Magnetic properties of three tetranuclear complexes Co3Fe(mp)4(Hmp)(PBu3^n)3(1) Co4(mp)4(Hmp)(PMe2Ph)3(2) and Co4(mp)4(PBu3^n)3Cl(MeOH)(3) have been studied in the temperature range of 1.5-300K. On the basis of isotropic Heisenberg model, the eigenvalues for the possible spin states were obtained with the full-matrix diagonalisation method and variable-temperature magnetic susceptibilities were fitted by the least-squares calculation. The fitting results show J1=-3.14cm^-^1, J2=-3.04cm^-^1, J3=2.92cm^-^1 and J4=4.08cm^-^1 for 1; J1=-3.07cm^-^1, J2=-3.19cm^-^1, J3=-0.33cm^-^1 and J4=-1.91cm^-^1 for 2; J1=-4.818cm^-^1, J2=-4.244cm^-^1, J3=-1.164cm^-^1 and J4=-2.634cm^-^1 for3, where J1 and J2 are the exchange coupling constants transmitted by two μ2-S bridges, J3 and J4 by one μ2-O and two μ2-O bridges, respectively.

Key words: PHENOL P, MERCAPTO COMPOUNDS, MAGNETIZATION