Mechanochemical reaction of polymeric oxovanadium(IV) complexes with Schiff base ligands derived from 5-nitrosalicylaldehyde and diamines

Light brown [VO(5-NO₂salen)]·2H₂O (1; H₂(5-NO₂ salen)=N, N'-di-5-nitrosalicylidene-1,2-ethanediamine) and orange [VO(5-NO₂sal-meso-stien)]·0.5H₂O (2; H₂(5-NO₂salmeso-stien) = N,N'-di-5-nitrosalicylidene-(R,S)(S,R)-1,2-diphenyl-1,2-ethanediamine) which have linear chain structures in the solid state turn dark brown and yellow-brown, respectively, when ground thoroughly in mortars. The IR spectra of 1 and 2 in Nujol mulls show strong V=O stretching bands at 875 and 905 cm^-1, respectively. On the other hand, the spectra of the finely ground complexes in Nujol mulls show very weak V=O stretching bands. X-ray powder diffraction patterns of the ground complexes scarcely show diffraction peaks. The spectroscopic and magnetic data suggest that the linear chain structures in the crystals of 1 and 2 are destroyed on grinding to yield the fragments of the polymeric chains. (C) 2000 Academic Press.