Small molecule activation by mixed methyl/methylidene rare earth metal complexes.

Diverse reactivity patterns of mixed tetramethyl/methylidene rare-earth complexes bearing bulky benzamidinate coligands L3Ln3(μ2-Me)3(μ3-Me)(μ3-CH2) [L = [PhC(NC6H3(i)Pr2-2,6)2](-); Ln = Y(), Lu()] with PhCN, alkynes, and CS2 have been established. Reaction of complexes with PhCN gave the μ3-CH2 addition complexes (NCN(dipp))3Lu3(μ2-Me)3(μ3-Me)[μ-η(1):η(1):η(3)-CH2C(Ph)N] [Ln = Y(), Lu()]. Treatment of complexes with phenylacetylene afforded unexpected alkenyl dianion complexes L3Ln3(μ2-Me)3(μ3-Me)(μ-η(1):η(3)-PhC[double bond, length as m-dash]CMe) [Ln = Y(), Lu()] through the insertion of rare earth methylidene into a C-H bond in a reductive fashion. However, reaction of complexes and HC[triple bond, length as m-dash]CSiMe3 gave μ3-Me protonolysis complexes L3Ln3(μ2-Me)3(μ3-C[triple bond, length as m-dash]CSiMe3)(μ3-CH2) [Ln = Y (), Lu ()] in excellent yields. Treatment of complexes with CS2 led to the formation of the methyl activation complexes L3Ln3(μ2-Me)2(μ3-CH2)(μ3-η(1):η(2):η(2)-S2C[double bond, length as m-dash]CH2) [Ln = Y(), Lu()]. All the new complexes were fully characterized.