- Email: [email protected]
Selenoketene substitution structure
Volume
CHEMICAL
55, number 1
SELENOKETENE
PHYSICS
LETTERS
1 April 1978
SUBSTITUTION STRUCTURE
B$rge BAK, Ole J. NIELSEN, Henrik SVANHOLT Cilemical Laboratory V, T12eH.C. &ted DK--3100 Copenhagen 0, Denmark
hstitrtte.
University of Copenhagen.
Chemical Laboratory II, The h’.C. @xted Institute, DK-2100 Copenhagen #, Denmark
University of Copenlragen.
and Ame HOLM
Received 3 January
1978
hlic:owave studies (26.5-40GHz) of further isotopic species of selenoketene formed by pyrolysis of 1,2,3-selenodiazole (12CH2=I’C=76.7’,a’Se, t2CHt=‘sC=auSe and tsCfi2=t2C= *OSe) and by pyrolysis of S-deuterio-1.2.3~selenodiazole has been (t2CHD=1zC=7s~goSe) are reported_ In conjunction with earlier results for 12Cf-iZ=12C=78~a0Se an restructure derived with distances Se=C (1.706 a), C=C (1.303 A), C-H (1.0908 A) and a HCH bond angle of1 19.7O. The geometry of the CHa XC moiety of selenoketene is closer to aUene, CH2 =C=CHa, than to ketene, CHa =C=O.
1. Experimental
2. Assignments
Observations in the 1840 GHz region of pure rotational transitions of two isotopic species of selenoketene, 12CHZ=12C=78~80Se [l] have been contimred by similar observations betweln 26.5 and 40 GHz for seven further isotopic species (tables I-3). Among these, 12CHD=12C=78*80Se are the most important for a molecular structure determination of selenoketene independent of assumed geometric parameters in contrast to what was possible earlier El]_ 2-deuterioselenoketene (fig. 1) was prepared by pyrolysis [I] of an available 1:2 mixture of 1,2,3selenodiazole and its S-deuterio derivative (fig. 1). This derivative was obtained by replacing CH,CHO, used in the synthesis of 1,23-selenodiazole [2] by CD&HO with the above-mentioned 1:2 mixture as a result_ In the microwave spectrum of the pyroiytic products no transitions from 12CD2=12C=80Se were observable. This indicates that an organized transfer of deuterium from C(5) to C(4) (fig. 1) is taking place. Except for the deuterated species all observations were carried out with molecular species in natural abundance_
Intensity criteria based on the abundance of molecular species (as given in tabIe4) and precalculated positions using the second model of selenoketene in ref. [l] served to estab!ish the unambiguous assignments of tables 1 and 3. The discrepancies between precalculated and observed transitions of the mono-deuterated species were 20 -30 MHz, clearly showing the possibiiity of deriving an improved structure. Table 2 contains the few data observed by us for the most abundant UC-containing species (0.5%). A final assigniient of the 3t2+4t3 transition in QCH?=13C=80Se pro ved impossible since two candidates appeared at 1.3 MHz interval in the low-frequency wing of the much stronger 330+4~~ transition in ECH2=*2C=82Se (table 1) at 30555.70 MHz. These alternative assignments are iabelied OLand 9 in table 2, with corresponding labels-on the derived rotational constants in table 4. Appropriate rotational and distortion constants of the seven isotopic species are given in table 4. Distortion constants of the J3C containing species were taken from parental 12CH2=12C=80Se in order to fix the
36
Volume 55. number L
CHEMICAL
PHYSICS
LETTERS
1 April 1978
Table 1 Ground state rotational transitions in MHz of gaseous ‘2CHa=12C=82Se, t*CHa=‘*C=“Se and t2CHa=‘2C=76Se as observed in natumL abundance (9.2:7.6:9-O%) at 26.5-40 GHz, room temperature and a total pressure of = 15 mtorr (Row system). Calculated frequencies from constants of table4 r2CH2= 12C=82Se
Transition
obs.
ohs.-talc.
-___
‘*CH2=**C=“Se
12CH2=‘2C=76Se
obs.
obs.
ohs.-talc.
ohs.-talc.
303 - 404 312 -413
30561.93 (-0.08) 30668.30 (-0.03)
30989.29 (+O.Ol) 3 1098.56 (-0.07)
31081.44 (-0.12) 31191.49 (-0.05)
313 '414
30454.36 (-0.02)
30878.69 (+0.06)
30970.17(-0.06)
322 - 423 321 - 452
30559.22 (+0.02) 30559.22 (-0.06)
30984.54 (+0.05) 30986.54 (-0.04)
3 1078-75 (+O. 10) 31078.75 (+0.02)
330d431 331+432 404 '50s
30555.70(+0.08) 30555.70<+0.08) 38202.27 (-0.06) 38067.79 (-0.04) 38335.23 (-0.03) 38199.00(-0.02) 38199_00(+0.14) 38194.51 (t0.11)
a) 3) 38736.39(-0.01) 38598.04 (-0.10) 38873.14(+0.01) 38733.13(+0.00) 38733.13(+0_17) 38728.50(-0.03)
31075.00(+0.06) 31075_00(+0_06) 38851.69(-0.03) 38989.20(-0.04) 38848.28(-0.04) 38848.28(-0.02) 38843.61(+0.09)
38194.51 (+O.ll) 38187.97 (-0.11)
38728.50 (-0.03) a)
38843.6 1(+0.09) 38836.87 (-0.10)
38187_97(-0.11)
3
38836.87(-O-10)
414+515
413'514 422 '523 423+524 432-533 431-532 440- 541 44~ -542
38712.57 (-0.03)
a) Not observed because of experimental conditions_ rotational constants B and C In addition to the “dual” assignment (table 2) this introduces a second source of error although probably small.
Table 3 Ground state rotational transitions in MHz of gaseous r2CHD=12C=soSe and ‘2CHD=12C=78Se as observed in 34 and 17% abundance at 26.5-40 GHz. room temperature and a total pressure of = 15 mtorr (flow system). Calculated frequencies from constants of table4 Transition
Table 2 Ground state rotational transitions in MHz of gaseous ‘*CH? =13C=80Se and UCH2=12C=80Se as observed in natural abundance (0.5%) at 26.5-40 GHz, room temperature
and a total pressure of ~40 mtorr (flow system). Calculated frequencies from constants of table4 Transition
313-414 3 12'413
-414'515 413 -514
‘*CHa &C=a’JSe
rsCH2=raC=soSe
obs
obs.talc.
obs.
30343.16
(0.05)
29337.05( 0.05)
30552.2 (a)
(-0.41)
30553.5@) (+0.38) 37928.76 (-0.04) (a) (+0.33) 38191.0 (0)
(-0.30)
obs.cak.
29535_46(-0.01) 36671.12(-O-011) 36919.25 (
0.01)
t2CHD=r2C=SoSe
r2CHD=‘2C=78Se
obs.
obs.
ohs.C&Z
303 '404 312-413 313 - 414 322 A 42s 321-+421
330 -431 331-432 404-505 414-51s 413-514 422-z523 423-524 432-533 431'532 440- 541 441-542
28723.63 (-0.02) 28860.21 (-0.02) 28586.53 (+0.02) 28722.21 (+O.lO) 28722.21 (-0.09) 28720.02(+0.01) 18720.01(+0.01) 35904.33 (-0.02) 35733.00 (-0-03) 36075.18 (i-0.00) 35902.73 (-0.18)
35902.73 35900.00 35900.00 35896.15 35896.15
(+0.20) (+0.04) (+O-O4)
(-0.03)
(-0.03)
ohs.cdc.
28889.15 29027.29 28750.44 28887.72 28887.72 28885.50 28885.50 36111.19 35937.88 36284.00 36109.58 36109.58 36106.81 36106.81 36102.92 36102.92
(-0.02) (-0.03) (-0.01) (t0.11) (-0.08) (+O.Ol) (+O.Ol) (-0.01) (-0.03) (-0.01) (-0.17) (+0.20) (‘0.04) (+O.O4) (-0.03) (-0.03)
37
Volume
CHEMICAL
55, number 1
PHYSICS
LETTERS
i Abiil
I978
Table S Atomi~~coordinate‘s of selenoketeiie in the principal ax@ system of UCH~+!2C=so~Se~in A units; co&&& x&?z** b&g the “heavy atdm”a&. BondI&igtI&ZnA &its, ai@es & degrks
Comparison to earlier model [ 1 j Se Cl
Fig. 1. Atomic numbering in S-deuterio-1,2,3-selenodiiole (left) and in 2-deuterioseIenoketene.
c2 H
3. Structure
1.70687 1.70536 1.30279 1.30430 1.0908 119.74
Se=C C=C CH HCH
and
0.9434
(a) (P) (p>
1.70169 1.3131s 1.oa3a) 122.58
a) As taken from ketene [4 1_
1,
(z~-Z;+Z~-z,)(z~-z~-z,)
_[
0.00
Second model of ref: [ 11
Atomic coordinates (a. b) of selenoketene in the principal axes system of 12CH2=t2C=*oSe have been taken as
b=
0.00 0.00
-0.60119 1.10568 (a) 1.10417 (8) 2.40847 2.9560
U2
p(zzb -Z,)
the latter being used only for hydrogen since the ‘%“axis coincides with 12C=12C=80Se. Ib, I, are parental moments of inertia, Zi, I,* being moments of isotopic species, p = A.ntM/(M+Am) etc. [3]. Introduction of an assumed inertial defect Z, -Zb -Z, < 0.20 u A2 had no appreciable effect on the coordinates_ Since all the species are close to symmetric tops (K <-O-999) experimental values of Z, are nor available. Values of
(a, b), of interatomic distances and bond angles are reported in table4. The structure of selenoketene derived earlier [l] was compared to several molecules. The now available “rs” structure of selenoketene may, in addition, be compared to an “r. ” structure of allene, CH,=C=CH,
PI
Table 4 Ground state rotational constants (MHz) and distortion constants (kHz) of seven isotopic species cf selenoketene Species (% abundance)
Aoa)
1~CH~=‘2C=82Se t2CH, =12C=76Se ‘2CH,=*2C=77Se
(9.0)
280384
‘2CH,=‘3C=80Se
(0.5)
(9.2)
(7.6)
13&j2=12~,80~,
”
‘2CHD=*ZC=80Se **CHD=t2C=‘*Se
(0.5)
(34) (17)
280419
280384 (284358 (a) 283656 (8) 280444 191953 191956
c,,W
Bob) 3847.0278
3912.8994
+ 0.017
+ O.Oi7
3901.1957 c 0.016 38322781d)+ 0.046 3832.3732d)c 0.043 m&t4s6‘h 0.0054 3624.7085 3645.7990
f 0.016 %0.017
AJK
3793.5409
90.12 93.36 89.56
3857.5718
3846.1962 3779.9035dj 3779.8717d) 3654.8287d) 3556.2789 3576.5796
3
a) Arbitrarily assumed inertial defect of 0.05 u A*. b, Conversion factor-to u A2 = 505376. d)Constants obtained by fitting only 4 observed transitions. e, Taken from UCHi=12C=80Se
38
BJ + 0.48 * 0.48 f 0.82
0.72 0.93 0.79
91.29e)
0,46 e)
91.29e) 53.64 f 0.47 .S4.21 -c0.48 Cl iimiti [l].
20.30 r0.30 r0.31
-
OA6e) 0.43 * 0.29 0.62 +0:30
of error as for Bo.
Volume 55, number 1
LHCH (de&
CHEMICAL
PHYSICS LETTERS
1 April 1978
selenoketene
allene
from the (o) and (~3) coordinates of table 5_ It corresponds to a C=C distance of 1.3097 A.
119.74
118.10
References
Most of the discrepancy might mainly be due to an expected difference between the “ro” structure and a future “f ” structure of allene. An ‘6 coordinate for CL may titernatively be fiied by using the Kraitchman coordinates for Se, C2 and H in a “first moment” condition Cm,Qi = 0. This results in a(C1) = 1.09878 A, deviating about 0.005 A
B. Bak, 0. Nielsen, H. Svanholtand A. Helm. Chem. Phys. Letters 53 (1978) 37’4. [2] I. Lalezari, A. Shaffiee and M. Yalpani, J. Org. Chem. 36 (1971) 2836. [3] J. Kraitchman, Am. J. Phys 21 (1953) 17. [4] A.P. Cox, L.F. Thomas and J. Sheridan, Spectrochim. Acta 15 (1959) 542. [5] A-G. Yaki and R-A. Toth, J- Mol. Spectry. 17 (1965) 136. [l]
39
CHEMICAL
55, number 1
SELENOKETENE
PHYSICS
LETTERS
1 April 1978
SUBSTITUTION STRUCTURE
B$rge BAK, Ole J. NIELSEN, Henrik SVANHOLT Cilemical Laboratory V, T12eH.C. &ted DK--3100 Copenhagen 0, Denmark
hstitrtte.
University of Copenhagen.
Chemical Laboratory II, The h’.C. @xted Institute, DK-2100 Copenhagen #, Denmark
University of Copenlragen.
and Ame HOLM
Received 3 January
1978
hlic:owave studies (26.5-40GHz) of further isotopic species of selenoketene formed by pyrolysis of 1,2,3-selenodiazole (12CH2=I’C=76.7’,a’Se, t2CHt=‘sC=auSe and tsCfi2=t2C= *OSe) and by pyrolysis of S-deuterio-1.2.3~selenodiazole has been (t2CHD=1zC=7s~goSe) are reported_ In conjunction with earlier results for 12Cf-iZ=12C=78~a0Se an restructure derived with distances Se=C (1.706 a), C=C (1.303 A), C-H (1.0908 A) and a HCH bond angle of1 19.7O. The geometry of the CHa XC moiety of selenoketene is closer to aUene, CH2 =C=CHa, than to ketene, CHa =C=O.
1. Experimental
2. Assignments
Observations in the 1840 GHz region of pure rotational transitions of two isotopic species of selenoketene, 12CHZ=12C=78~80Se [l] have been contimred by similar observations betweln 26.5 and 40 GHz for seven further isotopic species (tables I-3). Among these, 12CHD=12C=78*80Se are the most important for a molecular structure determination of selenoketene independent of assumed geometric parameters in contrast to what was possible earlier El]_ 2-deuterioselenoketene (fig. 1) was prepared by pyrolysis [I] of an available 1:2 mixture of 1,2,3selenodiazole and its S-deuterio derivative (fig. 1). This derivative was obtained by replacing CH,CHO, used in the synthesis of 1,23-selenodiazole [2] by CD&HO with the above-mentioned 1:2 mixture as a result_ In the microwave spectrum of the pyroiytic products no transitions from 12CD2=12C=80Se were observable. This indicates that an organized transfer of deuterium from C(5) to C(4) (fig. 1) is taking place. Except for the deuterated species all observations were carried out with molecular species in natural abundance_
Intensity criteria based on the abundance of molecular species (as given in tabIe4) and precalculated positions using the second model of selenoketene in ref. [l] served to estab!ish the unambiguous assignments of tables 1 and 3. The discrepancies between precalculated and observed transitions of the mono-deuterated species were 20 -30 MHz, clearly showing the possibiiity of deriving an improved structure. Table 2 contains the few data observed by us for the most abundant UC-containing species (0.5%). A final assigniient of the 3t2+4t3 transition in QCH?=13C=80Se pro ved impossible since two candidates appeared at 1.3 MHz interval in the low-frequency wing of the much stronger 330+4~~ transition in ECH2=*2C=82Se (table 1) at 30555.70 MHz. These alternative assignments are iabelied OLand 9 in table 2, with corresponding labels-on the derived rotational constants in table 4. Appropriate rotational and distortion constants of the seven isotopic species are given in table 4. Distortion constants of the J3C containing species were taken from parental 12CH2=12C=80Se in order to fix the
36
Volume 55. number L
CHEMICAL
PHYSICS
LETTERS
1 April 1978
Table 1 Ground state rotational transitions in MHz of gaseous ‘2CHa=12C=82Se, t*CHa=‘*C=“Se and t2CHa=‘2C=76Se as observed in natumL abundance (9.2:7.6:9-O%) at 26.5-40 GHz, room temperature and a total pressure of = 15 mtorr (Row system). Calculated frequencies from constants of table4 r2CH2= 12C=82Se
Transition
obs.
ohs.-talc.
-___
‘*CH2=**C=“Se
12CH2=‘2C=76Se
obs.
obs.
ohs.-talc.
ohs.-talc.
303 - 404 312 -413
30561.93 (-0.08) 30668.30 (-0.03)
30989.29 (+O.Ol) 3 1098.56 (-0.07)
31081.44 (-0.12) 31191.49 (-0.05)
313 '414
30454.36 (-0.02)
30878.69 (+0.06)
30970.17(-0.06)
322 - 423 321 - 452
30559.22 (+0.02) 30559.22 (-0.06)
30984.54 (+0.05) 30986.54 (-0.04)
3 1078-75 (+O. 10) 31078.75 (+0.02)
330d431 331+432 404 '50s
30555.70(+0.08) 30555.70<+0.08) 38202.27 (-0.06) 38067.79 (-0.04) 38335.23 (-0.03) 38199.00(-0.02) 38199_00(+0.14) 38194.51 (t0.11)
a) 3) 38736.39(-0.01) 38598.04 (-0.10) 38873.14(+0.01) 38733.13(+0.00) 38733.13(+0_17) 38728.50(-0.03)
31075.00(+0.06) 31075_00(+0_06) 38851.69(-0.03) 38989.20(-0.04) 38848.28(-0.04) 38848.28(-0.02) 38843.61(+0.09)
38194.51 (+O.ll) 38187.97 (-0.11)
38728.50 (-0.03) a)
38843.6 1(+0.09) 38836.87 (-0.10)
38187_97(-0.11)
3
38836.87(-O-10)
414+515
413'514 422 '523 423+524 432-533 431-532 440- 541 44~ -542
38712.57 (-0.03)
a) Not observed because of experimental conditions_ rotational constants B and C In addition to the “dual” assignment (table 2) this introduces a second source of error although probably small.
Table 3 Ground state rotational transitions in MHz of gaseous r2CHD=12C=soSe and ‘2CHD=12C=78Se as observed in 34 and 17% abundance at 26.5-40 GHz. room temperature and a total pressure of = 15 mtorr (flow system). Calculated frequencies from constants of table4 Transition
Table 2 Ground state rotational transitions in MHz of gaseous ‘*CH? =13C=80Se and UCH2=12C=80Se as observed in natural abundance (0.5%) at 26.5-40 GHz, room temperature
and a total pressure of ~40 mtorr (flow system). Calculated frequencies from constants of table4 Transition
313-414 3 12'413
-414'515 413 -514
‘*CHa &C=a’JSe
rsCH2=raC=soSe
obs
obs.talc.
obs.
30343.16
(0.05)
29337.05( 0.05)
30552.2 (a)
(-0.41)
30553.5@) (+0.38) 37928.76 (-0.04) (a) (+0.33) 38191.0 (0)
(-0.30)
obs.cak.
29535_46(-0.01) 36671.12(-O-011) 36919.25 (
0.01)
t2CHD=r2C=SoSe
r2CHD=‘2C=78Se
obs.
obs.
ohs.C&Z
303 '404 312-413 313 - 414 322 A 42s 321-+421
330 -431 331-432 404-505 414-51s 413-514 422-z523 423-524 432-533 431'532 440- 541 441-542
28723.63 (-0.02) 28860.21 (-0.02) 28586.53 (+0.02) 28722.21 (+O.lO) 28722.21 (-0.09) 28720.02(+0.01) 18720.01(+0.01) 35904.33 (-0.02) 35733.00 (-0-03) 36075.18 (i-0.00) 35902.73 (-0.18)
35902.73 35900.00 35900.00 35896.15 35896.15
(+0.20) (+0.04) (+O-O4)
(-0.03)
(-0.03)
ohs.cdc.
28889.15 29027.29 28750.44 28887.72 28887.72 28885.50 28885.50 36111.19 35937.88 36284.00 36109.58 36109.58 36106.81 36106.81 36102.92 36102.92
(-0.02) (-0.03) (-0.01) (t0.11) (-0.08) (+O.Ol) (+O.Ol) (-0.01) (-0.03) (-0.01) (-0.17) (+0.20) (‘0.04) (+O.O4) (-0.03) (-0.03)
37
Volume
CHEMICAL
55, number 1
PHYSICS
LETTERS
i Abiil
I978
Table S Atomi~~coordinate‘s of selenoketeiie in the principal ax@ system of UCH~+!2C=so~Se~in A units; co&&& x&?z** b&g the “heavy atdm”a&. BondI&igtI&ZnA &its, ai@es & degrks
Comparison to earlier model [ 1 j Se Cl
Fig. 1. Atomic numbering in S-deuterio-1,2,3-selenodiiole (left) and in 2-deuterioseIenoketene.
c2 H
3. Structure
1.70687 1.70536 1.30279 1.30430 1.0908 119.74
Se=C C=C CH HCH
and
0.9434
(a) (P) (p>
1.70169 1.3131s 1.oa3a) 122.58
a) As taken from ketene [4 1_
1,
(z~-Z;+Z~-z,)(z~-z~-z,)
_[
0.00
Second model of ref: [ 11
Atomic coordinates (a. b) of selenoketene in the principal axes system of 12CH2=t2C=*oSe have been taken as
b=
0.00 0.00
-0.60119 1.10568 (a) 1.10417 (8) 2.40847 2.9560
U2
p(zzb -Z,)
the latter being used only for hydrogen since the ‘%“axis coincides with 12C=12C=80Se. Ib, I, are parental moments of inertia, Zi, I,* being moments of isotopic species, p = A.ntM/(M+Am) etc. [3]. Introduction of an assumed inertial defect Z, -Zb -Z, < 0.20 u A2 had no appreciable effect on the coordinates_ Since all the species are close to symmetric tops (K <-O-999) experimental values of Z, are nor available. Values of
(a, b), of interatomic distances and bond angles are reported in table4. The structure of selenoketene derived earlier [l] was compared to several molecules. The now available “rs” structure of selenoketene may, in addition, be compared to an “r. ” structure of allene, CH,=C=CH,
PI
Table 4 Ground state rotational constants (MHz) and distortion constants (kHz) of seven isotopic species cf selenoketene Species (% abundance)
Aoa)
1~CH~=‘2C=82Se t2CH, =12C=76Se ‘2CH,=*2C=77Se
(9.0)
280384
‘2CH,=‘3C=80Se
(0.5)
(9.2)
(7.6)
13&j2=12~,80~,
”
‘2CHD=*ZC=80Se **CHD=t2C=‘*Se
(0.5)
(34) (17)
280419
280384 (284358 (a) 283656 (8) 280444 191953 191956
c,,W
Bob) 3847.0278
3912.8994
+ 0.017
+ O.Oi7
3901.1957 c 0.016 38322781d)+ 0.046 3832.3732d)c 0.043 m&t4s6‘h 0.0054 3624.7085 3645.7990
f 0.016 %0.017
AJK
3793.5409
90.12 93.36 89.56
3857.5718
3846.1962 3779.9035dj 3779.8717d) 3654.8287d) 3556.2789 3576.5796
3
a) Arbitrarily assumed inertial defect of 0.05 u A*. b, Conversion factor-to u A2 = 505376. d)Constants obtained by fitting only 4 observed transitions. e, Taken from UCHi=12C=80Se
38
BJ + 0.48 * 0.48 f 0.82
0.72 0.93 0.79
91.29e)
0,46 e)
91.29e) 53.64 f 0.47 .S4.21 -c0.48 Cl iimiti [l].
20.30 r0.30 r0.31
-
OA6e) 0.43 * 0.29 0.62 +0:30
of error as for Bo.
Volume 55, number 1
LHCH (de&
CHEMICAL
PHYSICS LETTERS
1 April 1978
selenoketene
allene
from the (o) and (~3) coordinates of table 5_ It corresponds to a C=C distance of 1.3097 A.
119.74
118.10
References
Most of the discrepancy might mainly be due to an expected difference between the “ro” structure and a future “f ” structure of allene. An ‘6 coordinate for CL may titernatively be fiied by using the Kraitchman coordinates for Se, C2 and H in a “first moment” condition Cm,Qi = 0. This results in a(C1) = 1.09878 A, deviating about 0.005 A
B. Bak, 0. Nielsen, H. Svanholtand A. Helm. Chem. Phys. Letters 53 (1978) 37’4. [2] I. Lalezari, A. Shaffiee and M. Yalpani, J. Org. Chem. 36 (1971) 2836. [3] J. Kraitchman, Am. J. Phys 21 (1953) 17. [4] A.P. Cox, L.F. Thomas and J. Sheridan, Spectrochim. Acta 15 (1959) 542. [5] A-G. Yaki and R-A. Toth, J- Mol. Spectry. 17 (1965) 136. [l]
39