Coordinating Tectons. Experimental and Computational Infrared Data as Tools to Identify Conformational Isomers and Explore Electronic Structures of 4-Ethynyl-2,2′-bipyridine Complexes

Campbell F.R. Mackenzie, Sören Bock, Chia Yang Lim, Brian W. Skelton, Carlo Nervi, Duncan A. Wild, Paul J. Low, George A. Koutsantonis

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Abstract

4-Ethynyl-2,2′-bipyridyl-substituted ruthenium alkynyl complexes have been prepared and used to access a range of binuclear homometallic ruthenium and heterometallic ruthenium-rhenium complexes. These have been characterized by a variety of spectroscopic and single-crystal X-ray diffraction experiments. The IR spectra of a number of these ruthenium alkynyls display multiple ν(C≡C) bands in the IR spectra, which are rationalized in terms of putative conformational isomers, whose calculated infrared stretching frequencies are comparable to those obtained experimentally. The mononuclear alkynyl ruthenium complexes undergo reversible one-electron oxidations centered largely on the alkynyl ligands, as inferred from the significant shift in ν(C≡C) frequency on oxidation, while the binuclear complex [Ru{C≡C-4-bpy-κ2-N,N′-RuClCp}(dppe)Cp∗]+ undergoes initial oxidation at the very electron rich {RuCl(bpy)Cp} fragment, causing only a small change in ν(C≡C). A combination of IR and UV-vis spectroelectrochemical experiments, supported by quantum chemical calculations on a selected range of conformers, led to the classification of [Ru{C≡C-4-bpy-κ2-N,N′-RuClCp}(dppe)Cp∗]+ as a weakly coupled class II mixed-valence compound (Hab = 306 cm-1). These results indicate that there is improved electronic communication through the 4-ethynyl-2,2′-bipyridyl ligand in comparison to the analogous 5-ethynyl-2,2′-bipyridyl complexes (Hab = 17 cm-1).

Original languageEnglish
Pages (from-to)1946-1961
Number of pages16
JournalOrganometallics
Volume36
Issue number10
DOIs
Publication statusPublished - 22 May 2017

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Ruthenium
Isomers
ruthenium
Electronic structure
isomers
2,2'-Dipyridyl
electronic structure
Infrared radiation
Oxidation
oxidation
Rhenium
Ligands
ligands
Electrons
rhenium
Stretching
electrons
Experiments
communication
fragments

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@article{932d3069934149f1822e6b3c93508564,
title = "Coordinating Tectons. Experimental and Computational Infrared Data as Tools to Identify Conformational Isomers and Explore Electronic Structures of 4-Ethynyl-2,2′-bipyridine Complexes",
abstract = "4-Ethynyl-2,2′-bipyridyl-substituted ruthenium alkynyl complexes have been prepared and used to access a range of binuclear homometallic ruthenium and heterometallic ruthenium-rhenium complexes. These have been characterized by a variety of spectroscopic and single-crystal X-ray diffraction experiments. The IR spectra of a number of these ruthenium alkynyls display multiple ν(C≡C) bands in the IR spectra, which are rationalized in terms of putative conformational isomers, whose calculated infrared stretching frequencies are comparable to those obtained experimentally. The mononuclear alkynyl ruthenium complexes undergo reversible one-electron oxidations centered largely on the alkynyl ligands, as inferred from the significant shift in ν(C≡C) frequency on oxidation, while the binuclear complex [Ru{C≡C-4-bpy-κ2-N,N′-RuClCp}(dppe)Cp∗]+ undergoes initial oxidation at the very electron rich {RuCl(bpy)Cp} fragment, causing only a small change in ν(C≡C). A combination of IR and UV-vis spectroelectrochemical experiments, supported by quantum chemical calculations on a selected range of conformers, led to the classification of [Ru{C≡C-4-bpy-κ2-N,N′-RuClCp}(dppe)Cp∗]+ as a weakly coupled class II mixed-valence compound (Hab = 306 cm-1). These results indicate that there is improved electronic communication through the 4-ethynyl-2,2′-bipyridyl ligand in comparison to the analogous 5-ethynyl-2,2′-bipyridyl complexes (Hab = 17 cm-1).",
author = "Mackenzie, {Campbell F.R.} and S{\"o}ren Bock and Lim, {Chia Yang} and Skelton, {Brian W.} and Carlo Nervi and Wild, {Duncan A.} and Low, {Paul J.} and Koutsantonis, {George A.}",
year = "2017",
month = "5",
day = "22",
doi = "10.1021/acs.organomet.7b00086",
language = "English",
volume = "36",
pages = "1946--1961",
journal = "Organometallics",
issn = "0276-7333",
publisher = "American Chemical Society",
number = "10",

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TY - JOUR

T1 - Coordinating Tectons. Experimental and Computational Infrared Data as Tools to Identify Conformational Isomers and Explore Electronic Structures of 4-Ethynyl-2,2′-bipyridine Complexes

AU - Mackenzie, Campbell F.R.

AU - Bock, Sören

AU - Lim, Chia Yang

AU - Skelton, Brian W.

AU - Nervi, Carlo

AU - Wild, Duncan A.

AU - Low, Paul J.

AU - Koutsantonis, George A.

PY - 2017/5/22

Y1 - 2017/5/22

N2 - 4-Ethynyl-2,2′-bipyridyl-substituted ruthenium alkynyl complexes have been prepared and used to access a range of binuclear homometallic ruthenium and heterometallic ruthenium-rhenium complexes. These have been characterized by a variety of spectroscopic and single-crystal X-ray diffraction experiments. The IR spectra of a number of these ruthenium alkynyls display multiple ν(C≡C) bands in the IR spectra, which are rationalized in terms of putative conformational isomers, whose calculated infrared stretching frequencies are comparable to those obtained experimentally. The mononuclear alkynyl ruthenium complexes undergo reversible one-electron oxidations centered largely on the alkynyl ligands, as inferred from the significant shift in ν(C≡C) frequency on oxidation, while the binuclear complex [Ru{C≡C-4-bpy-κ2-N,N′-RuClCp}(dppe)Cp∗]+ undergoes initial oxidation at the very electron rich {RuCl(bpy)Cp} fragment, causing only a small change in ν(C≡C). A combination of IR and UV-vis spectroelectrochemical experiments, supported by quantum chemical calculations on a selected range of conformers, led to the classification of [Ru{C≡C-4-bpy-κ2-N,N′-RuClCp}(dppe)Cp∗]+ as a weakly coupled class II mixed-valence compound (Hab = 306 cm-1). These results indicate that there is improved electronic communication through the 4-ethynyl-2,2′-bipyridyl ligand in comparison to the analogous 5-ethynyl-2,2′-bipyridyl complexes (Hab = 17 cm-1).

AB - 4-Ethynyl-2,2′-bipyridyl-substituted ruthenium alkynyl complexes have been prepared and used to access a range of binuclear homometallic ruthenium and heterometallic ruthenium-rhenium complexes. These have been characterized by a variety of spectroscopic and single-crystal X-ray diffraction experiments. The IR spectra of a number of these ruthenium alkynyls display multiple ν(C≡C) bands in the IR spectra, which are rationalized in terms of putative conformational isomers, whose calculated infrared stretching frequencies are comparable to those obtained experimentally. The mononuclear alkynyl ruthenium complexes undergo reversible one-electron oxidations centered largely on the alkynyl ligands, as inferred from the significant shift in ν(C≡C) frequency on oxidation, while the binuclear complex [Ru{C≡C-4-bpy-κ2-N,N′-RuClCp}(dppe)Cp∗]+ undergoes initial oxidation at the very electron rich {RuCl(bpy)Cp} fragment, causing only a small change in ν(C≡C). A combination of IR and UV-vis spectroelectrochemical experiments, supported by quantum chemical calculations on a selected range of conformers, led to the classification of [Ru{C≡C-4-bpy-κ2-N,N′-RuClCp}(dppe)Cp∗]+ as a weakly coupled class II mixed-valence compound (Hab = 306 cm-1). These results indicate that there is improved electronic communication through the 4-ethynyl-2,2′-bipyridyl ligand in comparison to the analogous 5-ethynyl-2,2′-bipyridyl complexes (Hab = 17 cm-1).

UR - http://www.scopus.com/inward/record.url?scp=85020461736&partnerID=8YFLogxK

U2 - 10.1021/acs.organomet.7b00086

DO - 10.1021/acs.organomet.7b00086

M3 - Article

VL - 36

SP - 1946

EP - 1961

JO - Organometallics

JF - Organometallics

SN - 0276-7333

IS - 10

ER -