A rare ΞΌ6β-oxo-centered Mn6β mixed-valent cluster (1) is prepared and used as a secondary building unit for the self-assembly of its azido-bridged polymeric analogue (2) in a systematic way with the retention of the Mn6β core of 1. Both complexes are characterized by X-ray single-crystal structure determination. The complex 1 was crystallized in a monoclinic system, space group P21β, a = 11.252(5) \AA, b = 20.893(9) \AA, c = 12.301(6) \AA, and Ξ²=115.853β(7)o, whereas the polymeric analogue 2 was crystallized in an orthorhombic system, space group P21β21β21β, a = 13.1941(8) \AA, b=14.9897(9) \AA, and c = 27.8746(14) \AA. Variable-temperature magnetic behavior showed the presence of strong antiferromagnetic interaction in both cases