The structure of the low-temperature modification of N,N-dimethylmorpholinium di-7,7,8,8-tetracyano-p-quinodimethanide; DMM(TCNQ)2 (Iα) at 95 K

Middeldorp, J. A. M.; Visser, R. J. J.; Boer, J. L. de

doi:10.1107/s0108768185002282

Cited by 4 publications

(6 citation statements)

References 5 publications

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“…Qualitatively, this appears to us a slightly less ideal intermolecular packing with respect to the maximin principle. This is substantiated by the smaller number of structures (ten) which adopt the staggered-short axis arrangement. ,,,,,,− This second arrangement, as it involves contacts between atoms all with large (although not the largest) HOMO presences, nonetheless seems a reasonable alternative.…”

Section: Resultsmentioning

confidence: 98%

“…In the CSD, reduced N-containing π-radicals with short C···C, C···N, or N···N contacts (contact distances < 0.95 the sum of the van der Waals radii, i.e., distances shorter than respectively 3.20, 3.09, and 2.95 Å) all prove to be nitriles. The five nitrile radicals uncovered (HCCP, , TCNQ, − DCNQI, BTCQ, and TCNE 68-75 ) are shown in Figure . All these species are in an open-shell form, with an anionic charge between 0.5 and 1.…”

Section: Resultsmentioning

confidence: 99%

“…The same procedure was adopted in our N-containing π-radical search except, of course, we allowed the presence of nitrogen atoms. The resulting data can be split in two groups: phthalocyanine (Pc) or related macrocycles, H 2 Pc, MPc, − and MPp 39-41 (we kept those Pc molecules coordinated to metal atoms, M), and nitrile derivatives, HCCP, , TCNQ, − DCNQI, BTCQ, and TCNE. − (See Supporting Information for CSD search results. Due to the large number of hits on TCNQ, only part of the TCNQ references are given here.)…”

Section: Technical Proceduresmentioning

confidence: 99%

“…We show for a number of N-containing π-systems that, from a knowledge of the HOMO or LUMO alone, we can correctly predict the most common crystal packing. π-Systems considered include all those N-containing systems with short C···C, C···N, or N···CN contacts (distances < 0.95 × the sum of the van der Waals radii): phthalocyanine (2HPc), metalated phthalocyanine (MPc), − metalated tetrabenzoporphyrin (MPp), − 1,2,3-tris(dicyanomethylene)cyclopropane (HCCP), , 7,7,8,8-tetra-cyanoquinodimethane (TCNQ), − N , N ‘-dicyano-1,4-benzoquinodiimine (DCNQI), 1,1,2,5,6,6-hexacyano-3,4-diazahexadiene (BTCQ), and tetracyanoethene (TCNE). − (See Supporting Information for CSD search results.) We further prepare two new phthalocyanine based cation radical salts which further verify the utility of the maximin principle.…”

Section: Introductionmentioning

confidence: 99%

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The Maximin Principle of π-Radical Packings

et al. 2005

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A two-term model is proposed for hydrocarbon and N-containing pi-radicals which are in close contact with one another. The first term is attractive (due to partially occupied frontier pi-orbitals), and the second, repulsive (due to hard-core repulsion between close-lying atoms). This model is applied to dimers where intermolecular contacts are closer than <0.95 x the sum of the atomic van der Waals radii. The maximin principle is proposed. The maximin principle states that the lowest energy conformation maximizes overlap of the frontier orbitals while simultaneously minimizing intermolecular contacts. A Hückel Hamiltonian, the mu(2)-Hamiltonian, which contains the above attractive and repulsive terms, is applied. The interaction surfaces of two pi-hydrocarbon radical cations were calculated for the three systems known crystallographically to contain cations in close contact: naphthalene, fluoranthene, and pyrene. The global minima of these surfaces correspond to the experimentally determined structures. The mu(2)-Hamiltonian energy surfaces of the naphthalene cation dimer are qualitatively similar to those calculated at the RHF/6-311G(d,p) and MP2/6-311G(d,p) levels. The maximin principle is applied to N-containing pi-radicals. Except in the case of tetracyanoethene, the maximin principle correctly predicts the most common dimer crystal packing. (MgPc)(NO(3)).0.5THF and (MgPc)(ReO(4)).1.5THF (Pc = phthalocyanine) were prepared: both new crystal structures follow the maximin principle. The maximin principle is used to suggest the dimer cation ground state of oligoacenes, cations important as organic hole-based semiconductors.

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Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

Section: Technical Proceduresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Maximin Principle of π-Radical Packings

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“…At high temperatures (475 K), a transition is observed suggestive of a 4kF transition to uniform chains as in MEM TCNQ2. Below Tc = 260 K, the chains are tetramerized, indicative of a spinPeierls or 2kF transition (20). At temperatures below T,, two lines are observed in the esr spectrum which gradually merge at T,.…”

Section: Discussionmentioning

confidence: 95%

Phase transitions in the organic semiconductor dipropylamine tetracyanoquinodimethane: DPA TCNQ₂

Bandrauk¹,

Truong²,

Aubin³

1988

Can. J. Chem.

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. Can. J. Chem. 66,938 (1988). Dipropylarnine tetracyanoquinodirnethane, DPA TCNQ2, is by stoichiometry a 1:2 organic salt giving rise to a f filled band quasi one dimensional electronic system. Conductivity measurements indicate the presence of at least three phase transitions. A dominant transition at 215 K shows simultaneous large discontinuities in both electric and magnetic properties. Infrared measurements suggest a structural change at 21 5 K related to conduction electron-molecular vibration interactions in view of the + appearance of A, TCNQ modes in the infrared spectrum. Deuteration of the donor N-H bond lowers the main transition temperature by 5 K but maintains the same physical properties as in the nondeuterated compound. Le dipropylarnine tCtracyanoquinodirnCthane (DPA TCNQ2) est un sel organique de stoechiomttrie 1:2 qui donne lieu a un systkme tlectronique quasi-unidimensionnel comportant une bande qui n'est remplie qu'au a. Des rnesures de conductivitC suggkrent la prisence d'au rnoins trois transitions de phases. Une transition dorninante a 215 K prtsente des discontinuitCs sirnultanCes irnportantes tant dans les propriCtCs Clectriques que magnktiques. Des mesures infrarouges perrnettent de voir apparaitre les modes A, du TCNQ et suggkrent qu'il se produit un changement de structure a 215 qui est reliC i d e s interactions de vibration de conduction Clectron-rnolCcule. La deutCration de la liaison donneur N-H diminue par 5 K la temperature d'apparition de la transition principale; toutefois, on retrouve les mernes propriCtCs physiques que celles du produit non-deutCrC.[Traduit par la revue]

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The structure of the copper(II) complexes of lysine [Cu(lys)2] [HgI3]2

Bino

1988

Inorganica Chimica Acta

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The structure of the low-temperature modification of N,N-dimethylmorpholinium di-7,7,8,8-tetracyano-p-quinodimethanide; DMM(TCNQ)₂ (Iα) at 95 K

Cited by 4 publications

References 5 publications

The Maximin Principle of π-Radical Packings

The Maximin Principle of π-Radical Packings

Phase transitions in the organic semiconductor dipropylamine tetracyanoquinodimethane: DPA TCNQ₂

The structure of the copper(II) complexes of lysine [Cu(lys)2] [HgI3]2

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The structure of the low-temperature modification of N,N-dimethylmorpholinium di-7,7,8,8-tetracyano-p-quinodimethanide; DMM(TCNQ)2 (Iα) at 95 K

Cited by 4 publications

References 5 publications

The Maximin Principle of π-Radical Packings

The Maximin Principle of π-Radical Packings

Phase transitions in the organic semiconductor dipropylamine tetracyanoquinodimethane: DPA TCNQ2

The structure of the copper(II) complexes of lysine [Cu(lys)2] [HgI3]2

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Resources

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The structure of the low-temperature modification of N,N-dimethylmorpholinium di-7,7,8,8-tetracyano-p-quinodimethanide; DMM(TCNQ)₂ (Iα) at 95 K

Phase transitions in the organic semiconductor dipropylamine tetracyanoquinodimethane: DPA TCNQ₂