Preparation and properties of AzaTCNQ − anion salts and mixed AzaTCNQ −/ TCNQ ⨪/TCNQ salts of some tetrakis(isocyanide)rhodium(I) cation, and x-ray crystal structure of the AzaTCNQ −-tetrakis(2,6-dimethylphenylisocyanide)rhodium(I) + salt

Abstract

The following ATCNQ − salts and mixed ACTNQ −/ TCNQ ⨪/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 = C 6H 5, 2,6-Me 2C 6H 3, and 2,4,6-Me 3C 6H 2), [Rh(RNC) 4] +(ATCNQ −) n(TCNQ) ⨪) 1-n (R = 2,6-Me 2C 6H 3, n = 0.2; R = C 6H 5 and 2,4,6-Me 3C 6H 2, n = 0.3), and [Rh(RNC) 4] +(ATCNQ −) a9(TCNQ ⨪) 0.1(TCNQ) 0.8 (R = 2,6-Me 2C 6H 3 and 2,4,6-Me 3C 6H 2). Of these salts, [Rh(2,6-Me 2C 6H 3NC) 4] +(ATCNQ −/ TCNQ ⨪ and [Rh(2,6-Me 2C 6H 3NC) 4] +(ATCNQ −)/ TCNQ ⨪/TCNQ) exhibit electrical resistivities of ∼1 X 10 5 Ωcm as compacted samples at 25 °C and behave as typical semi-conductors, while the resistivities of other salts are larger than 1 X 10 9 Ωcm. Electronic absorption spectra and magnetic susceptibilities of the salts are discussed in terms of stackings of TCNQ ⨪, TCNQ, and ATCNQ − in the solid state. The crystal structure of [Rh(2,6-Me 2C 6H 3NC) 4] +ATCNQ − was determined by single-crystal X-ray diffraction. The triclinic crystal, space group P 1 , has cell dimensions a = 10.964(2), b = 12.768(2), c = 8.375(1) Å, 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 ∣ F o∣ > 3σ( F), yielded an R factor of 0.052