tert-Butyl isocyanate

(CH₃)₃C-N=C=O

Nitrogen

Nuclear Quadrupole Coupling Constants

in tert-Butyl isocyanate

The complete ¹⁴N nqcc tensor in tert-butyl isocyanate was determined by Grabow et al. [1].

Calculation of the ¹⁴N nqcc tensor was made here on r_opt molecular structures given by B3LYP/6-311+G(3df,3pd) and MP2/6-311+G(3df,3pd) optimization. Calculated and experimental nqcc's are compared in Table 1. Structure parameters are given in Table 2; rotational constants and electric dipole moments in Table 3.

In Table 1, subscripts a,b,c refer to the principal axes of the inertia tensor; x,y,z to the principal axes of the nqcc tensor. The nqcc x-axis is chosen coincident with the inertia b-axis, these are perpendicular to the molecular plane. Ø (degrees) is the angle between its subscripted parameters. ETA = (X_xx - X_yy)/X_zz.

RMS is the root mean square difference between calculated and experimental diagonal nqcc's. RSD is the calibration residual standard deviation of the B3PW91/6-311+G(df,pd) model for calculation of nitrogen efg's/nqcc's.


Table 1. ¹⁴N nqcc's in tert-Butyl isocyanate (MHz). Calculation was made on molecular structures given by (1) B3LYP/6-311+G(3df,3pd) and (2) MP2/6-311+G(3df,3pd) optimization.

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

X_aa		2.681		2.676		2.6376(4)
X_bb	-	1.492	-	1.534	-	1.4935(7)
X_cc	-	1.189	-	1.142	-	1.1441(7)
\|X_ac\|		0.203		0.103		0.1731(15)

RMS		0.036 (2.0 %)		0.032 (1.8 %)
RSD		0.030 (1.3 %)		0.030 (1.3 %)

X_xx	-	1.492	-	1.534	-	1.4935
X_yy	-	1.200	-	1.145	-	1.1520
X_zz		2.692		2.679		2.6455
ETA	-	0.109	-	0.145
Ø_z,a		2.99		1.55		2.615
Ø_a,C(2)N		22.97		25.12
Ø_z,C(2)N		19.98		23.57


Table 2. tert-Butyl isocyanate. Optimized molecular structure parameters, r_opt (Å and degrees).

B3LYP/6-311+G(3df,3pd) and MP2/6-311+G(3df,3pd)

	C C,1,B1 N,2,B2,1,A1 C,3,B3,2,A2,1,D1,0 O,4,B4,3,A3,2,D2,0 C,2,B5,1,A4,3,D3,0 C,2,B6,1,A5,3,D4,0 H,1,B7,2,A6,3,D5,0 H,1,B8,2,A7,3,D6,0 H,1,B9,2,A8,3,D7,0 H,6,B10,2,A9,1,D8,0 H,6,B11,2,A10,1,D9,0 H,6,B12,2,A11,1,D10,0 H,7,B13,2,A12,1,D11,0 H,7,B14,2,A13,1,D12,0 H,7,B15,2,A14,1,D13,0

	B3LYP	MP2

	B1=1.53149082 B2=1.46682326 B3=1.19770649 B4=1.17265997 B5=1.53414376 B6=1.53414376 B7=1.08990392 B8=1.08939699 B9=1.08939699 B10=1.09036621 B11=1.08935385 B12=1.09026164 B13=1.08935385 B14=1.09036621 B15=1.09026164 A1=107.15460652 A2=139.13735300 A3=173.96371396 A4=110.44392464 A5=110.44392464 A6=110.25013180 A7=110.60998552 A8=110.60998552 A9=110.15970391 A10=110.64953188 A11=110.84091584 A12=110.64953188 A13=110.15970391 A14=110.84091584 D1=180. D2=180. D3=-118.61394644 D4=118.61394644 D5=180. D6=59.94041612 D7=-59.94041612 D8=-60.65587354 D9=59.21867776 D10=179.57484832 D11=-59.21867776 D12=60.65587354 D13=-179.57484832	B1=1.52214397 B2=1.4588154 B3=1.21149214 B4=1.1788562 B5=1.52455771 B6=1.52455771 B7=1.08940094 B8=1.08874946 B9=1.08874946 B10=1.0898967 B11=1.08889262 B12=1.08989552 B13=1.08889262 B14=1.0898967 B15=1.08989552 A1=107.0548629 A2=135.48317605 A3=173.01915046 A4=110.53471892 A5=110.53471892 A6=109.92809237 A7=110.3173426 A8=110.3173426 A9=109.95988415 A10=110.33002408 A11=110.46832715 A12=110.33002408 A13=109.95988415 A14=110.46832715 D1=180. D2=180. D3=-118.54056905 D4=118.54056905 D5=180. D6=59.96931595 D7=-59.96931595 D8=-60.64731314 D9=59.31746731 D10=179.51617279 D11=-59.31746731 D12=60.64731314 D13=-179.51617279


Table 3. tert-Butyl isocyanate. Rotational Constants (MHz) and Dipole Moments * (D).

	r_opt(1) = B3LYP/6-311+G(3df,3pd) optimization.
	r_opt(2) = MP2/6-311+G(3df,3pd) optimization.

		r_opt(1)	r_opt(2)	Expt [1]

	A	4551.1	4611.1	4572.6 (assumed)
	B	1608.6	1631.6	1632.948(15)
	C	1605.5	1628.1	1630.493(14)

	\|µ_a\|	3.23	3.08
	\|µ_c\|	0.70	0.76

	* B3PW91/6-311+G(df,pd) dipole moment calculation on r_opt structure.

[1] J.-U.Grabow, N.Heineking, and W.Stahl, J.Mol.Spectrosc. 154,129(1992).

HNCO

ClNCO

BrNCO

INCO

Difluoroisocyanato Silane

Ethylisocyanate

Methyldifluoroisocyanate Silane

Table of Contents

Molecules/Nitrogen

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Last Modified 24 Nov 2013