Structure and C–Cl bond in 1-Cl-3-NO2C6H4

The crystal structure of metachloro-nitrobenzene, C6H4C1(1)(NO2)(3)was redetermined atT= 298 K: Space groupPna21,Z= 4,a= 2114.90(40) pm,b= 593.20(10) pm,c= 529.00(10) pm,Rw(F) = 0.038. The molecule is almost planar, with a small out of plane bending of the NO2group. Measurements of Zeeman-split35Cl NQR spectra give a nuclear quadrupole coupling constante2ϕzzQh−1= (69.745 ± 0.002) MHz atT= 298 K and (70.608 ± 0.002) MHz atT= 129 K. The asymmetry parameter is 0.1091 ± 0.0015 at 298 K (0.1066 ± 0.0040 at 129 K).ϕzzis within 0.45° parallel to the bond direction C(1)– Cl(1);ϕyyandϕxxare almost in the C(1 … 6)-plane and perpendicular to it, respectively. The temperature dependencev(35Cl) =f(T) was studied from 77 K up to the melting point. Structure and electric field gradient orientation are discussed.