Half-Sandwich Complexes [Cp′4Ln4I8]4 (Ln=Ce, Pr):Emergence of Donor-Free Organolanthanide Nanowheels

Slow diffusion of Me3SiI into an n-hexane solution of lanthanide half-sandwich complexes [Cp ' Ln(AlMe4)(2)] (Ln=Ce, Pr; Cp '=C5H4SiMe3) gives access to the hexadecalanthanide ring-cluster hybrids [Cp '(4)Ln(4)I(8)](4), along with the cyclopentadienyl-bridged {Ce-8} cluster [Cp ' 4Ce4I7(mu(2)-Cp)](2). On the contrary, direct addition of the halogenating reagent to complex [Cp ' Ce(AlMe4)(2)] in solution affords the spherical dodecanuclear cluster [Cp ' CeI2](12) in addition to [Cp '(4)Ln(4)I(8)](4). The isostructural bromide and chloride clusters [Cp ' LnX(2)](12) (X=Cl, Br) were isolated via the same solution synthesis protocol, using the mild halogenido transfer reagents Me3GeX (X=Cl, Br). The reaction [Cp ' Ce(AlMe4)(2)]/Me3GeCl yielded the decanuclear heteroaluminato derivative [Cp ' 5Ce5Cl9(AlCl2Me2)](2) as a coproduct. Attempts to isolate any intermediate species by performing the reaction at low temperature resulted in incomplete AlMe4/iodido exchange, affording the hexanuclear homoaluminate cluster [Cp ' 6Pr6I8(AlMe4)(4)]. All cerium clusters show bright photoluminescence under UV light. The luminescence properties of the dodecanuclear clusters [Cp ' CeX2](12) (X=Cl, Br, I) were closer investigated.

Automated summary

Diffusion of Me3SiI or direct addition of halogenating reagents can lead to the synthesis of lanthanide ring-clusters hybrids as well as different halogenated cluster systems, along with some byproducts.