Ethyl chloroformate

CH₃CH₂-O-C(=O)Cl

Chlorine

Nuclear Quadrupole Coupling Constants

in Ethyl Chloroformate

For each conformer of ethyl chloroformate shown below, calculation of the chlorine nqcc tensors was made on a molecular structure given by MP2/6-311+G(3df,3pd) optimization with empirically corrected approximate equilibrium C-C, C=O, and CCl bond lengths. These calculated nqcc's are given in Tables 1 and 2. Structure parameters are given in Z-Matrix format in Table 3, rotational constants and dipole moments in Table 4.

syn-anti

syn-gauche

At the

MP2/6-311+G(3df,3pd)

level of theory,

E_syn-anti < E_syn-gauche

by 0.006 kJ/mol

O=COC Dihedral = 0^o

O=COC Dihedral = 1.9^o

COCC Dihedral = 180^o

COCC Dihedral = 80.5^o

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.

RSD is the calibration residual standard deviation of the B1LYP/TZV(3df,2p) model for calculation of the chlorine efg's/nqcc's.


Table 1. Chlorine nqcc tensor in syn-anti ethyl chloroformate (MHz). Calculation was made on a molecular structure given by MP2/6-311+G(3df,3pd) optimization with approximate r_e C-C, C=O, and C-Cl bond lengths.

			Calc.	Expt.

³⁵Cl	X_aa	-	34.05
	X_bb		7.15
	X_cc		26.90
	X_ab		52.44

	RSD		0.49 (1.1 %)

	X_xx		42.89
	X_yy		26.90
	X_zz	-	69.79
	ETA	-	0.229
	Ø_z,a		34.27
	Ø_a,CCl		34.98
	Ø_z,CCl		0.71

³⁷Cl	X_aa	-	27.53
	X_bb		6.33
	X_cc		21.20
	X_ab		41.05

	RSD		0.44 (1.1 %)


Table 2. Chlorine nqcc tensor in syn-gauche ethyl chloroformate (MHz). Calculation was made on a molecular structure given by MP2/6-311+G(3df,3pd) optimization with approximate r_e C-C, C=O, and C-Cl bond lengths.

			Calc.	Expt.

³⁵Cl	X_aa	-	54.22
	X_bb		30.42
	X_cc		23.80
	X_ab	-	34.70
	X_ac		15.62
	X_bc		7.15

	RSD		0.49 (1.1 %)

	X_xx		42.96
	X_yy		26.80
	X_zz	-	69.76
	ETA	-	0.232
	Ø_z,CCl		0.71

³⁷Cl	X_aa	-	43.04
	X_bb		24.18
	X_cc		18.86
	X_ab	-	27.09
	X_ac		12.10
	X_bc		5.53

	RSD		0.44 (1.1 %)


Table 3. Ethyl chloroformate. MP2/6-311+G(3df,3pd) optimized structure parameters (Å and degrees). Approximate r_e bond lenths are given in parentheses.

syn-anti				syn-gauche
		C O,1,B1 O,1,B2,2,A1 C,3,B3,1,A2,2,D1,0 C,4,B4,3,A3,1,D2,0 H,4,B5,3,A4,1,D3,0 H,4,B6,3,A5,1,D4,0 H,5,B7,4,A6,3,D5,0 H,5,B8,4,A7,3,D6,0 H,5,B9,4,A8,3,D7,0 Cl,1,B10,2,A9,3,D8,0

	B1=1.19490166 (1.1903) B2=1.32493349 B3=1.45006305 B4=1.50593089 (1.5046) B5=1.08810906 B6=1.08810906 B7=1.08825073 B8=1.08708979 B9=1.08708979 B10=1.74382794 (1.7480) A1=127.65260577 A2=113.8498172 A3=106.57593516 A4=108.23208944 A5=108.23208944 A6=109.38362694 A7=110.67632437 A8=110.67632437 A9=123.44566966 D1=0. D2=180. D3=58.76567359 D4=-58.76567359 D5=180. D6=-60.36313122 D7=60.36313122 D8=180.		B1=1.1952851 (1.1907) B2=1.3249287 B3=1.45102263 B4=1.50993788 (1.5084) B5=1.0872434 B6=1.0854498 B7=1.08889359 B8=1.08682389 B9=1.08747059 B10=1.7436971 (1.7479) A1=127.94428865 A2=114.34414129 A3=110.66659355 A4=108.52112544 A5=103.53770942 A6=109.35518473 A7=110.69327065 A8=110.47087971 A9=123.27576637 D1=1.92080453 D2=80.51834448 D3=-42.60686186 D4=-159.33932308 D5=176.2883134 D6=-64.38303769 D7=56.88682779 D8=-179.74391251


Table 4. Ethyl chloroformate, ³⁵Cl species, rotational constants (MHz) and dipole moments (D).

		________syn-anti_________		_______syn-gauche________
		Calc	Expt	Calc	Expt

	A	6917.6		7002.5
	B	1544.8		1626.7
	C	1283.0		1477.0

	\|µ_a\|	2.77		2.42
	\|µ_b\|	0.89		1.28
	\|µ_c\|	0 (symm)		0.22

Y.A.Tobón, H.E.Di Loreta, C.O.Della Védova, and R.M.Romano, J.Mol.Struct. 881,139(2008): IR

N.S.True and R.K.Bohn, OSU International Symposium on Molecular Spectroscopy, 1975: For ³⁵Cl species of syn-anti, B + C = 2819(3) MHz; and for syn-gauche, B + C = 3061(3) MHz. E_syn-anti < E_syn-gauche by 0.0(1) kcal/mol.

Vinyl Chloroformate

S-Methylchlorothioformate

Methyl Chloroformate

Ethyl Cyanoformate

Table of Contents

Molecules/Chlorine

CH3CH2OCOCl.html

Last Modified 18 Jan 2014