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Guan X, Law SM, Tse CW, Huang JS, Che CM. Density functional theory calculations on oxidative C-C bond cleavage and N-O bond formation of [Ru(II)(bpy)2(diamine)](2+) via reactive ruthenium imide intermediates. Chemistry 2014; 20:15122-30. [PMID: 25267445 DOI: 10.1002/chem.201402517] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2014] [Revised: 06/22/2014] [Indexed: 11/11/2022]
Abstract
DFT calculations are performed on [Ru(II)(bpy)2(tmen)](2+) (M1, tmen = 2,3-dimethyl-2,3-butanediamine) and [Ru(II)(bpy)2(heda)](2+) (M2, head = 2,5-dimethyl-2,5-hexanediamine), and on the oxidation reactions of M1 to give the C-C bond cleavage product [Ru(II)(bpy)2(NH=CMe2)2](2+) (M3) and the N-O bond formation product [Ru(II)(bpy)2(ONCMe2CMe2NO)](2+) (M4). The calculated geometrical parameters and oxidation potentials are in good agreement with the experimental data. As revealed by the DFT calculations, [Ru(II)(bpy)2(tmen)](2+) (M1) can undergo oxidative deprotonation to generate Ru-bis(imide) [Ru(bpy)2(tmen-4 H)](+) (A) or Ru-imide/amide [Ru(bpy)2(tmen-3 H)](2+) (A') intermediates. Both A and A' are prone to C-C bond cleavage, with low reaction barriers (ΔG(≠)) of 6.8 and 2.9 kcal mol(-1) for their doublet spin states (2)A and (2)A', respectively. The calculated reaction barrier for the nucleophilic attack of water molecules on (2)A' is relatively high (14.2 kcal mol(-1)). These calculation results are in agreement with the formation of the Ru(II)-bis(imine) complex M3 from the electrochemical oxidation of M1 in aqueous solution. The oxidation of M1 with Ce(IV) in aqueous solution to afford the Ru(II)-dinitrosoalkane complex M4 is proposed to proceed by attack of the cerium oxidant on the ruthenium imide intermediate. The findings of ESI-MS experiments are consistent with the generation of a ruthenium imide intermediate in the course of the oxidation.
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Affiliation(s)
- Xiangguo Guan
- Department of Chemistry and State Key Laboratory of Synthetic Chemistry, The University of Hong Kong, Pokfulam Road (Hong Kong), Fax: (+852) 2857-1586
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Huang JS, Wong KM, Chan SLF, Tso KCH, Jiang T, Che CM. Ketimido Metallophthalocyanines: An Approach to Phthalocyanine-Supported Mononuclear High-Valent Ruthenium Complexes. Chem Asian J 2013; 9:338-50. [DOI: 10.1002/asia.201301109] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2013] [Revised: 09/16/2013] [Indexed: 11/05/2022]
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Bolaño T, Buil ML, Esteruelas MA, Izquierdo S, Lalrempuia R, Oliván M, Oñate E. C−C Bond Activation of the NHC Ligand of an Osmium−Amido Complex. Organometallics 2010. [DOI: 10.1021/om100684a] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Tamara Bolaño
- Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón, Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
| | - María L. Buil
- Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón, Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
| | - Miguel A. Esteruelas
- Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón, Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
| | - Susana Izquierdo
- Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón, Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
| | - Ralte Lalrempuia
- Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón, Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
| | - Montserrat Oliván
- Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón, Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
| | - Enrique Oñate
- Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón, Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
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Wu A, Mayer JM. Hydrogen atom transfer reactions of a ruthenium imidazole complex: hydrogen tunneling and the applicability of the Marcus cross relation. J Am Chem Soc 2008; 130:14745-54. [PMID: 18841973 PMCID: PMC2633126 DOI: 10.1021/ja805067h] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The reaction of Ru(II)(acac)2(py-imH) (Ru(II)imH) with TEMPO(*) (2,2,6,6-tetramethylpiperidine-1-oxyl radical) in MeCN quantitatively gives Ru(III)(acac)2(py-im) (Ru(III)im) and the hydroxylamine TEMPO-H by transfer of H(*) (H(+) + e(-)) (acac = 2,4-pentanedionato, py-imH = 2-(2'-pyridyl)imidazole). Kinetic measurements of this reaction by UV-vis stopped-flow techniques indicate a bimolecular rate constant k(3H) = 1400 +/- 100 M(-1) s(-1) at 298 K. The reaction proceeds via a concerted hydrogen atom transfer (HAT) mechanism, as shown by ruling out the stepwise pathways of initial proton or electron transfer due to their very unfavorable thermochemistry (Delta G(o)). Deuterium transfer from Ru(II)(acac)2(py-imD) (Ru(II)imD) to TEMPO(*) is surprisingly much slower at k(3D) = 60 +/- 7 M(-1) s(-1), with k(3H)/k(3D) = 23 +/- 3 at 298 K. Temperature-dependent measurements of this deuterium kinetic isotope effect (KIE) show a large difference between the apparent activation energies, E(a3D) - E(a3H) = 1.9 +/- 0.8 kcal mol(-1). The large k(3H)/k(3D) and DeltaE(a) values appear to be greater than the semiclassical limits and thus suggest a tunneling mechanism. The self-exchange HAT reaction between Ru(II)imH and Ru(III)im, measured by (1)H NMR line broadening, occurs with k(4H) = (3.2 +/- 0.3) x 10(5) M(-1) s(-1) at 298 K and k(4H)/k(4D) = 1.5 +/- 0.2. Despite the small KIE, tunneling is suggested by the ratio of Arrhenius pre-exponential factors, log(A(4H)/A(4D)) = -0.5 +/- 0.3. These data provide a test of the applicability of the Marcus cross relation for H and D transfers, over a range of temperatures, for a reaction that involves substantial tunneling. The cross relation calculates rate constants for Ru(II)imH(D) + TEMPO(*) that are greater than those observed: k(3H,calc)/k(3H) = 31 +/- 4 and k(3D,calc)/k(3D) = 140 +/- 20 at 298 K. In these rate constants and in the activation parameters, there is a better agreement with the Marcus cross relation for H than for D transfer, despite the greater prevalence of tunneling for H. The cross relation does not explicitly include tunneling, so close agreement should not be expected. In light of these results, the strengths and weaknesses of applying the cross relation to HAT reactions are discussed.
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Affiliation(s)
- Adam Wu
- Department of Chemistry, University of Washington, Campus Box 351700, Seattle, WA, 98195-1700, USA
| | - James M. Mayer
- Department of Chemistry, University of Washington, Campus Box 351700, Seattle, WA, 98195-1700, USA
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Castro-Rodrigo R, Esteruelas MA, López AM, Oñate E. Reactions of a Dihydrogen Complex with Terminal Alkynes: Formation of Osmium−Carbyne and −Carbene Derivatives with the Hydridotris(pyrazolyl)borate Ligand. Organometallics 2008. [DOI: 10.1021/om800248e] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ruth Castro-Rodrigo
- Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón, Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
| | - Miguel A. Esteruelas
- Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón, Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
| | - Ana M. López
- Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón, Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
| | - Enrique Oñate
- Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón, Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
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Becker E, Pavlik S, Kirchner K. The Organometallic Chemistry of Group 8 Tris(pyrazolyl)borate Complexes. ADVANCES IN ORGANOMETALLIC CHEMISTRY 2008. [DOI: 10.1016/s0065-3055(07)56003-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
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Wu A, Masland J, Swartz RD, Kaminsky W, Mayer JM. Synthesis and characterization of ruthenium bis(beta-diketonato) pyridine-imidazole complexes for hydrogen atom transfer. Inorg Chem 2007; 46:11190-201. [PMID: 18052056 PMCID: PMC2596074 DOI: 10.1021/ic7015726] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ruthenium bis(beta-diketonato) complexes have been prepared at both the RuII and RuIII oxidation levels and with protonated and deprotonated pyridine-imidazole ligands. RuII(acac)2(py-imH) (1), [RuIII(acac)2(py-imH)]OTf (2), RuIII(acac)2(py-im) (3), RuII(hfac)2(py-imH) (4), and [DBU-H][RuII(hfac)2(py-im)] (5) have been fully characterized, including X-ray crystal structures (acac = 2,4-pentanedionato, hfac = 1,1,1,5,5,5-hexafluoro-2,4-pentanedionato, py-imH = 2-(2'-pyridyl)imidazole, DBU = 1,8-diazabicyclo[5.4.0]undec-7-ene). For the acac-imidazole complexes 1 and 2, cyclic voltammetry in MeCN shows the RuIII/II reduction potential (E1/2) to be -0.64 V versus Cp2Fe+/0. E1/2 for the deprotonated imidazolate complex 3 (-1.00 V) is 0.36 V more negative. The RuII bis-hfac analogues 4 and 5 show the same DeltaE1/2 = 0.36 V but are 0.93 V harder to oxidize than the acac derivatives (0.29 and -0.07 V). The difference in acidity between the acac and hfac derivatives is much smaller, with pKa values of 22.1 and 19.3 in MeCN for 1 and 4, respectively. From the E1/2 and pKa values, the bond dissociation free energies (BDFEs) of the N-H bonds in 1 and 4 are calculated to be 62.0 and 79.6 kcal mol(-1) in MeCN - a remarkable difference of 17.6 kcal mol(-1) for such structurally similar compounds. Consistent with these values, there is a facile net hydrogen atom transfer from 1 to TEMPO* (2,2,6,6-tetramethylpiperidine-1-oxyl radical) to give 3 and TEMPO-H. The DeltaG degrees for this reaction is -4.5 kcal mol(-1). 4 is not oxidized by TEMPO* (DeltaG degrees = +13.1 kcal mol(-1)), but in the reverse direction TEMPO-H readily reduces in situ generated RuIII(hfac)2(py-im) (6). A RuII-imidazoline analogue of 1, RuII(acac)2(py-imnH) (7), reacts with 3 equiv of TEMPO* to give the imidazolate 3 and TEMPO-H, with dehydrogenation of the imidazoline ring.
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Affiliation(s)
- Adam Wu
- Department of Chemistry, University of Washington, Campus Box 351700, Seattle, WA, 98195-1700, USA
| | - Joshua Masland
- Department of Chemistry, University of Washington, Campus Box 351700, Seattle, WA, 98195-1700, USA
| | | | | | - James M. Mayer
- Department of Chemistry, University of Washington, Campus Box 351700, Seattle, WA, 98195-1700, USA
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Castro-Rodrigo R, Esteruelas MA, López AM, Oliván M, Oñate E. Preparation, Spectroscopic Characterization, X-ray Structure, and Theoretical Investigation of Hydride−, Dihydrogen−, and Acetone−OsTp Complexes: A Hydridotris(pyrazolyl)borate−Cyclopentadienyl Comparison. Organometallics 2007. [DOI: 10.1021/om700480t] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ruth Castro-Rodrigo
- Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón, Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
| | - Miguel A. Esteruelas
- Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón, Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
| | - Ana M. López
- Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón, Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
| | - Montserrat Oliván
- Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón, Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
| | - Enrique Oñate
- Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón, Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
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Dickinson PW, Girolami GS. Synthesis and Characterization of Osmium(II) Trispyrazolylborate Complexes. Inorg Chem 2006; 45:5215-24. [PMID: 16780347 DOI: 10.1021/ic0602291] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Treatment of H2OsBr6 with excess 1,5-cyclooctadiene (cod) in boiling tert-butyl alcohol affords the polymer [OsBr2(cod)]x (1), which reacts with acetonitrile to form the mononuclear adduct OsBr2(cod)(CH3CN)2 (2). Polymer 1 reacts with potassium trispyrazolylborate (KTp) in ethanol to afford the hydride TpOs(cod)H (3) and the bromide complex TpOs(cod)Br (4). Bromide complex 4 reacts with sodium methoxide in methanol to afford TpOs(cod)OMe (5), which has been structurally characterized. Treatment of hydride 3 with methyl trifluoromethanesulfonate (MeOTf) in diethyl ether results in loss of methane and formation of the triflate complex TpOs(cod)OTf (6), which reacts with MgMe2 to give the methyl complex TpOs(cod)Me (7). The addition of bis(dimethylphosphino)methane (dmpm) to the known compound TpOs(PPh3)2Cl yields a mixture of the substitution products TpOs(eta1-dmpm)(PPh3)Cl (8) and TpOs(eta2-dmpm)Cl (9); the latter reacts with methyllithium to generate the methyl compound TpOs(dmpm)Me (10). NMR and IR data for these new compounds are reported. Crystal data for 5.MeOH at -80 degrees C are as follows: monoclinic, P2(1)/n, a = 10.728(1) A, b = 14.004(2) A, c = 13.906(2) A, beta = 102.42(6) degrees , V = 2040.3(5) A3, Z = 4, R(F) = 0.0247 for I > or = 2sigma(I), and R(wF2) = 0.0539 for all data.
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Affiliation(s)
- Paul W Dickinson
- School of Chemical Sciences, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, USA
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Soper JD, Saganic E, Weinberg D, Hrovat DA, Benedict JB, Kaminsky W, Mayer JM. Nucleophilic aromatic substitution on aryl-amido ligands promoted by oxidizing osmium(IV) centers. Inorg Chem 2004; 43:5804-15. [PMID: 15360229 DOI: 10.1021/ic0498743] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Addition of amine nucleophiles to acetonitrile solutions of the OsIV anilido complex TpOs(NHPh)Cl2 (1) [Tp = hydrotris(1-pyrazolyl)borate] gives products with derivatized anilido ligands, i.e., TpOs[NH-p-C6H4(N(CH2)5)]Cl2 (2) from piperidine and TpOs[NH-p-C6H4N(CH2)4]Cl2 (3) from pyrrolidine. These materials are formed in approximately 30% yield under anaerobic conditions, together with approximately 60% yields of the OsIII aniline complex TpOs(NH2Ph)Cl2 (5). Formation of the para-substituted materials 2 or 3 from 1 involves oxidative removal of two hydrogen atoms (two H+ and two e-). The oxidation can be accomplished by 1, forming 5, or by O2. Related reactions have been observed with other amines and with the 2-naphthylamido derivative, which gives an ortho-substituted product. Kinetic studies indicate an addition-elimination mechanism involving initial attack of the amine nucleophile on the anilido ligand. These are unusual examples of nucleophilic aromatic substitution of hydrogen. Ab initio calculations on 1 show that the LUMO has significant density at the ortho and para positions of the anilido ligand, resembling the LUMO of nitrobenzene. By analogy with nucleophilic aromatic substitution, 2 is quantitatively formed from piperidine and the p-chloroanilide TpOs(NH-p-C6H4Cl)Cl2 (7). Binding the anilide ligands to an oxidizing OsIV center thus causes a remarkable umpolung or inversion of chemical character from a typically electron-rich anilido to an electron-deficient aromatic functionality. This occurs because of the coupling of redox changes at the TpOsIV center with bond formation at the coordinated ligand.
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Affiliation(s)
- Jake D Soper
- Department of Chemistry, Campus Box 351700, University of Washington, Seattle, Washington 98195-1700, USA
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Abstract
Proton-coupled electron transfer (PCET) reactions involve the concerted transfer of an electron and a proton. Such reactions play an important role in many areas of chemistry and biology. Concerted PCET is thermochemically more favorable than the first step in competing consecutive processes involving stepwise electron transfer (ET) and proton transfer (PT), often by >=1 eV. PCET reactions of the form X-H + Y X + H-Y can be termed hydrogen atom transfer (HAT). Another PCET class involves outersphere electron transfer concerted with deprotonation by another reagent, Y+ + XH-B Y + X-HB+. Many PCET/HAT rate constants are predicted well by the Marcus cross relation. The cross-relation calculation uses rate constants for self-exchange reactions to provide information on intrinsic barriers. Intrinsic barriers for PCET can be comparable to or larger than those for ET. These properties are discussed in light of recent theoretical treatments of PCET.
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Affiliation(s)
- James M Mayer
- Department of Chemistry, University of Washington, Campus Box 351700, Seattle, Washington 98195-1700, USA.
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