Structure and magnetism of a polycrystalline transition metal soap - Co-II[OOC(CH2)(10)COO](H2O)(2)

Diaquacobalt(II) n-dodecane-alpha,omega -dioate (2) has been synthesized by metathesis of the corresponding potassium soap I and has been fully characterized by chemical and spectroscopic analysis. The crystal structure of 2 has been established by X-ray powder diffraction techniques combined with electron diffraction experiments, It crystallizes in a monoclinic cell [P2(1)/a; a = 9.6558(8), b = 7,4793(6), c = 19.8936(2) Angstrom, beta = 95.648(9)degrees, V = 1429.7(3) Angstrom (3); Z = 2] and consists of stacked layers of cobalt(II) ions connected by carboxylato bridges, thus forming chains that extend along the a axis. These layers are separated by alkyl chains arranged quasi-perpendicularly to the polar sheets. Structure analysis reveals a rare anti-anti conformation of the Co-OCO-Co fragments, which is thought to be responsible for the weak antiferromagnetism of the Co-II chains. The exchange coupling constant between the magnetic centres has been estimated as J = -2.08 K.