Electrochemistry of rhodium-dipyridyl complexes

Kew, Gregory; DeArmond, Keith; Hanck, Kenneth W.

doi:10.1021/j100600a017

Cited by 101 publications

(71 citation statements)

References 6 publications

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“…Calculations are also in accordance with a sequential two-electron reduction of the catalyst by [Ru II (bpy) 2 (bpy •− )] + through an ECEC mechanism, which is based on the release of one monodentate ligand (chloro or aquo) after each one-electron reduction step of the initial Rh III complex. This ECEC mechanism was initially suggested by DeArmond [115] through an electrochemical study. Then the Rh I catalyst reacts with protons to form the [Rh III (H)(dmbpy) 2 (H 2 O)] 2+ hydride, that adopts preferentially a hexa-coordinated octahedral geometry (Fig.…”

Section: Rhodium(iii) Bis(bipyridine) Bis(chloro) As Catalystmentioning

confidence: 81%

“…Electrochemical investigations [23,112,115] indicated a sequential two-electron reduction process (Rh III → Rh I ) for [Rh III (bpy) 3 ] 3+ (Ep c ∼ −0.94 V versus SCE at pH 10) [23,115] according to an ECEC mechanism, i.e. a one-electron reduction first followed by the release of one Cl − and then a second one-electron reduction followed by another Cl − loss, leading to the formation of the distorted square planar [Rh I (bpy) 2 ] + complex as final species.…”

Section: G Modelmentioning

confidence: 99%

“…Although this photocatalytic system functions between pH 2 and pH 5.5, the maximum catalytic activity is observed at pH 4.0, the pK a of the HA − /H 2 A buffer. Rh9 is an analog of the rhodium(III) tris-bipyridyl complex (Rh1) since its irreversible two-electron reduction (Rh III /Rh I ) is coupled to the release of two monodentate ligands [39,115,125] giving rise to similar low-valent distorted tetracoordinated Rh I bis(bipyridyl) species [126]. Interestingly here higher TONs Cat were obtained in water in comparison with the previous studies of Lehn, Sauvage [23] and Creutz, Sutin [111,112] described above using Rh1 as catalyst (TONs Cat < 10 without colloidal platinum).…”

Section: Rhodium(iii) Bis(bipyridine) Bis(chloro) As Catalystmentioning

confidence: 99%

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Photo-induced redox catalysis for proton reduction to hydrogen with homogeneous molecular systems using rhodium-based catalysts

Stoll

Castillo

Kayanuma

et al. 2015

Coordination Chemistry Reviews

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Section: Rhodium(iii) Bis(bipyridine) Bis(chloro) As Catalystmentioning

confidence: 81%

Section: G Modelmentioning

confidence: 99%

Section: Rhodium(iii) Bis(bipyridine) Bis(chloro) As Catalystmentioning

confidence: 99%

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Photo-induced redox catalysis for proton reduction to hydrogen with homogeneous molecular systems using rhodium-based catalysts

Stoll

Castillo

Kayanuma

et al. 2015

Coordination Chemistry Reviews

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“…The reductive electrochemistry shows irreversible Rh III/II/I reductions, followed by two reversible dpp 0/À reductions [59,63,66]. The Rh III/II/I reduction is followed by the loss of halides, similar to that reported for [Rh(bpy) 2 Cl 2 ] þ [67]. The variation of the identity of the halides on the rhodium impact the reductive electrochemistry.…”

Section: Redox Properties Of Rhodium-centered Electron Collectorssupporting

confidence: 65%

Supramolecular Complexes as Photoinitiated Electron Collectors: Applications in Solar Hydrogen Production

Arachchige

Brewer

On Solar Hydrogen &Amp; Nanotechnology

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The urgent need to explore alternative energy sources has stimulated solar energy research globally. Solar energy that reaches the southern United States has an instantaneous maximum intensity of 1 kW m À2 and an average 24 h intensity of 250 W m À2 in a year [1]. It is a clean, abundant, and renewable energy source. Solar energy research is concentrated on its direct conversion to electricity in photovoltaic devices, conversion to heat in solar thermal devices, or conversion to chemical energy to produce fuels via artificial photosynthesis. Hydrogen has been proposed as an energy solution for the future due to its high energy content per gram (120 kJ g À1 ) and burning hydrogen results in only energy and water, having no impact on our carbon foot print. Solar Water SplittingSolar hydrogen production through water splitting is an attractive alternative energy solution for the future [1][2][3][4][5][6][7]. Solar water splitting uses light energy from the sun to convert water into hydrogen and oxygen. Water splitting is a challenging, energetically uphill process. The reactions involved in water splitting require bond breaking, bond formation and multielectron

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“…22 As stated ear lier, the emis sion spec trum of the com plex is con firmed to be d-d* tran si tion. The two-electron trans fer re duc tion (wave cI) re sults in more ac cu mu la tion of elec tron den si ties on the metal and hence destabilization of the complex.…”

Section: -21mentioning

confidence: 92%

Synthesis and Spectral Properties of Phenyl‐Pyridin‐2‐Ylmethylene‐Amine Complex of Rhodium(III)

Lee¹,

Lung²,

Huang³

2002

J Chinese Chemical Soc

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A new com plex of [Rh(PA)2Cl2]Cl·H2O (where PA = phenyl-pyridin-2-ylmethylene-amine) has been synthe sized and char ac ter ized. The com plex shows high in ten sity bands in the UV re gion, and these are as signed to spin-allowed -* tran si tions. The me dium-intensity ab sorp tion band pro file in the lower en ergy re gion can be ex plained by con vo lu tion of spin-allowed CT and d-d* tran si tions. Emis sion spec trum at low tem per ature (77 K) of the com plex in EtOH/MeOH (4:1 v/v) has also been in ves ti gated. It shows a broad, sym met ric, and structureless red emis sion with mi cro sec ond life time and hence is as signed as d-d* phos p ho res cence. Voltammetric data have also been ob tained for the com plex. There were three re duc tion peaks ob served for the com plex. The first peak, in clud ing two re duc tion steps with elim i na tion of two chlo rides, is con sis tent with ECEC re ac tion. IN TRO DUC TIONThe syn thetic pro ce dures of phenyl-pyridin-2-yl methyl ene-amine (PA), a Schiff base ligand, have been re ported ear lier.1 Syn thetic stud ies in volv ing complexation of PA have been re ported for some tran si tion met als such as Ag(I), PA is an un sym met ri cal bidentate ligand and thus al lows it to form metal com plexes of var i ous co or di na tion struc tures. 5 In the pres ent work, we have first fo cused on prep a ra tion of the rho dium(III) com plex co or di nated with two PA lig ands. In or der to get a closer un der stand ing of bond ing in forma tion in co or di na tion chem is try, we have also ex am ined the tran si tion types through the ob served elec tronic spec tra from photophysical prop er ties of the PA com plex pre pared at this lab. Elec tro chem i cal stud ies of this newly syn the sized complex have been car ried out with the aim to get com par a tive and sup ple men tary in for ma tion in con trast to those ob tained via emis sion spec tros copy in clud ing lu mi nes cence data. RE SULTS AND DIS CUS SIONThe base peak in mass spec trum of the com plex is m/z = 537, con sis tent with the mo lec u lar mass of [Rh(PA)2Cl2] + .The in fra red spec trum of [Rh(PA)2Cl2] + ex hib its the (C=N) band in the vi cin ity of 1600 cm -1 . This fre quency is slightly smaller than that in the free PA ligand (ca 1625 cm -1 ) and is in ac cord with the ru the nium an a logue, Ru(PA) 2 Cl 2 . 5a The complex shows two ad di tional bands near 343 and 325 cm -1 , which were not ob served in the free PA ligand, had been assigned to the Rh-Cl stretch ing. 11 More over, the dou blet nature of Rh-Cl stretch ing in di cates that the two chlo rides are cis to each other. 12The pro ton NMR spec trum ac quired for the com plex reveals 8 unequivalent pro tons and the 13 C spec trum ex hib its 10 car bon res o nance sig nals. Ac cord ing to these NMR data, the two PA lig ands are chem i cally equiv a lent in [Rh(PA)2Cl2] + . There are 3 pos si ble iso mers for cis-[Rh(PA) 2 Cl 2 ] + de duced from the two-PA co or di nated com plexes as dis played be low.In the cis-iso mer, two PA lig ands are not...

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Electrochemistry of rhodium-dipyridyl complexes

Cited by 101 publications

References 6 publications

Photo-induced redox catalysis for proton reduction to hydrogen with homogeneous molecular systems using rhodium-based catalysts

Photo-induced redox catalysis for proton reduction to hydrogen with homogeneous molecular systems using rhodium-based catalysts

Supramolecular Complexes as Photoinitiated Electron Collectors: Applications in Solar Hydrogen Production

Synthesis and Spectral Properties of Phenyl‐Pyridin‐2‐Ylmethylene‐Amine Complex of Rhodium(III)

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