1. Microwave Measurements of Maleimide and its Doubly Hydrogen Bonded Dimer with Formic Acid
Aaron M. Pejlovas, Onur Oncer, and Dr. Stephen G. Kukolich
Dr. Lu Kang (Kennesaw State University)
ISMS June 2016

2. Earlier Work

3. Maleimide Monomer Microwave measurements (PBFT) at 5-12 GHz
Heat sample to 70 °C
Parent, -ND (synthesized), all singly substituted 13C (natural abundance)
Determined structure

4.  = -0.054 amu Å2 (planar structure, no large amp. motions on –NH)
Parent
MP2/aug-cc-pVTZ
B3LYP/aug-cc-pVTZ
13C(1&4)
13C(2&3)
-ND
A/MHz
(12)
(16)
(18)
(13)
B/MHz
(64)
(18)
(19)
(80)
C/MHZ
(64)
(10)
(10)
(56)
DJ/kHz
0.232(24)
0.232*
DJK/kHz
0.546(54)
0.546*
14N 1.5χaa/MHz
2.4227(53)
2.2901
2.4968
2.4130(87)
2.437(12)
2.436(11)
14N 0.25(χbb- χcc)/MHz
1.3679(15)
1.3009
1.4156
1.3702(30)
1.3731(32)
1.3826(24) N 36 13 12
σ/kHz 3 4
 = amu Å2 (planar structure, no large amp. motions on –NH)

5. Maleimide – FA Dimer
Transitions measured at GHz for parent and 3 singly D substituted isoto.
FA cooled to -8 °C, maleimide and pulsed valve heated to 70 °C

6. Structure fit to determine H-bond lengths
Parent
B3LYP/aug-cc-pVTZ
-ND
D-FA
FA-OD
A/MHz
(11)
(43)
(22)
(22)
B/MHz
(41)
(70)
(54)
(55)
C/MHZ
(36)
(28)
(25)
(25)
1.5χaa/MHz
2.083(15)
2.150
1.86(11)
1.860(44)
1.694(40)
0.25(χbb- χcc)/MHz
1.1565(32)
1.1865
1.118(17)
1.136(10)
1.117(12)
DJ/kHz
0.0616(69)
0.0616*
DJK/kHz
-0.118(38)
-0.118*
DK/kHz
-1.38(16)
-1.38* N 45 19 24 20
σ/kHz 4 5
B3LYP within 0.1%!
Structure fit to determine H-bond lengths
No concerted double proton tunneling observed (singlet a- and b-type)

7.  = -0.528 amu Å2 (planar structure)
Interatomic Distance
Microwave Fit Value
Calculated (B3LYP) Value
r(H6-O13)
2.027
1.874
r(O12-H10)
1.634
1.685
COM Separation
4.06
 = amu Å2 (planar structure)

8. Acknowledgements Dr. Stephen Kukolich
Dr. Lu Kang (Kennesaw State University)
Onur Oncer
NSF
University of Arizona