. C.
Allen
and
E. K.
Plyler
,
J. Am. Chem. Soc.
80
,
2673
(
1958
).
13.
D.
Kivelson
,
E. B.
Wilson
, and
D. R.
Lide
,
J. Chem. Phys.
32
,
205
(
1960
).
14.
D. R.
Lide
and
D.
Christensen
,
Spectrochim. Acta
17
,
665
(
1961
).
15.
C. C.
Costain
and
B. P.
Stoicheff
,
J. Chem. Phys.
30
,
777
(
1959
).
16.
J. M.
O’Reilly
and
L.
Pierce
,
J. Chem. Phys.
34
,
1176
(
1961
).
17.
L.
Pierce
and
L. C.
Krisher
,
J. Chem. Phys.
31
,
875
(
1959
).
18.
L. C.
Krisher
and
E. B.
Wilson
,
J. Chem. Phys.
31
,
882
(
1959
).
19.
R. W.
Kilb
,
C. C.
Lin
, and
E. B.
Wilson
,
J. Chem. Phys.
26
,
1695
(
1957
). This is an r0 structure, but a recalculation shows that rs for the CC bond probably does not differ from r0 by more than 0.005 A.
20.
It may be shown that the ∢HCH and rCH given in reference 12 differ insignificantly from rs values. See also reference 11.
21.
Even the planarity of the vinyl group has been experimentally confirmed, since any deviation would destroy the Cs symmetry of propylene and lead to a splitting of the lines of the asy(CH2D)CHCH2 species (designated here as H4,5). This is an extremely sensitive test for planarity.
This content is only available via PDF.
You do not currently have access to this content.