Syntheses, properties and structures of copper and nickel complexes of 6,7‐dihydro‐5H‐1,4‐dithiepin‐2,3‐dithiolate

Abstract

AbstractThe reaction of CuCl2·2H2O or NiCl2·6H2O with K2(C5H6S4) [potassium salt of 6,7‐dihydro‐5H‐1,4‐dithiepin‐2,3‐dithiolate] under nitrogen atmosphere resulted in the isolation of [Cu(C5H6S4)2]− or [Ni(C5H6S4)2]− as the tetrabutylammonium salt. Both complexes show characteristic IR and UV −Vis absorptions of transition metal dithiolenes. Cyclic voltammograms contain two waves indicating a two step electrochemical procedure [M(C5H6S4)2]0 = [M(C5H6S4)2]1‐= [M(C5H6S4)2]2‐ Single crystal structure study has been carried out on the nickel complex. Crystal of [Bu4N][Ni(C5H6S4)2] belongs to monoclinic space group P21/c with a=17.576(5), b=10.883(2), c=17.773(4) A, β=91.07(2)°, Z=4, and ρ(calcd.)=1.348 g/cm3. Final result is R=0.059 for 2959 reflections. The NiS4 core exhibits square planar coordination with average Ni—S bond length of 2.134(5) Å. There are not anion pairs in crystal. The anions stack along a and c axes while the cations intercalate in them. The nearest S—S contact is 4.429 Å. The solid powder ESR spectrum of the nickel complex shows three broadening signals at g1 =2.097, g2=2.042, g3=2.022. Magnetic susceptibility data for [Bu4N][Ni(C5H6S4)2] reveal enhanced anti‐ferromagnetic interaction.