The topotactic reduction of Sr3Co2O5Cl2 and Sr3Co2O5.80 yields the Co(II) phases Sr3Co2O4Cl2 and Sr3Co2O5 respectively. These phases contain corner linked arrays of square-planar CoO4 units which form a 2D network in the case of the oxychloride and a 1D spin-ladder type arrangement in the case of the oxide.We propose to collect high resolution neutron powder diffraction data from Sr3Co2O4Cl2, Sr3Fe0.2Co1.8O4Cl2, Sr3Fe0.4Co1.6O4Cl2 and Sr3Co2O5 at room temperature to establish the anion vacancy ordered structures of these phases. Furthermore we propose to collect variable temperature neutron diffraction data to characterize the magnetically ordered states these phases adopt.