Transition Metal Acetylide Rearrangement and Coupling Induced by Coordinative Unsaturation
The reaction of Ar′Fe(μ-Br)2 (Ar′ = C 6H3-2,6-(C6H3-2,6-iPr 2)2) with LiC=CPh afforded the unusual 1,3-butadiene-1,4-diyl Fe(I)-coupled derivative Fe2Ar′C=C(Ph)- C(Ph)=CAr′ (1), whereas the reaction of Ar′Fe(μ-Br) 2 with LiC≡CtBu yielded the monomeric Fe(II) “ate” complex Ar′Fe(C≡CtBu)2Li(THF) 2 (2). Complexes 1 and 2 were characterized by X-ray crystallography, NMR, and UV-vis spectroscopy and magnetic measurements. In 1 the dimeric structure is a result of Ar′ group transfer to the iron-bound carbon of the acetylide ligand and subsequent dimerization via coupling of the phenyl-substituted carbons. The irons are antiferromagnetically coupled, and the iron-iron separation is 2.5559(3) Å. In 2 the high-spin iron atom has distorted trigonal-planar coordination with a THF-complexed lithium ion associated with the Ar′Fe(C≡CtBu)2 anion via interactions with the tBu-substituted alkyne carbons. © 2009 American Chemical Society.
C. Ni et al., "Transition Metal Acetylide Rearrangement and Coupling Induced by Coordinative Unsaturation," Organometallics, American Chemical Society (ACS), Jan 2009.
The definitive version is available at http://dx.doi.org/10.1021/om900542j
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