Proton-assisted addition reactions on trimethylsilylalkynyl nitrosylrutheniums of hydrotris(pyrazolyl)borate

Incorporation of H2O or HCl on treatment of trimethylsilylalkynyl nitrosylruthenium TpRuCl(Ctriple bond; length of mdashCSiMe3)(NO) (1) (Tp = hydrotris(pyrazolyl)borate) with protic acid, and the dependence of its product formation on the reaction solvents, are reported. Reactions of 1 with HBF4 or HCl (aq.) in MeOH gave rise to the mixture of the mono(ethynyl) TpRuCl(Ctriple bond; length of mdashCH)(NO) (2) and the mono(acyl) TpRuCl{C(O)CH3}(NO) (3). The H2O-incorporated 3 was quantitatively obtained from the reactions of 2 with HCl (aq.) in MeOH. On the other hand, reactions of 1 with HCl (aq.) in CH2Cl2 gave the η1-α-chlorovinyl TpRuCl{C(Cl)double bond; length as m-dashCH2}(NO) (4). In the bis(alkynyl) system TpRu(Ctriple bond; length of mdashCSiMe3)2(NO) (5), the similar reactivities were observed. Proton-assisted hydration of 5 afforded the bis(acyl) TpRu{C(O)CH3}2(NO) (6), while the HCl-treatment led to the formation of the bis(α-chlorovinyl) TpRu{C(Cl)double bond; length as m-dashCH2}2(NO) (7).