Ethyl(nitrosyl)ruthenium [TpRuCl(Et)(NO)] (2) was isolated from the reaction of [TpRuCl2(NO)] (1) with LiBHEt3. NO insertion of 2 was observed from heating a solution of 2. In the presence of PPh3, nitrosoethane complex [TpRuCl{N(=O)Et}(PPh3)] (3) was isolated, but the absence of PPh3 led to nitrosoethane-bridged dimer [(TpRuCl)2{μ-N(=O)Et}2] (6). Also, in complex 3, conversion of the nitrosoethane moiety to acetaldoxime and acetonitrile was observed.

Nitrosation of anilines at the ortho position was found to proceed on a ruthenium hydridotris(pyrazolyl)borato (Tp) complex. Reactions of [TpRuCl2(NO)] (1) with primary anilines 4-NH2C6H4R (R = tBu, H) in the presence of excess Et3N in CH2Cl2 gave amine-chelated nitrosoarene complexes [TpRuCl{N(O)–C6H3R–NH2-κ2 N,N}] (R = tBu (2a), H (2b)). Use of 2,4,6-trimethylaniline afforded an aryldiazenido complex [TpRuCl2{NNC6H2(Me)3}] (3) without forming the nitrosation product because of the introduction of the Me substituents at the ortho positions. On the other hand, in the case of secondary amines (N-methylanilines 4-NH(Me)C6H4R (R = tBu, H)), similar reactions gave amine-chelated nitroso complexes [TpRuCl{N(O)–C6H3R–NHMe-κ2 N,N}] (R = tBu (4a), H (4b)) and imine-chelated nitroso complexes [TpRuCl{N(O)–C6H3R–NCH2-κ2 N,N}] (R = tBu (5a), H (5b)). Conversion of 4b into 5b by O2 was disclosed by 1H NMR monitoring. Moreover, oxidative reaction of 2a afforded an amide-chelated nitroso complex [TpRuCl{N(O)–C6H3(tBu)–NH-κ2 N,N}] (6a) through one-proton release from the NH2 group.

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