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Deuteration of organic molecules using D2O as the deuterium source is affected with catalytic systems based on the ruthenium solvento hydride complex TpRu(PPh3)(CH3CN)H. The deuteration reactions c...

The η2-dihydrogen complex [TpRu(L2)(H2)]+ (L2 = dppm, dppp, or (PPh3)2) prepared in situ by protonation of the hydride precursor reacts with O2 to yield the paramagnetic RuIII-superoxo complex [TpRuIII(L2)(O2)]+, in which antiferromagnetic coupling between the RuIII ion (d5, S = 1/2) and the coordinated superoxide radical (S = 1/2) does not seem to be present. In THF, the superoxo moiety of the complex readily abstracts a hydrogen atom from the solvent to generate the hydroperoxo (−OOH-) group, which then changes into the hydroxo ligand by transferring an oxygen atom to a phosphine ligand. Density functional theory calculation at the B3LYP level on the model complex [TpRu(PH3)2(O2)]+ shows that the RuIII-superoxo(O2-) structure with a triplet state is more stable than the RuIV-peroxo(O22-) structure with a singlet state by 5.2 kcal/mol. On the other hand, the analogous Cp model complex [CpRu(PH3)2(O2)]+ prefers the RuIV-peroxo(O22-) structure over the RuIII-superoxo(O2-) structure by 2.9 kcal/mol.

The ruthenium complex TpRu(PPh3)(CH3CN)H (Tp = hydrotris(pyrazolyl)borate) catalyzes H/D exchange between CH4 and some deuterated organic solventsbenzene-d6, tetrahydrofuran-d8, diethyl ether-d10, ...

Replacement of the dppm ligand in (η5-C5H4(CH2)2NMe2H+)Ru(dppm)H with two less donating triphenyl phosphite ligands reduces the strength of the intramolecular Ru−H···H−N dihydrogen bond to such an extent that it is hardly evidenced by NMR measurements. Unlike its dihydrogen-bonded dppm analogue, the triphenyl phosphite complex (η5-C5H4(CH2)2NMe2H+)Ru(P(OPh)3)2H shows no catalytic activity for reduction of carbon dioxide to formic acid.

A strong promoting effect of water in the catalytic hydrogenation of CO2 to formic acid with the solvento metal hydride species TpRu(PPh3)(CH3CN)H is observed. High-pressure NMR monitoring of the c...

Protonation of indenyl complexes (η5-C9H7)Ru(dppm)H and (η5-C9H7)Ru(PPh3)2H with CF3SO3H or HBF4·Et2O at −60 °C gives the η2-dihydrogen complex [(η5-C9H7)Ru(dppm)(H2)]+ and the dihydride [(η5-C9H7)Ru(PPh3)2H2]+, respectively. Upon warming to room temperature, proton shift from the η2-H2 ligand of the former to the indenyl ligand and subsequent migration of the metal fragment from the five-membered ring to the six-membered ring of the indene ligand results in the formation of the η6-indene complex [(η6-C9H8)Ru(dppm)H]+. The PPh3 analogue [(η6-C9H8)Ru(PPh3)2H]+ is formed in a similar fashion, but in this case, the proton shift is from Ru−H to the indenyl ligand. Low-temperature acidification of (η5-C9H7)Ru(dppe)H and (η5-C9H7)Ru(dppp)H yield mixtures of η2-dihydrogen complex and dihydride in both cases. Similar to the dppm and PPh3 analogues, η6-indene complexes [(η6-C9H8)Ru(dppe)H]+ and [(η6-C9H8)Ru(dppp)H]+ are generated upon warming solutions of the η2-dihydrogen complex/dihydride mixtures to room temper...

Reactions of TpRuH(CH3CN)(PPh3) with free silanes HSiR3 (R3 = Et3, (EtO)3, Ph3, HEt2, HPh2, and H2Ph) in THF yield the complexes TpRu(PPh3)(H)(η2-HSiR3), the formulation of which is inferred from NMR spectroscopic data. The chemical equivalence of the two hydrogen atoms of TpRu(PPh3)(H)(η2-HSiR3) down to −100 °C is attributed to rapid fluxionality between the two, i.e., TpRu(PPh3)(Ha)(η2-HbSiR3) ⇋ TpRu(PPh3)(Hb)(η2-HaSiR3). Molecular orbital calculations at the B3LYP level have been performed to investigate the stereochemistry and the interconversion processes of various structural isomers for TpRu(PPh3)(H)(η2-HSiR3). The results further support the existence of a η2-silane formulation for these complexes. Two stable structures, with a nonclassical η2-silane ligand, have been found. These two structural isomers are found to be in equilibrium with a low reaction barrier (7.5 kcal/mol). The interconversion between the enantiomeric pair of the most stable structure has almost no reaction barrier (0.5 kcal/mo...

Protonation of [RCnRuH(L)(L‘)]+ (RCn = 1,4,7-triazacyclononane and 1,4,7-trimethyl-1,4,7-triazacyclononane; L,L‘ = (PPh3)2, dppe, and CO,PPh3) produced the corresponding dicationic dihydrogen complexes [RCnRu(H2)(L)(L‘)]2+. Protonation of TpRuH(dppe) (Tp = hydrotris(pyrazolyl)borato) yielded the new monocationic dihydrogen complex [TpRu(H2)(dppe)]+. The acidity of the dihydrogen complexes [RCnRu(H2)(L)(L‘)]2+ and monocationic dihydrogen complexes [TpRu(H2)(L)(L‘)]+ (L,L‘ = dppe, (PPh3)2, CH3CN,PPh3, and CO,PPh3) has been studied. It was found that the dicationic complexes are more acidic than their monocationic Tp and Cp counterparts. [MeCnRu(H2)(CO)(PPh3)]2+ was found to be more acidic than [HCnRu(H2)(CO)(PPh3)]2+, probably due to the stronger H−H interaction in the latter complex. It is also noted that triazacyclononane and hydrotris(pyrazolyl)borato dihydrogen complexes with pseudo aqueous pKa values well above that of H3O+ can be deprotonated by H2O to form the corresponding monohydride complexes in o...

A series of new hydrotris(1-pyrazolyl)borate complexes of ruthenium were synthesized. Reaction of RuCl(HB(pz)3)(PPh3)2 with NaBH4 in ethanol produced the yellow monohydride complex RuH(HB(pz)3)(PPh3)2. Protonation of the monohydride complex RuH(HB(pz)3)(PPh3)2 with HBF4·Et2O in dichloromethane gave the molecular dihydrogen complex [Ru(HB(pz)3)(PPh3)2(H2)]BF4. Reactions of the dihydrogen complex [Ru(HB(pz)3)(PPh3)2(H2)]BF4 with L (L = CH3CN, H2O, N2) produced the adducts [Ru(HB(pz)3)(PPh3)2(L)]BF4. The dihydrogen complex [Ru(HB(pz)3)(PPh3)2(H2)]BF4 could be regenerated by reactions of [Ru(HB(pz)3)(PPh3)2(L)]BF4 (L = CH3CN, H2O) with pressurized H2. Deprotonation of the molecular dihydrogen complex [Ru(HB(pz)3)(PPh3)2(H2)]BF4 occurred with NEt3 or H2O under hydrogen pressure. Treatment of RuCl(HB(pz)3)(PPh3)2 with LiBF4 in acetonitrile produced the bis-solvento complex [Ru(HB(pz)3)(PPh3)(CH3CN)2]BF4. Heating a THF/CH3CN (9/1) solution of RuCl(HB(pz)3)(PPh3)2 at 60 °C led to the formation of RuCl(HB(pz)3)(PP...