Reactivity of tetracyanoquinodimethane with cobalt(II) chloride and bis(diphylphospino)methane in air

The reactions of CoCl2·6H2O, dppm (bis(diphenylphosphino)methane) and TCNQ (7,7,8,8-tetracyanoquinodimethane), with different ratios of the components, provided three new compounds, [Co(dppmdo)3][TCNQ]21 (dppmdo = P,P′-dioxo-bis(diphenylphosphinyl)methane), [Co(dppmdo)3][(μ-TCNQ)-CoCl3] 2, and [Co(dppmdo)3][(μ-DCBE)-CoCl3] 3 (DCBE = p-dicyanomethyl-benzoic ethyl ester). These products were characterized by IR, UV–Vis and UV–Vis-NIR spectra, X-ray crystallography, magnetic susceptibility measurements and cyclic voltammograms. 1 and 2 reveal low-energy transitions in the near-infrared region, which can be attributed to intra-ligand transitions involving radical anions (TCNQ/TCNQ−). It is interesting to note that, except for the redox potentials which are anodically shifted, indicating that it is easier to reduce TCNQ in 1 and 2 than the free TCNQ molecule, the electrochemistry of compounds 1 and 2 resemble that of the independent organic acceptor TCNQ. The magnetic properties suggest that an amount of electron transfer has occurred from the CoII complex, [Co(dppmdo)3]2+, to the TCNQ− anions in 1; an amount of electron transfer also has occurred from the CoII cation to the TCNQ− anion via a cyanide-bridge in 2; there is a mixture of spin transition of CoII ions and antiferromagnetic coupling between CoII ions in 3.

The reactions of CoCl2·6H2O, dppm (bis(diphenylphosphino)methane) and TCNQ (7,7,8,8-tetracyanoquinodimethane) with different ratios of components provided three new compounds, [Co(dppmdo)3][TCNQ]21 (dppmdo = P,P′-dioxo-bis(diphenylphosphinyl) methane), [Co(dppmdo)3][(μ-TCNQ)-CoCl3] 2 and [Co(dppmdo)3][(μ-DCBE)-CoCl3] 3 (DCBE = p-dicyanomethyl-benzoic ethyl ester). The products were characterized by IR, UV–Vis and UV–Vis-NIR spectra, X-ray crystallography, magnetic susceptibility measurements and cyclic voltammograms.Figure optionsDownload as PowerPoint slide