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Cropek DM, Metz A, Müller AM, Gray HB, Horne T, Horton DC, Poluektov O, Tiede DM, Weber RT, Jarrett WL, Phillips JD, Holder AA. A novel ruthenium(II)-cobaloxime supramolecular complex for photocatalytic H2 evolution: synthesis, characterisation and mechanistic studies. Dalton Trans 2012; 41:13060-73. [PMID: 23001132 PMCID: PMC3482109 DOI: 10.1039/c2dt30309d] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report the synthesis and characterization of novel mixed-metal binuclear ruthenium(II)-cobalt(II) photocatalysts for hydrogen evolution in acidic acetonitrile. First, 2-(2'-pyridyl)benzothiazole (pbt), 1, was reacted with RuCl(3)·xH(2)O to produce [Ru(pbt)(2)Cl(2)]·0.25CH(3)COCH(3), 2, which was then reacted with 1,10-phenanthroline-5,6-dione (phendione), 3, in order to produce [Ru(pbt)(2)(phendione)](PF(6))(2)·4H(2)O, 4. Compound 4 was then reacted with 4-pyridinecarboxaldehyde in order to produce [Ru(pbt)(2)(L-pyr)](PF(6))(2)·9.5H(2)O, 5 (where L-pyr = (4-pyridine)oxazolo[4,5-f]phenanthroline). Compound 5 was then reacted with [Co(dmgBF(2))(2)(H(2)O)(2)] (where dmgBF(2) = difluoroboryldimethylglyoximato) in order to produce the mixed-metal binuclear complex, [Ru(pbt)(2)(L-pyr)Co(dmgBF(2))(2)(H(2)O)](PF(6))(2)·11H(2)O·1.5CH(3)COCH(3), 6. [Ru(Me(2)bpy)(2)(L-pyr)Co(dmgBF(2))(2)(OH(2))](PF(6))(2), 7 (where Me(2)bpy = 1,10-phenanthroline, 4,4'-dimethyl-2,2'-bipyridine) and [Ru(phen)(2)(L-pyr)Co(dmgBF(2))(2)(OH(2))](PF(6))(2), 8 were also synthesised. All complexes were characterized by elemental analysis, ESI MS, HRMS, UV-visible absorption, (11)B, (19)F, and (59)Co NMR, ESR spectroscopy, and cyclic voltammetry, where appropriate. Photocatalytic studies carried out in acidified acetonitrile demonstrated constant hydrogen generation longer than a 42 hour period as detected by gas chromatography. Time resolved spectroscopic measurements were performed on compound 6, which proved an intramolecular electron transfer from an excited Ru(II) metal centre to the Co(II) metal centre via the bridging L-pyr ligand. This resulted in the formation of a cobalt(I)-containing species that is essential for the production of H(2) gas in the presence of H(+) ions. A proposed mechanism for the generation of hydrogen is presented.
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Affiliation(s)
- Donald M. Cropek
- U.S. Army Corps of Engineers, Construction Engineering Research Laboratory, Champaign, IL 61822, U.S.A
| | - Anja Metz
- U.S. Army Corps of Engineers, Construction Engineering Research Laboratory, Champaign, IL 61822, U.S.A
| | - Astrid M. Müller
- California Institute of Technology, Beckman Institute, Pasadena, CA 91125, U.S.A
| | - Harry B. Gray
- California Institute of Technology, Beckman Institute, Pasadena, CA 91125, U.S.A
| | - Toyketa Horne
- Department of Chemistry and Biochemistry, The University of Southern Mississippi, 118 College Drive, # 5043, Hattiesburg, Mississippi 39406-0001, U.S.A. telephone: 601-266-4767, and fax: 601-266-6075
| | - Dorothy C. Horton
- Department of Chemistry and Biochemistry, The University of Southern Mississippi, 118 College Drive, # 5043, Hattiesburg, Mississippi 39406-0001, U.S.A. telephone: 601-266-4767, and fax: 601-266-6075
| | - Oleg Poluektov
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, IL 60439, U.S.A
| | - David M. Tiede
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, IL 60439, U.S.A
| | - Ralph T. Weber
- EPR Division Bruker BioSpin, 44 Manning Road, Billerica, MA 01821, U.S.A
| | - William L. Jarrett
- School of Polymers and High-Performance Materials, The University of Southern Mississippi, 118 College Dive, #5050, Hattiesburg, MS 39406-0076, U.S.A
| | - Joshua D. Phillips
- Department of Chemistry and Biochemistry, The University of Southern Mississippi, 118 College Drive, # 5043, Hattiesburg, Mississippi 39406-0001, U.S.A. telephone: 601-266-4767, and fax: 601-266-6075
| | - Alvin A. Holder
- Department of Chemistry and Biochemistry, The University of Southern Mississippi, 118 College Drive, # 5043, Hattiesburg, Mississippi 39406-0001, U.S.A. telephone: 601-266-4767, and fax: 601-266-6075
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Geller JM, Wosnick JH, Butler IS, Gilson DFR, Morin FG, Bélanger-Gariépy F. X-ray diffraction, Raman spectroscopic, and solid-state NMR studies of the group 14 metal-(tetracarbonyl)cobalt complexes Ph3MCo(CO)4 (M = Si, Sn, Pb). CAN J CHEM 2002. [DOI: 10.1139/v02-110] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Single-crystal X-ray diffraction studies illustrate that the three title compounds are isomorphous, belonging to the triclinic space group P[Formula: see text], with slightly distorted trigonal bipyramidal geometry about cobalt. The solid-state 29Si, 119Sn, and 207Pb cross-polarization magic angle spinning (CP MAS) NMR spectra are presented. The indirect spinspin coupling constant (J), quadrupolardipolar shift (d), direct dipolar coupling constant (D' ), anisotropy in spinspin coupling (ΔJ), and the chemical shift tensor were extracted. A plot of the reduced coupling constant vs. s-electron densities at the nucleus indicates that the Fermi contact term may be dominant for the tin and lead complexes; however, the large ΔJ for all complexes indicate that there are also significant anisotropic terms. Trends in the Raman scattering spectra are also discussed.Key words: 29Si, 119Sn, and 207Pb CP MAS NMR, tetracarbonyl cobalt, spinspin coupling, chemical shift tensor, quadrupole coupling, Fermi contact, cobaltgroup 14.
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Schurko RW, Wasylishen RE. Nitrogen-15 NMR Study of Solid Cobaloximes Containing 15N-Labeled Pyridine and Aniline. J Phys Chem A 2000. [DOI: 10.1021/jp994254m] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Robert W. Schurko
- Department of Chemistry, Dalhousie University, Halifax, Nova Scotia, Canada B3H 4J3
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Schurko RW, Wasylishen RE, Moore SJ, Marzilli LG, Nelson JH. Article. CAN J CHEM 1999. [DOI: 10.1139/v99-188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Solid-state 31P NMR spectra of two phosphite- and 17 phosphine-substituted cobaloximes have been acquired under conditions of magic-angle spinning (MAS) and cross polarization (CP) at two applied magnetic fields. In the majority of cases, eight-peak multiplets are observed in the 31P CPMAS NMR spectra, arising from one-bond indirect spin-spin coupling to cobalt (spin S = 7/2). The spacings between adjacent peaks gradually increase or decrease from low to high frequency, due to the presence of residual dipolar coupling between the cobalt and phosphorus nuclei. Values of 1J(59Co,31P) were estimated from the spacing between the central peaks of the eight-peak multiplets. For the phosphine-substituted cobaloximes, values of 1J(59Co,31P) range from 225 to 372 Hz, while in the phosphite derivatives this coupling is considerably larger, from 420 to 615 Hz. From comparison with cobaloximes for which the cobalt nuclear quadrupole coupling interaction is fully characterized, the residual dipolar shift, d, and sense of the 31P NMR spectrum can be utilized to infer the electric field gradient (EFG) orientations at the cobalt nucleus in cobaloximes for which such data are unavailable. The magnitudes of 1J(59Co,31P) and d, as well as the sense of the spectra, are shown to be dependent upon the nature of the axially-substituted ligands. Phosphorus-31 CPMAS NMR spectra of several cobaloximes exhibit broad peak shapes at room temperature. Variable-temperature 31P NMR experiments reveal that the cobalt nucleus is effectively self-decoupled at room temperature; however, splittings due to 1J(59Co,31P) were observed in spectra acquired at low temperatures.Key words: solid-state 31P NMR, 59Co-31P spin-spin coupling constants, 59Co electric field gradient tensors, cobaloximes.
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