The trinuclear complexes are synthesized by Cu(hfac)(2) and 5-substituted-1,3-bis(N-tert-butylaminoxyl)benzene (1(x); X=H, F and Cl), pi-conjugated bis-aminoxyl radical with a triplet ground state([1]). It is found that the [Cu(hfac)(2)](3)(1(x))(2) complexes are paramagnetic and have a trinuclear cluster crystal structure. They have symmetric structure whereas the complex with X = Br is asymmetric.([1]) While the complex with X = Br shows a ferromagnetic interaction within central three spins (J/k(B) = 33.9 K) and exhibits a first-order type structural transition around 48 K and below this temperature it has an S=1/2 ground state, the complexes with X = F and Cl do not show any transformation. The intracluster exchanges for X = F and Cl are characterized by larger exchange parameters Y/k(B) = 40 5 K and 41.6 K, respectively. They keep ferromagnetic interaction within the trimers down to lowest temperatures and their ground states have S = 3/2.