Single-crystal X-ray structure analyses and the measurements of static magnetic susceptibility and ESR have been performed for the title compounds. Crystal data: for Cu[C(CN)3]2, space group Pmna, a = 7.212(5) A, b = 5.452(7) A, c = 10.696(7) A, and Z = 2; for Mn[C(CN)3]2, space group Pmna, a = 7.742(5) A, b = 5.411(6) A, c = 10.561(6) A, and Z = 2. Both salts are essentially isostructural. The Cu atoms are bridged by two [C(CN)3]- anions to form an infinite double chain structure, in which Cu has a square planar coordination (dCu-N = 1.986(6) A). The third CN end of the anion is weakly coordinated to the adjacent Cu chain (dCu-N = 2.47(1) A), making a three-dimensional network. The crystal is composed of two such interwoven networks. In the Mn complex, the third Mn−N distance (2.256(6) A) is as short as the equatorial coordinations (2.236(4) A), so that Mn is coordinated octahedrally. These compounds exhibit paramagnetic behavior following the Curie−Weiss law with Weiss temperatures −1.4 and −9 K, respe...