Magnetically Ordered (Tc = 200 K) Bis(tetracyanopyrazine)vanadium, V[TCNP]2·yCH2Cl2

We study numerically the crystal and electronic structure of the room temperature organometallic ferromagnet of general composition V(TCNE)(x) x y solvent with x approximately 2, starting from both the experimental structure of its iron analog which results from the EXAFS experiment as well as the theoretical model structure compatible with magnetic measurements on this type of compounds. The results of the numerical study performed at the density functional level of theory show that the experimentally determined structure complies with the magnetic measurements and thus can serve as a prototype structure for the entire family of the M(TCNE)(2) organometallic magnets. Both the results of the numerical study and the magnetic experiments are interpreted using a proposed model Hamiltonian.

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“…For example, Figure 1. Hypothetical structure of V(TCNE) 2 following. 6 the V-TCNE compound is known in two forms -the original of ref.…”

Section: Introductionmentioning

confidence: 99%

A computational study of the crystal and electronic structure of the room temperature organometallic ferromagnet V(TCNE)₂

Tchougréeff¹,

Dronskowski

2008

J Comput Chem

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“…These include a,a′-dicyanoperfluorostilbene, (T c = 205 K), [6] tetracyanopyrazine (T c = 200 K), [7] and 7,7,8,8-tetracyano-p-quinodimethane (TCNQ; T c = 52 K). (CO) 6 ] 1/2 ·zS (4>x > 3.5; S = CH 2 Cl 2 , PhCF 3 ) composition that orders above room temperature at 50°C (323 K).…”

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confidence: 99%

A Methyl Tricyanoethylenecarboxylate‐Based Room‐Temperature Magnet

2007

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Since the discovery of the first organic-based magnet, [Fe(C 5 Me 5 ) 2 ][TCNE] (TCNE = tetracyanoethylene), [1] efforts worldwide have focused on the discovery and characterization of new magnetic materials with enhanced and controllable magnetic properties.[2]The organic-based magnet of V[TCNE] x ·zCH 2 Cl 2 (x ≈ 2; z ≈ 0.5) composition with an ordering temperature T c of about 400 K can be synthesized via the reaction of V(C 6 H 6 ) 2 [3a] or V(CO) [5]With the goal of finding new organic-based magnets the reaction of V(CO) 6 with numerous polynitrile electron acceptors led to the discovery of several new V-based magnets with T c below room temperature. These include a,a′-dicyanoperfluorostilbene, (T c = 205 K), [6] tetracyanopyrazine (T c = 200 K), [7] and 7,7,8,8-tetracyano-p-quinodimethane (TCNQ; T c = 52 K). (CO) 6 ] 1/2 ·zS (4>x > 3.5; S = CH 2 Cl 2 , PhCF 3 ) composition that orders above room temperature at 50°C (323 K). [9] A mild electronic acceptor methyl tricyanoethylenecarboxylate (MeTCEC; Scheme 1) has recently been used to synthesize isostructural decamethylmetallocene electron-transfer salt magnets of [MCp* 2 ][MeTCEC] (M = Cr, Mn, Fe) composition from which only Mn salt orders ferromagnetically below 7 K.[10] This is a little attenuated with respect to that observed for [MCp* 2 ][TCNE] (T c = 8.8 K).[11] Nonetheless, we targeted V[MeTCEC] 2 as a new organic-based magnet to identify the advantages and disadvantages of the reduced symmetry of the electron acceptor as well as the role of the ester carbonyl oxygen (C = O) in formation of additional superexchange pathways. Herein, we report a new organicbased magnet prepared from the reaction of V(CO) 6 and MeTCEC with T c close to room temperature. MeTCEC underwent a reversible one-electron reduction at -0.05 V (vs. saturated calomel electrode (SCE) in MeCN), [12] that is ca. 0.3 V harder to reduce than TCNE, but easier to reduce than tetracyanopyrazine (-0.31 V), [13] and a reaction with V(CO) 6 was expected. Reaction of MeTCEC with V(CO) 6 in CH 2 Cl 2 rapidly occurred and the system turned dark blue with CO evolution, and a dark precipitate formed suggesting the formation of an organometallic polymer similar to V

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“…(solv. = solvent) [15] and V[TCNE] x ·z CH 2 Cl 2 (x % 2; z % 0.5) that have three absorptions present between 2215 and 2150 cm À1 .…”

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confidence: 99%

“…[23] Nonetheless, absorptions in these regions were not observed for the reaction of [V(CO) 6 ] and TCNE, [3b, 8, 10] TCNQ, [16] TCNP, [15] , and others [14] as CO is facilely lost. [18] Heating the V CO ·solv.…”

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confidence: 99%

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Room‐Temperature Organic‐Based Magnet (T_c≈50 °C) Containing Tetracyanobenzene and Hexacarbonylvanadate(−I)

2006

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The discovery of the first organic-based magnet, Me 5 ) 2 ]C + [TCNE]C À (TCNE = tetracyanoethylene), [1] led to the development of several new families of magnetically ordered materials based on unpaired electron spins residing in p orbitals. These include [Mn II (hfac) 2 (NITR)] (hfac = hexafluoroacetylactonate; NITR = 2-R-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazolyl-1-oxy-3-oxide) [2] and [Mn

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Magnetically Ordered (T_c = 200 K) Bis(tetracyanopyrazine)vanadium, V[TCNP]₂·yCH₂Cl₂

Cited by 45 publications

References 12 publications

A computational study of the crystal and electronic structure of the room temperature organometallic ferromagnet V(TCNE)₂

A computational study of the crystal and electronic structure of the room temperature organometallic ferromagnet V(TCNE)₂

A Methyl Tricyanoethylenecarboxylate‐Based Room‐Temperature Magnet

Room‐Temperature Organic‐Based Magnet (T_c≈50 °C) Containing Tetracyanobenzene and Hexacarbonylvanadate(−I)

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Magnetically Ordered (Tc = 200 K) Bis(tetracyanopyrazine)vanadium, V[TCNP]2·yCH2Cl2

Cited by 45 publications

References 12 publications

A computational study of the crystal and electronic structure of the room temperature organometallic ferromagnet V(TCNE)2

A computational study of the crystal and electronic structure of the room temperature organometallic ferromagnet V(TCNE)2

A Methyl Tricyanoethylenecarboxylate‐Based Room‐Temperature Magnet

Room‐Temperature Organic‐Based Magnet (Tc≈50 °C) Containing Tetracyanobenzene and Hexacarbonylvanadate(−I)

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Magnetically Ordered (T_c = 200 K) Bis(tetracyanopyrazine)vanadium, V[TCNP]₂·yCH₂Cl₂

A computational study of the crystal and electronic structure of the room temperature organometallic ferromagnet V(TCNE)₂

A computational study of the crystal and electronic structure of the room temperature organometallic ferromagnet V(TCNE)₂

Room‐Temperature Organic‐Based Magnet (T_c≈50 °C) Containing Tetracyanobenzene and Hexacarbonylvanadate(−I)