Hydride, dihydrogen, dinitrogen and related complexes of ruthenium containing the ligand hydrotris(pyrazolyl)borate. X-ray crystal structure of [{HB(pz) 3}Ru( η2-H 2)(dippe)] [BPh 4] (dippe = 1,2-bis(diisopropylphosphino)ethane)

Abstract

The complex [HB(pz) 3)RuCl(PPh 3) 2] reacts with one equivalent ofdippe in toluene toyield [(HB(pz) 3)RuCl(dippe)]. This compound reacts with NaBH 4 in MeOH furnishing the monohydride [(HB(pz) 3)RuH(dippe)], whereas [(HB(pz) 3)RuH(PPh 3) 2] was obtained by reaction of [RuHCl(PPh 3) 3] with K[HB(pz) 3]. Both monohydride complexes are protonated by HBF4·OEt 2 at −80°C to give the corresponding dihydrogen adducts [(HB(pz) 3)Ru(H 2)(dippe)] + and [(HB(pz) 3]Ru(H 2)(PPh 3) 2] +, as inferred from longitudinal relaxation time ( T 1) and 1 J(H,D) measurements. The latter complex is unstable and decomposes at room temperature, but the former is a stable species which does not rearrange to the dihydride form when the temperature is raised. The X-ray crystal structure of [(HB(pz) 3)Ru(H2)-(dippe)][BPh4] has been determined. The dihydrogen ligand in this compound is labile, and readily replaced by a range of neutral donor molecules, yielding the corresponding complexes [(HB(pz) 3)Ru(L)(dippe)][BPh 4] (L = CO, CNBu 1, Me 2CO, thf, N 2). There is also supporting evidence for the formation of a paramagnetic Ru III methoxide complex, namely [(HB(pz) 3)Ru(OMe)(dippe)][BPh 4]. All compounds were characterized by IR, NMR and microanalysis.