Design and Synthesis of a “Starburst”‐Type Nonadiazo Compound and Magnetic Characterization of Its Photoproduct

Matsuda, Kenji; Nakamura, N.; Inoue, Katsuya; Koga, Noboru; Iwamura, Hiizu

doi:10.1002/chem.19960020305

Cited by 45 publications

(17 citation statements)

References 43 publications

(1 reference statement)

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“…The polycarbenes have been known as one of the most important organic molecular magnets . As the spin quantum number ( S ) of the ground state is naïvely considered to be in proportion to n , there have been efforts devoted to synthesize polycarbenes with a high susceptibility as organic ferromagnets by increasing number of the monomeric units . Despite these efforts, persistent high‐spin (ferromagnetic) states with S > 5 have not been experimentally observed for one‐dimensional (1D) polycarbenes .…”

Section: Applicationsmentioning

confidence: 99%

Density matrix renormalization group for ab initio Calculations and associated dynamic correlation methods: A review of theory and applications

Yanai

Kurashige

Mizukami

et al. 2014

Int J of Quantum Chemistry

173

185

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The recent advent of the density matrix renormalization group (DMRG) theory has delivered a new capability to compute multireference (MR) wave function with large configuration space, which far exceeds the limitation of conventional approaches. Here, we provide an overview of our recent work on the developments of ab initio DMRG methods in the context of the active space approaches and their applications to MR chemical systems.

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Section: Applicationsmentioning

confidence: 99%

Density matrix renormalization group for ab initio Calculations and associated dynamic correlation methods: A review of theory and applications

Yanai

Kurashige

Mizukami

et al. 2014

Int J of Quantum Chemistry

173

185

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“…The net magnetization generated by the irradiation of 1a -N 2 was estimated from the difference between M a and the corresponding magnetization values, M b , obtained before irradiation. The plot of the magnetization ( M ) versus the magnetic field ( H ) was analyzed in terms of the Brillouin function as follows [30,31,32,33,34,35]: M = M a − M b = FNgJμ B B ( χ ) where F is the generation factor for carbene estimated from saturated magnetization, N is the number of the molecule, g is the Landé g -factor, J is the quantum number for the total angular momentum, and μ B is the Bohr magneton. Since diphenylcarbene is composed of light elements, the orbital angular momentum should be negligible, and J can be replaced with the spin quantum number S .…”

Section: Resultsmentioning

confidence: 99%

Diphenylcarbene Protected by Four ortho-Iodine Groups: An Unusually Persistent Triplet Carbene

et al. 2016

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Diphenyldiazomethane with four iodine groups at the ortho positions and two tert-butyl groups at the para positions, i.e., bis(4-tert-butyl-2,6-diiodophenyl)diazomethane (1a-N 2 ), was synthesized as a sterically hindered triplet carbene precursor. Irradiation of 1a-N 2 in solution effectively generated the corresponding triplet diphenylcarbene 3 1a, which was characterized by UV-vis spectroscopy at low temperature, along with laser flash photolysis techniques at room temperature. The UV-vis spectrum of 3 1a was obtained by irradiating 1a-N 2 in a 2-methyltetrahydrofuran matrix at 77 K. The ESR spectrum showed no triplet carbene signals, while a radical species was observed at the anticipated temperature of the decomposition of triplet carbene 3 1a. Transient absorption bands ascribable to 3 1a were observed by laser flash photolysis of 1a-N 2 in a degassed benzene solution and decayed very slowly with a second-order rate constant (2k/εl) of 5.5 × 10 −3 ·s −1 . Steady-state irradiation of 1a-N 2 in degassed benzene afforded 9,10-diarylphenanthrene derivative 2a in a 31% yield. Triplet carbene 3 1a was also trapped by either oxygen (k O2 = 6.5 × 10 5 M −1 ·s −1 ) or 1,4-cyclohexadiene (k CHD = 1.5 M −1 ·s −1 ) to afford the corresponding ketone 1a-O or the diarylmethane 1a-H 2 . The carbene was shown to be much less reactive than the triplet diphenylcarbene that is protected by two ortho-iodo and two ortho-bromo groups, 3 1b.

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“…An extensively used concept for the synthesis of bi-, tri-or oligoradicals is to connect stable organic radicals, e.g., nitroxides [6], inorganic coordination complexes, e.g., vanadyl derivatives [7], or organometallic compounds [8], e.g., [9], via different organic [10] or inorganic [11] bridges. Meta-substituted phenylene groups, for example, are widely used as bridges in the design of ferromagnetically coupled radicals [12][13][14]. Ir was, however, found in some cases that meta-phenylene derivatives can also display antiferromagnetically coupled ground states [15][16][17], pointing to the fact that the acquired knowledge does not yet allow an unequivocal understanding of the magneto-structural correlations.…”

Section: Introductionmentioning

confidence: 95%

Trovacenyl-based organometallic triradicals: Spin frustration, competing interactions and redox splitting

et al. 2004

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Two new triradicals based on trovacene [(q7-tropylium)vanadium(qS-cyclopentadienyl)], 1,3,5-tri ([5]trovacenyl)benzene 4 and 1,3,5-tri([5]trovacenyl)-6-methoxybenzene 5 were prepared and their magnetic properties were studied by continuous-wave X-band electron paramagnetic resonance (EPR) spectroscopy and by temperature-dependent magnetic susceptometry. The EPR spectra of 4 and 5 in liquid toluene solution demonstrate that the three unpaired electrons localized on the vanadium atoms interact with each other in both complexes. The data from magnetic susceptometry revealed that the electron spins in both triradicals ate antiferromagnetically coupled despite the meta-phenylene bridge. The exchange coupling constants ate equal in the C3-symmetrical triradical 4 (J = J' = -0.68 cm-~), which leads to a twofold degenerate spin ground state (spin frustration). The symmetry lowering by methoxy substitution of the benzene spacer in 5 results in the effect of competing interactions ( 3 " = -1 . 8 3 cm -~ and J ' = -2 . 3 8 cm-~). In addition to magnetocommunication, the effect of ring substitution on electrocommunication is also discernable. It manifests itself in disparate redox splittings 8E1/2 (0/-, -/ 2 -) and 5EI/2 ( -/ 2 -, 2 -/ 3 -) for 5, while these parameters are equal for the C3-symmetrical trinuclear complex 4.

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Design and Synthesis of a “Starburst”‐Type Nonadiazo Compound and Magnetic Characterization of Its Photoproduct

Cited by 45 publications

References 43 publications

Density matrix renormalization group for ab initio Calculations and associated dynamic correlation methods: A review of theory and applications

Density matrix renormalization group for ab initio Calculations and associated dynamic correlation methods: A review of theory and applications

Diphenylcarbene Protected by Four ortho-Iodine Groups: An Unusually Persistent Triplet Carbene

Trovacenyl-based organometallic triradicals: Spin frustration, competing interactions and redox splitting

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