Microwave spectrum of tellurium pentafluoride chloride

Abstract

The microwave spectra of twelve isotopic species of tellurium pentafluoride chloride are reported. Each spectrum shows rigid symmetric top behaviour with nuclear quadrupole coupling effects due to the ³⁵Cl and ³⁷Cl nuclei unresolved. The rotational constants, B₀, for the ground vibrational state of the various isotopic species of ClTeF₅ are as follows. [graphic omitted]

The r_s distance for the Te—Cl bond is directly determined from the rotational constants as 2.250 ± 0.002 Å. Although a unique determination of the remaining three structural parameters is not possible, a graph is presented which shows the variation of r(Te—F)_axial and r(Te—F)_equatorial as a function of the angle (F—Te—F_axial) assuming a structure of C_4ν symmetry. Thus, if one of the three unknown parameters can be determined by another method, the remaining two can be obtained uniquely from the graph. If equality of the axial and equatorial Te—F distances is assumed the resulting structure is: r(Te—F)= 1.8305 ± 0.0012 Å, angle (F—Te—F)_axial= 88°15′± 7′.

An excited vibrational state, probably the Te—Cl wagging vibration, ν₁₁, has been assigned and the values α₁₁= 0.775 and 0.718 MHz for the ³⁵Cl and ³⁷Cl species respectively are reported.