Neutron powder diffraction data show that Sr2Fe0.5Ir0.5O4, Sr2Co0.5Ir0.5O4, and La0.5Sr1.5Co0.5 Ir0.5O4 all adopt undistorted, n = 1 Ruddlesden-Popper structures in which the Ir5+ and Fe3+/Co3+/Co2+ cations are statistically disordered over all the octahedral coordination sites. Magnetization data indicate the two cobalt phases are spin glasses at low temperature, while Sr2Fe0.5Ir0.5O4 appears to adopt an antiferromagnetic state with very small magnetically ordered domains. Topochemical reduction with a Zr getter converts the tetragonal A(2)M(0.5)Ir(0.5)O(4) phases to the corresponding orthorhombic A(2)M(0.5)Ir(0.5)O(3) phases in which the Ir2+ and Fe2+/Co2+/Co1+ cations are located in approximately square-planar coordination sites. Magnetization data indicate Sr2Fe0.5Ir0.5O3 is a spin glass below T-G similar to 30 K, while Sr2Co0.5Ir0.5O3 appears to be antiferromagnetic below T-N similar to 25 K and La0.5Sr1.5Co0.5Ir0.5O3 shows no sign of magnetic order for T > 5 K. The magnetic behavior of both the A(2)M(0.5)Ir(0.5)O(4) and A(2)M(0.5)Ir(0.5)O(3) phases is discussed on the basis of metal d-electron count and structural features.