Scandium─Group 13 Heterobimetallic Methylidene Clusters.

A straightforward synthesis of Cp*2Sc(AlMe4) (Cp* = C5Me5) applying Cp*2ScCl(thf) and LiAlMe4/AlMe3 is described. Donor-assisted trimethyltriel exchange gives access to Cp*2Sc(EMe4) (E = Ga, In), which represent the first scandium tetramethylgallate and tetramethylindate complexes. Thermal treatment of Cp*2Sc(EMe4) (E = Ga, In) in benzene leads to the isolation of methylidene clusters Cp*6Sc4E8(CH2)12Me6 (E = Ga, In). This methyl group deprotonation differs from the benzene activation previously observed for Cp*2Y(EMe4) (E = Al, Ga). Treatment of Cp*2Sc(EMe4) (E = Al, Ga) with excess GaMe3 in benzene at elevated temperatures generated Ga8(CH2)12, following the known reactivities of Cp*2Ln(GaMe4) (Ln = Y, Lu) with GaMe3. Analogous reactions of scandocene complexes Cp*2Sc(EMe4) (E = Al, In) with excess InMe3 at elevated temperatures did not yield the putative homoleptic indium methylidene. Instead, the methylidene cluster Cp*4Sc4In8(CH2)12Me8 was isolated, which features half-sandwich scandium fragments exclusively. A reaction of InMe3 and HCp* at high temperatures yielded Me2InCp*InMe3, 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 Cp*2Sc(EMe4) (E = Ga, In) and [Cp*2Sc(ClAlMe3)]2 were additionally analyzed by 1H, 13C{1H}, 45Sc NMR as well as 1H and 45Sc variable temperature NMR studies.