1,3‐Dipolar Cycloaddition Reactions of Neutral and Cationic Hydridotris(pyrazolyl)borate–Ruthenium(II) Azido Complexes

Neutral half‐sandwich azidoruthenium(II) complexes [Ru(N 3 ){κ 3 ( N , N , N )‐Tp}(PPh 3 )(PTA)] ( 1a ) [Tp = hydridotris(pyrazolyl)borate, PTA = 1,3,5‐triaza‐7‐phosphaadamantane] and cationic [Ru(N 3 ){κ 3 ( N , N , N )‐Tp}(PPh 3 )(1‐R‐PTA)][X] [R = Me ( 1b ), CH 2 CH=CH 2 ( 1c )] have been synthesized. Complexes 1a – c react with tetracyanoethylene through a 1,3‐dipolar cycloaddition to give the corresponding tetrazolato derivatives [Ru(N 4 C{C(CN)=C(CN) 2 }){κ 3 ( N , N , N )‐Tp}(PPh 3 )(PTA)] ( 2a ) and [Ru(N 4 C{C(CN)=C(CN) 2 }){κ 3 ( N , N , N )‐Tp}(PPh 3 )(1‐R‐PTA)][X] [R = Me ( 2b ), CH 2 CH=CH 2 ( 2c )]. Neutral azido complex 1a also reacts with activated alkynes dimethyl acetylenedicarboxylate (DMAD) and diethyl acetylenedicarboxylate (DEAD) to give the corresponding triazolato derivatives [Ru{N 3 C 2 (CO 2 R) 2 }{κ 3 ( N , N , N )‐Tp}(PPh 3 )(PTA)] [R = Me ( 3 ), Et ( 4 )].