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CONFORMATIONAL TRANSFORMATION
OF FIVE-MEMBERED RINGS:
THE GAS PHASE STRUCTURES OF
2-METHYLTETRAHYDROFURANVinh Van
22. June 2015
CONFORMATIONAL TRANSFORMATION OF FIVE-MEMBERED RINGS: THE GAS PHASE STRUCTURES OF 2-METHYLTETRAHYDROFURAN
2-methyltetrahydrofuran (2-MeTHF): Green Chemistry
1
[1] V. Pace, P. Hoyos, L. Castoldi, P. Domínguez de María, A. R. Alcántara, ChemSusChem 5 (2012), 1369 – 1379.[2] D. F. Aycock, Org. Process Res. Dev. 11 (2007),156 – 159.[3] M. Smoleń, M. Kędziorek, K. Grela, Catalysis Communications 44 (2014), 80 – 84.[3b] (c) www.fb.com/effe.fineart Graphical abstract of [3]. [4] Z.-Q. Duan, F. Hu, J. Biotechnol. 163 (2013), 45 – 49.
• biofuel component derived from renewable resources [1]
• promising environmentally friendly solvent
• evaluated in various fields like
• organometallics [2]
• metathesis [3]
• biosynthesis [4]
way to more eco-friendly syntheses
[3b]
2-MeTHF
CONFORMATIONAL TRANSFORMATION OF FIVE-MEMBERED RINGS: THE GAS PHASE STRUCTURES OF 2-METHYLTETRAHYDROFURAN
Five-membered rings
2
CONFORMATIONAL TRANSFORMATION OF FIVE-MEMBERED RINGS: THE GAS PHASE STRUCTURES OF 2-METHYLTETRAHYDROFURAN
Five-membered rings
2
CONFORMATIONAL TRANSFORMATION OF FIVE-MEMBERED RINGS: THE GAS PHASE STRUCTURES OF 2-METHYLTETRAHYDROFURAN
Five-membered rings
3
twist envelope
two typical ring structures
prototype: cyclopentane
envelope fold
CONFORMATIONAL TRANSFORMATION OF FIVE-MEMBERED RINGS: THE GAS PHASE STRUCTURES OF 2-METHYLTETRAHYDROFURAN
• stable twists
• most stable conformer: same tilt direction
• envelope transition states
Five-membered rings
4
[1] V. Van, C. Dindic, H.V.L. Nguyen, and W. Stahl, ChemPhysChem 16, 291–294 (2015). [2] L. Margulès, M E. Sanz, S. Kassi, D. Petitprez, G. Wlodarczak, J. C. López, J. E. Boggs, Chemical Physics 263 (2001), 1, 19−31. [3] J.L. Alonso, J. C. López, and R. M. Villamañán, J. Mol. Spectrosc. 126 (1987), 348−355.[4] H. Mouhib, V. Van and W. Stahl, J. Phys. Chem. A 117 (2013), 6652−6656.
[2] [3]
[4][1]
CONFORMATIONAL TRANSFORMATION OF FIVE-MEMBERED RINGS: THE GAS PHASE STRUCTURES OF 2-METHYLTETRAHYDROFURAN
2-Methyltetrahydrofuran (2-MeTHF)
twist
envelope
5
CONFORMATIONAL TRANSFORMATION OF FIVE-MEMBERED RINGS: THE GAS PHASE STRUCTURES OF 2-METHYLTETRAHYDROFURAN
MTH F Conformational analysis
6
MP2/6-311++G(d,p)
CONFORMATIONAL TRANSFORMATION OF FIVE-MEMBERED RINGS: THE GAS PHASE STRUCTURES OF 2-METHYLTETRAHYDROFURAN
I0.0 kJ∙ mol─1
Conformational analysis
6
below
ring plane
above
II4.4 kJ∙ mol─1
CONFORMATIONAL TRANSFORMATION OF FIVE-MEMBERED RINGS: THE GAS PHASE STRUCTURES OF 2-METHYLTETRAHYDROFURAN
Calculated molecular parameters
7
= −0.624
conformer I
conf.A
[GHz]B
[GHz]C
[GHz]μa [D]
μb [D]
μc
[D]E rel
[kJ∙mol−1]I 6.649 3.172 2.367 −0.69 1.60 0.63 0.00II 5.207 3.624 2.922 −0.26 1.76 0.80 4.36
MP2/6-311++G(d,p)
CONFORMATIONAL TRANSFORMATION OF FIVE-MEMBERED RINGS: THE GAS PHASE STRUCTURES OF 2-METHYLTETRAHYDROFURAN
Intramolecular conversion
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twist
envelope
MP2/6-311++G(d,p)
CONFORMATIONAL TRANSFORMATION OF FIVE-MEMBERED RINGS: THE GAS PHASE STRUCTURES OF 2-METHYLTETRAHYDROFURAN
Measurements
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Molecular beam Fourier transform microwave spectrometer (frequency range 2 − 26.5 GHz)
scan-mode high-resolution mode
step width: 250 kHz instrumental line width: 2 kHz
co-added decays / step: 50
CONFORMATIONAL TRANSFORMATION OF FIVE-MEMBERED RINGS: THE GAS PHASE STRUCTURES OF 2-METHYLTETRAHYDROFURAN
Assignments
10
CONFORMATIONAL TRANSFORMATION OF FIVE-MEMBERED RINGS: THE GAS PHASE STRUCTURES OF 2-METHYLTETRAHYDROFURAN
Assignments
11
A [GHz]
B [GHz]
C [GHz]
exp. 6.591 3.170 2.367
calc. 6.649 3.172 2.367
MP2/6-311++G(d,p)
CONFORMATIONAL TRANSFORMATION OF FIVE-MEMBERED RINGS: THE GAS PHASE STRUCTURES OF 2-METHYLTETRAHYDROFURAN
Molecular parameters fitted with the XIAM program
12
Parametera Unit Fit I (J ≤ 15) Fit II Fit III (J ≤ 6) MP2/6-311++G(d,p)
A GHz 6.59156823(22) 6.59156821(25) 6.59156814(18) 6.6489
B GHz 3.170370175(84) 3.17036995(14) 3.170370550(94) 3.1721
C GHz 2.367116054(88) 2.36711645(14) 2.36711598(11) 2.3673
J kHz 0.3312(13) 0.3340(21) 0.3368(20) 0.257
JK kHz 0.0641(35) 0.0822(45) 0.0703(58) 0.761
K kHz 2.855(20) 2.756(21) 2.787(14) 0.849
J kHz 0.05881(44) 0.05533(36) 0.06016(89) 0.057
K kHz 0.5322(69) 0.5516(59) 0.580(10) 0.561
HJK Hz −0.788(96)
HKJ Hz 2.83(35)
hJK Hz 0.331(46)
hK Hz −2.84(55)
kHz 2.2 3.6 1.4
N 111 111 72 a Principal axis system, Watson’s A reduction in Ir representation
CONFORMATIONAL TRANSFORMATION OF FIVE-MEMBERED RINGS: THE GAS PHASE STRUCTURES OF 2-METHYLTETRAHYDROFURAN
Methyl internal rotation
13
Only 8 decays were co-added!!!
V3 (calc) = 1142 cm─1
130 decays were co-added.
CONFORMATIONAL TRANSFORMATION OF FIVE-MEMBERED RINGS: THE GAS PHASE STRUCTURES OF 2-METHYLTETRAHYDROFURAN
Methyl internal rotation
14
Parameter Unit Fit I Fit IV (Int.Rot.)A GHz 6.59156823(22) 6.59156543(31)B GHz 3.170370175(84) 3.17040277(28)C GHz 2.367116054(88) 2.36708337(27)J kHz 0.3312(13) 0.3303(20)JK kHz 0.0641(35) 0.0706(50)K kHz 2.855(20) 2.688(18)J kHz 0.05881(44) 0.05615(38)K kHz 0.5322(69) 0.5336(61)HJK Hz −0.788(96) −0.111(16)HKJ Hz 2.83(35)hJK Hz 0.331(46)hK Hz −2.84(55)V3 cm−1 1057(14)Iα uÅ2 3.1986(fixed)
∠(i,a) ° 17.16(fixed)∠(i,b) ° 88.75(fixed)∠(i,c) ° 72.89(fixed)Dpi2J kHz 0.0178(48)Dpi2− kHz 0.00273(52) kHz 2.2 3.7N 111 138
CONFORMATIONAL TRANSFORMATION OF FIVE-MEMBERED RINGS: THE GAS PHASE STRUCTURES OF 2-METHYLTETRAHYDROFURAN
Isotopologues
15
conformer I
frequency [MHz]
unassigned
CONFORMATIONAL TRANSFORMATION OF FIVE-MEMBERED RINGS: THE GAS PHASE STRUCTURES OF 2-METHYLTETRAHYDROFURAN
“Noises?“
15
conformer I
frequency [MHz]
unassigned
CONFORMATIONAL TRANSFORMATION OF FIVE-MEMBERED RINGS: THE GAS PHASE STRUCTURES OF 2-METHYLTETRAHYDROFURAN
13C or conformer II?
16
13C isotopologue in natural abundance of 1.1 %. 97 decays were co-added.
CONFORMATIONAL TRANSFORMATION OF FIVE-MEMBERED RINGS: THE GAS PHASE STRUCTURES OF 2-METHYLTETRAHYDROFURAN
IsotopologueA
[GHz]B
[GHz]C
[GHz]parent 6.649 3.172 2.36713C(9) 6.648 3.082 2.31713C(5) 6.607 3.125 2.33613C(1) 6.590 3.136 2.34013C(4) 6.637 3.159 2.362
13C(14) 6.518 3.172 2.35118O 6.451 3.171 2.342
Assignments of the isotopologues
17
CONFORMATIONAL TRANSFORMATION OF FIVE-MEMBERED RINGS: THE GAS PHASE STRUCTURES OF 2-METHYLTETRAHYDROFURAN
Molecular parameters fitted with the XIAM program
18
Parameter Unit 13C(1) 13C(4) 13C(5) 13C(9) 13C(14)A GHz 6.53423752(71) 6.57970964(61) 6.55107431(70) 6.59028755(61) 6.46187441(69)B GHz 3.13465551(41) 3.15713442(33) 3.12372913(38) 3.08086383(37) 3.17000430(43)C GHz 2.34012997(37) 2.36130876(29) 2.33611689(36) 2.31701145(35) 2.34994423(31)J kHz 0.3235(76) 0.3318(69) 0.329(12) 0.3143(72) 0.3355(82)K kHz 2.610(59) 3.021(51) 2.696(55) 2.997(50) 2.781(53)J kHz 0.0496(44) 0.0665(30) 0.0553(27) 0.0513(48) 0.0663(35)K kHz 0.709(43) 0.596(26) 0.544(27) 0.617(56) 0.662(39) kHz 2.4 2.3 2.8 3.0 2.3N 30 33 37 37 31
CONFORMATIONAL TRANSFORMATION OF FIVE-MEMBERED RINGS: THE GAS PHASE STRUCTURES OF 2-METHYLTETRAHYDROFURAN
Search of 18O-isotopologue
19
18O isotopologue in natural abundance: 0.2 %.
6 Scans of 10 - 15 MHz
Parameter broadband scan for 13C isotopologues
broadband scan for 18O isotopologue
step width 250 kHz 200 kHz
decays / step 50 750time 50 MHz / hour 2 MHz / hour
CONFORMATIONAL TRANSFORMATION OF FIVE-MEMBERED RINGS: THE GAS PHASE STRUCTURES OF 2-METHYLTETRAHYDROFURAN
Search of 18O-isotopologue
19
18O isotopologue in natural abundance: 0.2 %.
6 Scans of 10 - 15 MHz
Parameter broadband scan for 13C isotopologues
broadband scan for 18O isotopologue
step width 250 kHz 200 kHz
decays / step 50 750time 50 MHz / hour 2 MHz / hour
CONFORMATIONAL TRANSFORMATION OF FIVE-MEMBERED RINGS: THE GAS PHASE STRUCTURES OF 2-METHYLTETRAHYDROFURAN
Search of 18O-isotopologue
20
303 202 noise
CONFORMATIONAL TRANSFORMATION OF FIVE-MEMBERED RINGS: THE GAS PHASE STRUCTURES OF 2-METHYLTETRAHYDROFURAN
Search of 18O-isotopologue
20
303 202 750 FPDs 5000 FPDs
CONFORMATIONAL TRANSFORMATION OF FIVE-MEMBERED RINGS: THE GAS PHASE STRUCTURES OF 2-METHYLTETRAHYDROFURAN
Intensities of the isotopologues
21
CONFORMATIONAL TRANSFORMATION OF FIVE-MEMBERED RINGS: THE GAS PHASE STRUCTURES OF 2-METHYLTETRAHYDROFURAN
Intensities of the isotopologues
22
1000 FPDs 5000 FPDs2 FPDs !
CONFORMATIONAL TRANSFORMATION OF FIVE-MEMBERED RINGS: THE GAS PHASE STRUCTURES OF 2-METHYLTETRAHYDROFURAN
18O-Molecular parameters fitted with the XIAM program
23
Parameter Unit parent species (Fit III) all 13C-isotopologues 18O(8)-isotopologue
A GHz 6.59156814(18) 6.462 - 6.580 6.3962301(30)
B GHz 3.170370550(94) 3.081 - 3.170 3.16966061(63)
C GHz 2.36711598(11) 2.317 - 2.361 2.34229427(70)
J kHz 0.3368(20) 0.314 - 0.336 0.332(29)
JK kHz 0.0703(58) - -
K kHz 2.787(14) 2.610 - 3.021 2.53(53)
J kHz 0.06016(89) 0.0496 - 0.0665 0.06016(fixed)
K kHz 0.580(10) 0.544 - 0.709 0.580(fixed) kHz 1.4 2.2 - 3.0 3.0N 72 30 - 37 14
CONFORMATIONAL TRANSFORMATION OF FIVE-MEMBERED RINGS: THE GAS PHASE STRUCTURES OF 2-METHYLTETRAHYDROFURAN
Microwave structure determination using Kraitchman‘s equation
24
|a|/Å |b|/Å |c|/ÅC(1) 1.34277(90) 0.8240(15) 0.118(11)C(4) 0.7290(17) 0.050(24) 0.3774(32)C(5) 1.54132(78) 0.6932(18) 0.104(12)O(8) 0.104(12) 1.0794(12) 0.1748(69)C(9) 2.15737(56) 0.019(63) 0.1231(98)
C(14) 0.1402(86) 1.24634(97) 0.039(31)
blue: experimental atom positionsgrey: MP2/6-311++G(d,p)
CONFORMATIONAL TRANSFORMATION OF FIVE-MEMBERED RINGS: THE GAS PHASE STRUCTURES OF 2-METHYLTETRAHYDROFURAN
Microwave structure determination using Kraitchman‘s equation
25
blue: experimental atom positionsgrey: MP2/6-311++G(d,p)
exp. / ° calc. / °ring plane
φ −6.48(21) −3.66envelope fold
γ' 135.715(48) 137.46
γ 139.950(54) 139.90
Place to Be – RWTH Start-Up
Acknowledgements
Prof. Dr. Wolfgang StahlRWTH Aachen University, Germany
Dr. Ha Vinh Lam NguyenLaboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), UPEC, France
JARA-HPC
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