Quintet ground states of m-dicarbene and m-dinitrene compounds

Wasserman, E.; Murray, Robert W.; Yager, W. A.; Trozzolo, A. M.; Smolinsky, G.

doi:10.1021/ja00995a066

Cited by 205 publications

(73 citation statements)

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“…[45][46][47] Trindle and Datta, 31 interpreted this feature on the basis of previous heuristic theories 48 and with more robust arguments based on the spin polarization of the triplet unrestricted Hartree-Fock ͑UHF͒ wave function. According to this theory, if the number of atoms in the chain connecting the two magnetic sites is odd, the triplet is favored since an excess spin alternation along the chain is possible, which strongly stabilizes the triplet state.…”

Section: Ferromagnetic/antiferromagnetic Coupling In Meta/para Submentioning

confidence: 84%

Magnetic coupling in bis-nitronylnitroxide radicals: The role of aromatic bridges

Barone

Cacelli

Ferretti

2009

The Journal of Chemical Physics

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Configuration interaction calculations have been applied to the study of the magnetic coupling in bis-nitronyl nitroxide radicals with benzene bridges. Molecular orbitals obtained with different localization schemes have been considered in the generation of the CI space, with the aim of investigating the role played by the various fragments in the magnetic interaction. The aromatic bridge is found significant, while fragments outside the magnetic-bridge-magnetic moiety can be neglected. Using simplified model molecular species, an accurate analysis of the ferromagnetic/antiferromagnetic coupling in the meta and para diradicals is reported.

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Section: Ferromagnetic/antiferromagnetic Coupling In Meta/para Submentioning

confidence: 84%

Magnetic coupling in bis-nitronylnitroxide radicals: The role of aromatic bridges

Barone

Cacelli

Ferretti

2009

The Journal of Chemical Physics

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“…Keywords: density functional calculations · EPR spectroscopy · molecular spintronics · radicals · spin alignment [ this context, and especially for organic magnetism, a longstanding quest [10][11][12][13] is the design of entities-whether discrete (molecules and dendrimers) [14] or extended (1D-3D assemblies) [15] -showing a ferromagnetic [16] spin alignment. Spin manipulation here can be used to make this behavior switchable, and the most widely used strategy consists of promoting the interplay between this property and one or more other properties within so-called multifunctional systems.…”

Section: Introductionmentioning

confidence: 99%

Intramolecular Spin Alignment within Mono‐Oxidized and Photoexcited Anthracene‐Based π Radicals as Prototypical Photomagnetic Molecular Devices: Relationships Between Electrochemical, Photophysical, and Photochemical Control Pathways

Matsumoto

Ciofini

Lainé

et al. 2009

Chemistry A European J

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AnOV is a pi-conjugated radical built from an anthracene (An) unit linked by a p-phenylene to an oxoverdazyl (OV) moiety. The mono-oxidized (cationic) form of AnOV was generated both electrochemically and photochemically (in the presence of an electron acceptor). The triplet nature (S=1) of the electronic ground state of AnOV(+) was demonstrated by combining spectroelectrochemistry, electron-spin resonance (ESR) experiments, and ab initio molecular orbital (MO) calculations. The intramolecular spin alignment (ISA) within AnOV(+) results from the ferromagnetic coupling (J(electrochem)>0) of the two unpaired electrons located on the oxidized electron donor (An(+)) and on the pendant OV radical. The spin-density distribution pattern of AnOV(+) is akin to that of AnOV when photopromoted (AnOV*) to its high-spin (HS) lowest excited quartet (S=3/2) state. This high-spin state results from the ferromagnetic coupling (J(photophys)>0) of the triplet locally excited state of An ((3)An*) with the doublet ground state of OV. As a shared salient feature, AnOV(+) and AnOV* (HS) show a spin delocalization within the domain of activated An in either An(+) or (3)An* (nexus states) forms. The present study essentially contributes to establish and clarify relationships between electrochemical, photophysical, and photochemical pathways to achieve ISA processes within AnOV. In particular, we discuss the impact of the spin polarization of the unpaired electron of OV on electronic features of the An electron-donating subunit. Close analysis of this polarizing interplay allows one to derive a novel functional paradigm to manipulate electron spins at the intramolecular level with light and under an external magnetic field. Indeed, two original functional elements are identified: light-triggered donors of spin-polarized electrons and spin-selective electron acceptors, which are of potential interest for molecular spintronics.

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“…In 1967, however, the authar (1) and independently Wasserman et al (2) found that the electronic ground state af the aromatic hydracarban, m-phenylene-bisphenylmethylene, is the quintet state (S=2). This unusual malecule has the structure of type I in Fig.…”

Section: Introductionmentioning

confidence: 99%

Electronic structures of aromatic hydrocarbons with high spin multiplicities in the electronic ground state

Itoh

1978

Pure and Applied Chemistry

187

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-It has been established experimentally that there are alternant hydrocarbons (AH) with high spin multiplicities in the electr~pic ground state, the highest multiplicity known up to date being septet. Such electronic structures are rationalized by utilizing the degeneracy of non-bonding pi molecular orbitals (NBMO) predictable from the theory of Longuet-Higgins in conjunction with the non-bonding orbitals of divalent carbon atoms which are perpendicular to pn orbitals and are nearly degenerate with NBMO. The degeneracy of NBMO is determined by the topological nature of molecules which permits the ground state with high spin multiplicities according to Hund's rule in spite of their low molecular symmetries. The nature of AH having high spin multiplicities in the ground state reported so far is understood in this manner.It was found, however, that for some AH the high spin multiplet states are unexpectedly not the ground states although they lie very close to the singlet ground state. The difference between these two types of AH with high spin multiplicities is associated with the fact that the spin distribution of NBMO is alternant in the former AH, but not in the latter. To the latter AH the weak interaction model was found to apply in which a molecule is divided into two units weakly interacting with each other.

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Quintet ground states of m-dicarbene and m-dinitrene compounds

Cited by 205 publications

References 1 publication

Magnetic coupling in bis-nitronylnitroxide radicals: The role of aromatic bridges

Magnetic coupling in bis-nitronylnitroxide radicals: The role of aromatic bridges

Intramolecular Spin Alignment within Mono‐Oxidized and Photoexcited Anthracene‐Based π Radicals as Prototypical Photomagnetic Molecular Devices: Relationships Between Electrochemical, Photophysical, and Photochemical Control Pathways

Electronic structures of aromatic hydrocarbons with high spin multiplicities in the electronic ground state

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