Reactions of Ni(II) and Mn(II) hexafluoroacetylacetonates with pyrazole-containing nitronylnitroxyl radicals (L) result in dimeric heterospin complexes [M(hfac)(2)L](2) or [M(hfac)(2)L](2).C6H6. The paramagnetic ligands in the centrosymmetric binuclear molecules function as a bridge, with the nitroxyl O atom being bound to one metal and the imine N atom of the pyrazole ring to the other metal atom. The metal environment is a cis-octahedron with short M-O-NO distances, which specifies a strong antiferromagnetic interaction between the lone electrons of paramagnetic centers in M-O . -N drop exchange clusters.