Preparation and properties of AzaTCNQ- anion salts and mixed AzaTCNQ-/ TCNQ{minus sign, dot below}/TCNQ salts of some tetrakis(isocyanide)rhodium(I) cation, and x-ray crystal structure of the AzaTCNQ--tetrakis(2,6-dimethylphenylisocyanide)rhodium(I)+ salt

Article abstract of DOI:10.1016/S0020-1693(00)81916-7

The following ATCNQ^- salts and mixed ACTNQ^-/ TCNQ^{{minus sign, dot below}}/TCNQ salts (ATCNQ^- = 4-dicyanomethylenepyridinium dicyanomethylide, so-called aza-tetracyanoquinodimethan anion; TCNQ = 7,7,8,8-tetracyano-p-quinodimethan) of tetrakis(isocyanide)rhodium(I) cation were prepared; [Rh(RNC)₄]⁺ATCNQ^- (R = C₆H₅, 2,6-Me₂C₆H₃, and 2,4,6-Me₃C₆H₂), [Rh(RNC)₄]⁺(ATCNQ^-)_n(TCNQ)^{{minus sign, dot below}})_1-n (R = 2,6-Me₂C₆H₃, n = 0.2; R = C₆H₅ and 2,4,6-Me₃C₆H₂, n = 0.3), and [Rh(RNC)₄]⁺(ATCNQ^-)_a9(TCNQ^{{minus sign, dot below}})_0.1(TCNQ)_0.8 (R = 2,6-Me₂C₆H₃ and 2,4,6-Me₃C₆H₂). Of these salts, [Rh(2,6-Me₂C₆H₃NC)₄]⁺(ATCNQ^-/ TCNQ^{{minus sign, dot below}} and [Rh(2,6-Me₂C₆H₃NC)₄]⁺(ATCNQ^-)/ TCNQ^{{minus sign, dot below}}/TCNQ) exhibit electrical resistivities of ～1 X 10⁵ Ωcm as compacted samples at 25 °C and behave as typical semi-conductors, while the resistivities of other salts are larger than 1 X 10⁹ Ωcm. Electronic absorption spectra and magnetic susceptibilities of the salts are discussed in terms of stackings of TCNQ^{{minus sign, dot below}}, TCNQ, and ATCNQ^- in the solid state. The crystal structure of [Rh(2,6-Me₂C₆H₃NC)₄]⁺ATCNQ^- was determined by single-crystal X-ray diffraction. The triclinic crystal, space group P1, has cell dimensions a = 10.964(2), b = 12.768(2), c = 8.375(1) A, α = 102.03(2), β = 88.84(2), gg = 112.07(2)°, and Z = 1, where the orientation of the ATCNQ^- anion moiety is disordered with respect to the pyridinium ring. Least-squares refinement, based on 4094 independent reflections with {divides}F_o{divides} > 3σ(F), yielded an R factor of 0.052.