1-Bromobutane

BrCH₂CH₂CH₂CH₃

Bromine

Nuclear Quadrupole Coupling Constants

in 1-Bromobutane, AA

Calculation of the bromine nqcc tensors in 1-bromobutane, AA was made here on a molecular structure given by MP/6-311+G(3df,3pd) optimization, and on this same structure but with empirically corrected approximate equilibrium C-C and CBr bond lengths. These calculated nqcc's are compared with the experimental values of Kim et al. [1] in Tables 1 and 2. Structure parameters are given in Table 3, rotational constants in Table 4. (Links to GA and GG conformers are given below.)

In Tables 1 and 2, subscripts a,b,c refer to the principal axes of the inertia tensor; x,y,z to the principal axes of the nqcc tensor. ETA = (X_xx - X_yy)/X_zz. Ø (degrees) is the angle between its subscripted parameters.

RMS is the root mean square difference between calculated and experimental diagonal nqcc's (percentage of the average of the magnitudes of the experimental nqcc's). RSD is the calibration residual standard deviation of the B1LYP/TZV(3df,3p) model for calculation of the efg's/nqcc's.


Table 1. ⁷⁹Br nqcc's in 1-Bromobutane, AA (MHz).

Calc (1) was made on the MP2/6-311+G(3df,3pd) optimized molecular structure.
Calc (2) was made on this same structure but with empirically corrected C-C and CBr bond lengths.

		Calc (1)		Calc (2)		Expt. [1]

X_aa		366.80		367.49		363.04(34)
X_bb		- 92.68		- 93.11		- 89.07(59) *
X_cc	-	274.12	-	274.38	-	273.97(59) *
X_ab		337.57		337.80	-	337.81(13)

RMS		3.01 (1.24 %)		3.48 (1.43 %)
RSD		1.58 (0.39 %)		1.58 (0.39 %)

X_xx	-	271.27	-	271.64	-	269.48(48)
X_yy	-	274.12	-	274.38	-	273.97(59)
X_zz		545.39		546.02		543.45(32)
ETA		0.00522		0.00501
Ø_z,a		27.88		27.86
Ø_a,CBr		27.15		27.11
Ø_z,CBr		0.73		0.75

* Calculated here from experimental X_aa and X_bb - X_cc = 184.90(113) MHz.


Table 2. ⁸¹Br nqcc's in 1-Bromobutane, AA (MHz).

Calc (1) was made on the MP2/6-311+G(3df,3pd) optimized molecular structure.
Calc (2) was made on this same structure but with empirically corrected C-C and CBr bond lengths.

		Calc (1)		Calc (2)		Expt. [1]

X_aa		306.78		307.35		303.67(33)
X_bb		- 77.76		- 78.12		- 75.23(58) *
X_cc	-	229.02	-	229.24	-	228.44(58) *
X_ab		281.81		282.00	-	282.01(20)

RMS		2.34 (1.15 %)		2.74 (1.35 %)
RSD		1.38 (0.40 %)		1.38 (0.40 %)

* Calculated here from experimental X_aa and X_bb - X_cc = 153.21(110) MHz.


Table 3. 1-Bromobutane, AA. MP2/6-311+G(3df,3pd) structure parameters (Å and degrees). Approximate equilibrium bond lengths for C-C and CBr are given in parentheses.


	C C,1,B1 C,2,B2,1,A1 C,3,B3,2,A2,1,D1,0 Br,4,B4,3,A3,2,D2,0 H,1,B5,2,A4,3,D3,0 H,1,B6,2,A5,3,D4,0 H,1,B7,2,A6,3,D5,0 H,2,B8,1,A7,3,D6,0 H,2,B9,1,A8,3,D7,0 H,3,B10,2,A9,1,D8,0 H,3,B11,2,A10,1,D9,0 H,4,B12,3,A11,2,D10,0 H,4,B13,3,A12,2,D11,0

	B1=1.5233987 (1.5212) B2=1.52519819 (1.5229) B3=1.51324964 (1.5115) B4=1.94186625 (1.9454) B5=1.08862014 B6=1.08959381 B7=1.08959381 B8=1.09216004 B9=1.09216004 B10=1.09131407 B11=1.09131407 B12=1.08688459 B13=1.08688459 A1=111.81336913 A2=111.07100665 A3=111.59062799 A4=111.41186495 A5=110.76021695 A6=110.76021695 A7=109.71371607 A8=109.71371607 A9=109.92567402 A10=109.92567402 A11=111.75030794 A12=111.75030794 D1=180. D2=180. D3=180. D4=-59.78802994 D5=59.78802994 D6=121.52991133 D7=-121.52991133 D8=-58.82931504 D9=58.82931504 D10=-61.38432848 D11=61.38432848


Table 4. 1-Bromobutane, AA. Rotational constants (MHz), ⁷⁹Br species.

	r (1) = MP2/6-311+G(3df,3pd) opt structure.
	r (2) = r (1) but with corrected C-C and CBr bond length.

		r (1)	r (2)	Expt. [1]

	A	15988.	15992.	15770.66(99)
	B	923.	923.	914.89072(63)
	C	891.	892.	883.90660(67)

[1] J.Kim, H.Jang, S.Ka, D.A.Obenchain, R.A.Peebles, S.A.Peebles, and J.J.Oh, J.Mol.Spectrosc. 328,50(2016).

S.Ka, J.Kim, H.Jang, and J.J.Oh, Abstract MG03, 70th International Symposium on Molecular Spectroscopy, Champaign-Urbana, 2015.

1-Bromobutane, GA

1-Bromobutane, GG

Table of Contents

Molecules/Bromine

1BrButane.html

Last Modified 26 Sept 2016