Two new cobalt(II) complexes [Co-2(2,2'-bipy)(2)(dpa)(2)(H2O)(5)]center dot 4H(2)O (1) and Co(2,2'-bipy)(3)(SO (4))center dot 7.5H(2)O (2) have been synthesized with diaphonic acid (H(2)dpa) and 2,2'-bipyridine (2,2'-bipy) as ligands. In 1, two neighboring cobalt(II) ions are linked together by one bridging diaphonic acid group, forming an asymmetric dinuclear structure. 1 crystallizes in triclinic, space group P (1) over bar with alpha = 9.825(6), b = 13.007(8), c = 19.586(1) angstrom, alpha = 80.773(1)degrees, beta = 77.065(1)degrees, gamma = 85.902(1)degrees, M-r = 431.4, V = 2406.5(3) angs...