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

Abstract

AbstractSlow 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′4Ln4I8]4, along with the cyclopentadienyl‐bridged {Ce8} cluster [Cp′4Ce4I7(μ2‐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′4Ln4I8]4. The isostructural bromide and chloride clusters [Cp′LnX2]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.