Synthesis and Characterization of a Series of Structurally and Electronically Diverse Fe(II) Complexes Featuring a Family of Triphenylamido-amine Ligands
A family of triphenylamido-amine ligands of the general stoichiometry LxH3=[R-NH-(2-C6H4)]3N (R=4-t-BuPh (L1H3), 3,5-t-Bu2Ph (L2H3), 3,5-(CF3)2Ph (L3H3), CO-t-Bu(L4H3), 3,5-Cl2Ph (L5H3), COPh (L6H3), CO-i-Pr (L7H3), COCF3 (L8H3), and i-Pr (L9H3) has been synthesized and characterized, featuring a rigid triphenylamido-amine scaffold and an array of stereoelectronically diverse aryl, acyl, and alkyl substituents (R). These ligands are deprotonated by potassium hydride in THF or DMA and reacted with anhydrous FeCI2 to afford a series of ferrous complexes, exhibiting stoichiometric variation and structural complexity. The prevalent [(Lx)Fe(II)-SoIv]- structures (Lx=L1, L2, L3, L5, Solv=THF; Lx=L8, solv=DMA; Lx=L6, L8, Solv=MeCN) reveal a distorted trigonal bipyramidal geometry, featuring ligand-derived [N3, amidoNamine] coordination and solvent attachment trans to the N amine atom. Specifically for [(L8)Fe(ll)-DMA]-, a Namido residue is coordinated as the corresponding Nimino moiety (Fe-N(Ar)=C(CF3)-O-). In contrast, compounds [(L4)Fe(ll)]-, [(L6)2Fe(ll)2]2-, [K(L7)2Fe(ll)2]22- , and [K(L9)Fe]2 are all solvent-free in their coordination sphere and exhibit four-coordinate geometries of significant diversity. In particular, [(L4)Fe(ll)]- demonstrates coordination of one amidato residue via the O-atom end (Fe-O-C(t-Bu)=N(Ar)). Furthermore, [(L6)2Fe(ll)2]2- and [K(L7)2Fe(ll)2]22- are similar structures exhibiting bridging amidato residues (Fe-N(Ar)C(R)=O-Fe) in dimeric structural units. Finally, the structure of [K(L9)Fe]2 is the only example featuring a minimal [N 3, amidoN amine] coordination sphere around each Fe(II) site. All compounds have been characterized by a variety of physicochemical techniques, including MÃ¶ssbauer spectroscopy and electrochemistry, to reveal electronic attributes that are responsible for a range of Fe(ll)/Fe(lll) redox potentials exceeding 1.0 V.
P. Paraskevopoulou and L. Ai and Q. Wang and D. Pinnapareddy and R. Acharyya and R. Dinda and P. Das and R. Çelenligil-Çetin and G. Floros and Y. Sanakis and A. Choudhury and N. P. Rath and P. Stavropoulos, "Synthesis and Characterization of a Series of Structurally and Electronically Diverse Fe(II) Complexes Featuring a Family of Triphenylamido-amine Ligands," Inorganic Chemistry, vol. 49, no. 1, pp. 108 - 122, American Chemical Society (ACS), Jan 2010.
The definitive version is available at https://doi.org/10.1021/ic9015838
Keywords and Phrases
Amide; Amine; Ferrous Ion; Ligand; Chemical Structure; Chemistry; Synthesis; Ferrous Compounds; Models, Molecular; Molecular Structure
International Standard Serial Number (ISSN)
Article - Journal
© 2010 American Chemical Society (ACS), All rights reserved.
01 Jan 2010