New oxamido bridged molecular based magnets and high-spin molecules

Abstract The reaction of copper(II) bis-oxamido monomers with a manganese(II) salt leads to compounds 1, 2 and 3 of general formula (PPh4)2Mn2[CuL]3-nH2O where L= (PhMe2opbox)4−, (PhPr2opbox)4−, (PhBu2opbox)4− for 1, 2 and 3 respectively. Critical temperatures of 12.5, 11.5 and 13.5 K were measured for 1, 2 and 3 respectively. This range of temperature likely indicates that this family of compounds assumes a 2D structure. Two tetrameric complexes 10 and 11 were prepared from the Cr(III) tamox 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 estimated to be +10.8 cm−1 which is twice the value observed for the oxalato bridge. On the other hand, an antiferromagnetic exchange is observed for the CrMn3 complex 11. The magnetic behavior can be reproduced using the interaction parameter JCrMn= −3 cm-1, JMnMn= −0.5 cm-1, gCr=1.98 and gMn= 2.07.