Arsenic Trichloride

AsCl₃

PDF

Arsenic

Nuclear Quadrupole Coupling Constants

in Arsenic Trichloride

Dore et al. [1] determined both arsenic and chlorine nqcc's in arsenic trichloride. A substitution structure was determined by Cazzoli et al. [2].

Calculation was made here on the substitution structure of both arsenic and chlorine nqcc's. The results are given in Table 1. Structure parameters and atomic coordinates are given in Tables 2 and 3.

Coordinate Systems

X_uu is the component of the nqcc tensor along the threefold symmetry axis. Corresponding to the atomic coordinates given below in Table 3, X_vv and X_ww are the components along the v- and w- axes for the Cl atom in the uv-plane.

The subscripts x,y,z refer to the principal axes of the nqcc tensor. The nqcc y-axis is chosen coincident with the w-axis. Ø (degrees) is the angle between its subscripted parameters. ETA = (X_xx - X_yy)/X_zz.


Table 1. Arsenic and Chlorine nqcc's in AsCl₃ (MHz).

			Calc.		Expt. [1]

⁷⁵As	X_zz	-	169.5	-	175.67(69)

³⁵Cl	X_uu		10.31		11.0(12)
	X_vv	-	35.26
	X_ww		24.95
	X_uv		32.36

	X_xx		27.10
	X_yy		24.95
	X_zz	-	52.06	-	71.1 *
	ETA	-	0.0413
	Ø_z,u		62.57
	Ø_u,AsCl		61.33
	Ø_z,AsCl		1.24

³⁷Cl	X_uu		8.12
	X_vv	-	27.79
	X_ww		19.67
	X_uv		25.51

* Bond axis value derived in Ref. [1] using X_zz = X_uu/cos(ClAsCl).

The pyramid formed by the z-principal axes of the three Cl nqcc tensors is somewhat 'flatter' than the molecular pyramid. This is typical of the pyramidal trichlorides.

Table 2. Structure parameters, r_s [2] (Å and degrees).

AsCl

2.160(3)

ClAsCl

98.9(4)


Table 3. Atomic coordinates
(More figures are show than are significant.)

		u (Å)	v (Å)	w (Å)

	Cl	-0.407131	1.895155	0.0
	Cl	-0.407131	-0.947577	±1.641252
	As	0.629203	0.0	0.0