A [(Mn11Mn6II)-Mn-III(mu(4)-O)(8)(mu(3)-L)(4)](25+) (L = N-3(-) or OCN-) octahedral unit is reported, occurring within 1 D (1)(infinity) and 2D (2)(infinity) coordination polymers, as well as the corresponding OD discrete cluster 3. It possesses a giant ground-state spin value, determined in the case of 3 to be S = 37, the second largest to be reported to date. In addition, compound 3 displays single-molecule magnet (SMM) behavior, and is thus the largest-spin SMM.