Scandium─Group 13 Heterobimetallic Methylidene Clusters.

A straightforward synthesis of CpSc(AlMe) (Cp = CMe) applying CpScCl(thf) and LiAlMe/AlMe is described. Donor-assisted trimethyltriel exchange gives access to CpSc(EMe) (E = Ga, In), which represent the first scandium tetramethylgallate and tetramethylindate complexes. Thermal treatment of CpSc(EMe) (E = Ga, In) in benzene leads to the isolation of methylidene clusters CpScE(CH)Me (E = Ga, In). This methyl group deprotonation differs from the benzene activation previously observed for CpY(EMe) (E = Al, Ga). Treatment of CpSc(EMe) (E = Al, Ga) with excess GaMe in benzene at elevated temperatures generated Ga(CH), following the known reactivities of CpLn(GaMe) (Ln = Y, Lu) with GaMe. Analogous reactions of scandocene complexes CpSc(EMe) (E = Al, In) with excess InMe at elevated temperatures did not yield the putative homoleptic indium methylidene. Instead, the methylidene cluster CpScIn(CH)Me was isolated, which features half-sandwich scandium fragments exclusively. A reaction of InMe and HCp at high temperatures yielded MeInCpInMe, which might incorporate the missing Cp ligands in the cluster formations. Rare-earth-metal compounds were analyzed by SC-XRD, ICP-OES and elemental analysis. Compounds CpSc(EMe) (E = Ga, In) and [CpSc(ClAlMe)] were additionally analyzed by H, C{H}, Sc NMR as well as H and Sc variable temperature NMR studies.