Neutron powder diffraction has been used to determine the magnetic str
uctures of antiferromagnetic chain pentafluoromanganates A(2)MnF(5), x
H(2)O (A/x = Li/0; Na/0 and Rb/0, 1). Collinear magnetic structures, w
ith Mn3+ magnetic moments parallel to the chain axis, have been observ
ed in all compounds and can be characterized by different interchain m
agnetic interactions, depending on Mn-Mn distances.