Re2Rh2 μ3-[η1-C(Re):η1-O(Rh):η1-O‘(Rh‘)] Bis(carbon dioxide) Complexes [(η5-C5R5)(L)(NO)Re(CO2)Rh(η4-diene)]2 That Are Structurally Related to Rhodium(I) Carboxylate Dimers [Rh(O2CR)(η4-diene)]2

Tetrick, Stephen M.; Tham, Fook S.; Cutler, Alan R.

doi:10.1021/ja970341l

Cited by 18 publications

(7 citation statements)

References 30 publications

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“…However, this reaction was observed by 1 H NMR spectroscopy to produce equal amounts of the known complexes [CpRe(PPh 3 )(NO)(CHOMe)] + , CpRe(PPh 3 )(NO)(CH 3 ), and Cp*Re(NO)(CO)(COOMe) (Scheme S1 and Figures S2–S3). , These reaction products are consistent with transfer of MeO – from CpRe(PPh 3 )(NO)(CH 2 OMe) to [Cp*Re(NO)(CO) 2 ] + , followed by a rapid and irreversible H – transfer from CpRe(PPh 3 )(NO)(CH 2 OMe) to transient [CpRe(PPh 3 )(NO)(CH 2 )] + . No resonances could be observed for Cp*Re(NO)(CO)(CHO), which would be the product of H – transfer from CpRe(PPh 3 )(NO)(CH 2 OMe) to [Cp*Re(NO)(CO) 2 ] + .…”

Section: Resultssupporting

confidence: 62%

Thermochemical Insight into the Reduction of CO to CH₃OH with [Re(CO)]⁺and [Mn(CO)]⁺Complexes

Wiedner¹,

Appel²

2014

J. Am. Chem. Soc.

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To gain insight into thermodynamic barriers for reduction of CO into CH3OH, free energies for reduction of [CpRe(PPh3)(NO)(CO)](+) into CpRe(PPh3)(NO)(CH2OH) have been determined from experimental measurements. Using model complexes, the free energies for the transfer of H(+), H(-), and e(-) have been determined. A pKa of 10.6 was estimated for [CpRe(PPh3)(NO)(CHOH)](+) by measuring the pKa for the analogous [CpRe(PPh3)(NO)(CMeOH)](+). The hydride donor ability (ΔG°H(-)) of CpRe(PPh3)(NO)(CH2OH) was estimated to be 58.0 kcal mol(-1), based on calorimetry measurements of the hydride-transfer reaction between CpRe(PPh3)(NO)(CHO) and [CpRe(PPh3)(NO)(CHOMe)](+) to generate the methylated analogue, CpRe(PPh3)(NO)(CH2OMe). Cyclic voltammograms recorded on CpRe(PPh3)(NO)(CMeO), CpRe(PPh3)(NO)(CH2OMe), and [CpRe(PPh3)(NO)(CHOMe)](+) displayed either a quasireversible oxidation (neutral species) or reduction (cationic species). These potentials were used as estimates for the oxidation of CpRe(PPh3)(NO)(CHO) or CpRe(PPh3)(NO)(CH2OH) or the reduction of [CpRe(PPh3)(NO)(CHOH)](+). Combination of the thermodynamic data permits construction of three-dimensional free energy landscapes under varying conditions of pH and PH2. The free energy for H2 addition (ΔG°H2) to [CpRe(PPh3)(NO)(CO)](+) (+15 kcal mol(-1)) was identified as the most significant thermodynamic impediment for the reduction of CO. DFT computations on a series of [Cp(X)M(L)(NO)(CO)](+) (M = Re, Mn) complexes indicate that ΔG°H2 can be varied by 11 kcal mol(-1) through variation of both the ancillary ligands and the metal.

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Section: Resultssupporting

confidence: 62%

Thermochemical Insight into the Reduction of CO to CH₃OH with [Re(CO)]⁺and [Mn(CO)]⁺Complexes

Wiedner¹,

Appel²

2014

J. Am. Chem. Soc.

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“…To test the viability of the synthetic procedure, the structures of two representative in situ generated diimine rhodium complexes ( 3 and 6 ) have been confirmed by X-ray diffraction (Figure ), multinuclear NMR spectroscopy and elemental analysis. As depicted in Figure , both complexes 3 and 6 possess dimeric structures which are commonly observed in Rh(I) complexes. − The N–Rh–N bond angles of complexes 3 and 6 are compressed from the ideal 90° bond angles of a four-coordinate square planar structure to less than 80°, which are typical for Rh(I) diimine complexes. , The N–Rh–N and O–Rh–O bond angles are larger for complex 6 than complex 3 .…”

Section: Resultsmentioning

confidence: 95%

Mechanistic Studies of Single-Step Styrene Production Catalyzed by Rh Complexes with Diimine Ligands: An Evaluation of the Role of Ligands and Induction Period

et al. 2019

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Studies of catalytic benzene alkenylation using different diimine ligated Rh(I) acetate complexes and Cu(OAc)2 as the oxidant revealed statistically identical results in terms of activity and product selectivity. Under ethylene pressure, two representative diimine ligated rhodium(I) acetate complexes were demonstrated to exchange the diimine ligand with ethylene rapidly to form [Rh(μ-OAc)(η2-C2H4)2]2 and free diimine. Thus, it was concluded that diimine ligands are not likely coordinated to the active Rh catalysts under catalytic conditions. At 150 °C under catalytic conditions using commercial Cu(OAc)2 as the oxidant, [Rh(μ-OAc)(η2-C2H4)2]2 undergoes rapid decomposition to form catalytically inactive and insoluble Rh species, followed by gradual dissolution of the insoluble Rh to form the soluble Rh, which is active for styrene production. Thus, the observed induction period under some conditions is likely due to the formation of insoluble Rh (rapid), followed by redissolution of the Rh (slow). The Rh decomposition process can be suppressed and the catalytically active Rh species maintained by using soluble Cu(II) oxidants or Cu(OAc)2 that has been preheated. In such cases, an induction period is not observed.

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“…Several tetrametallic bis(carbon dioxide) complexes [(η 5 -C 5 R 5 )(L)(L‘)M(CO 2 )Rh(η 4 -COD)] 2 (C 5 R 5 = Cp* (R = Me), M = Fe, Ru (L, L‘ = CO) and Re (L = NO, L‘ = CO); C 5 R 5 = Cp (R = H), M = Re (L = NO, L‘ = PPh 3 ) ( 1 )) recently have been reported . An X-ray crystallographic structure determination of [Cp*(CO)(NO)Re(CO 2 )Rh(η 4 -COD)] 2 and spectroscopic data for the others established a M 2 Rh 2 (μ 3 -CO 2 ) 2 structural motif in which each μ 3 -η 1 (C(Re)):η 1 (O(Rh)):η 1 (O‘(Rh‘)) carboxylate ligand bridges two Rh I (η 4 -COD) moieties 1a. The resulting “open-book” structure resembles that of the catalytically active Rh(I) carboxylates [(RCO 2 )Rh(diene)] 2 …”

mentioning

confidence: 98%

Unusual Degradation of the Rhenium Silyl Ester Cp(NO)(PPh₃)ReCO₂SiMe₂Ph to the Bimetallic μ-η¹(C(Re)):η¹(O,O‘(Re)) Carbon Dioxide Complex Cp(NO)(PPh₃)ReCO₂Re(NO)(CO)(PPh₃)OSiMe₂Ph

et al. 1998

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The silyl esters Cp(PPh3)(NO)ReCO2SiR3 (2) are produced from treatment of Cp(PPh3)(NO)ReCOBF4 with the silanolates R3SiONa (R3Si = PhMe2Si, Et3Si) in CH2Cl2 (0 °C) or of Cp(PPh3)(NO)ReCO2K with R3SiCl in THF. Upon handling, 2 degraded to the bimetallocarboxylates Cp(PPh3)(NO)ReCO2Re(CO)(NO)(PPh3)(OSiR3) (3), one of which (SiR3 = SiMe2Ph) was characterized by X-ray crystallography as a μ-η1(C(Re1)):η2(O,O‘(Re2)) bimetallocarboxylate.

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Re₂Rh₂ μ₃-[η¹-C(Re):η¹-O(Rh):η¹-O‘(Rh‘)] Bis(carbon dioxide) Complexes [(η⁵-C₅R₅)(L)(NO)Re(CO₂)Rh(η⁴-diene)]₂ That Are Structurally Related to Rhodium(I) Carboxylate Dimers [Rh(O₂CR)(η⁴-diene)]₂

Cited by 18 publications

References 30 publications

Thermochemical Insight into the Reduction of CO to CH₃OH with [Re(CO)]⁺and [Mn(CO)]⁺Complexes

Thermochemical Insight into the Reduction of CO to CH₃OH with [Re(CO)]⁺and [Mn(CO)]⁺Complexes

Mechanistic Studies of Single-Step Styrene Production Catalyzed by Rh Complexes with Diimine Ligands: An Evaluation of the Role of Ligands and Induction Period

Unusual Degradation of the Rhenium Silyl Ester Cp(NO)(PPh₃)ReCO₂SiMe₂Ph to the Bimetallic μ-η¹(C(Re)):η¹(O,O‘(Re)) Carbon Dioxide Complex Cp(NO)(PPh₃)ReCO₂Re(NO)(CO)(PPh₃)OSiMe₂Ph

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Re2Rh2 μ3-[η1-C(Re):η1-O(Rh):η1-O‘(Rh‘)] Bis(carbon dioxide) Complexes [(η5-C5R5)(L)(NO)Re(CO2)Rh(η4-diene)]2 That Are Structurally Related to Rhodium(I) Carboxylate Dimers [Rh(O2CR)(η4-diene)]2

Cited by 18 publications

References 30 publications

Thermochemical Insight into the Reduction of CO to CH3OH with [Re(CO)]+and [Mn(CO)]+Complexes

Thermochemical Insight into the Reduction of CO to CH3OH with [Re(CO)]+and [Mn(CO)]+Complexes

Mechanistic Studies of Single-Step Styrene Production Catalyzed by Rh Complexes with Diimine Ligands: An Evaluation of the Role of Ligands and Induction Period

Unusual Degradation of the Rhenium Silyl Ester Cp(NO)(PPh3)ReCO2SiMe2Ph to the Bimetallic μ-η1(C(Re)):η1(O,O‘(Re)) Carbon Dioxide Complex Cp(NO)(PPh3)ReCO2Re(NO)(CO)(PPh3)OSiMe2Ph

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Re₂Rh₂ μ₃-[η¹-C(Re):η¹-O(Rh):η¹-O‘(Rh‘)] Bis(carbon dioxide) Complexes [(η⁵-C₅R₅)(L)(NO)Re(CO₂)Rh(η⁴-diene)]₂ That Are Structurally Related to Rhodium(I) Carboxylate Dimers [Rh(O₂CR)(η⁴-diene)]₂

Thermochemical Insight into the Reduction of CO to CH₃OH with [Re(CO)]⁺and [Mn(CO)]⁺Complexes

Thermochemical Insight into the Reduction of CO to CH₃OH with [Re(CO)]⁺and [Mn(CO)]⁺Complexes

Unusual Degradation of the Rhenium Silyl Ester Cp(NO)(PPh₃)ReCO₂SiMe₂Ph to the Bimetallic μ-η¹(C(Re)):η¹(O,O‘(Re)) Carbon Dioxide Complex Cp(NO)(PPh₃)ReCO₂Re(NO)(CO)(PPh₃)OSiMe₂Ph