TY - JOUR
T1 - Oxidative Coupling of Ruthenium Alkenyl Acetylide Complexes as a Route to Dinuclear Complexes Featuring Carbon-Rich Bridging Ligands
AU - Hall, Michael R.
AU - Korb, Marcus
AU - Moggach, Stephen A.
AU - Low, Paul J.
N1 - Funding Information:
M.R.H. holds a Dean’s Excellence in Science PhD Scholarship from the Faculty of Science, University of Western Australia. The Forrest Research Foundation is sincerely thanked for the award of a Forrest Fellowship to M.K. S.A.M. thanks the Australian Research Council (ARC) for a Future Fellowship (FT200100243). The authors gratefully acknowledge the facilities and the scientific and technical assistance of Microscopy Australian at the Centre for Microscopy, Characterisation Analysis, the University of Western Australia, a facility funded by the University, State, and Commonwealth Governments.
Publisher Copyright:
© 2022 American Chemical Society. All rights reserved.
PY - 2022/11/14
Y1 - 2022/11/14
N2 - Reaction of [RuCl(dppe)Cp*] with the propargylic alcohols HCCC(OH)(R)Me [R = Ph (A), 4-pyridyl (B), and 4-NO2-C6H4(C)] in the presence of NH4PF6in MeOH, followed by treatment with base (t-BuOK) and workup under air, resulted in the unanticipated formation of the dinuclear bis(acetylide) species [{Ru(dppe)Cp*}2{μ-CCC(R)=HC-CH=C(R)CC}] [R = Ph (2a), 4-py (2b), 4-NO2-C6H4(2c)]. The dimeric complexes 2 containing an octa-3,5-diene-1,7-diyndiyl bridging ligand are formed through a sequence of reactions involving formation of the methyl allenylidene complexes [Ru{C=C=C(R)Me}(dppe)Cp*]+and deprotonation to give the transient alkenylacetylide species [Ru{CCC(R)=CH2}(dppe)Cp*] (1). Oxidation of 1 affords the radical cation [1]+, which homocouples to give the dimeric ethane-bridged bis(allenylidene) [{Ru(dppe)Cp*}2{μ-C=C=C(R)CH2-CH2C(R)=C=C}]2+[(2-H2)2+] and is deprotonated to give 2. Examples of these various intermediates have been spectroscopically observed and isolated through stoichiometric reactions and the reaction pathway mapped by in situ electrochemical (cyclic voltammetry, CV) and infrared-spectroelectrochemical (IR-SEC) measurements. The bimetallic complexes 2a-c each undergo two sequential oxidation events at low potentials, giving species characterized by IR-SEC as a strongly delocalized mixed-valence radical cations [2a-c]+and the dicationic bis(allenylidene) species [{Ru(dppe)Cp*}2{μ-C=C=C(R)-HC=CH-C(R)=C=C}]2+[(2a-c)2+]. Chemical oxidation of 2a with one or two equivalents of [FeCp2]PF6allowed for isolation of the monocation [2a]PF6and dication [2a][PF6]2, respectively.
AB - Reaction of [RuCl(dppe)Cp*] with the propargylic alcohols HCCC(OH)(R)Me [R = Ph (A), 4-pyridyl (B), and 4-NO2-C6H4(C)] in the presence of NH4PF6in MeOH, followed by treatment with base (t-BuOK) and workup under air, resulted in the unanticipated formation of the dinuclear bis(acetylide) species [{Ru(dppe)Cp*}2{μ-CCC(R)=HC-CH=C(R)CC}] [R = Ph (2a), 4-py (2b), 4-NO2-C6H4(2c)]. The dimeric complexes 2 containing an octa-3,5-diene-1,7-diyndiyl bridging ligand are formed through a sequence of reactions involving formation of the methyl allenylidene complexes [Ru{C=C=C(R)Me}(dppe)Cp*]+and deprotonation to give the transient alkenylacetylide species [Ru{CCC(R)=CH2}(dppe)Cp*] (1). Oxidation of 1 affords the radical cation [1]+, which homocouples to give the dimeric ethane-bridged bis(allenylidene) [{Ru(dppe)Cp*}2{μ-C=C=C(R)CH2-CH2C(R)=C=C}]2+[(2-H2)2+] and is deprotonated to give 2. Examples of these various intermediates have been spectroscopically observed and isolated through stoichiometric reactions and the reaction pathway mapped by in situ electrochemical (cyclic voltammetry, CV) and infrared-spectroelectrochemical (IR-SEC) measurements. The bimetallic complexes 2a-c each undergo two sequential oxidation events at low potentials, giving species characterized by IR-SEC as a strongly delocalized mixed-valence radical cations [2a-c]+and the dicationic bis(allenylidene) species [{Ru(dppe)Cp*}2{μ-C=C=C(R)-HC=CH-C(R)=C=C}]2+[(2a-c)2+]. Chemical oxidation of 2a with one or two equivalents of [FeCp2]PF6allowed for isolation of the monocation [2a]PF6and dication [2a][PF6]2, respectively.
UR - http://www.scopus.com/inward/record.url?scp=85141632017&partnerID=8YFLogxK
U2 - 10.1021/acs.organomet.2c00402
DO - 10.1021/acs.organomet.2c00402
M3 - Article
AN - SCOPUS:85141632017
VL - 41
SP - 2958
EP - 2973
JO - Organometallics
JF - Organometallics
SN - 0276-7333
IS - 21
ER -