Studies on the acid-base properties of (arene)Ru(C4R4S) complexes are summarized. The reactivity of π-thiophene complexes towards H+ and OH- depends on the oxidation state of the complex which in turn determines the hapticity of the thiophene ligand. Weak acids protonate (C6Me6)Ru(η4-C4R4S) to give monocationic η4-2-C4R4HS complexes. The S-C(sp3) bond in the C4H5S complex spontaneously cleaves in the solid state as well as in solution to give a 1-thiapentadienyl derivative. For other R groups the protonated thiophene complexes do not undergo C-S bond scission. The thiophene ring in other (C6Me6)Ru(η4-C4R4S) complexes can be cleaved using sources of (C5R′5)Ru+ (R′ = H, Me) to give products containing the Ru2-(μ-η3:η4-SC4R 4) group. This demonstrates the superior ability of two metals to effect C-S bond activation. In the case of Ru(II) complexes, such as (arene)Ru(η5-C4R′4S)2+, their C-S bonds are easily cleaved using aqueous base to give acylthiolato complexes of the type (arene)Ru(η4-SC3R′3COR′). One of the curiosities of this chemistry is that the nucleophile, OH-, initially attacks at sulfur. Amines and ammonia react with the dicationic complexes to give the iminium salts (arene)Ru(η4-SC3R′ 3C(NHR)R′)+.
ASJC Scopus subject areas
- Chemical Engineering(all)