An alkylyttrium complex supported by an N,N'-bis(2,6-diisopropylphenyl)ethylenediamido ligand, (ArNCH2CH2NAr)Y(CH2SiMe3)(THF)2 (1, Ar = 2,6-iPr2C6H3), activated an ortho-Ph C-H bond of 2-phenylpyridine (2a) to form a (2-pyridylphenyl)yttrium complex (3a) contg. a five-membered metallacycle. Subsequently, a unique C(sp2)-C(sp2) coupling of 2-phenylpyridine proceeded through a bimetallic yttrium intermediate, derived from an intramol. shift of the yttrium center to an ortho-position of the pyridine ring in 3a, to yield a bimetallic yttrium complex (4a) bridged by two-electron reduced 6,6'-diphenyl-2,2'-bipyridyl. Aryl substituents at the ortho-position of the pyridine ring were key in order to destabilize the ﾎｼ,ﾎｺ2-(C,N)-pyridyldiyttrium intermediate prior to the C(sp2)-C(sp2) bond formation. [on SciFinder(R)]
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