[en] The crystal structure, magnetization and electrical resistivity properties of the anion-deficient La_1-xBa_xMnO_3-x/2 (0 ≤ x ≤ 0.50) perovskite manganites without Mn⁴⁺ ions have been investigated. It is established the reduced samples in the region 0 ≤ x ≤ 0.05 are O'-orthorhombic perovskites, in 0.10 ≤ x ≤ 0.25 they are rhombohedric whereas in 0.27 ≤ x ≤ 0.50 they are cubic. It is found that, as the x doping level increases, the samples undergo a transition from a weak ferromagnetic state (x = 0) to an inhomogeneous ferromagnetic one, (x ≥ 0.03) being a mixture of antiferromagnetic and ferromagnetic phases. At x ≥ 0.12 competition between antiferromagnetic and ferromagnetic interactions leads to a cluster spin glass state appearance with a magnetic moment freezing temperature of ∼ 45 K. The dominant magnetic phase for x ≥ 0.22 is supposed to be antiferromagnetic. All the reduced samples are semiconductors and show considerable magnetoresistance over a wide temperature range in a magnetically ordered state. The largest magnetoresistance (∼ 34% in a 9 kOe field at liquid nitrogen temperatures) is observed for an x = 0.30 sample. The magnetic phase diagram of La_1-x³⁺Ba _x²⁺Mn³⁺O_3-x/2^2- manganites has been established by combining the results of magnetic and electrical measurements. The results obtained could be understood in terms of the phase separation and the 180 deg. superexchange Mn³⁺-O-Mn³⁺ interaction model