Manifestation of electron-nuclear dynamics in 59Co NQR spectra of a series of cobaltocenium derivatives

A coupling equation relating the quadrupole coupling constant (e2 Qq zz ) to the asymmetry parameter (η) of the electric field gradient for a series of cobaltocenium derivatives (59Co NQR) is derived. The estimates of the correlation times of “slow” modulations of electron motions by tunneling processes lie in the range from 10−12 to 10−14 s. This corresponds to the interval of the characteristic times of nuclear motions.