Synthesis of(Vinylidene)- and(Cyclopropenyl)ruthenium Complexes Containing a Tris(pyrazolyl)borato(Tp)Ligand

摘要

A convenient high-yield route to[Ru(C=C-Ph)(Tp)(PPH_3)_2][2;Tp=HB(pz)_3,pz=pyrazolyl]has been found through the intermediacy of[RuCl_2(Hpz)_2(PPH_3)_2](1).This complex is readily obtained on treatment of[RuCl_2(PPH_3)_3]with 2 equiv.of pyrazole in boiling THF.The molecular structures of complexes 1 and 2 have been confirmed by single-crystal X-ray diffraction analysis.A number of new cationic vinylidene complexes[Ru{=C=C(Ph)CH_2R)(Tp)(PPH_3)_2]~+[3a,R=CN;3b,R=HC=CH_2;3c,R=CH=C(CH_3)_2;3d,R=Ph;3e,R=C(O)OMe]have been prepared by electrophilic addition of organic halides to complex 2.The deprotonation reaction of 3a yields the cyclopropenyl complex 4a.One phosphane ligand of 4a is remarkably labile,being replaced by donor ligands L to yield diastereomeric mixtures of the cyclopropenyl complexes 5a-5d mostly in an approximate 4:1 ratio.The cyclopropenyl rings in 4a and 5a are susceptible to ring opening by I_2.In addition,treatment of 4a with nBuNC in the presence of MeOH results in substitution of a phosphane li-gand by nBuNC followed by protonation of the three-mem-bered ring by MeOH.This is then followed by addition of methoxide to give the vinyl ether complex[RujC(OMe)=C(Ph)CH_2CN)(Tp)(PPH_3)(nBuNC)l(8a).