NEW OXAMIDO BRIDGED MOLECULAR-BASED MAGNETS AND HIGH-SPIN MOLECULES

The reaction of copper(II) bis-oxamido monomers with a manganese(II) s alt leads to compounds 1, 2 and 3 of general formula (PPh4)(2)Mn-2[CuL ](3).nH(2)O where L=(PhMe(2)opbox)(4-), (PhPr(2)opbox)(4-), (PhBu(2)op box)(4-) for 1, 2 and 3 respectively. Critical temperatures of 12.5, 1 1.5 and 13.5 K were measured for 1, 2 and 3 respectively. This range o f temperature likely indicates that this family of compounds assumes a 2D structure. Two tetrameric complexes 10 and 11 were prepared from t he Cr(III) tamer precursor. Magnetic investigations of 10 in the 2-300 K temperature range reveal a ferromagnetic interaction between the Cr (III) and Ni(II) magnetic centers with a spin coupling constant J esti mated to be +10.8 cm(-1) which is twice the value observed for the ora lato bridge. On the other hand, an antiferromagnetic exchange is obser ved for the CrMn3 complex 11. The magnetic behavior can be reproduced using the interaction parameter J(CrMn)= -3 cm-1, J(MmMn)= -0.5 cm-1, g(Cr)=1.98 and g(Mn)= 2.07.