Transfer of hydrogen, oxygen, or both hydrogen and oxygen to unsaturated substrates from [ReH2(O)(Cyttp)]+ (Cyttp=PhP(CH2CH2CH2PCy2)2)

Reactions of the hydrido-oxo complex [ReH2(O)(Cyttp)]SbF6 (1(SbF6): Cyttp=PhP(CH2CH2CH2PCy2)2) or [ReH2(O)(Cyttp)]OTf (1(OTf): OTf=O3SCF3) with various unsaturated compounds proceed by transfer of hydrogen, oxygen, or both hydrogen and oxygen to the unsaturated substrate. Thus, 1(SbF6) reacts with CO in acetone at 0 °C to afford the formate [ReH(η2-HCO2)(CO)(Cyttp)]SbF6 (2(SbF6)), and in benzene at 25 °C to yield 2(SbF6) and [Re(CO)3(Cyttp)]SbF6 (3(SbF6)). Control experiments showed that the formation of 3(SbF6) takes place by two pathways, viz., with or without 2(SbF6) intermediate. Isocyanides react with 1(SbF6) in benzene at 25 °C to produce [Re(CNR)3(Cyttp)]SbF6 (R=t-Bu, Cy); when R=t-Bu, RNCO was also observed. The reaction of 1(SbF6) with SO2 in benzene at 25 °C affords the sulfito-O,O′ complex [ReH2(η2-SO3)(Cyttp)]SbF6 (6(SbF6)) by oxide transfer. Heating 6(SbF6) at 50 °C causes loss of SO2 and regeneration of 1(SbF6). The phosphite P(OMe)3 behaves as an oxygen atom acceptor from 1(SbF6) in benzene at 25 °C by furnishing OP(OMe)3 and [ReH2(P(OMe)3)2(Cyttp)]SbF6. The alkenes cyclohexene, norbornene, 3,3-dimethyl-1-butene, and diethyl fumarate require ca. 100 °C to react at a reasonable rate with 1(OTf) in THF or benzene under pressure by hydrogenation of the CC bond. No oxygen-transfer products were detected. The alkyne PhCCH also reacts with 1(OTf) by hydrogenation to afford, at 100 °C, styrene, a small amount of ethylbenzene, and a mixture of inorganic products. Reactions of 1(OTf) with nitriles under anhydrous conditions are sensitive to the nature of the nitrile. Thus, ClCH2CN reacts at ambient temperature in benzene solution to yield MeCN, ClCH2C(O)NH2, [Re(OH)(O)(Cl)(Cyttp)]OTf, ReCl3(Cyttp), and uncharacterized minor products. In contrast, the aliphatic nitriles MeCN, EtCN, and Me2CHCN require heating (75 °C) to undergo low-yield hydration to the appropriate amides. The aromatic nitriles also react differently to generate at 75 °C the amidato-O,N complexes [ReH(η2-ArC(O)NH)(NCAr)(Cyttp)]OTf (Ar=Ph, p-Tol, p-ClC6H4) and minor quantities of the appropriate aldehyde ArC(O)H. With added ca. one equivalent H2O and in the presence of a small amount (ca. 0.01 equivalent) of 1(OTf), the nitriles MeCN, PhCN, and p-ClC6H4CN afford at 60 °C the corresponding amides; these catalytic reactions proceed through the appropriate η2-amidato-O,N complexes. All new compounds were characterized by a combination of elemental analysis, mass spectrometry, and IR and NMR spectroscopy. The structure of 6 (as 6(SbF6)·C6H6) was determined by single-crystal X-ray diffraction analysis.