The reaction of [Sm{N(SiMe3)(2)}(2)(THF)(2)] (THF = tetrahydrofuran) with carbodiimides RN=C=NR (R = Cy, C6H3-2,6-Pr-i(2)) led to the formation of dinuclear SmIll complexes via differing C-C coupling processes. For R = Cy, the product [{(Me3Si)(2)N}(2)Sm(mu-C2N4Cy4)Sm{N(SiMe3)(2)}(2)] (1) has an oxalamidinate [C2N4Cy4](2-) ligand resulting from coupling at the central C atoms of two CyNCNCy moieties. In contrast, for R = C6H3-2,6-Pr-i(2), H transfer and an unusual coupling of two Pr-i methine C atoms resulted in a linked formamidinate complex, [{(Me3Si)(2)N}(2)Sm{mu-(RNC(H)N(Ar-Ar)NC(H)NR)}Sm{N(SiMe3)(2)}(2)] (2) (Ar-Ar = C6H3-2-Pr-i-6-C(CH3)(2)C(CH3)(2)-6'-C6H3-2'-Pr-i). Analogous reactions of RN=C=NR (R = Cy, C6H3-2,6-Pr-i(2)) with the Sm-II "ate" complex [Sm{N(SiMe2)(3)Na] gave 1 for R = Cy, but a novel C-substituted amidinate complex, [(THF)Na{N(R)C(NR)CH2Si(Me-2)N(SiMe3)}Sm{N(SiMe3)(2)}(2)] (3), for R = C6H3-2,6(i)Pr(2), via gamma C-H activation of a N(SiMe3)(2) ligand.