Spin Transitions in a Dithiazolyl Radical:  Preparation, Crystal Structures, and Magnetic Properties of 3-Cyanobenzo-1,3,2-dithiazolyl, C7H3S2N2•

Alberola, Antonio; Collis, Rebecca J.; Humphrey, Simon M.; Less, Robert J.; Rawson, Jeremy M.

doi:10.1021/ic051935p

Cited by 66 publications

(58 citation statements)

References 22 publications

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“…This encompasses not only many magnetic semiconducting or insulating tetrathiafulvalene salts and all radical dithiolene complexes, [35,36] but also the well known neutral radicals: in the phenalenyl [37][38][39] and in the thiazolyl [40,41] series, for example. In this work we describe original syntheses and X-ray crystal structures of [CpNiA C H T U N G T R E N N U N G (tfd)] and [CpNiA C H T U N G T R E N N U N G (adt)] and investigate the relationship between the solid-state structures of the three…”

Section: Introductionmentioning

confidence: 99%

Strong Magnetic Interactions through Weak Bonding Interactions in Organometallic Radicals: Combined Experimental and Theoretical Study

Cauchy

Ruiz

Jeannin

et al. 2007

Chemistry A European J

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The magnetic properties of a series of three neutral radical organometallic complexes of general formula [CpNi(dithiolene)]. have been investigated by a combination of X-ray crystal structure analysis and magnetic susceptibility measurements, while the assignment of the exchange coupling constants to the possible exchange pathways has been accomplished with the help of calculations based on density functional theory (DFT). The syntheses and X-ray structures of [CpNi(adt)] (adt=acrylonitrile-2,3-dithiolate) and [CpNi(tfd)] (tfd=1,2-bis(trifluoromethyl)ethene-1,2-dithiolate) complexes are described, while [CpNi(mnt)] (mnt=maleonitriledithiolate) was reported earlier. In the three complexes, we observed strong antiferromagnetic coupling that could not be explained solely by short SS intermolecular contacts. Our calculations indicated that spin density in these complexes is strongly delocalized on the NiS2 moiety, with up to 20% on the Cp ring. As a consequence, CpCp and Cpdithiolene overlap interactions have been identified as responsible for antiferromagnetic couplings. The [CpNi(adt)] complex thus has a value J=-369.5 cm(-1) for an exchange interaction through a pi stacking due to the CpCp overlap.

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Section: Introductionmentioning

confidence: 99%

Strong Magnetic Interactions through Weak Bonding Interactions in Organometallic Radicals: Combined Experimental and Theoretical Study

Cauchy

Ruiz

Jeannin

et al. 2007

Chemistry A European J

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“…We also demonstrate that this unique dynamics is a major source of vibrational entropy and plays a prime role in driving the LT-HT phase transition. This mechanism is very likely to be operative in other DTA-based bistable or switchable materials [17][18][19][20][21] .…”

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confidence: 96%

“…Some of these magnetic phase transitions are associated with a hysteretic behaviour 11,12,[16][17][18][19] (thus giving rise to a region of bistability), while other transitions occur without hysteresis 20,21 . In addition to these intriguing solid state phase transitions, many other members of the key family of thiazyl radicals show remarkable conductivity and magnetic properties 16,[22][23][24][25] .…”

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confidence: 99%

The key role of vibrational entropy in the phase transitions of dithiazolyl-based bistable magnetic materials

et al. 2014

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The neutral radical 1,3,5-trithia-2,4,6-triazapentalenyl (TTTA) is a prototype of moleculebased bistable materials. TTTA crystals undergo a first-order phase transition between their low-temperature diamagnetic and high-temperature paramagnetic phases, with a large hysteresis loop that encompasses room temperature. Here, based on ab initio molecular dynamics simulations and new X-ray measurements, we uncover that the regular stacking motif of the high-temperature polymorph is the result of a fast intra-stack pair-exchange dynamics, whereby TTTA radicals continually exchange the adjacent TTTA neighbour (upper or lower) with which they form an eclipsed dimer. Such unique dynamics, observed in the paramagnetic phase within the whole hysteresis loop, is the origin of a significant vibrational entropic gain in the low-temperature to high-temperature transition and thereby it plays a key role in driving the phase transition. This finding provides a new key concept that needs to be explored for the rational design of novel molecule-based bistable magnetic materials.

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“…The two nearly coplanar phenyl rings are almost eclipsed with respect to each other, with their centroids separated by 3.72 . Valence-isoelectronic dithiazolyl radicals commonly dimerize by a similar cisoid mode, [13] involving 2e À p-p interaction of the singly occupied molecular orbitals (SOMO) of each monomer between their SPNPS units. [14] In 2, however, the build-up of negative charge on the phosphorus centers leads to the apparent predominance of SbÀSb bonding.…”

Section: Methodsmentioning

confidence: 99%

Formation and Structure of the [(1,2‐C₆H₄P₂Sb)₂]⁴⁻ Ion: Implications for an Extended Family of Isoelectronic Main‐Group Radicals

et al. 2007

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We have previously developed a strategy for the preparation of heterometallic main-group imido (RN 2À ) and phosphinidene (RP 2À ) compounds involving stepwise deprotonation of REH 2 (E = N,P) with alkali-metal organometallics (for example nBuLi), followed by reaction with M(NMe 2 ) n (M = As, Sb, Bi, n = 3; Sn n = 2; Scheme 1).[1] Recently, however, we have recognized the behavior of this type of mixed-metal system as superbases. [2] This effect was first apparent in the reaction of MesPH 2 (Mes = 2,4,6-Me 3 C 6 H 2 ) with Sn(NMe 2 ) 2 /PhCH 2 Na, which gives the unusual stannate ion [Sn{P(2-CH 2 -4,6-Me 2 C 6 H 2 )}{PMes}] 3À [3] as a result of deprotonation of a PH 2 group and an ortho-CH 3 group. Remarkably, quadruple deprotonation of the PH 2 and NH 2 groups occurs in 1-NH 2 -2-PH 2 -C 6 H 4 (LH 4 ) using a similar Sn(NMe 2 ) 2 /nBuLi mixture, givingcontaining the L 4À tetraanion and LC 3À radical.[4]Herein we report the reaction of 1,2-(PH 2 ) 2 C 6 H 4 with Sb(NMe 2 ) 3 /nBuLi, which results in the complete deprotonation of the PH 2 groups, giving the 6p-aromatic anion [1,2-C 6 H 4 P 2 Sb] À . Upon one-electron reduction, the [1,2-C 6 H 4 P 2 Sb] 2 4À tetraanion is formed. As established from DFT calculations, this highly charged, Sb À Sb-bonded distibane is best described as a dimer of two 7p-[1,2-C 6 H 4 P 2 Sb]C 2À radicals (Scheme 2 a) and is valence-isoelectronic with the important class of sulfur/nitrogen-based thiazolyl radicals (Scheme 2 b).[5]Lithiation of 1,2-(PH 2 ) 2 C 6 H 4 (1 equiv) with nBuLi (2 equiv) in tmeda (tmeda = Me 2 NCH 2 CH 2 NMe 2 ) followed by reaction with Sb(NMe 2 ) 3 (0.67 equiv) gives [Li-(tmeda) 2 ]+ [1,2-C 6 H 4 P 2 Sb] À (1) after crystallization from THF/tmeda. However, black crystals of [{1,2-C 6 H 4 P 2 Sb} 2 {Li-(tmeda)} 4 ] (2) [6] are obtained if this reaction is undertaken in toluene and the product crystallized from toluene/tmeda. Compound 2 presumably arises from one-electron reduction of the 6p-aromatic anion of 1 (Scheme 3). The diamagnetic nature of 2 persists in the solid state and in dilute solutions in toluene as a result of spin-pairing of the electrons within the SbÀSb-bonded dimer, as shown by the structural characterization (see below). This situation contrasts with the behavior of valence-isoelectronic dithiazolyl dimers, for which a dissociation energy of about 0 kJ mol À1 results in extensive dissociation in solution.[5]

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Spin Transitions in a Dithiazolyl Radical: Preparation, Crystal Structures, and Magnetic Properties of 3-Cyanobenzo-1,3,2-dithiazolyl, C₇H₃S₂N₂^•

Cited by 66 publications

References 22 publications

Strong Magnetic Interactions through Weak Bonding Interactions in Organometallic Radicals: Combined Experimental and Theoretical Study

Strong Magnetic Interactions through Weak Bonding Interactions in Organometallic Radicals: Combined Experimental and Theoretical Study

The key role of vibrational entropy in the phase transitions of dithiazolyl-based bistable magnetic materials

Formation and Structure of the [(1,2‐C₆H₄P₂Sb)₂]⁴⁻ Ion: Implications for an Extended Family of Isoelectronic Main‐Group Radicals

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Spin Transitions in a Dithiazolyl Radical: Preparation, Crystal Structures, and Magnetic Properties of 3-Cyanobenzo-1,3,2-dithiazolyl, C7H3S2N2•

Cited by 66 publications

References 22 publications

Strong Magnetic Interactions through Weak Bonding Interactions in Organometallic Radicals: Combined Experimental and Theoretical Study

Strong Magnetic Interactions through Weak Bonding Interactions in Organometallic Radicals: Combined Experimental and Theoretical Study

The key role of vibrational entropy in the phase transitions of dithiazolyl-based bistable magnetic materials

Formation and Structure of the [(1,2‐C6H4P2Sb)2]4− Ion: Implications for an Extended Family of Isoelectronic Main‐Group Radicals

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Spin Transitions in a Dithiazolyl Radical: Preparation, Crystal Structures, and Magnetic Properties of 3-Cyanobenzo-1,3,2-dithiazolyl, C₇H₃S₂N₂^•

Formation and Structure of the [(1,2‐C₆H₄P₂Sb)₂]⁴⁻ Ion: Implications for an Extended Family of Isoelectronic Main‐Group Radicals