Magnetic Behavior Control in Niccolite Structural Metal Formate Frameworks [NH₂(CH₃)₂][Fe^IIIM^II(HCOO)₆] (M = Fe, Mn, and Co) by Varying the Divalent Metal Ions

Abstract

By changing template cation but introducing trivalent iron ions in the known niccolite structural metal formate frameworks, three complexes formulated [NH 2 (CH 3 ) 2 ][Fe III M II (HCOO) 6 ] (M = Fe for 1, Mn for 2, and Co for 3) were synthesized and magnetically characterized. The variation in the compositions of the complexes leads to three different complexes: mixed-valent complex 1, heterometallic but with the same spin state complex 2, and heterometallic heterospin complex 3. The magnetic behaviors are closely related to the divalent metal ions used. Complex 1 exhibits negative magnetization assigned as N eel N-Type ferrimagnet, with an asymmetric magnetization reversal in the hysteresis loop, and complex 2 is an antiferromagnet with small spin canting (R canting ≈ 0.06°and T canting = 35 K), while complex 3 is a ferrimagnet with T N = 32 K.

A Niccolite Structural Multiferroic Metal–Organic Framework Possessing Four Different Types of Bistability in Response to Dielectric and Magnetic Modulation

“…Compared with the extensively studied perovskite structural metal formates, some of which exhibit interesting switchable dielectric, switchable polarization, and multiferroic properties, the most important feature of metal formates with niccolite structure is that it may contain iron in two valence states, which would give rise to more complex and fascinating magnetic properties than those in the perovskites . In this regard, a N‐type of ferrimagnetism accompanied by order–disorder transitions were revealed in a mixed valence complex [(CH 3 ) 2 NH 2 ][Fe III Fe II (HCOO) 6 ] . Very recently, another interesting example of mixed valence iron formates was reported by Mączka et al, that is, [(CH 3 CH 2 ) 2 NH 2 ][Fe III Fe II (HCOO) 6 ] ( 1 ), which exhibited intriguing crystallographic, magnetic and dielectric behaviors.…”

“…At 293 K, that is, high‐temperature phase (HTP), 1 crystallizes in the trigonal space group with the parameter sets of a HTP = 8.4563(12) Å, c HTP = 13.789(3) Å, and V HTP = 854.0(2) Å 3 (Table S1, Supporting Information). A common structural feature of 1 is that its anionic cages formed by Fe II HCOO − Fe III units accommodate the DEA cations for charge balance ( Figure a,b), where the valence states of the involved iron ions located at the (4 12 • 6 3 ) and (4 9 • 6 6 ) nodes of the niccolite framework were identified based on the bond lengths: Fe III O = 2.0107(15) Å and Fe II O = 2.1350(16) Å (Table S2, Supporting Information). At 113 K (LTP), 1 crystallizes in the triclinic space group , where a LTP = 8.2974(17) Å, b LTP = 8.4878(17)Å, c LTP = 13.482(3) Å, and V LTP = 835.5(3).…”

Temperature-dependent studies of [(CH3)2NH2][FeIIIMII(HCOO)6] frameworks (MII = Fe and Mg): structural, magnetic, dielectric and phonon properties

“…The former one is an antiferromagnet and the latter ferrimagnet, respectively. 15 Very recently, we have reported 4 the Novo-Control Quattro system, with use of a nitrogen gas cryostat. The measurements were taken every 1 deg and temperature stability of the samples was better than 0.1 K. Magnetic properties of a large number of freely oriented single crystals of DMFeMg (about 100 mg in total) were measured using a commercial superconducting quantum interference device (SQUID) magnetometer in the temperature range 2−30 K and in external magnetic fields up to 10 kOe.…”

A Series of Bimetallic Ammonium AlNa Formates

“…The bimetallic or double metallic [AH][M III M II (HCOO) 6 ] consisting of trivalent metal M III (M III =Al III /Fe III /Cr III ) and M II possess quite broad and interesting electric and magnetic properties . For example, the mostly investigated [(CH 3 ) 2 NH 2 ][Fe III Fe II (HCOO) 6 ] niccolite, showed an unprecedented disorder–order type antiferroelectric phase transition with the ordering of the (CH 3 ) 2 NH 2 + cation in three different orientations and a nine‐fold multiple unit cell, and the material is a rare Néel N‐type ferrimagnet. Clearly, these fabrications on the metal and/or ammonium components can extremely expand the field of AMFF research, as happened for the conventional materials such as oxides.…”