Electrochemical Investigation of Transition—Metal Complexes of the Ligand Tetrakis(2-Pyridylmethyl)-Ethylenediamine (Tpen). Crystal Structure of [Ni(tpen)](CIO4)2·2/3H2O

Luz, Denise Da; Franco, Carlos; Vencato, Ivo; Neves, Ademir; Mascarenhas, Yvonne P.

doi:10.1080/00958979209407929

Cited by 19 publications

(6 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The very positive potential for oxidation of the Fe complex falls between reported potentials assigned to the Fe 3+/2+ couple for similar [Fe(iminopyridine) 3 ] 2+ complexes. , The assigned Co 3+/2+ couple for 4 also matches closely to the potential reported for a similar [Co(iminopyridine) 3 ] 2+ complex . The Ni complex 5 exhibits an additional quasi - reversible reduction at −2.51 V, tentatively assigned to the Ni 2+/1+ couple, which occurs at slightly more negative potentials than those reported for hexacoordinate iminopyridine Ni(II) complexes. , An irreversible oxidation occurs at +1.04 V and is tentatively assigned to the oxidation of Ni(II) to Ni(III). The Cu complex 6 displays an additional reversible reduction at −0.43 V, which is assigned to the 2+/1+ couple.…”

Section: Resultssupporting

confidence: 77%

“…53 The Ni complex 5 exhibits an additional quasi-reversible reduction at −2.51 V, tentatively assigned to the Ni 2+/1+ couple, which occurs at slightly more negative potentials than those reported for hexacoordinate iminopyridine Ni(II) complexes. 54,55 An irreversible oxidation occurs at +1.04 V and is tentatively assigned to the oxidation of Ni(II) to Ni(III). The Cu complex 6 displays an additional reversible reduction at −0.43 V, which is assigned to the 2+/1+ couple.…”

Section: ■ Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Structural and Electronic Comparison of 1st Row Transition Metal Complexes of a Tripodal Iminopyridine Ligand

2012

View full text Add to dashboard Cite

We report the preparation and characterization of a series of divalent 3d transition metal complexes (Cr to Zn, 1-7), featuring the multidentate, tripodal iminopyridine Schiff-base ligand trimethyl 6,6',6″-((1E,1'E,1″E)-((nitrilotris(ethane-2,1-diyl))tris(azanylylidene))tris-(methanylylidene))trinicotinate (L(5-OOMe)). X-ray structural studies carried out on 1-5 and 7 reveal complex geometries ranging from local octahedral coordination to significant distortion toward trigonal prismatic geometry to heptacoordinate environments. Regardless of coordination mode, magnetic and spectroscopic studies show the ligand to provide moderately strong ligand fields: the Fe complex is low-spin, while the Co and Mn complexes are high-spin at all temperatures probed. Cyclic voltammograms exhibit multiple reversible ligand-based reductions, which are relatively consistent throughout the series; however, the electrochemical behavior of the Cr complex 1 is fundamentally different from those of the other complexes. Time-dependent (TD) density functional theory (DFT) and natural transition orbital (NTO) computational analyses are presented for the ligand, its anion, and complexes 1-7: the computed spectra reproduce the major differential features of the observed visible absorption spectra, and NTOs provide viable interpretations for the observed features. The combined studies indicate that all complexes contain neutral ligands bound to M(II) ions, except for the Cr complex 1, which is best described as a Cr(III) species bound to a radical anionic ligand.

show abstract

Section: Resultssupporting

confidence: 77%

Section: ■ Resultsmentioning

confidence: 99%

Structural and Electronic Comparison of 1st Row Transition Metal Complexes of a Tripodal Iminopyridine Ligand

2012

View full text Add to dashboard Cite

show abstract

“…In contrast to expectations based on published data and associated interpretations of the tetradentate ligand L 1 , , but as expected from experiments and computations with L 3 , the two hexadentate ligands tolerate rather large variations in metal ion size: 12.6 Å < ( M − N i ) < 13.2 Å (see Table ). The individual bond distances are in the expected ranges for the corresponding metal ions, generally at the longer limit of the corresponding average distances; for example, they are approximately 0.01 Å longer than distances to the hexadentate tpen ligand [tpen = N,N,N‘,N‘-tetra(2‘-pyridylmethyl)ethane-1,2-diamine], , and this is confirmed by force field calculations, which indicate that the ligand does not induce severe strain on the metal ions nor vice versa (see Table ; see also the ligand field and redox properties). Admittedly, some of the computed bond distances are only in fair agreement with the observed structural data.…”

Section: Resultsmentioning

confidence: 71%

Coordination Chemistry of a New Rigid, Hexadentate Bispidine-Based Bis(amine)tetrakis(pyridine) Ligand

et al. 2005

View full text Add to dashboard Cite

The hexadentate bispidine-based ligand 2,4-bis(2-pyridyl)-3,7-bis(2-methylenepyridine)-3,7-diazabicyclo[3.3.1]nonane-9-on-1,5-bis(carbonic acid methyl ester), L(6m), with four pyridine and two tertiary amine donors, based on a very rigid diazaadamantane-derived backbone, is coordinated to a range of metal ions. On the basis of experimental and computed structural data, the ligand is predicted to form very stable complexes. Force field calculations indicate that short metal-donor distances lead to a buildup of strain in the ligand; that is, the coordination of large metal ions is preferred. This is confirmed by experimentally determined stability constants, which indicate that, in general, stabilities comparable to those with macrocyclic ligands are obtained with the relative order Cu(2+) > Zn(2+) >> Ni(2+) < Co(2+), which is not the typical Irving-Williams behavior. The preference for large M-N distances also emerges from relatively high redox potentials (the higher oxidation states, that is, the smaller metal ions, are destabilized) and from relatively weak ligand fields (dd-transition, high-spin electronic ground states). The potentiometric titrations confirm the efficient encapsulation of the metal ions since only 1:1 complexes are observed, and, over a large pH range, ML is generally the only species present in solution.

show abstract

“…The crystal structure of a complex obtained from the reaction of tpen and Ni(ClO 4 ) 2 in aqueous solution was previously reported by Neves. [51] 7Å). [51] The UV-Vis absorption spectra of 1 ( Figure S1a) and S2 ( Figure S1b) in 0.1 M aqueous phosphate buffer solution (PBS) of pH 8.0 show the absorption bands at 305 nm which were assigned to metal-to-ligand charge transfer transition (MLCT).…”

Section: Synthesis and Characterizationmentioning

confidence: 99%

“…[51] 7Å). [51] The UV-Vis absorption spectra of 1 ( Figure S1a) and S2 ( Figure S1b) in 0.1 M aqueous phosphate buffer solution (PBS) of pH 8.0 show the absorption bands at 305 nm which were assigned to metal-to-ligand charge transfer transition (MLCT). The absorption bands at 517 nm and 530 nm for 1 and 2, respectively, were attributed to the d-d transition.…”

Section: Synthesis and Characterizationmentioning

confidence: 99%

Nickel (II) tetrapyridyl complexes as electrocatalysts and precatalysts for water oxidation

Ren

Xie

et al. 2020

Applied Organom Chemis

View full text Add to dashboard Cite

Two nickel complexes, [Ni(tpen)](ClO4)2.0.5CH3COCH3 (1) and [Ni(tpbn)](ClO4)2 (2), of tetrapyridyl ligands N,N,N′,N′‐tetrakis(2‐pyridyl‐methyl)‐1,2‐ethanediamine (tpen) and N,N,N′,N′‐tetrakis(2‐pyridyl‐methyl)‐1,4‐butanediamine (tpbn) were prepared and their catalysis for water oxidation reaction (WOR) studied. In 0.1 M phosphate buffer solution (PBS) of pH 8.0, complex 1 is a homogeneous molecular catalyst with an overpotential of ~440 mV and a Faradaic efficiency of 89%. At pH ≥ 9.0, complex 1 degraded gradually during the catalytic process and formed NiOx composite (nickel oxide with general formula NixOyHz) active for WOR. In contrast, complex 2 deteriorated under measured conditions (pH 8.0–12.0) and formed NiOx composite active for WOR. The NiOx composite derived from 1 in 0.1 M PBS at pH 11.0 showed an activity with an overpotential of ~500 mV, a Tafel slope of ~90 mV/decade and a Faradaic efficiency of 97%. Mechanisms were proposed for water oxidation catalyzed by 1 and 2. This work revealed that the catalytic activity of the nickel complexes was related to the flexibility of the tetrapyridyl ligands and the adaptability of the coordination sphere of the nickel(II) center.

show abstract

Electrochemical Investigation of Transition—Metal Complexes of the Ligand Tetrakis(2-Pyridylmethyl)-Ethylenediamine (Tpen). Crystal Structure of [Ni(tpen)](CIO₄)₂·2/3H₂O

Cited by 19 publications

References 18 publications

Structural and Electronic Comparison of 1st Row Transition Metal Complexes of a Tripodal Iminopyridine Ligand

Structural and Electronic Comparison of 1st Row Transition Metal Complexes of a Tripodal Iminopyridine Ligand

Coordination Chemistry of a New Rigid, Hexadentate Bispidine-Based Bis(amine)tetrakis(pyridine) Ligand

Nickel (II) tetrapyridyl complexes as electrocatalysts and precatalysts for water oxidation

Contact Info

Product

Resources

About