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 L(3)Ln(3)(mu(2)-Me)(3)(mu(3)-Me)(mu(3)-CH2) [L = [PhC((NC6H3Pr2)-Pr-i-2,6)(2)](-); Ln = Y(1a), Lu(1b)] with PhCN, alkynes, and CS2 have been established. Reaction of complexes 1 with PhCN gave the mu(3)-CH2 addition complexes (NCNdipp)(3)Lu-3(mu(2)-Me)(3)(mu(3)-Me)[mu-eta(1):eta(1):eta(3)-CH2C(Ph)N] [Ln = Y(2a), Lu(2b)]. Treatment of complexes 1 with phenylacetylene afforded unexpected alkenyl dianion complexes L(3)Ln(3)(mu(2)-Me)(3)-(mu(3)-Me) (mu-eta(1):eta(3)-PhCvCMe) [Ln = Y(3a), Lu(3b)] through the insertion of rare earth methylidene into a C-H bond in a reductive fashion. However, reaction of complexes 1 and HC CSiMe3 gave mu(3)-Me protonolysis complexes L(3)Ln(3)(mu(2)-Me)(3)(mu(3)-Cu SiMe3)(mu(3)-CH2) [Ln = Y (4a), Lu (4b)] in excellent yields. Treatment of complexes 1 with CS2 led to the formation of the methyl activation complexes L(3)Ln(3)(mu(2)-Me)(2)-(mu(3)-CH2) (mu(3)-eta(1):eta(2):eta(2)-S2C=CH2) [Ln = Y(5a), Lu(5b)]. All the new complexes were fully characterized.