skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Positional effects of hydroxy groups on catalytic activity of proton-responsive half-sandwich Cp*Iridium(III) complexes

Journal Article · · Organometallics
DOI:https://doi.org/10.1021/om500832d· OSTI ID:1182539
 [1];  [2];  [2];  [3];  [1];  [1];  [2];  [4]
  1. National Inst. of Advanced Industrial Science and Technology, Higashi, Tsukuba, Ibaraki (Japan)
  2. Brookhaven National Lab. (BNL), Upton, NY (United States)
  3. National Inst. of Advanced Industrial Science and Technology, Higashi, Tsukuba, Ibaraki (Japan); Japan Science and Technology Agency, Honcho, Kawaguchi, Saitama (Japan); Univ. of Technology, Panjin (China)
  4. National Inst. of Advanced Industrial Science and Technology, Higashi, Tsukuba, Ibaraki (Japan); Japan Science and Technology Agency, Honcho, Kawaguchi, Saitama (Japan)
+ Show Author Affiliations

Proton-responsive half-sandwich Cp*Ir(III) complexes possessing a bipyridine ligand with two hydroxy groups at the 3,3'-, 4,4'-, 5,5'- or 6,6'-positions (3DHBP, 4DHBP, 5DHBP, or 6DHBP) were systematically investigated. UV-vis titration data provided average pK a values of the hydroxy groups on the ligands. Both hydroxy groups were found to deprotonate in the pH 4.6–5.6 range for the 4–6DHBP complexes. One of the hydroxy groups of the 3DHBP complex exhibited the low pKa value of < 0.4 because the deprotonation is facilitated by the strong intramolecular hydrogen bond formed between the generated oxyanion and the remaining hydroxy group, which in turn leads to an elevated pKa value of ~13.6 for the second deprotonation step. The crystal structures of the 4– and 6DHBP complexes obtained from basic aqueous solutions revealed their deprotonated forms. The intramolecular hydrogen bond in the 3DHBP complex was also observed in the crystal structures. The catalytic activities of these complexes in aqueous phase reactions, at appropriate pH, for hydrogenation of carbon dioxide (pH 8.5), dehydrogenation of formic acid (pH 1.8), transfer hydrogenation reactions using formic acid/formate as a hydrogen source (pH 7.2 and 2.6) were investigated to compare the positional effects of the hydroxy groups. The 4– and 6DHBP complexes exhibited remarkably enhanced catalytic activities under basic conditions because of the resonance effect of the strong electrondonating oxyanions, whereas the 5DHBP complex exhibited negligible activity despite the presence of electron-donating groups. The 3DHBP complex exhibited relatively high catalytic activity at low pH owing to the one strong electron-donating oxyanion group stabilized by the intramolecular hydrogen bond. DFT calculations were employed to study the mechanism of CO₂ hydrogenation by the 4DHBP and 6DHBP complexes, and comparison of the activation free energies of the H₂ heterolysis and CO₂ insertion steps indicated that H₂ heterolysis is the rate-determining step for both complexes. The presence of a pendent base in the 6DHBP complex was found to facilitate the rate-determining step, and renders 6DHBP a more effective catalyst for formate production.

Research Organization:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
Grant/Contract Number:
SC00112704
OSTI ID:
1182539
Report Number(s):
BNL-107640-2015-JA; R&D Project: CO026; KC0304030
Journal Information:
Organometallics, Vol. 33, Issue 22; ISSN 0276-7333
Publisher:
American Chemical SocietyCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 84 works
Citation information provided by
Web of Science

References (98)

Creating Ligands with Multiple Personalities journal October 2010
Multifunctional ligands in transition metal catalysis journal January 2011
N–N Bond Cleavage of Hydrazines with a Multiproton-Responsive Pincer-Type Iron Complex journal April 2013
6,6′-Dihydroxy terpyridine: a proton-responsive bifunctional ligand and its application in catalytic transfer hydrogenation of ketones journal January 2013
Efficient Copper-Catalyzed Ullmann Reaction of Aryl Bromides with Imidazoles in Water Promoted by a pH-Responsive Ligand journal June 2013
Conversion of Carbohydrate Biomass to γ-Valerolactone by using Water-Soluble and Reusable Iridium Complexes in Acidic Aqueous Media journal June 2013
Dehydrogenative Oxidation of Alcohols in Aqueous Media Using Water-Soluble and Reusable Cp*Ir Catalysts Bearing a Functional Bipyridine Ligand journal February 2012
Structural, electronic and acid/base properties of [Ru(bpy(OH)2)3]2+ (bpy(OH)2 = 4,4′-dihydroxy-2,2′-bipyridine) journal January 2012
Conjugate addition of arylboronic acids to α,β-unsaturated carbonyl compounds in aqueous medium using Pd(ii) complexes with dihydroxy-2,2′-bipyridine ligands: homogeneous or heterogeneous nano-catalysis? journal January 2011
Transfer Hydrogenation in Water via a Ruthenium Catalyst with OH Groups near the Metal Center on a bipy Scaffold journal December 2011
Structural, Electronic, and Acid/Base Properties of [Ru(bpy) 2 (bpy(OH) 2 )] 2+ (bpy = 2,2′-Bipyridine, bpy(OH) 2 = 4,4′-Dihydroxy-2,2′-bipyridine) journal April 2011
Polydentate Analogues of 8-Hydroxyquinoline and Their Complexes with Ruthenium journal November 2011
First metal complexes of 6,6′-dihydroxy-2,2′-bipyridine: from molecular wires to applications in carbonylation catalysis journal January 2011
Anion-Exchange-Triggered 1,3-Shift of an NH Proton to Iridium in Protic N-Heterocyclic Carbenes: Hydrogen-Bonding and Ion-Pairing Effects journal December 2009
Acceleration of Nucleophilic CH Activation by Strongly Basic Solvents journal September 2010
Simultaneous Tuning of Activity and Water Solubility of Complex Catalysts by Acid−Base Equilibrium of Ligands for Conversion of Carbon Dioxide journal January 2007
Highly efficient conversion of carbon dioxide catalyzed by half-sandwich complexes with pyridinol ligand: The electronic effect of oxyanion journal September 2006
Interconversion between Formic Acid and H2/CO2 using Rhodium and Ruthenium Catalysts for CO2 Fixation and H2 Storage journal January 2011
pH-Dependent Catalytic Activity and Chemoselectivity in Transfer Hydrogenation Catalyzed by Iridium Complex with 4,4′-Dihydroxy-2,2′-bipyridine journal December 2008
Half-Sandwich Complexes with 4,7-Dihydroxy-1,10-phenanthroline:  Water-Soluble, Highly Efficient Catalysts for Hydrogenation of Bicarbonate Attributable to the Generation of an Oxyanion on the Catalyst Ligand journal March 2004
Reversible hydrogen storage using CO2 and a proton-switchable iridium catalyst in aqueous media under mild temperatures and pressures journal March 2012
Highly efficient hydrogen evolution by decomposition of formic acid using an iridium catalyst with 4,4′-dihydroxy-2,2′-bipyridine journal January 2009
Recyclable Catalyst for Conversion of Carbon Dioxide into Formate Attributable to an Oxyanion on the Catalyst Ligand journal September 2005
A QM/MM Investigation of the Activation and Catalytic Mechanism of Fe-Only Hydrogenases journal July 2007
Crystallographic and FTIR Spectroscopic Evidence of Changes in Fe Coordination Upon Reduction of the Active Site of the Fe-Only Hydrogenase from Desulfovibrio d esulfuricans journal February 2001
A Capable Bridging Ligand for Fe-Only Hydrogenase:  Density Functional Calculations of a Low-Energy Route for Heterolytic Cleavage and Formation of Dihydrogen journal April 2001
The NH Functional Group in Organometallic Catalysis journal March 2013
Outer sphere hydrogenation catalysis journal January 2013
The roles of the first and second coordination spheres in the design of molecular catalysts for H 2 production and oxidation journal January 2009
Highly Stereoselective Proton/Hydride Exchange: Assistance of Hydrogen Bonding for the Heterolytic Splitting of H 2 journal December 2009
Pendant Bases as Proton Relays in Iron Hydride and Dihydrogen Complexes journal March 2006
Heterolytic dihydrogen activation in an iridium complex with a pendant basic group journal January 1999
Intramolecular N−H···H−Ru Proton−Hydride Interaction in Ruthenium Complexes with (2-(Dimethylamino)ethyl)cyclopentadienyl and (3-(Dimethylamino)propyl)cyclopentadienyl Ligands. Hydrogenation of CO 2 to Formic Acid via the N−H···H−Ru Hydrogen-Bonded Complexes journal June 1998
Switching On and Off a New Intramolecular Hydrogen-Hydrogen Interaction and the Heterolytic Splitting of Dihydrogen. Crystal and Molecular Structure of [Ir{H(.eta.1-SC5H4NH)}2(PCy3)2]BF4.cntdot.2.7CH2Cl2 journal September 1994
An Unusual Type of H.cntdot..cntdot..cntdot.H Interaction: Ir-H.cntdot..cntdot..cntdot.H-O and Ir-H.cntdot..cntdot..cntdot.H-N Hydrogen Bonding and Its Involvement in .sigma.-Bond Metathesis journal November 1994
Mechanistic Insight through Factors Controlling Effective Hydrogenation of CO 2 Catalyzed by Bioinspired Proton-Responsive Iridium(III) Complexes journal April 2013
Second-coordination-sphere and electronic effects enhance iridium(iii)-catalyzed homogeneous hydrogenation of carbon dioxide in water near ambient temperature and pressure journal January 2012
Novel Seco Cyclopropa[ c ]pyrrolo[3,2- e ]indole Bisalkylators Bearing a 3,3‘-Arylenebisacryloyl Group as a Linker journal April 2001
Synthesis, Properties, and Reactivity of N,N ‘-Difluorobipyridinium and Related Salts and Their Applications as Reactive and Easy-To-Handle Electrophilic Fluorinating Agents with High Effective Fluorine Content 1 journal May 1998
Ruthenium dihydroxybipyridine complexes are tumor activated prodrugs due to low pH and blue light induced ligand release journal January 2014
Mono- and di-nuclear ruthenium( II ) complexes of the ambidentate ligand 3,3′-dihydroxy-2,2′-bipyridine: spectroscopic, electrochemical and mixed-valence properties journal January 1996
The coordination chemistry of 2-pyridone and its derivatives journal February 1995
Excited state proton transfer of ruthenium(II) complexes of 4,7-dihydroxy-1,10-phenanthroline. Increased acidity in the excited state journal October 1978
pH-Dependent Transfer Hydrogenation of Ketones with HCOONa as a Hydrogen Donor Promoted by ( η 6 -C 6 Me 6 )Ru Complexes journal July 2002
.pi.-Arene Aqua Complexes of Cobalt, Rhodium, Iridium, and Ruthenium: Preparation, Structure, and Kinetics of Water Exchange and Water Substitution journal January 1995
Synthesis and protonation-deprotonation reactions of ruthenium(II) complexes containing 2, 2′-bibenzimidazole and related ligands journal January 1983
ACIDITY MEASUREMENTS WITH THE GLASS ELECTRODE IN H 2 O-D 2 O MIXTURES journal May 1960
Organometallic Half-Sandwich Iridium Anticancer Complexes journal April 2011
Iridium Dihydroxybipyridine Complexes Show That Ligand Deprotonation Dramatically Speeds Rates of Catalytic Water Oxidation journal August 2013
A formula for correlating p K a values determined in D 2 O and H 2 O journal January 2004
Direct synthesis of formic acid from carbon dioxide by hydrogenation in acidic media journal June 2014
Highly Efficient Reversible Hydrogenation of Carbon Dioxide to Formates Using a Ruthenium PNP-Pincer Catalyst journal April 2014
A Cobalt-Based Catalyst for the Hydrogenation of CO 2 under Ambient Conditions journal July 2013
Secondary Coordination Sphere Interactions Facilitate the Insertion Step in an Iridium(III) CO 2 Reduction Catalyst journal June 2011
Water-Soluble IrIII N-Heterocyclic Carbene Based Catalysts for the Reduction of CO2 to Formate by Transfer Hydrogenation and the Deuteration of Aryl Amines in Water journal March 2011
Catalytic Hydrogenation of Carbon Dioxide Using Ir(III)−Pincer Complexes journal October 2009
Mechanistic investigation of CO2 hydrogenation by Ru(ii) and Ir(iii) aqua complexes under acidic conditions: two catalytic systems differing in the nature of the rate determining step journal January 2006
Aqueous hydrogenation of carbon dioxide catalysed by water-soluble ruthenium aqua complexes under acidic conditions journal January 2004
Anthropogenic Chemical Carbon Cycle for a Sustainable Future journal August 2011
Recent developments in carbon dioxide utilization under mild conditions journal January 2010
Breakthroughs in Hydrogen Storage-Formic Acid as a Sustainable Storage Material for Hydrogen journal October 2008
Carbon Dioxide-The Hydrogen-Storage Material of the Future? journal October 2008
Transformation of Carbon Dioxide journal June 2007
Recent advances in the homogeneous hydrogenation of carbon dioxide journal December 2004
Carbon Dioxide as a Raw Material: The Synthesis of Formic Acid and Its Derivatives from CO2 journal November 1995
Aluminium–ligand cooperation promotes selective dehydrogenation of formic acid to H 2 and CO 2 journal January 2014
Efficient H 2 generation from formic acid using azole complexes in water journal January 2014
A Rechargeable Hydrogen Battery Based on Ru Catalysis journal May 2014
Towards a Practical Setup for Hydrogen Production from Formic Acid journal June 2013
Chemical Equilibria in Formic Acid/Amine-CO 2 Cycles under Isochoric Conditions using a Ruthenium(II) 1,2-Bis(diphenylphosphino)ethane Catalyst journal November 2013
Catalytic interconversion between hydrogen and formic acid at ambient temperature and pressure journal January 2012
A Charge/Discharge Device for Chemical Hydrogen Storage and Generation journal September 2011
Hydrogen Generation from Formic Acid Decomposition by Ruthenium Carbonyl Complexes. Tetraruthenium Dodecacarbonyl Tetrahydride as an Active Intermediate journal March 2011
Catalytic Generation of Hydrogen from Formic acid and its Derivatives: Useful Hydrogen Storage Materials journal May 2010
Controlled Generation of Hydrogen from Formic Acid Amine Adducts at Room Temperature and Application in H 2 /O 2 Fuel Cells journal May 2008
Efficient Catalytic Decomposition of Formic Acid for the Selective Generation of H 2 and H/D Exchange with a Water-Soluble Rhodium Complex in Aqueous Solution journal October 2008
A Viable Hydrogen-Storage System Based On Selective Formic Acid Decomposition with a Ruthenium Catalyst journal May 2008
Formic Acid Dehydrogenation with Bioinspired Iridium Complexes: A Kinetic Isotope Effect Study and Mechanistic Insight journal May 2014
Cyclometalated iridium complexes for transfer hydrogenation of carbonyl groups in water journal January 2013
The development of aqueous transfer hydrogenation catalysts journal January 2011
pH-Regulated Asymmetric Transfer Hydrogenation of Quinolines in Water journal August 2009
Aqueous Biphasic Hydrogenations journal June 2002
Efficient catalytic reduction of ketones with formic acid and ruthenium complexes journal May 1996
Iridium-Catalyzed Hydrogen Transfer Reactions book November 2010
Mechanism of Asymmetric Hydrogenation of Acetophenone Catalyzed by Chiral η6-Arene–N-Tosylethylenediamine–Ruthenium(II) Complexes journal July 2006
Complex-Catalyzed Hydrogenation Reactions in Aqueous Media journal June 2002
Asymmetric Catalysis by Architectural and Functional Molecular Engineering: Practical Chemo- and Stereoselective Hydrogenation of Ketones journal January 2001
Transfer Hydrogenation in Water: Enantioselective, Catalytic Reduction of α-Cyano and α-Nitro Substituted Acetophenones journal June 2010
RhIII- and IrIII-Catalyzed Asymmetric Transfer Hydrogenation of Ketones in Water journal February 2008
A practical synthesis of optically active aromatic epoxides via asymmetric transfer hydrogenation of α-chlorinated ketones with chiral rhodium–diamine catalyst journal August 2004
Isolation and Crystal Structure of a Water-Soluble Iridium Hydride:  A Robust and Highly Active Catalyst for Acid-Catalyzed Transfer Hydrogenations of Carbonyl Compounds in Acidic Media journal April 2003
Chemoselective Conjugate Reduction of α,β-Unsaturated Ketones Catalyzed by Rhodium Amido Complexes in Aqueous Media journal April 2010
Titanocene-Catalyzed Conjugate Reduction of α,β-Unsaturated Carbonyl Derivatives journal December 2009
A New Entry to Pd−H Chemistry:  Catalytic Asymmetric Conjugate Reduction of Enones with EtOH and a Highly Enantioselective Synthesis of Warfarin journal October 2006
A Chemoselective Hydrogenation of the Olefinic Bond of α,β-Unsaturated Carbonyl Compounds in Aqueous Medium under Microwave Irradiation journal February 2006
Hydrogenation of olefins using water and zinc metal catalyzed by a rhodium complex journal October 2006
Selective reduction of alkenes, α,β-unsaturated carbonyl compounds, nitroarenes, nitroso compounds, N,N-hydrogenolysis of azo and hydrazo functions as well as simultaneous hydrodehalogenation and reduction of substituted aryl halides over PdMCM-41 catalyst under transfer hydrogen conditions journal April 2004
Iridium-Catalyzed Transfer Hydrogenation of α,β-Unsaturated and Saturated Carbonyl Compounds with 2-Propanol journal June 2001

Cited By (20)

CO 2 hydrogenation by phosphorus–nitrogen PN 3 P-pincer iridium hydride complexes: elucidation of the deactivation pathway journal January 2019
Impact of {Os(pap) 2 } in fine-tuning the binding modes and non-innocent potential of deprotonated 2,2′-bipyridine-3,3′-diol journal January 2016
Bifunctional Ru II -Complex-Catalysed Tandem C−C Bond Formation: Efficient and Atom Economical Strategy for the Utilisation of Alcohols as Alkylating Agents journal October 2016
Unprecedentedly High Formic Acid Dehydrogenation Activity on an Iridium Complex with an N , N ′-Diimine Ligand in Water journal July 2015
Metall-Ligand-Kooperation journal September 2015
Utilization of a Fluorescent Dye Molecule as a Proton and Electron Reservoir journal February 2018
Metal-Ligand Cooperation journal September 2015
Mechanistic Considerations on Homogeneously Catalyzed Formic Acid Dehydrogenation: Mechanistic Considerations on Homogeneously Catalyzed Formic Acid Dehydrogenation journal April 2018
Platinum Complexes with a Phosphino-Oxime/Oximate Ligand: Platinum Complexes with a Phosphino-Oxime/Oximate Ligand journal July 2018
Development of an Iridium-Based Catalyst for High-Pressure Evolution of Hydrogen from Formic Acid journal August 2016
Development of Effective Catalysts for Hydrogen Storage Technology Using Formic Acid journal September 2018
Light-driven catalytic hydrogenation of carbon dioxide at low-pressure by a trinuclear iridium polyhydride complex journal January 2019
Carbon Dioxide Hydrogenation and Formic Acid Dehydrogenation Catalyzed by Iridium Complexes Bearing Pyridyl-pyrazole Ligands: Effect of an Electron-donating Substituent on the Pyrazole Ring on the Catalytic Activity and Durability journal November 2018
Optimum bifunctionality in a 2-(2-pyridyl-2-ol)-1,10-phenanthroline based ruthenium complex for transfer hydrogenation of ketones and nitriles: impact of the number of 2-hydroxypyridine fragments journal January 2016
Catalytic reactivity of an iridium complex with a proton responsive N-donor ligand in CO 2 hydrogenation to formate journal January 2018
Mechanistic insights into catalytic CO 2 hydrogenation using Mn( i )-complexes with pendant oxygen ligands journal January 2018
Mechanistic insights into HCO 2 H dehydrogenation and CO 2 hydrogenation catalyzed by Ir(Cp*) containing tetrahydroxy bipyrimidine ligand: the role of sodium and proton shuttle journal January 2018
Electronic effects on reactivity and anticancer activity by half-sandwich N,N-chelated iridium( iii ) complexes journal January 2018
Iridium Complexes with Proton-Responsive Azole-Type Ligands as Effective Catalysts for CO 2 Hydrogenation journal November 2017
Utilization of a Fluorescent Dye Molecule as a Proton and Electron Reservoir journal February 2018

Linked Research (8)

Figures / Tables (47)

Scheme 1(p. 4)figure Scheme 1
Scheme 2(p. 5)figure Scheme 2
Chart 1(p. 6)figure Chart 1
Figure 1(p. 13)figure Figure 1
Table 1(p. 13)table Table 1
Table 1, continued(p. 14)table Table 1, continued
Table 2(p. 14)table Table 2
Figure 2(p. 17)figure Figure 2
Figure 3(p. 18)figure Figure 3
Table 3(p. 18)table Table 3
Table 4(p. 20)table Table 4
Table 5(p. 22)table Table 5
Table 6(p. 23)table Table 6
Figure 4(p. 24)figure Figure 4
Table 7(p. 25)table Table 7
Figure 5(p. 27)figure Figure 5
Figure 6(p. 29)figure Figure 6
Figure 7(p. 30)figure Figure 7
Figure S1(p. 38)figure Figure S1
Figure S2(p. 38)figure Figure S2
Figure S3(p. 39)figure Figure S3
Figure S4(p. 39)figure Figure S4
Figure S5(p. 40)figure Figure S5
Figure S6(p. 40)figure Figure S6
Figure S7(p. 41)figure Figure S7
Table S1(p. 41)table Table S1
Table S2(p. 42)table Table S2
Table S3(p. 43)table Table S3
Table S4(p. 45)table Table S4
Table S5(p. 45)table Table S5
Table S6(p. 46)table Table S6
Table S7(p. 47)table Table S7
Table S8(p. 48)table Table S8
Table S9(p. 48)table Table S9
Table S10(p. 49)table Table S10
Table S11(p. 49)table Table S11
Table S12(p. 50)table Table S12
Table S13(p. 51)table Table S13
Table S14(p. 51)table Table S14
Table S15(p. 52)table Table S15
Table S16(p. 53)table Table S16
Table S17(p. 53)table Table S17
Table S18(p. 54)table Table S18
Table S19(p. 55)table Table S19
Table S20(p. 55)table Table S20
Table S21(p. 56)table Table S21
Figure S8(p. 57)figure Figure S8

Similar Records

CO2 Hydrogenation and Formic Acid Dehydrogenation Using Ir Catalysts with Amide-Based Ligands
Journal Article · Wed Feb 05 00:00:00 EST 2020 · Organometallics · OSTI ID:1182539
+3 more
Push or Pull? Proton Responsive Ligand Effects in Rhenium Tricarbonyl CO 2 Reduction Catalysts
Journal Article · Thu Feb 19 00:00:00 EST 2015 · Journal of Physical Chemistry. B, Condensed Matter, Materials, Surfaces, Interfaces and Biophysical Chemistry · OSTI ID:1182539
+2 more
Understanding the Role of Inter- and Intramolecular Promoters in Electro- and Photochemical CO 2 Reduction Using Mn, Re, and Ru Catalysts
Journal Article · Tue Feb 08 00:00:00 EST 2022 · Accounts of Chemical Research · OSTI ID:1182539
+1 more

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY