Flipping of the coordinated triazine moiety in Cu(i)-L2 and the small electronic factor, κel, for direct outer-sphere cross reactions: Syntheses, crystal structures and redox behaviour of copper(II)/(i)-L2 complexes (L = 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine)

Atsutoshi Yamada, Takuya Mabe, Ryohei Yamane, Kyoko Noda, Yuko Wasada, Masahiko Inamo, Koji Ishihara, Takayoshi Suzuki, Hideo D. Takagi

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Six-coordinate [Cu(pdt)2(H2O)2]2+ and four-coordinate [Cu(pdt)2]+ complexes were synthesized and the cross redox reactions were studied in acetonitrile (pdt = 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine). Single crystal analyses revealed that [Cu(pdt)2(H2O)2](BF4)2 was of pseudo-D2h symmetry with two axial water molecules and two symmetrically coordinated equatorial pdt ligands, while the coordination structure of [Cu(pdt)2]BF4 was a squashed tetrahedron (dihedral angle = 54.87°) with an asymmetric coordination by two pdt ligands: one pdt ligand was coordinated to Cu(i) through pyridine-N and triazine-N2 while another pdt ligand was coordinated through pyridine-N and triazine-N4, and a stacking interaction between the phenyl ring on one pdt ligand and the triazine ring on another pdt ligand caused the squashed structure and non-equivalent Cu-N bond lengths. The cyclic voltammograms for [Cu(pdt)2(H2O)2]2+ and [Cu(pdt)2]+ in acetonitrile were identical to each other and quasi-reversible. The reduction of [Cu(pdt)2(H2O)2]2+ by decamethylferrocene and the oxidation of [Cu(pdt)2]+ by [Co(2,2′-bipyridine)3]3+ in acetonitrile revealed that both cross reactions were sluggish through a gated process (the structural change took place prior to the electron transfer) accompanied by slow direct electron transfer processes. It was found that the triazine ring of the coordinated pdt ligand rotates around the C-C bond between the triazine and pyridine rings with the kinetic parameters k = 51 ± 5 s-1 (297.8 K), ΔH = 6.2 ± 1.1 kJ mol-1 and ΔS = -192 ± 4 J mol-1 K-1. The electron self-exchange process was directly measured using the line-broadening method: kex = (9.9 ± 0.5) × 104 kg mol-1 s-1 (297.8 K) with ΔH = 44 ± 7 kJ mol-1 and ΔS = 0.2 ± 2.6 J mol-1 K-1. By comparing this rate constant with the self-exchange rate constants estimated from the cross reactions using the Marcus cross relation, the non-adiabaticity (electronic) factors, κel, for the direct electron transfer processes between [Cu(pdt)2]+/2+ and non-copper metal (Fe2+ and Co3+) complexes were estimated as ca. 10-7, indicating that the electronic coupling between the d orbitals of copper and of non-copper metals is very small.

Original languageEnglish
Pages (from-to)13979-13990
Number of pages12
JournalDalton Transactions
Volume44
Issue number31
DOIs
Publication statusPublished - Jun 19 2015

Fingerprint

Triazines
Copper
Crystal structure
Ligands
Electrons
Rate constants
Metals
Redox reactions
Bond length
Dihedral angle
Oxidation-Reduction
3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine
Kinetic parameters
Single crystals
Oxidation
Molecules
Water

ASJC Scopus subject areas

  • Inorganic Chemistry

Cite this

Flipping of the coordinated triazine moiety in Cu(i)-L2 and the small electronic factor, κel, for direct outer-sphere cross reactions : Syntheses, crystal structures and redox behaviour of copper(II)/(i)-L2 complexes (L = 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine). / Yamada, Atsutoshi; Mabe, Takuya; Yamane, Ryohei; Noda, Kyoko; Wasada, Yuko; Inamo, Masahiko; Ishihara, Koji; Suzuki, Takayoshi; Takagi, Hideo D.

In: Dalton Transactions, Vol. 44, No. 31, 19.06.2015, p. 13979-13990.

Research output: Contribution to journalArticle

@article{c396caad407d4d9f986190dd6df2cce3,
title = "Flipping of the coordinated triazine moiety in Cu(i)-L2 and the small electronic factor, κel, for direct outer-sphere cross reactions: Syntheses, crystal structures and redox behaviour of copper(II)/(i)-L2 complexes (L = 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine)",
abstract = "Six-coordinate [Cu(pdt)2(H2O)2]2+ and four-coordinate [Cu(pdt)2]+ complexes were synthesized and the cross redox reactions were studied in acetonitrile (pdt = 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine). Single crystal analyses revealed that [Cu(pdt)2(H2O)2](BF4)2 was of pseudo-D2h symmetry with two axial water molecules and two symmetrically coordinated equatorial pdt ligands, while the coordination structure of [Cu(pdt)2]BF4 was a squashed tetrahedron (dihedral angle = 54.87°) with an asymmetric coordination by two pdt ligands: one pdt ligand was coordinated to Cu(i) through pyridine-N and triazine-N2 while another pdt ligand was coordinated through pyridine-N and triazine-N4, and a stacking interaction between the phenyl ring on one pdt ligand and the triazine ring on another pdt ligand caused the squashed structure and non-equivalent Cu-N bond lengths. The cyclic voltammograms for [Cu(pdt)2(H2O)2]2+ and [Cu(pdt)2]+ in acetonitrile were identical to each other and quasi-reversible. The reduction of [Cu(pdt)2(H2O)2]2+ by decamethylferrocene and the oxidation of [Cu(pdt)2]+ by [Co(2,2′-bipyridine)3]3+ in acetonitrile revealed that both cross reactions were sluggish through a gated process (the structural change took place prior to the electron transfer) accompanied by slow direct electron transfer processes. It was found that the triazine ring of the coordinated pdt ligand rotates around the C-C bond between the triazine and pyridine rings with the kinetic parameters k = 51 ± 5 s-1 (297.8 K), ΔH‡ = 6.2 ± 1.1 kJ mol-1 and ΔS‡ = -192 ± 4 J mol-1 K-1. The electron self-exchange process was directly measured using the line-broadening method: kex = (9.9 ± 0.5) × 104 kg mol-1 s-1 (297.8 K) with ΔH‡ = 44 ± 7 kJ mol-1 and ΔS‡ = 0.2 ± 2.6 J mol-1 K-1. By comparing this rate constant with the self-exchange rate constants estimated from the cross reactions using the Marcus cross relation, the non-adiabaticity (electronic) factors, κel, for the direct electron transfer processes between [Cu(pdt)2]+/2+ and non-copper metal (Fe2+ and Co3+) complexes were estimated as ca. 10-7, indicating that the electronic coupling between the d orbitals of copper and of non-copper metals is very small.",
author = "Atsutoshi Yamada and Takuya Mabe and Ryohei Yamane and Kyoko Noda and Yuko Wasada and Masahiko Inamo and Koji Ishihara and Takayoshi Suzuki and Takagi, {Hideo D.}",
year = "2015",
month = "6",
day = "19",
doi = "10.1039/c5dt01808k",
language = "English",
volume = "44",
pages = "13979--13990",
journal = "Dalton Transactions",
issn = "1477-9226",
publisher = "Royal Society of Chemistry",
number = "31",

}

TY - JOUR

T1 - Flipping of the coordinated triazine moiety in Cu(i)-L2 and the small electronic factor, κel, for direct outer-sphere cross reactions

T2 - Syntheses, crystal structures and redox behaviour of copper(II)/(i)-L2 complexes (L = 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine)

AU - Yamada, Atsutoshi

AU - Mabe, Takuya

AU - Yamane, Ryohei

AU - Noda, Kyoko

AU - Wasada, Yuko

AU - Inamo, Masahiko

AU - Ishihara, Koji

AU - Suzuki, Takayoshi

AU - Takagi, Hideo D.

PY - 2015/6/19

Y1 - 2015/6/19

N2 - Six-coordinate [Cu(pdt)2(H2O)2]2+ and four-coordinate [Cu(pdt)2]+ complexes were synthesized and the cross redox reactions were studied in acetonitrile (pdt = 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine). Single crystal analyses revealed that [Cu(pdt)2(H2O)2](BF4)2 was of pseudo-D2h symmetry with two axial water molecules and two symmetrically coordinated equatorial pdt ligands, while the coordination structure of [Cu(pdt)2]BF4 was a squashed tetrahedron (dihedral angle = 54.87°) with an asymmetric coordination by two pdt ligands: one pdt ligand was coordinated to Cu(i) through pyridine-N and triazine-N2 while another pdt ligand was coordinated through pyridine-N and triazine-N4, and a stacking interaction between the phenyl ring on one pdt ligand and the triazine ring on another pdt ligand caused the squashed structure and non-equivalent Cu-N bond lengths. The cyclic voltammograms for [Cu(pdt)2(H2O)2]2+ and [Cu(pdt)2]+ in acetonitrile were identical to each other and quasi-reversible. The reduction of [Cu(pdt)2(H2O)2]2+ by decamethylferrocene and the oxidation of [Cu(pdt)2]+ by [Co(2,2′-bipyridine)3]3+ in acetonitrile revealed that both cross reactions were sluggish through a gated process (the structural change took place prior to the electron transfer) accompanied by slow direct electron transfer processes. It was found that the triazine ring of the coordinated pdt ligand rotates around the C-C bond between the triazine and pyridine rings with the kinetic parameters k = 51 ± 5 s-1 (297.8 K), ΔH‡ = 6.2 ± 1.1 kJ mol-1 and ΔS‡ = -192 ± 4 J mol-1 K-1. The electron self-exchange process was directly measured using the line-broadening method: kex = (9.9 ± 0.5) × 104 kg mol-1 s-1 (297.8 K) with ΔH‡ = 44 ± 7 kJ mol-1 and ΔS‡ = 0.2 ± 2.6 J mol-1 K-1. By comparing this rate constant with the self-exchange rate constants estimated from the cross reactions using the Marcus cross relation, the non-adiabaticity (electronic) factors, κel, for the direct electron transfer processes between [Cu(pdt)2]+/2+ and non-copper metal (Fe2+ and Co3+) complexes were estimated as ca. 10-7, indicating that the electronic coupling between the d orbitals of copper and of non-copper metals is very small.

AB - Six-coordinate [Cu(pdt)2(H2O)2]2+ and four-coordinate [Cu(pdt)2]+ complexes were synthesized and the cross redox reactions were studied in acetonitrile (pdt = 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine). Single crystal analyses revealed that [Cu(pdt)2(H2O)2](BF4)2 was of pseudo-D2h symmetry with two axial water molecules and two symmetrically coordinated equatorial pdt ligands, while the coordination structure of [Cu(pdt)2]BF4 was a squashed tetrahedron (dihedral angle = 54.87°) with an asymmetric coordination by two pdt ligands: one pdt ligand was coordinated to Cu(i) through pyridine-N and triazine-N2 while another pdt ligand was coordinated through pyridine-N and triazine-N4, and a stacking interaction between the phenyl ring on one pdt ligand and the triazine ring on another pdt ligand caused the squashed structure and non-equivalent Cu-N bond lengths. The cyclic voltammograms for [Cu(pdt)2(H2O)2]2+ and [Cu(pdt)2]+ in acetonitrile were identical to each other and quasi-reversible. The reduction of [Cu(pdt)2(H2O)2]2+ by decamethylferrocene and the oxidation of [Cu(pdt)2]+ by [Co(2,2′-bipyridine)3]3+ in acetonitrile revealed that both cross reactions were sluggish through a gated process (the structural change took place prior to the electron transfer) accompanied by slow direct electron transfer processes. It was found that the triazine ring of the coordinated pdt ligand rotates around the C-C bond between the triazine and pyridine rings with the kinetic parameters k = 51 ± 5 s-1 (297.8 K), ΔH‡ = 6.2 ± 1.1 kJ mol-1 and ΔS‡ = -192 ± 4 J mol-1 K-1. The electron self-exchange process was directly measured using the line-broadening method: kex = (9.9 ± 0.5) × 104 kg mol-1 s-1 (297.8 K) with ΔH‡ = 44 ± 7 kJ mol-1 and ΔS‡ = 0.2 ± 2.6 J mol-1 K-1. By comparing this rate constant with the self-exchange rate constants estimated from the cross reactions using the Marcus cross relation, the non-adiabaticity (electronic) factors, κel, for the direct electron transfer processes between [Cu(pdt)2]+/2+ and non-copper metal (Fe2+ and Co3+) complexes were estimated as ca. 10-7, indicating that the electronic coupling between the d orbitals of copper and of non-copper metals is very small.

UR - http://www.scopus.com/inward/record.url?scp=84938772976&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84938772976&partnerID=8YFLogxK

U2 - 10.1039/c5dt01808k

DO - 10.1039/c5dt01808k

M3 - Article

AN - SCOPUS:84938772976

VL - 44

SP - 13979

EP - 13990

JO - Dalton Transactions

JF - Dalton Transactions

SN - 1477-9226

IS - 31

ER -