Supporting Information
Iminopropadienones RN=C=C=C=O and Bisiminopropadienes RN=C=C=C=NR:
Matrix Infrared Spectra and Anharmonic Frequency Calculations
Didier Bégué,*† Isabelle Baraille, † Heidi Gade Andersen,‡ and Curt Wentrup*‡
Institut des Sciences Analytiques et de Physico-Chimie pour l’Environnement et les Matériaux,
†
Equipe Chimie Physique, UMR 5254, Université de Pau et des Pays de l'Adour, 64000 Pau,
France and
‡
School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane,
Queensland 4072, Australia.
E-mail: didier.begue@univ-pau.fr, wentrup@uq.edu.au
Contents:
Figure S1. MeNCCCO 1a formed by FVT of 4a at 650 oC
p S2
Figure S2. MeNCCCO 1a formed by FVT of 5 at 800 oC
p S3
o
Figure S3. PhNCCCO 1b formed by FVT of 2b (X = NMe2) at 600 C
p S4
Figure S4. PhNCCCNPh 9 generated by FVT of 8 at 800 oC
p S5
Experimental Section
p S6
Computational data
p S7
Table S1 Experimental and calculated wavenumbers of Ph-NCCCO 1b and isotopomers p S9
Table S2 Experimental and calculated wavenumbers of PhNCCCNPh 9 and isotopomers p S10
References
p S11
S
1
Figure S1. IR spectrum of MeN=C=C=C=O 1a formed by FVT of
5-[bis(methylamino)methylene]-Meldrum’s acid 4a at 650 oC and isolated in Ar matrix at 14 K.
W: water; C: CO2 (2340, 2345 cm-1), CO (2138 cm-1), A: acetone; D: dimethylamine.
Thermolysis is not complete at this temperature. A significant quantity of the oxoketnimine
intermediate I (Me2N-CO=CH=C=N-Me) (see Scheme 2) is seen at 2076 cm-1 MeNC3O 1a has
bands at 2279 (vs, NCCCO asym stretch), 2269, 2243, 2184, 2163 (NCCCO sym stetch), 1611,
1418, and 1137 cm-1 (vw) (compare with Figure 1).
S
2
P
2.0
1.8
1.6
1.4
A
M
1.2
S
1.0
M
0.8
a
0.6
b
M
P
S
0.4
0.2
4000
M
M
3000
2000
1500
1000
400
Figure S2. IR spectrum of a mixture of methyliminopropadienone 1a and (2pyridyl)iminopropadienone 7 (Ar matrix, 10 K), generated by FVT of the pyridopyrimidinone 5
at 800 oC according to Scheme 3. M = Me-N=C=C=C=O 1a (2915 (w), 2279, 2269, 2245, 2225,
2184, 2164, 2126, 1417, 1137 (w), 558 (vw) cm-1), P = 2-pyridyl-N=C=C=C=O 7 (2249 (vs),
2128 (vw), 1611, 1594, 1587, 1567, 1459, 1433, 1261, 776 cm-1); for spectra of pure 7 see
reference 1 below. S = Starting material 5 (1712, 1288 cm-1), a = carbon dioxide (2345, 2340 cm1
), b = carbon monoxide (2138 cm-1). Methylamine: 3415 (w), 3352 (w), 797 (s) cm-1. 2Aminopyridine: 3535 (m), 3429 (m), 3074 (w), 3031 (w), 1611 (vs), 1608 (vs), 1586 (w), 1575
(m), 1497 (w), 1484 (s), 1445 (s), 1317 (m), 1273 (w), 1149 (w), 987 (w), 846 (w), 803 (w), 785
(w), 772 (w), 765 (w), 735 (w), 519 (w), 419 (w), 403 (m) cm-1.
S
3
Figure S3. IR spectrum of PhN=C=C=C=O 1b formed by FVT of
5-[(dimethylamino)(phenylamino)methylene]-Meldrum’s acid 2b (X = NMe2) at 600 oC and
isolated in Ar matrix at 15 K. W: water; D: dimethylamine, C: CO2 (2340, 2345 cm-1), CO (2138
cm-1), A: acetone. PhNCCCO 1b has bands at 2247 (s), 2243 (s), ca. 2220 (shoulder), 2140 (vw),
2042 (w), 1633 (m), 1620 (m), 1490 (m), 1284 (w), 1210 (w) cm-1 (see Figure 4 for details).
S
4
Figure S4. IR spectrum of bis(phenylimino)propadiene 9 generated by FVT of
4-[(dimethylamino)(phenylamino)methylene]-3-phenylisoxazol-5(4H)-one 8 at 800 oC and
isolated in Ar matrix at 12 K. 9 has bands at 2175 (vs), 2162 (vs), 2156 (vs), 2138 (w), 2060 (w),
1584 (s), 1450 (w), 1445 (w), 1287 (vw), 1144 (vw), 1074 (vw) cm-1.
S
5
Experimental Section
The starting materials 2b,2,3 4a,b,c,3,4 55 and 86 were prepared according to literature procedures.
Apparatus and methodology for FVT and matrix isolation were as reported previously.7
Preparation of methyliminopropadienone 1a
(a) From 5-[(dimethylamino)(methylamino)methylene]-2,2-dimethyl-1,3-dioxane-4,6-dione 4c.
A sample of 4c (10 mg, 0.04 mmol) was placed in the sublimation zone of the FVT apparatus 7,8
connected to the closed-cycle liquid He cryostat. The apparatus was evacuated at 10-5 hPa. The
temperature of the quartz pyrolysis tube was 500-800 oC. The sample was heated to 100 oC and
gently sublimed in a steam of Ar. The products of FVT were isolated in Ar on BaF2 or CsI disks
at 14 K. The spectra resulting from the FVT reactions at 800 and 600 oC are shown in Figures 1
and S1, respectively. MeNC3O 1a: 2279 (vs) (as NCCCO), 2269, 2243, 2224, 2214 (shoulder),
2184, 2163 (s NCCCO), 2126, 1611 and 1418, 1445 (vw), 1433 (vw), 1137 (vw), 1018 (vw) and
558 (vw) cm-1. CO2: 2345 and 2340 cm-1; CO: 2138 cm-1; acetone: 1721, 1361, 1216, 1094, 883
cm-1; dimethylamine: 3193, 2973, 2838, 2793, 2789, 1482, 1478, 1457 cm-1.
(b) From 2-methylamino-4H-pyrido[1,2-a]pyrimidin-4-one 5
The pyridopyrimidinone (ca. 10 mg) was subjected to FVT in the apparatus described above at a
pressure of 10-5 hPa and a sublimation temperature of 80-90 oC. The products were isolated in Ar
at 7 K. At an FVT temperature of 700 oC, mainly unchanged starting material (1711 cm-1) was
obtained. At 800-900 oC a mixture of starting material (1712, 1288 cm-1), methylamine (3415
(w), 3352 (w), 797 (s) cm-1), 2-aminopyridine (1484 and 1445 cm-1), 1a and 7 was isolated.
Methyliminopropadienone 1a: 2915 (w), 2279, 2269, 2245, 2225, 2184, 2164, 2126, 1417, 1137
(w), 558 (vw) cm-1. 2-Pyridyliminopropadienone, 2Py-N=C=C=C=O 7:7 2249 (vs), 2128 (vw),
1611, 1594, 1587, 1567, 1459, 1433, 1261, 776 cm-1. Starting material 5:. CO2: 2345, 2340 cm-1.
CO 2138 cm-1. The spectrum from the FVT at 800 oC is shown in Figure S2.
Phenyliminopropadienone
1b
was
generated
by
FVT
of
5-
[(dimethylamino)(phenylamino)methylene]-2,2-dimethyl-1,3-dioxane-4,6-dione2,3,8 2b (X =
NMe2) at 600 oC and isolated in Ar matrix at 15 K as described above. IR (Ar, 15 K): 2247 (vs),
2243 (vs), ca. 2220 (w, shoulder), 2140 (w), 2042 (w), 1633 (m), 1620 (m), 1490 (m), 1284 (w),
1210 (w) cm-1 (see Figure S3 and Figure 4).
S
6
Bis(phenylimino)propadiene 9 was generated by FVT of
4-[(dimethylamino)(phenylamino)methylene]-3-phenylisoxazol-5(4H)-one 8 at 800
o 6
C
and
isolated in Ar matrix at 18 K as described above. IR (Ar, 12 K): 2175 (vs), 2162 (vs), 2156 (vs),
2138 (w), 2060 (w), 1584 (s), 1450 (w),1445 (w), 1287 (vw), 1144 (vw), 1074 (vw) cm-1 (see
Figure S3 and Figure 6). When the thermolysate was isolated neat, without Ar, it showed a
strong, broad, unresolved peak around 2150 cm-1, which disappeared on warming to -70 to -60
o
C.
Computational Data
See references 9-11 for details, and reference 12 below for post-anharmonic corrections.
LCCSD(T)/cc-pVTZ optimized structures (Cartesian coordinates) :
Bent Me-NCCCO structure 1a’
C
N
C
C
C
O
H
H
H
0.987370
0.055450
-1.251380
-2.529510
-3.678980
-4.683570
1.999220
0.701780
0.952130
0.049340
-0.150520
-0.336510
-0.405730
0.157390
0.737390
0.170100
0.942610
-0.816500
-0.2886
-1.40775
-1.40775
-1.40775
-1.40775
-1.40775
-0.6755
0.26693
0.37261
Linear Me-NCCCO structure 1a
C
N
C
C
C
O
H
H
H
0.000003
0.000194
0.000096
0.000003
0.000048
-0.000102
-0.000141
-0.890543
0.890528
0.006806
-0.080773
0.618691
1.263215
1.931042
2.545389
-0.997801
0.537274
0.537127
0.005693
1.446954
2.422559
3.542836
4.627414
5.627881
-0.413201
-0.337523
-0.337764
B3LYP/6-31G* optimized structures (Cartesian coordinates):
Me-NCCCO 1a
C
N
C
C
-2.97963
-1.68148
-0.50221
0.78177
0.25235
-0.35221
-0.16949
-0.07922
0.00000
0.00000
0.00000
0.00000
S
7
C
O
H
H
H
2.04371
3.20963
-3.74444
-3.11206
-3.11206
0.02943
0.1303
-0.52394
0.87428
0.87429
0.00000
0.00000
-0.00001
0.88985
-0.88983
Ph-NCCCO 1b
C
N
C
C
C
O
C
C
C
C
C
H
H
H
H
H
-0.92084
0.40041
1.55368
2.81233
4.05367
5.19702
-1.93897
-3.26968
-3.59453
-2.57709
-1.24283
-1.67343
-4.05554
-4.6334
-2.8227
-0.44846
-0.30128 -0.00001
-0.72456 -0.00002
-0.39539 -0.00007
-0.14853 -0.00004
0.1138 0.00001
0.35596 0.00006
-1.26174 0.00001
-0.85652 0.00003
0.49969 0.00002
1.45487 0.00000
1.0643 -0.00002
-2.31259 0.00002
-1.60442 0.00005
0.8115 0.00003
2.51177 -0.00001
1.80275 -0.00003
Ph-NCCCN-Ph 9
C
N
C
C
C
N
C
C
C
C
C
H
H
H
H
H
C
C
C
C
C
C
H
H
H
H
H
3.60116 -0.29217 0.25947
2.41657 -0.92902 0.63888
1.2492 -0.84886 0.28263
0.00000 -0.85425 0.00000
-1.2492 -0.84886 -0.28264
-2.41657 -0.92901 -0.63889
4.78474 -0.65500 0.91694
5.98791 -0.04429 0.56983
6.02236 0.92906 -0.43115
4.84157 1.29034 -1.08696
3.63388 0.68708 -0.74858
4.74037 -1.41318 1.69229
6.90163 -0.33032 1.08347
6.96192 1.40343 -0.6998
4.86153 2.04659 -1.86718
2.71269 0.96246 -1.25442
-3.60116 -0.29217 -0.25947
-4.78474 -0.65499 -0.91695
-3.63388 0.68707 0.74859
-4.84157 1.29033 1.08697
-6.02236 0.92905 0.43115
-5.98791 -0.04429 -0.56983
-4.74036 -1.41317 -1.69231
-2.71269 0.96244 1.25443
-4.86153 2.04658 1.8672
-6.96192 1.40343 0.6998
-6.90163 -0.33031 -1.08348
S
8
Table S1. Experimental and calculated wavenumbers for Ph-NCCCO 1b and its isotopomers.
mode
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
description
CCO
CCC cycle
CH cycle
CCC cycle +
CNC
CH cycle
CH cycle
CCC + NCCCO
CH cycle
CH cycle
CH cycle
CCC cycle
CH cycle
CH cycle
CH cycle
CH cycle
CCC + CN
CC cycle
CC cycle + CH
Intensity (km/mol)
a
b
c
23.6
4.5
31.6
I13C)
I15N)
+3
-1
-1
+1
8.7
66.7
0.1
7.4
5.3
0.1
0.3
0.6
3.0
11.1
0.7
6.2
15.6
14.8
-3
+2
-2
+9
+1
-2
+8
+1
Wavenumber (cm-1)
exp
a
d
1210
1284
e
13C)
15N)
583
618
680
-17
-1
-1
684
-5
-4
-8
-9
-4
-1
-2
-1
733
807
869
883
945
961
984
1007
1053
1148
1157
1187
1259
0.2
1310
3.0
1426
cycle
19
20
21
22
23
24
25
CC cycle
CC cycle +
NCCCO
CC cycle
CC cycle
NCCCO
sym, NCCCO
 asym, NCCCO
37.5
+2
+3
10.3
62.2
255.2
24.6
>500
-3
+71
-3
+1
-2
+37
-14
1490
1458
1620 – 1633
2143 - 2140
2243/2247
1544
1561
1627
2135
2254
+1
-20
-37
-30
-16
-16
-3
a : B3LYP/6-31G*
b : I (km/mol) = I(Ph-NCC13CO) - I(Ph-NCCCO)
c : I (km/mol) = I(Ph-15NCCCO) - I(Ph-NCCCO)
d :  (km/mol) = (Ph-NCC13CO) - (Ph-NCCCO)
e :  (km/mol) = (Ph-15NCCCO) - (Ph-NCCCO)
S
9
Table S2. Experimental and calculated wavenumbers for Ph-NCCCN-Ph 9 and its isotopomers.
mode
description
Intensity (km/mol)
a
b
c
I13C)
1
2
3
4
5
6
7
NCCCN
NCCCN
CCC
CCC
CH cycle
CH cycle
CCC + CNC
12.2
350.8
0.3
9.6
14.0
14.0
Wavenumber (cm-1)
exp
a
d
I15N)
532
534
600
603
666
668
+2
-3
10.8
668
47.6
46.2
733
736
10.0
757
0.0
0.0
4.4
4.4
803
803
876
876
0.0
882
0.0
0.1
0.2
0.2
3.3
0.1
7.7
0.7
3.8
23.0
33.9
0.2
2.8
0.4
31.7
9.3
65.3
0.1
5.2
0.1
927
927
945
945
967
967
998
998
1046
1046
1128
1138
1138
1141
1156
1224
1261
1262
1299
1299
e
13C)
15N)
-30
-5
-12
+5
-3
(NCCCN)
8
9
10
CH cycle
CH cycle
CCC + CNC
(NCCCN)
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
CH cycle
CH cycle
CH cycle
CH cycle
respiration+
CC (NCCCN)
CH cycle
CH cycle
CH cycle
CH cycle
CCC
CCC
CH cycle
CH cycle
CH cycle
CH cycle
CH cycle + CN
CH cycle
CH cycle
CH cycle
CH cycle + CN
CH cycle + CN
CC cycle
CC cycle
CC cycle
CC cycle
1074
1144
1287
-3
S 10
45
CC cycle
CC cycle
CC cycle
CC cycle
CC cycle
CC cycle
CC cycle + CN
CC cycle
asym, NCCCN + CC
cycle
sym, NCCCN
46
asym, NCCCN
36
37
38
39
40
41
42
43
44
0.7
12.4
83.4
15.3
2.4
59.3
1445- 1450
-4
1417
1418
1449
1453
1535
1536
1553
1557
+2
+4
+12
+4
+30
+36
170.5
+434
+78
1584
1580
-2
-13
0.3
+48
+2
2060
2156 – 2162
2175
2030
-35
-9
2168
-16
-4
39.6
1.8
>500
+2
+1
-3
a : B3LYP/6-31G*
b : I (km/mol) = I(Ph-N13CCCN-Ph) - I(Ph-NCCCN-Ph)
c : I (km/mol) = I(Ph-15NCCCN-Ph) - I(Ph-NCCCN-Ph)
d :  (km/mol) = (Ph-N13CCCN-Ph) - (Ph-NCCCN-Ph)
e :  (km/mol) = (Ph-15NCCCN-Ph) - (Ph-NCCCN-Ph)
 : The intensity of the 42 mode is predicted to be intense at the harmonic level of theory. This vibration substantially transfers her intensity to
the 44 mode.
References
1. (a) Plüg, C.; Frank, W.; Wentrup, C. J. Chem. Soc., Perkin 2, 1087 (1999) (b) H. G. Andersen,
U. Mitschke, C. Wentrup, J. Chem. Soc. Perkin 2, 602 (2001). (c) Andersen, H. G.; Wentrup, C.
Aust. J. Chem. 65, 105-112 (2011).
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1571-1573 (1999).
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Wentrup, C. J. Org. Chem. 56, 970 (1991).
4. Huang, X.; Chen, B.-C.; Ye, F.-C. Synthesis, 317 (1989).
5. Roma, G.; Braccio, M. D.; Grossi, G. C.; Ciarallo, G. J. Heterocyclic Chem. 29, 25-31 (1992).
6. Wolf, R.; Stadtmüller, S.; Wong, M. W.; Barbieux-Flammang, M.; Flammang, R.; Wentrup,
C. Chem. Eur. J. 2, 1318-1329 (1996).
7. Addicott, C.; Wentrup, C. Aust. J. Chem. 61, 592 (2008). Wentrup, C.; Kvaskoff, D. Aust. J.
Chem. 66, 286 (2013).
8. Mosandl, T.; Stadtmüller, S.; Wong, M. W.; Wentrup, C. J. Phys. Chem. 98, 1080-1086
(1994).
9. Bégué, D.; Gohaud, N.; Pouchan, C.; Cassam-Chenai, P.; Lievin, J. J. Chem. Phys. 127,
164115 (2007).
10. Bégué, D. ; Baraille, I.; Garrain, P.-A.; Dargelos, A.; Tassaing T. J. Chem. Phys. 133,
034102 (2010).
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S 11