Synthesis and reactivity of hydride and dihydrogen complexes of ruthenium with tris(pyrazolyl)borate and phosphite ligands

Chloro phosphite complexes RuClTpL(PPh3) (1a, 1b) [L = P(OEt)3, PPh(OEt)2] and RuClTp[P(OEt)3]2 (1c) [Tp = hydridotris(pyrazolyl)borate] were prepared by allowing RuClTp(PPh3)2 to react with an excess of phosphite. Treatment of the chloro complexes 1 with NaBH4 in ethanol yielded the hydride RuHTpL(PPh3) (2a, 2b) and RuHTp[P(OEt)3]2 (2c) derivatives. Protonation reaction of 2 with Brønsted acids was studied and led to thermally unstable (above 10 °C) dihydrogen [Ru(η2- H2)TpL(PPh3)]+ (3a, 3b) and [Ru(η2-H2)Tp{P(OEt)3}2]+ (3c) complexes. The presence of the η2-H2 ligand is indicated by short T1 min values and JHD measurements of the partially deuterated derivatives. Aquo [RuTp(H2O)L(PPh3)]BPh4 (4), carbonyl [RuTp(CO)L(PPh3)]BPh4 (5), and nitrile [RuTp(CH3CN)L(PPh3)]BPh4 (6) derivatives [L = P(OEt)3] were prepared by substituting H2 in the η2-H2 derivatives 3. Vinylidene [RuTp{double bond; length as m-dashCdouble bond; length as m-dashC(H)R}L(PPh3)]BPh4 (7, 8) (R = Ph, tBu) and allenylidene [RuTp(double bond; length as m-dashCdouble bond; length as m-dashCdouble bond; length as m-dashCR1R2)L(PPh3)]BPh4 (9–11) complexes (R1 = R2 = Ph, R1 = Ph R2 = Me) were also prepared by allowing dihydrogen complexes 3 to react with the appropriate HCtriple bond; length of mdashCR and HCtriple bond; length of mdashCC(OH)R1R2 alkynes. Deprotonation of vinylidene complexes 7, 8 with NEt3 was studied and led to acetylide Ru(Ctriple bond; length of mdashCR)TpL(PPh3) (12, 13) derivatives. The trichlorostannyl Ru(SnCl3)TpL(PPh3) (14) compound was also prepared by allowing the chloro complex RuClTpL(PPh3) to react with SnCl2 · 2H2O in CH2Cl2.