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

Title: Synthesis and Reactivity of Tripodal Complexes Containing Pendant Bases

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC); Center for Molecular Electrocatalysis (CME)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1167842
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Inorganic Chemistry; Journal Volume: 53; Related Information: CME partners with Pacific Northwest National Laboratory (lead); University of Illinois, Urbana-Champaign; Pennsylvania State University; University of Washington; University of Wyoming
Country of Publication:
United States
Language:
English
Subject:
catalysis (homogeneous), catalysis (heterogeneous), solar (fuels), bio-inspired, energy storage (including batteries and capacitors), hydrogen and fuel cells, charge transport, materials and chemistry by design, synthesis (novel materials)

Citation Formats

Blacquiere, Johanna M, Pegis, Michael L, Raugei, Simone, Kaminsky, Werner, Forget, Amélie, Cook, Sarah A, Taguchi, Taketo, and Mayer, James M. Synthesis and Reactivity of Tripodal Complexes Containing Pendant Bases. United States: N. p., 2014. Web. doi:10.1021/ic5013389.
Blacquiere, Johanna M, Pegis, Michael L, Raugei, Simone, Kaminsky, Werner, Forget, Amélie, Cook, Sarah A, Taguchi, Taketo, & Mayer, James M. Synthesis and Reactivity of Tripodal Complexes Containing Pendant Bases. United States. doi:10.1021/ic5013389.
Blacquiere, Johanna M, Pegis, Michael L, Raugei, Simone, Kaminsky, Werner, Forget, Amélie, Cook, Sarah A, Taguchi, Taketo, and Mayer, James M. Tue . "Synthesis and Reactivity of Tripodal Complexes Containing Pendant Bases". United States. doi:10.1021/ic5013389.
@article{osti_1167842,
title = {Synthesis and Reactivity of Tripodal Complexes Containing Pendant Bases},
author = {Blacquiere, Johanna M and Pegis, Michael L and Raugei, Simone and Kaminsky, Werner and Forget, Amélie and Cook, Sarah A and Taguchi, Taketo and Mayer, James M},
abstractNote = {},
doi = {10.1021/ic5013389},
journal = {Inorganic Chemistry},
number = ,
volume = 53,
place = {United States},
year = {Tue Sep 02 00:00:00 EDT 2014},
month = {Tue Sep 02 00:00:00 EDT 2014}
}
  • The synthesis of a new tripodal ligand family is reported, with tertiary-amine groups in the second-coordination sphere. The ligands are tris(amido)amine derivatives, with the pendant amines attached via a peptide coupling strategy. They were designed to be used in new catalysts for the oxygen reduction reaction (ORR), in which the pendant acid/base group could improve catalyst performance. Two members of the new ligand family were each metallated with Co(II) and Zn(II) to afford trigonal monopyramidal complexes. Reaction of the cobalt complexes, [Co(L)]-, with dioxygen reversibly generates a small amount of a Co(III)-superoxo species, which was characterized by EPR. Protonation ofmore » the zinc complex Zn[N{CH2CH2NC(O)CH2N(CH2Ph)2}3)-– ([Zn(TNBn)]-) with one equivalent of acid occurs with displacement and dissociation of an amide ligand. Addition of excess acid to the any of the complexes [M(L)]- results in complete proteolysis and formation of the ligands H3L. This decomposition limits the use of these complexes as catalysts for the ORR. An alternative ligand with two pyridyl arms was also prepared but could not be metallated. These studies highlight the importance of stability of the primary-coordination sphere of ORR electrocatalysts to both oxidative and acidic conditions. This research was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences.« less
  • The iron complexes CpFe(PPh2NBn2)Cl (1-Cl), CpFe(PPh2NPh2)Cl (2-Cl), CpFe(PPh2C5)Cl (3-Cl) (where PPh2NBn2 is 1,5-dibenzyl-1,5-diaza-3,7-diphenyl-3,7-diphosphacyclooctane, PPh2NPh2 is 1,3,5,7-tetraphenyl-1,5-diaza-3,7-diphosphacyclooctane, and PPh2C5 is 1,4-diphenyl-1,4-diphosphacycloheptane) have been synthesized and characterized by NMR spectroscopy, electrochemical studies, and X-ray diffraction studies. These chloride derivatives are readily converted to the corresponding hydride complexes CpFe(PPh2NBn2)H (1-H), CpFe(PPh2NPh2)H (2-H), CpFe(PPh2C5)H (3-H)] and H2 complexes [CpFe(PPh2NBn2)(H2)]BArF4, [1-H2]BArF4, (where BArF4 is B[(3,5-(CF3)2C6H3)4]-), [CpFe(PPh2NPh2)(H2)]BArF4, [2-H2]BArF4, and [CpFe(PPh2C5)(H2)]BArF4, [3-H2]BArF4 as well as [CpFe(PPh2NBn2)(CO)]BArF4, [1-CO]BArF4. Structural studies are reported for [1-H2]BArF4, 1-H, 2-H, and [1-CO]BArF4. The conformations adopted by the chelate rings of the PPh2NBn2 ligand in the different complexes are determined by attractive ormore » repulsive interactions between the sixth ligand of these pseudo-octahedral complexes and the pendant N atom of the ring adjacent to the sixth ligand. An example of an attractive interaction is the observation that the distance between the N atom of the pendant amine and the C atom of the coordinated CO ligand for [1-CO]BArF4 is 2.848 Å, considerably shorter than the sum of the van der Waals radii of N and C atoms. Experimental and theoretical studies of H/D exchange by the complexes [1-H2]+, [2-H2]+, and [3-H2]+ indicate that the relatively rapid exchange observed for [1-H2]+ and [2-H2]+ compared to [3-H2]+ is consistent with intramolecular heterolytic cleavage of H2 mediated by the pendant amine. These mononuclear FeII dihydrogen complexes containing pendant amines in the ligands mimic crucial features of the distal Fe site of the active site of the [FeFe] hydrogenase required for H-H bond formation and cleavage. We thank the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Biosciences and Geosciences, for support of this research. S.C. (DFT computations) and M. J. O. (NMR experiments) were supported by the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under FWP 56073. Pacific Northwest National Laboratory is operated by Battelle for the U.S. Department of Energy.« less
  • In this study, we report the synthesis and characterization of molybdenum bis(dinitrogen) complexes supported by two PNP diphosphine ligands, Mo(N{sub 2}){sub 2}(PNP){sub 2}; PNP = [(R{sub 2}PCH{sub 2}){sub 2}N(R'), R = Et (ethyl), Ph (phenyl); R'= Me (methyl), Bn (benzyl)], and a series of tungsten bis(dinitrogen) complexes containing one or two PNP ligands, W(N{sub 2}){sub 2}(dppe)(PNP) and W(N{sub 2}){sub 2}(PNP){sub 2}, respectively, and the analogues complexes without pendant amines for comparison. These Mo- and W-N{sub 2} complexes were characterized by NMR, IR, spectroscopy, cyclic voltammetry and structurally characterized by X-ray crystallography. In addition, reactivity of the complexes with CO ismore » described.« less