SYNTHESIS, CRYSTAL-STRUCTURE AND MAGNETIC-PROPERTIES OF NOVEL STABLE NITRONYL-NITROXIDE PYRIDINE-BASED RADICALS (NIT)PY(X) X FOR BR, C-EQUIVALENT-TO CSIME(3), C-EQUIVALENT-TO CH

The synthesis of hybrid nitronyl-nitroxide pyridine-based radicals has been achieved by the use of an original protocol based on a Pd(0) cro ss-coupling reaction between the (NIT)Py(Br) radical and Me(3)SiC=CH. The (NIT)Py(C=CH) radical 3, obtained from the radical (NIT)Py(C=CSiMe (3)) 2, forms infinite zigzag chains of molecules linked by hydrogen b onds. The magnetic susceptibility measurements show that radicals 1 an d 2 are coupled antiferromagnetically while the magnetic behavior of 3 was best analyzed in terms of a one-dimensional Heisenberg chain mode l for ferromagnetically coupled linear arrays of spins 1/2. The best-f it data are obtained by considering an intrachain ferromagnetic intera ction of J = +1.40 K and a weak interchain antiferromagnetic interacti on of zj' = -0.27 K.