Crystal structure and excited triplet-state electron paramagnetic resonance of the .SIGMA.-bonded TCNQ dimer in bis(2,9-dimethyl-1,10-phenanthroline)copper(I) tetracyanoquinodimethane dimer [Cu(DMP)2]2[TCNQ]2

Abstract

Reaction of bis(2,9-dimethyl-1,10-phenanthroline)copper(I) iodide [Cu(DMP)2I] with lithium tetracyanoquinodimethanide, LiTCNQ, yields the compound [Cu(DMP)2]2[TCNQ]2, which crystallizes in the triclinic system, space group PI, with lattice parameters a = 12.784 A, b = 13.400 A, c = 12.136 k, a = 113.51°, ß = 112.58°, and 7 = 62.80°. The structure of the compound was solved by Fourier methods and refined by least-squares techniques to R = 0.060 on the basis of 1957 observed reflections. The structure consists of [Cu(DMP)2]+ cations and exocyclically -bonded [TCNQ]22~d imers. The carbon-carbon bond in the dimer is 1.630 (13) A, and the [TCNQ]22_ dimeric ions are arranged in linear chains along the [110] direction. Single-crystal electron paramagnetic resonance studies have been carried out in the temperature range 300-490 K, and thermally activated triplet-state (5=1) EPR spectra as well as doublet-state (5 = */2) EPR spectra have been detected and thoroughly characterized. The data show that strongly localized triplet excitons on [TCNQ]22" anions (self-trapped Frenkel excitons) give rise to triplet-state EPR spectra with zero-field splitting parameters \D/hc\ = 0.0111 cm"1 and \E/hc\ = 0.0015 cm"1. Theoretical calculations of the dipolar splitting indicate that the electronic and molecular structure of the excited state of the [TCNQ]22" dimeric anion is best characterized by two distorted TCNQ" anions with a distorted distribution of spin densities. An EPR signal at g = 2.0025 has been attributed to isolated TCNQ" radical anions. The activation energies for the triplet excitons (which corresponds to the breaking of the -bond) and for the isolated TCNQ" radical anions are 0.55 and 0.24 eV, respectively.

Organic Super‐Acceptors with Efficient Intramolecular Charge‐Transfer Interactions by [2+2] Cycloadditions of TCNE, TCNQ, and F4‐TCNQ to Donor‐Substituted Cyanoalkynes

“…[6a, 11] Charge-transfer salt {[FeCp* 2 ] + } 2 [12] 2 2À (15): While exploring the ability of the TCNQ-derived acceptor 12 to form charge-transfer complexes with various electron donors, we found that the TCNQ moiety in 12 undergoes reductive s-dimerization upon reaction with the strong electron donor decamethylferrocene ([FeCp* 2 ]; E ox,1 = À0.59 V), [20] as previously observed for TCNQ. [33] Thus, an intense green solution was obtained upon addition of yellow [FeCp* 2 ] in CH 2 Cl 2 to the originally deeppurple solution of 12 in dry acetonitrile at 25 8C. The solid obtained after evaporation of the solvents was recrystallized by slow diffusion of n-hexane into CH 2 Cl 2 solution to afford dark-green crystals of {[FeCp* 2 ] + } 2 [12] A and B), four [FeCp* 2 ] + molecules, one of which is disordered, and three disordered CH 2 Cl 2 molecules ( Figure 6, for details, see the Experimental Section; for molecule B, see the Supporting Information).…”

Tetracyanoquinodimethane complexes of copper and a 17-membered N,O-donor macrocycle

“…Solid state conductivities of 2 and 3 at room temperature are of the order of 10 À10 S cm À1 , indicating that the complexes are weak conductors. This may be attributed to structural arrangements of TCNQ species in the complexes [23].…”

Imitating trumpet shells: Möbius container molecules

“…. [24][25][26][27] Notably, the small   1 of about 94° and the   2 bond angle of 100° exist in these one-sided molecules and in the graphitic Y junctions [28]. For stability, although small bond angles   1 and   2 are unfavorable (  1 and   2 may be improved by changing the sizes of the cage and the bridge), the formed single bonds R2 and R3 are favorable factors.…”