Bromomethyl methyl ether

CH₃-O-CH₂Br

Bromine

Nuclear Quadrupole Coupling Constants

in gauche-Bromomethyl Methyl Ether

Bromine nqcc's in g-bromomethyl methyl ether were determined by Hayashi et al. [1].

Calculation of the nqcc tensor was made here on a molecular structure given by MP2/aug-cc-pVTZ optimization and on this same structure but with empirically corrected CBr bond length. These calculated nqcc's are compared with the experimental values in Tables 1 - 4. Structure parameters are given in Table 5, rotational constants in Table 6.

In Tables 1 - 4, subscripts a,b,c refer to the principal axes of the inertia tensor; x,y,z to the principal axes of the nqcc tensor. Ø_z,CBr (degrees) is the angle between the z-principal axis and the CBr bond direction. ETA = (X_xx - X_yy)/X_zz.

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 nqcc's.


Table 1. ⁷⁹Br nqcc's in g-CH₃-O-CH₂Br (MHz).

Calc (1) was made on the MP2/aug-cc-pVTZ(G03) optimized molecular structure.
Calc (2) was made on this same structure but with empirically corrected CBr bond length.

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

X_aa		286.94		288.82		284.6(76)
X_bb		- 47.08		- 48.39		- 46.9 *
X_cc	-	239.86	-	240.43	-	237.6 *
\|X_ab\|		322.85 **		322.91 **		320.4(168)
\|X_ac\|		100.13		100.09		109.3(232)
\|X_bc\|		77.16		76.66		70.6(128)

RMS		1.9 (0.99 %)		3.0 (1.61 %)
RSD		1.58 (0.39 %)		1.58 (0.39 %)

X_xx	-	236.09	-	236.71	-	241.3(172)
X_yy	-	268.54	-	268.84	-	261.1(139)
X_zz		504.63		505.55		502.4(279)
ETA		0.0643		0.0636		0.0395(1174)
Ø_z,CBr		0.75		0.76

* Derived here from X_aa and (X_bb - X_cc)/X_aa = 0.6701(296) [1].

** The algabraic sign of the product X_abX_acX_bc is positive.


Table 2. ⁸¹Br nqcc's in g-CH₃-O-CH₂Br (MHz).

Calc (1) was made on the MP2/aug-cc-pVTZ(G03) optimized molecular structure.
Calc (2) was made on this same structure but with empirically corrected CBr bond length.

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

X_aa		240.31		241.87		237.1(61)
X_bb		- 39.87		- 40.96		- 39.5 *
X_cc	-	200.44	-	200.92	-	197.6 *
\|X_ab\|		269.47 **		269.52 **		270.1(188)
\|X_ac\|		83.60		83.58		91.4(57)
\|X_bc\|		64.31		63.90		63.9(103)

RMS		2.5 (1.57 %)		3.5 (2.19 %)
RSD		1.38 (0.40 %)		1.38 (0.40 %)

X_xx	-	197.25	-	197.76	-	201.8(104)
X_yy	-	224.36	-	224.61	-	220.5(152)
X_zz		421.60		422.38		422.3(229)
ETA		0.0643		0.0636		0.0442(1148)
Ø_z,CBr		0.75		0.76

* Derived here from X_aa and (X_bb - X_cc)/X_aa = 0.6665(287) [1].

** The algabraic sign of the product X_abX_acX_bc is positive.


Table 3. Bromine nqcc's in g-CD₃-O-CH₂Br (MHz).

Calc (1) was made on the MP2/aug-cc-pVTZ(G03) optimized molecular structure.
Calc (2) was made on this same structure but with empirically corrected CBr bond length.

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

X_aa(⁷⁹Br)		262.95		264.86		258.0(110)
X_bb		- 23.83		- 25.17		- 22.5 *
X_cc	-	239.12	-	239.69	-	235.5 *
\|X_ab\|		334.11 ***		334.26 ***		350.6(177)
\|X_ac\|		97.76		97.75
\|X_bc\|		81.38		80.87

RMS		3.6 (2.10 %)		4.9 (2.84 %)
RSD		1.58 (0.39 %)		1.58 (0.39 %)

X_aa(⁸¹Br)		220.33		221.92		218.0(93)
X_bb		- 20.51		- 21.62		- 20.7 **
X_cc	-	199.82	-	200.30	-	197.3 **
\|X_ab\|		278.90 ***		279.02 ***		299.3(108)
\|X_ac\|		81.64		81.63
\|X_bc\|		67.82		67.41

RMS		2.0 (1.37 %)		2.9 (2.00 %)
RSD		1.38 (0.40 %)		1.38 (0.40 %)

* Derived here from X_aa and (X_bb - X_cc)/X_aa = 0.8258(500) [1].

** Derived here from X_aa and (X_bb - X_cc)/X_aa = 0.8103(498) [1].

*** The algabraic sign of the product X_abX_acX_bc is positive.


Table 4. Bromine nqcc's in g-CH₃-O-CD₂Br (MHz).

Calc (1) was made on the MP2/aug-cc-pVTZ(G03) optimized molecular structure.
Calc (2) was made on this same structure but with empirically corrected CBr bond length.

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

X_aa(⁷⁹Br)		294.58		296.52		294.2(100)
X_bb		- 47.91		- 49.32		- 49.2 *
X_cc	-	246.68	-	247.20	-	245.0 *
\|X_ab\|		323.51 ***		323.50 ***		321.2(178)
\|X_ac\|		84.44		84.86
\|X_bc\|		66.52		66.07

RMS		1.2 (0.63 %)		1.8 (0.94 %)
RSD		1.58 (0.39 %)		1.58 (0.39 %)

X_aa(⁸¹Br)		246.79		248.40		245.0(80)
X_bb		- 40.66		- 41.83		- 40.6 **
X_cc	-	206.13	-	206.57	-	204.4 **
\|X_ab\|		269.96 ***		269.95 ***		272.8(179)
\|X_ac\|		70.86		70.84
\|X_bc\|		55.42		55.04

RMS		1.4 (0.88 %)		2.4 (1.49 %)
RSD		1.38 (0.40 %)		1.38 (0.40 %)

* Derived here from X_aa and (X_bb - X_cc)/X_aa = 0.6657(340) [1].

** Derived here from X_aa and (X_bb - X_cc)/X_aa = 0.6688(333) [1].

*** The algabraic sign of the product X_abX_acX_bc is positive.


Table 5. Bromomethyl Methyl Ether. Heavy atom structure parameters (Å and degrees). Complete structures are given here in Z.matrix format.

Point Group C₁	r (1) = MP2/aug-cc-pVTZ(G03) opt.
	r (2) = r (1) but with corrected Br bond length.

		r (1)	r (2)

	BrC(2)	1.9712	1.9790
	C(2)O	1.3705
	OC(4)	1.4239
	BrC(2)O	113.10
	C(2)OC(4)	112.88
	C(4)OC(2)Br	70.11

Click on image to enlarge.


Table 6. Bromomethyl Methyl Ether. Rotational constants (MHz). ⁷⁹Br species.

	r (1) = MP2/aug-cc-pVTZ(G03) opt.
	r (2) = r (1) but with corrected CCl bond length.

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

	A	13259.1	13235.8	13312.38(61)
	B	2361.7	2351.2	2306.30(8)
	C	2125.5	2116.4	2081.51(9)

[1] M.Hayashi, K.Kuwada, and H.Imaishi, Chemistry Letters (Chem. Soc. Jpn.) 913(1974).

CH₃-O-CH₂I

CH₃-O-CH₂Cl

Table of Contents

Molecules/Bromine

gCH3OCH2Br.html

Last Modified 14 Feb 2009