1. IDENTIFICATION AND CHARACTERIZATION OF 1,2-BN CYCLOHEXENE USING MICROWAVE SPECTROSCOPY
STEPHEN G. KUKOLICH, MING SUN, ADAM M. DALY University of Arizona
JACOB S. A. ISHIBASHI, SHIH YUAN LIU
Boston College .
ISMS – 16 – WK01

2. B-N substitution in benzene and cyclohexane
AZABORINE - AROMATIC
S. Y. Liu – > OSU
PLANAR MOLECULE 0 = 0.02 amuÅ2
BOND LENGTH 1.45Å BETWEEN SINGLE AND DOUBLE BOND LENGTH
C) eqQ’s CONSISTENT WITH PARTIAL DELOCALIZATION of p ELECTRONS 2 2 2

3. B-N substitution in benzene and cyclohexane
B-N cyclohexane –synthesized by the LIU group
 Possible HYDROGEN STORAGE cmpd
IN SOLUTION (TOP) 
GAS PHASE (BOTTOM)  3 3 3

4.  Shih-Yuan Liu sent the compound synthesized as 1,2-BN Cyclohexane  (C4H12BN).1 (a)  G09 calculacations were carried out for 1,2-BN Cyclohexene (C4H10BN) [OOPS!] to predict transitions and get the structure. (b) and predict transitions Microwave transitions were found close to the calculated frequencies. 10BN Cyclohexene and11BN Cyclohexene and lines were measured in the frequency range of 5-13 GHz, Shih-Yuan Liu looked at our struture and said “You are have the WRONG COMPOUND! B and N should each have 2 H atoms.
1. Wei Luo, Lev N. Zakharov, and Shih-Yuan Liu, J. Am. Chem. Soc. 2011, 133. 4 4

5.  EXPERIMENTAL
1,2- BN Cyclohexane synthesized by the Liu lab was placed in a glass cell attached to the pulse valve and sample cell and valve heated to 50 to 90° C to obtain sufficient vapor pressure
Flygare-Balle Spectrometer – Homodyne Detection Spectra for 1,2-10BN Cyclohexene (63 lines) and 1,2-11BN Cyclohexene (83 lines) measured in GHz range
1 atm neon gas stream
Accurate values for 14N, 11B, and 10B eQq ( ij ) parameters obtained and compared with High-level ab initio calculations – G09
Nuclear spin angular momenta for Boron and Nitrogen are (11B: I= 3/2 and 14N: I = 1) They are coupled as F1 = J + I(11B) and F = F1 + I(14N), where F is the total angular momentum.

6.  The 111 000 transitions for 1,2- 11BN Cyclohexene showing the quadrupole hyperfine structure arising from 11B and 14N interactions.  F1 = J + I(11B) and F = F1 + I(14N)

7. Calculated A, B. and C and eQq for 1,2-BN cyclohexane (a) DO NOT AGREE with the EXPERIMENTAL VALUES, essentially ruling out that structure for our gas-phase experiments. .
Parameter
BN-Cyclohexane
BN-Cyclohexene
B3LYP(TZ)
Experiment
MP2(QZ) A
(2) B
(1) C
(1)
1.5 χaa (B)
0.905
-2.698(8)
-2.980
-2.804
0.25(χbb- χcc)(B)
0.266
-1.357(3)
-1.150
-1.469
1.5χaa (N)
-1.463
0.553(6)
0. 629
0.404
0.25(χbb- χcc)(N)
-0.168
1.157(2)
1.227
1.136 7 7

8. The assignment of the EXPERIMENTAL SPECTRA to BN-CYCLOHEXENE is even more clearly supported when we compare the QUADRUPOLE COUPLING ( ij ) values. The 11B ij values for Cyclohexene are close to those for Azaborine.
Parameter
Cyclohexane
Cyclohexene
Azaborine
MP2
Experiment
χaa (B)
0.603
(45)
-1.71(1)
χbb (B)
0.231
(53)
-1.33(2)
χcc (B)
-0.834
3.6135(26)
3.03(2)
χaa (N)
-0.975
0.3687(43)
0.45(1)
χbb (N)
0.152
2.1295(29)
0.25(6)
χcc (N)
0.824
(23)
-0.71(6) 8 8

9.  Results from the microwave measurements show that heating 1,2 BN cyclohexane in a 1 atm neon stream results in the loss of H2 and conversion to 1,2 BN cyclohexene.
 Comparison of the calculated rotational constants for the 1,2-BN cyclohexane and 1,2-BN cyclohexene provides confirmation that the observed spectra arise from the BN cyclohexene.
 The differences in the calculated quadrupole coupling constants for the BN cyclohexane and observed values are much more larger and provide a definitive assignment of the observed spectra to the 1,2-BN cyclohexene structure.

10. Acknowledgements:
Prof. Shih-Yuan Liu , Jacob Ishibashi – Boston College
We thank Spencer J. Carey for help in collecting some of the preliminary data for this compound and Kexin Li for NMR measurements.
N$F – We thank the National Science Foundation for Grants CHE , CHE 10 10

11. ISMS – 16 – P1531

12. Current Research Group (most)
Onur Oncer, Zunwu Zhou, David Mills, Aaron Pejlovas Adam Daly, Mandy Olmut,
Stacie Munden, Steven Edwards, Kexin Li, Steve Kukolich