Perfluorocyclopropene: Experimental and Theoretical Studies of Its Structure in Gaseous, Solution, and Crystalline Phases

The structure of 1,2,3,3-tetrafluorocyclopropene,
C3F4, has been determined at 156 K by
X-ray
crystallography and in the gas phase by a combined analysis of
electron-diffraction data, rotation constants derived
from the microwave spectrum, and dipolar coupling constants derived
from the liquid crystal 19F NMR spectrum.
Structural parameters (distances/pm, angles/deg) for the solid at
156 K and gas phase (distances (rg),
angles (∠α)),
respectively, are the following: 
r(C1−C3) = 145.3(3),
146.1(3); r(C1C2) =
129.6(4), 130.7(13);
r(C3−F6) =
137.0(2),
136.1(4); r(C1−F4) =
131.2(2), 131.5(3);
∠C1C2F5 = 150.4(9),
149.9(6); ∠F6C3F7 =
104.1(2), 105.4(5);
∠C1C2C3
= 63.5(1), 63.4(3). These values are in excellent
agreement with those obtained in an ab initio study of the
molecular
geometry at the electron-correlated MP2/TZ2P level. The dipole
moment of C3F4 has been determined from
Stark
effect measurements to be 1.313(4) D.