Decamethylchromocene, CrII(η5-C 5(CH3)5)2 (2), readily reduced [1,2,5]thiadiazolo[3,4-c][1,2,5]thiadiazole (1) in a tetrahydrofuran solvent at ambient temperature with the formation of radical-anion salt  +- (3) isolated in 97% yield. The heterospin salt 3 (+, S = 3/2; -, S = 1/2) was characterized by single-crystal X-ray diffraction as well as magnetic susceptibility measurements in the temperature range 2-300 K. The experimental data together with theoretical analysis of the salt-s magnetic structure within the CASSCF and spin-unrestricted broken-symmetry (BS) density functional theory (DFT) approaches revealed antiferromagnetic (AF) interactions in the crystalline 3: significant between anions -, weak between cations +, and very weak between - and +. Experimental temperature dependences of the magnetic susceptibility and the effective magnetic moment of 3 were very well reproduced in the assumption of the AF-coupled -⋯- (J1 = -40 ± 9 cm-1) and +⋯ + (J2 = -0.58 ± 0.03 cm-1) pairs. The experimental J1 value is in reasonable agreement with the value calculated using BS UB3LYP/6-31+G(d) (-61 cm-1) and CASSCF(10,10)/6-31+G(d) (-15.3 cm-1) approaches. The experimental J2 value is also in agreement with that calculated using the BS DFT approach (-0.33 cm-1).
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry