Cross‐Linked Layered Structure of Magnetically Ordered [Fe(TCNE)₂]⋅z CH₂Cl₂ Determined by Rietveld Refinement of Synchrotron Powder Diffraction Data

Abstract

Since the report of the first organic-based magnet [Fe(C 5 [6c] Albeit important, the structures of [M(TCNE) 2 ]·z CH 2 Cl 2 (M = V, Mn, Fe) have been elusive because of the unavailability of single crystals. Herein, we report the structure of [Fe(TCNE) 2 ]·z CH 2 Cl 2 determined from synchrotron powder diffraction data and the implications it provides with respect to the structure of the [V(TCNE) x ] room temperature magnet.Although single crystals of the brown compounds [M(TCNE) 2 ]·z CH 2 Cl 2 (M = Mn, Fe) did not form, X-ray powder diffraction (XRPD) was observed and indicated that they are isomorphous.[6c] Thus, a high-resolution XRPD pattern for M = Fe was collected at the National Synchrotron Light Source at ambient temperature (Figure 1).

Density functional study of the magnetic coupling inV(TCNE)2

“…The same structural motifs have been experimentally observed for 1D ͓Mn͑porphyrin͔͓͒TCNE͔-based magnets 8 and ͓Fe͑TCNE͒ 2 ͔ compounds. 29 A local structure of V͑TCNE͒ 2 with ͕V͑ 4 − ͓TCNE͔͒ ·− ͖ layers interconnected by trans-͕ − ͓TCNE͔͖ ·− linkages has been previously suggested. 29 The structure proposed herein serves as a model system within which the material electronic and magnetic properties can be computed and analyzed.…”

“…29 A local structure of V͑TCNE͒ 2 with ͕V͑ 4 − ͓TCNE͔͒ ·− ͖ layers interconnected by trans-͕ − ͓TCNE͔͖ ·− linkages has been previously suggested. 29 The structure proposed herein serves as a model system within which the material electronic and magnetic properties can be computed and analyzed. The geometric parameters of an isolated ͓TCNE͔ ·− ion, as determined from PND studies of ͓Bu 4 N͔ + ͓TCNE͔ ·− , were taken as an initial geometry of the ligands.…”

“…8 and 28͒ and ͓Fe͑TCNE͒ 2 ͔ · z͑CH 2 Cl 2 ͒. 29 The first is a linear-chain ferrimagnet with Mn III ions coordinated by four porphyrin nitrogens and two ͓TCNE͔ ·− nitrogens, forming an octahedral complex. Each ͓TCNE͔ ·− is trans--bonded to two metal ions and connects the planar ͓MnTPP͔ + groups thus forming infinite one-dimensional ͑1D͒ chains.…”

MnII(TCNE)3/2(I3)1/2–A 3D Network‐Structured Organic‐Based Magnet and Comparison to a 2D Analog

“…[10] In addition to this family of M[TCNE] x (x $ 2) magnets, the reaction of TCNE and FeCl 2 (NCMe) 2 8 ] 1/2 has essentially zero dispersive susceptibility above 50 K, and an unusual hysteresis. The present work offers a framework for understanding these differences, as well as the behavior of other previously studied magnets.…”

“…[9] However, the paucity of structural information has thwarted elucidation of the spin coupling mechanism, and rational development of enhanced materials. Related magnets known to date are, at most, 2D magnetically coupled with significantly lower T c s $ 100 K. [10,11] Herein, we describe a new ferrimagnet, Mn II (TCNE) 3/2 (I 3 ) 1/2 , which orders with a significant remnant magnetization at a substantially higher temperature [T c ¼ 171 K at ambient pressure and 273 K (0 8C) at 14.2 kbar] than any previously structurally characterized TCNE-based magnet.…”