Ferrimagnetic Ordering and Anomalous Stoichiometry Observed for the Cubic, Extended 3D Prussian Blue Analogues (NEt Me) Mn (CN) and (NEt Me ) Mn (CN) : A Cation-Adaptive Structure.

The reactions of Mn (O CCH ) with NEt Me CN and NEt Me CN form (NEt Me) Mn (CN) (1) and (NEt Me ) Mn (CN) (2), respectively. Structure model-building and Rietveld refinement of high-resolution synchrotron powder diffraction data revealed a cubic [a=24.0093 Å (1), 23.8804 Å (2)] 3D extended structural motif with adjacent tetrahedral and octahedral Mn sites in a 3:2 ratio. Each tetrahedral Mn site is surrounded by four low-spin octahedral Mn sites, and each octahedral Mn site is surrounded by six high-spin tetrahedral Mn sites; adjacent sites are antiferromagnetically coupled in 3D. Compensation does not occur, and magnetic ordering as a ferrimagnet is observed at T =13 K for 2 based on the temperature at which remnant magnetization, M (T)→0. The hysteresis has an unusual constricted shape with inflection points around 50 and 1.2 kOe with a 5 K coercivity of 16 Oe and remnant magnetization, M , of 2050 emuOe mol . The unusual structure and stoichiometry are attributed to the very ionic nature of the high-spin N-bonded Mn ion, which enables the maximization of the attractive van der Waals interactions through minimization of void space via a reduced ∠ MnNC. This results in an additional example of the A Mn (CN) (x=0, y=1; x=1, y=3; x=2, y=1; x=2, y=2; x=2, y=3; x=3, y=5; and x=4, y=1) family of compounds possessing an unprecedented stoichiometry and lattice motif that are cation adaptive structured materials.