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



Neutral half-sandwich azidoruthenium(II) complexes [Ru(N3){κ3(N,N,N)-Tp}(PPh3)(PTA)] (1a) [Tp = hydridotris(pyrazolyl)borate, PTA = 1,3,5-triaza-7-phosphaadamantane] and cationic [Ru(N3){κ3(N,N,N)-Tp}(PPh3)(1-R-PTA)][X] [R = Me (1b), CH2CH=CH2 (1c)] have been synthesized. Complexes 1ac react with tetracyanoethylene through a 1,3-dipolar cycloaddition to give the corresponding tetrazolato derivatives [Ru(N4C{C(CN)=C(CN)2}){κ3(N,N,N)-Tp}(PPh3)(PTA)] (2a) and [Ru(N4C{C(CN)=C(CN)2}){κ3(N,N,N)-Tp}(PPh3)(1-R-PTA)][X] [R = Me (2b), CH2CH=CH2 (2c)]. Neutral azido complex 1a also reacts with activated alkynes dimethyl acetylenedicarboxylate (DMAD) and diethyl acetylenedicarboxylate (DEAD) to give the corresponding triazolato derivatives [Ru{N3C2(CO2R)2}{κ3(N,N,N)-Tp}(PPh3)(PTA)] [R = Me (3), Et (4)].