Synthesis of a Bis(indenyl) Co(I) Anion: A Reactive Source of a 14 Electron Indenyl Co(I) Equivalent

Fernando Hung-Low, Christopher A Bradley

Inorg Chem. 2013 Mar 4;52(5):2446-57.

PMID: 23427933

Abstract:

Alkali metal reduction of (η(5)-C9H5-1,3-(SiMe3)2)2Co (1) in tetrahydrofuran (THF) permits isolation of the unusual and reactive 20 electron Co(I) anion [Na(THF)6][(η(5)-C9H5-1,3-(SiMe3)2)2Co] (2). Crystallographic characterization of both 1 and 2 provide support for the one electron reduction from Co(II) to Co(I). Reactivity studies of 2 are further consistent with a Co(I) equivalent, based on both one electron chemical oxidation to reform 1 and reaction with a variety of σ and π donors. Upon addition of pyridines or vinyltrimethylsilane to 2, known dimer [(C9H5-1,3-(SiMe3)2)2Co2] (3) is formed, likely through 16 electron (η(5)-C9H5-1,3-(SiMe3)2)Co(L) intermediates. Ethylene addition to 2 establishes an equilibrium between (η(5)-C9H5-1,3-(SiMe3)2)Co(η(2)-H2C═CH2)2 (8) and 2, suggestive of reversible ligand ejection from 2. Crossover experiments between a related metal indenide salt and 2 confirm ligand extrusion from the anion, even in the absence of strong supporting donors. Reaction of 2 with PMe3 results in formation of 3, (η(5)-C9H5-1,3-(SiMe3)2)Co(PMe3)2 (13), and a paramagnetic species, with the product ratios being highly dependent on the conditions of synthesis. Collectively, 2 demonstrates an alternative entry point into the chemistry of 14 electron Co(I) equivalents when compared to typical ligand loss from neutral 18 electron cyclopentadienyl cobalt bis(ligand) complexes, perhaps permitting generation of low electron count species more effective for small molecule activation.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AP1277436	Bis(cyclopentadienyl)cobalt(II)		1277-43-6	Price

Catalog Number

Product Name

Structure

CAS Number

Price

AP1277436

Bis(cyclopentadienyl)cobalt(II)

1277-43-6

Price

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