CT Complexes Derived from Verdazyl Radicals

Abstract

Shin'ichi N akatsuji3 *, A k ari K itam u ra3, A tsushi T akai3 Kazuyoshi N ishikaw ab, Yukio M o rim o to b, N o ritaki Y asuokab, H aru k i K aw am ura,3 H iroyuki A nzai3 a D ep artm en t o f M aterial Scien ce and b D ep artm en t o f Life Scien ce, Faculty o f S cien ce, H im eji Institute o f T echnology, K am igori, H yogo 6 7 8 -1 2 , Japan Z. N aturforsch. 53 b, 4 9 5 -5 0 2 (1998); Verdazyl R adical, Stable R adical, CT C om p lex, M agnetic Property, X -R ay D ata Several charge-transfer (C T ) com p lexes d erived from l,5-d ip h en yl-3-(p -su b stitu ted -p h enyl)-verdazyl radicals and T C N Q F 4 (2,3,5,6-tetraflu oro-7,7,8,8-tetracyan oquinod im ethan e) or D D Q (2,3-d ich lo ro -5 ,6 -d icy a n o -l,4 -b en zo q u in o n e) w ere prepared and their m agnetic properties w ere investigated . T he X-ray crystal structural analyses on the CT com p lexes consisted o f 3-(4-m eth oxyp h en yl)-, 3 -(4 -to ly l)-as w ell as 3-(4-ch lorop henyl)-verdazyl radicals and T C N Q F 4 w ere carried out and correlated w ith their m agnetic properties in which large decrease o f m agnetic su scep tib ility was o b serv ed in each com plex.

Genuine organic magnetic semiconductors: electrical and magnetic properties of the TCNQ and iodide salts of methylpyridinium-substituted verdazyl radicals

“…If the verdazyl moiety of the [p-MePyDV] 1 I 2 salt ( 1) is oxidized forming the verdazylium ion, the N-N distance becomes shorter than that of the neutral TPV radical, as can be found in the case of the [TPV] 1 [TCNQF 4 ] 2 salt. 8,19 Table 2 shows that the bond lengths and bond angles of the verdazyl moiety (N1-N2-C1-N3-N4-C2) in salt ( 1) are very similar to those of the neutral TPV radical, indicating that the verdazyl moiety is not oxidized. In fact, the hyperfine coupling constants (a N1 ~aN2 ~0.619 mT) of salt (1) in ethanol solution are similar to those (a N1 ~aN2 ~0.605 mT) of TPV, suggesting that the unpaired electron distribution of salt ( 1) is similar to that of TPV.…”

“…The 1 : 1 CT salt [TPV] 1 [TCNQF 4 ] 2 was prepared by the reaction between 1,3,5-triphenylverdazyl (TPV) neutral radical and TCNQF 4 molecule, and the magnetic and electrical properties of the complex were studied. 8 The verdazyl moiety of the verdazyl radical is oxidized forming the nonmagnetic verdazylium ion (S ~0). The 1 : 1 salt exhibited magnetic insulator properties.…”

Anomalously slow rates of reduction of iron(III) polypyridine complexes by triphenyl verdazyl radicals in acetonitrile

“…However, the extinction coefficients for the Table 1 Second (k 1 K, dm 6 mol -2 s -1 ) and third-order rate constant products (k 2 K, dm 9 mol -3 s -1 ) for reaction of verdazyl radicals with iron(III) complexes in acetonitrile at 25 verdazyl-TCNQF 4 CT complexes (>10 5 ) are ten times larger than those of the verdazylium ions from which they are derived. 24 The greater than predicted increase in absorption at 560 nm is readily understandable in view of these results.…”

Verdazyls and Related Radicals Containing the Hydrazyl [R2N‐NR] Group

“…Nakatsuji prepared charge transfer salts of verdazylium cations (5 + ) and radical anions of the acceptor molecules TCNQ 40, tetrafluoroTCNQ 41, and DDQ 42 by reaction of the two neutral reagents. 89 Hynes has studied the kinetics of outer sphere electron transfer reactions between Kuhn 96 induce ring opening to form either 1,2,4-triazoles 43 or N-formylformazans 44 (Scheme 7.13). 1,2,4-Triazoles are also produced by simple thermolysis of verdazyls, either by heating the radical as a solid to 200 • C 12 or in solution at 80 • C. 97 There have been a few studies on the chemistry of verdazylium cations.…”