Neutral tri- and tetracobalt complexes Co3(mp)2(HMP)2(PEt3)3 (1) and Co4(mp)4(PBu(n)3)3Cl(MeOH) (2) with mixed trialkylphosphine and o-mercaptophenolate (Mp2-) ligands were obtained by the reactions of cobaltous salts with mp2- in the presence of phosphine in alcoholic solutions. Complex 1 crystallizes in the triclinic space group P1BAR, with fw = 1029.95, a = 13.668(5) angstrom, b = 16.988(6) angstrom, c = 11.237(3) angstrom, alpha = 100.36(2)-degrees, beta = 103.90(3)-degrees, gamma = 81.41(3)-degrees, V = 2476.0 angstrom3, Z = 2, R = 0.055, and R. = 0.057. Complex 2 crystallizes also in the triclinic space group P1BAR, with fw = 1406.85, a = 13.316(6) angstrom, b = 24.721(7) angstrom, c = 11.946(4) angstrom, alpha = 91.20(3)-degrees, beta = 11 1.83(3)-degrees, gamma = 75.17(3)-degrees, V = 3516.9 angstrom3, Z = 2, R = 0.066, and R(w) = 0.067. Structural analyses revealed that both complexes are unsymmetrical due to the different bonding characters of the sulfur and oxygen donor atoms of the o-mercaptophenol ligand. Possible reactive fragments are proposed for the formation of these complexes. Variable-temperature magnetic susceptibility measurements revealed the antiferromagnetic interaction in 1 and 2.