Chromium(III) and Chromium(II) Phenolate Complexes with Bulky Alkylcyclopentadienyl Ligands. Issue 22 (5th June 2019)

• Record Type: Journal Article
• Authors: Smytschkow, Igor; Gidt, Wjatscheslaw; Kunz, Christoph; Sun, Yu; Langer, Jens; Oelkers, Benjamin; Böttcher, Tobias; Sitzmann, Helmut
• Is Part Of: European journal of inorganic chemistry. Issue 22(2019)
• Page Start: 2742
• Page End: 2749
• Publication Date: 2019-06-05
• Subjects: Chromium -- Cyclopentadienyl ligands -- Ligand effects -- Structure elucidation -- Magnetic properties; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.201900275
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract : The chromium(II) tricarbonyl methyl complex [Cp′′′Cr(CO)3 CH3 ] (1, Cp′′′ = η 5 ‐C5 H2 t Bu3 ‐1, 2, 4) was obtained from chromium hexacarbonyl, NaCp′′′, and methyl iodide.1 was found to establish an equilibrium with the dicarbonyl acetyl isomer [Cp′′′Cr(CO)2 (COCH3 )] in solution via reversible, slightly endothermic methyl migration from chromium to a carbonyl ligand with Δ H ca. 3.6 kJ/mol and E a ca. 49.5 kJ/mol. Phosphorus pentachloride oxidized1 to the green, dinuclear tetrachloro complex [Cp′′′CrCl(µ‐Cl)]2 (2 ), which was crystallized as the blue‐green chromium(III) half sandwich complex [Cp′′′CrCl2 (THF)] (3 ) in the presence of tetrahydrofuran vapor. Attempted sublimation of the known chromium(II) iodo complex [ 4 CpCr(µ‐I)]2 resulted in a redox reaction with formation of the chromium(III) iodo dimer [ 4 CpCrI(µ‐I)]2, whose tri( tert ‐butyl)cyclopentadienyl derivative [Cp′′′CrI(µ‐I)]2 (4 ) could also be prepared by oxidation of [Cp′′′Cr(µ‐I)]2 with iodine. The chromium(III) bis(2, 6‐diisopropylphenolate) complex [ 4 CpCr(OC6 H3 i Pr2 ‐2, 6)2 ] (5 ) was obtained from chromium trichloride in a one pot reaction with sodium tetraisopropylcyclopentadienide, followed by sodium 2, 6‐diisopropylphenolate. The chromium(III) starting compound2 reacted with 2, 6‐diisopropylphenolate to the Cp′′′ derivative [Cp′′′Cr(OC6 H3 i Pr2 ‐2, 6)2 ] (6 ). The chromium(II) starting compound [Cp′′′Cr(µ‐Br)]2 afforded the phenolate‐bridged chromium(II) dimer [Cp′′′Cr(µ‐OC6 H5 )]2 (7 ) upon treatment with sodium phenolate, while the product of the analogous reaction with 2, 6‐di( tert ‐butyl)phenolate was the mononuclear tetrahydrofuran adduct [Cp′′′Cr(OC6 H3 t Bu2 ‐2, 6)(THF)] (8 ). Abstract : Unlike the analogous iron(II) complex, [Cp′′′Cr(µ‐Br)]2 does not form a π complex with 2, 6‐di( tert ‐butyl)phenolate, but favors σ coordination of the phenolate ligand and preserves its high spin character. Tetrahydrofuran uptake results in a coordination number of five for the chromium center.