Polymeric cobalt(ii) thiolato complexes – syntheses, structures and properties of 1∞[Co(SMes)2] and 1∞[Co(SPh)2NH3]

Abstract

Reactions of [Co(N(SiMe₃)₂)₂thf] with 2.1 equiv. of MesSH (Mes = C₆H₂-2,4,6-(CH₃)₃) yield dark brown crystals of the one dimensional chain compound ¹_∞[Co(SMes)₂]. In contrast reactions of [Co(N(SiMe₃)₂)₂thf] with 2.1 equiv. of PhSH result in the formation of a dark brown almost X-ray amorphous powder of ‘Co(SPh)₂’. Addition of aliquots of CH₃OH to the latter reaction resulted in the almost quantitative formation of crystalline ammonia thiolato complexes either [Co(SPh)₂(NH₃)₂] or ¹_∞[Co(SPh)₂NH₃]. Single crystal XRD reveals that ¹_∞[Co(SPh)₂NH₃] forms one-dimensional chains in the crystal via μ₂-SPh bridges whereas [Co(SPh)₂(NH₃)₂] consists at a first glance of isolated distorted tetrahedral units. Magnetic measurements suggest strong antiferromagnetic coupling for the two chain compounds ¹_∞[Co(SMes)₂] (J = −38.6 cm⁻¹) and ¹_∞[Co(SPh)₂NH₃] (J = −27.1 cm⁻¹). Interestingly, also the temperature dependence of the susceptibility of tetrahedral [Co(SPh)₂(NH₃)₂] shows an antiferromagnetic transition at around 6 K. UV-Vis-NIR spectra display d–d bands in the NIR region between 500 and 2250 nm. Thermal gravimetric analysis of [Co(SPh)₂(NH₃)₂] and ¹_∞[Co(SPh)₂NH₃] reveals two well separated cleavage processes for NH₃ and SPh₂ upon heating accompanied by the stepwise formation of ‘Co(SPh)₂’ and cobalt sulfide.