Cobalt‐Mediated SS Bond Formation: Crystal Structure and Spectroscopic Properties of [Co₂(S₂)₂(tren)₂]₃[SbS₄]₂·21.5 H₂O Containing a Co₂S₄ H

The reaction of an aqueous solution of Na 3 SbS 4 ·9H 2 O with a Co(II) salt dissolved in acetonitrile in the presence of tris(2‐aminoethyl)amine affords crystallization of [Co 2 (S 2 ) 2 (tren) 2 ] 3 [SbS 4 ] 2 ·21.5 H 2 O which contains in situ formed S 2 2− anions and Co(III) cations formed by oxidation of Co(II). The Co(III) centers of the two independent [Co 2 S 4 ] 2+ cores are complemented by the tetradentate amine molecules and distorted CoN 4 S 2 octahedra are formed. Charge compensation is achieved by the tetrahedral [SbS 4 ] 3− anions. The two intriguing experimental findings, i.e., the oxidation of Co(II) and the formation of S 2 2− dumbbells, are explained on the basis of the detailed calculation of the reaction mechanism indicating SS bond formation by radical coupling of two terminal thiyl ligands. The bands of the Co 2 S 4 heterocycle in the infrared and Raman spectra can also be assigned with density functional theory calculations.