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1,3‐Diethynyl‐5‐(X)‐benzene‐Bridged [Cp*(dppe)Fe] n+ Units: Effect of Substituents on the Metal‐Metal Interactions
Author(s) -
Lepont Joseph,
Roisnel Thierry,
Hamon JeanRené,
Lapinte Claude
Publication year - 2021
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.202100789
Subject(s) - chemistry , comproportionation , metal , crystallography , aryl , valence (chemistry) , cyclic voltammetry , stereochemistry , medicinal chemistry , electrochemistry , alkyl , organic chemistry , electrode
The new complexes [1,3‐{Cp*(dppe)Fe−C≡C‐} 2 ‐5‐(X)‐(C 6 H 3 )] (X=CH 3 , [ m ‐ 1 b] ; X=C(O)OCH 3 , [ m ‐ 1 c] ; X=C≡C−4−C 6 H 4 −C(O)OCH 3 , [ m ‐ 1 d] ; X=C≡C−4−C 6 H 4 ‐NO 2 , [ m ‐ 1 e] ) were prepared by reaction of the iron chloride Cp*(dppe)FeCl ( 4 ) and the proligands 3 b – e obtained by a cross coupling reaction between the suitable aryl dibromides and trimethylsylilacethylene. After purification the complexes [ m ‐ 1 b–e] were isolated in yields ranging from 14 to 37 % and characterized by elemental analysis, high‐resolution, ESI‐mass spectra, multinuclear NMR, cyclic voltammetry, and IR spectroscopy. The complexes [ m ‐ 1 b] , [ m ‐ 1 d] , and [ m ‐ 1 e] were also characterized by XRD analyses on single crystals. The doubly oxidized complexes [ m ‐ 1 b–e](PF 6 ) 2 were prepared (in ca. 64–87 % yields) by treatment of a CH 2 Cl 2 solution of the corresponding neutral complexes [ m ‐ 1 b–e] with two equiv. of [(C 5 H 5 ) 2 Fe](PF 6 ). The mixed‐valence complexes (MV) [ m ‐ 1 b–e](PF 6 ) were obtained by comproportionation between one equiv. of [ m ‐ 1 b–e] and one equiv. of [ m ‐ 1 b–e](PF 6 ) 2 . CV, IR and NIR data led to the conclusion that the MV [ m ‐ 1 b–e](PF 6 ) complexes are weakly coupled Class II MV derivatives and the distribution of the charge between the alkynyl iron centers and the phenyl ring might be tuned by the X‐substituents in a limited extend.