Framework and coordination strain in two isostructural hybrid metal–organic perovskites†
Monotonic compression of two iso-structural hybrid metal–organic perovskites [DMA]M(HCOO)3 (M = Co, Ni) has been connected to their structural distortions. The strongest effects of pressure occur in the tilts of the MO6 octahedra, M–O bond compression, angular distortions within the MO6 octahedra and small folding between the octahedra and formate units. The anisotropic stronger compression along the trigonal axis is consistent with NH⋯O bonding nearly perpendicular to this direction. Raman spectra indicate a first order solid-state phase transition between 3–5 GPa in both formates, which can be associated with the symmetry breaking induced by the ordering of the Dma cation.