Framework and coordination strain in two isostructural hybrid metal–organic perovskites

Abstract

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.