Phosphine/thiolate-containing dinitrosyl cobalt complexes (DNCCs): synthesis, characterization, interconversion, X-ray diffraction identification and NO release

Abstract

Cobalt carbonyl/nitrosyl complexes, (PPh₃)(CO)₂Co(NO) (1) and (PPh₃)₂(CO)Co(NO) (2), were obtained by reacting (CO)₃Co(NO) with one equiv. and two equiv. of PPh₃, respectively. The process of isoelectronic replacement of CO with NO⁺ resulted in the formation of a cationic complex {Co(NO)₂}¹⁰ [(PPh₃)₂Co(NO)₂][BF₄] (3). Complex (PPh₃)(SPh)Co(NO)₂ (4), which contains a thiophenolate ligand, was synthesized by ligand exchange of complex 3 with [PPh₄][SPh] in a 1 : 1 molar ratio in THF solution. The addition of one equiv. of [PPh₄][SPh] to complex 4 led to the formation of complex [PPh₄][(SPh)₂Co(NO)₂] (5). The interconversions among complexes 1–5 were substantiated with the application of IR spectroscopy and X-ray single-crystal diffraction techniques. Notably, complex 4 exhibited commendable NOs (nitric oxide species: NO⁺/˙NO/NO⁻) transfer capabilities in the presence of [Fe(TPP)Cl] (5,10,15,20-tetraphenyl-21H,23H-porphine iron(III) chloride).