  Charge order affects most of the electronic properties but is believed not to
alter the spin arrangement since the magnetic susceptibility remains unchanged.
We present electron-spin-resonance experiments on quasi-one-dimensional
(TMTTF)2X salts (X= PF6, AsF6 and SbF6), which reveal that the magnetic
properties are modified below TCO when electronic ferroelectricity sets in. The
coupling of anions and organic molecules rotates the g-tensor out of the
molecular plane creating magnetically non-equivalent sites on neighboring
chains at domain walls. Due to anisotropic Zeeman interaction a novel magnetic
interaction mechanism in the charge-ordered state is observed as a doubling of
the rotational periodicity of Delta H.
