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

By changing template cation but introducing trivalent iron ions in the known niccolite structural metal formate frameworks, three complexes formulated [NH2(CH3)2][FeIIIMII(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 Néel N-Type ferrimagnet, with an asymmetric magnetization reversal in the hysteresis loop, and complex 2 is an antiferromagnet with small spin canting (αcanting ≈ 0.06° and Tcanting = 35 K), while complex 3 is a ferrimagnet with TN = 32 K.