Diazoalkane complexes of ruthenium with tris(pyrazolyl)borate and bis(pyrazolyl)acetate ligands

Abstract

Diazoalkane complexes [Ru(Tp)(N₂CAr1Ar2)(PPh₃)L]BPh₄ (1 and 2) [Tp = tris(pyrazolyl)borate; L = P(OMe)₃, P(OEt)₃; Ar1 = Ar2 = Ph; Ar1 = Ph, Ar2 = p-tolyl; Ar1Ar2 = C₁₂H₈] were prepared by allowing chloro-compounds RuCl(Tp)(PPh₃)L to react with diazoalkane in the presence of NaBPh₄. Acrylonitrile CH₂C(H)CN reacts with diazoalkane complexes to give 3H-pyrazole derivatives [Ru(Tp){NNC(Ar1Ar2)CH(CN)CH₂}(PPh₃){P(OMe)₃}]BPh₄ and [Ru(Tp){NNC(Ar1Ar2)CH₂C(H)CN}(PPh₃){P(OMe)₃}]BPh₄ (3). Diazoalkane complexes [Ru(bpza)(N₂CAr1Ar2)(PPh₃)₂]BPh₄ (4) [bpza = bis(pyrazolyl)acetate] were also prepared. All complexes were characterised by IR and NMR spectroscopy and X-ray crystal structure determination of [Ru(Tp){N₂C(Ph)(p-tolyl)}(PPh₃){P(OMe)₃}]BPh₄ (1b). The differences exhibited by [Ru(Tp){N₂C(Ph)(p-tolyl)}(PPh₃){P(OMe)₃}]⁺ and [Ru(Cp){N₂C(Ph)(p-tolyl)}(PPh₃){P(OMe)₃}]⁺, as regards coordination of the diazoalkane ligand and reactivity towards alkenes, were explained on the basis of a comparative DFT study.