Crystallographic analyses and magnetic measurements for two polymorphs, the prism form and the needle form of bis [N-(4-chlorophenyl) salicylideneaminato] oxovanadium (IV) are carried out. The polymeric structure is observed for the needle form against the monomeric structure for the prism form. The ferromagnetic interaction is observed for the needle form, while the appreciable magnetic coupling is not detected for the prism form. The large negative spin density is found on each of the axial oxygen of these crystals. The intermolecular ferromagnetic interaction of these complexes is greatly affected by the formation of polymeric V=O center dot center dot center dot V=O center dot center dot center dot structures in the solid state. (C) 2010 Elsevier B. V. All rights reserved.