Ten new ruthenium compounds based on the N,N,N,N-chelate Me2bpbMe2 (bpb = 1,2-bis(pyridine-2-carboximido)benzene) have prepared and characterized by 1H NMR and IR spectroscopy. The monocarbonyl compound (Me2bpbMe2)Ru(CO)(H2O) compound was generated from the reaction of the free base Me2bpbMe2H2 with Ru3(CO)12 in refluxing DMF. Isoamyl nitrite reacts with this compound to yield the trans-addition nitrosyl alkoxide (Me2bpbMe2)Ru(NO)(O-i-C5H11). Nitrosothiols similarly add in a formal trans-addition manner to yield (Me2bpbMe2)Ru(NO)(SR/Ar) (SR/Ar = S-i-C5H11, SPh, SC6F4H, SC(Me)2CHNHC(O)Me) derivatives. The (Me2bpbMe2)Ru(NO)(O-i-C5H11) compound undergoes alkoxide exchange reactions with PhOH and HOC6F4H to generate (Me2bpbMe2)Ru(NO)(OPh) and (Me2bpbMe2)Ru(NO)(OC6F4H), respectively. The neutral alkoxide/aryloxide nitrosyl compounds exhibit higher NO bands (1809–1842 cm-1) relative to their thiolate analogues (1755–1823 cm-1). The X-ray crystal structures of (Me2bpbMe2)Ru(NO)(OPh), (Me2bpbMe2)Ru(NO)(OC6F4H), and (Me2bpbMe2)Ru(NO)(SPh), have been determined, and reveal linear axial (O)N–Ru–O/S linkages consistent with trans positioning of the NO and aryloxide and -thiolate groups, and near-linear Ru–N–O moieties (164–174°) consistent with these complexes being formulated as {RuNO}6 species. The electrooxidation behavior of (Me2bpbMe2)Ru(NO)(OC6F4H), (Me2bpbMe2)Ru(NO)(SC6F4H), and (Me2bpbMe2)Ru(NO)(SPh) were examined by cyclic voltammetry and IR spectroelectrochemistry in CH2Cl2. (Me2bpbMe2)Ru(NO)(OC6F4H) and (Me2bpbMe2)Ru(NO)(SC6F4H) display reversible first oxidations, whereas (Me2bpbMe2)Ru(NO)(SPh) displays an irreversible first oxidation with likely loss of the thiolate ligand. Chemical reactivity of (Me2bpbMe2)Ru(NO)(SPh) with H+ and Me+ results in the generation of the free thiol PhSH and thioether PhSMe, respectively.
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This content will become publicly available on January 27, 2026
Zerovalent Triphosphine Ruthenium Complexes for Coupling Carbon Dioxide and Ethylene
The coupling of carbon dioxide and ethylene to generate value added chemicals has been part of recent fundamental advances to improve sustainability in commercial chemical synthons. A formal zerovalent triphosphine ligated ruthenium complex, (tBuP(CH2CH2PEt2)2)Ru(κ-S-DMSO)(C2H4), was found to promote CO2 activation, affording products derived from both a 1:1 and 1:2 ethylene to CO2 coupling stoichiometry. The equimolecular coupling reaction selectively afforded a five-membered ruthenium lactone species, (tBuP(CH2CH2PEt2)2)Ru(κ-S-DMSO)(κ-C,κ-O-CH2CH2CO2), under low CO2 pressure. At higher CO2 pressure, the ruthenium lactone complex activated a second equivalent of CO2, yielding a dimeric methylmalonate ruthenium compound, [(tBuP(CH2CH2PEt2)2)Ru(μ2, κ1-O, κ2-O,O-O2CCHCH3CO2)]2. Both carbon dioxide activation products were characterized by X-ray diffraction. Preliminary mechanistic studies suggest that reversible β-H elimination is a key process in conversion between the two ruthenium carboxylate species. A rare formally zerovalent ruthenium coordination compound stabilized only by ethylene and DMSO ligands was also isolated and characterized.
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- Award ID(s):
- 2349537
- PAR ID:
- 10627732
- Publisher / Repository:
- American Chemical Society
- Date Published:
- Journal Name:
- Organometallics
- Volume:
- 44
- Issue:
- 2
- ISSN:
- 0276-7333
- Page Range / eLocation ID:
- 385 to 393
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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