Organolanthanide Thermolysis Generates Ln/Al Tuck-Over Complexes and a 9,10-Dialumina-9,10-dihydroanthracenide Derivative

来源：ACS Publications

The synthesis of two new organoaluminum stabilized rare-earth-metal phenyl motifs is reported, featuring heterobimetallic Ln/Al tuck-over complexes Cp*Ln[C5Me4(CH2Al(μ–Ph)Ph2)] (Cp* = C5Me5, Ln = Y, La, Lu) and 9,10-dialumina-9,10-dihydroanthracenido derivatives Cp*Ln[(μ-C6H4)2Al2(μ–Ph)Ph3] (Ln = Y, Lu). Prolonged thermal treatment of Cp*2Ln(AlMe4) (Ln = Y, La, Lu) in benzene leads to stepwise methyl/phenyl exchange and then metalation of a Cp* methyl group and concomitant elimination of benzene to yield Ln/Al tuck-overcomplexes Cp*Ln[C5Me4(CH2Al(μ-Ph)Ph2)]. Isolated Cp*2Ln(AlPh4) (Ln = Y, La) also reacts to Cp*Ln[C5Me4(CH2Al(μ-Ph)Ph2)] at elevated temperatures. Treatment of Cp*Ln[C5Me4(CH2Al(μ-Ph)Ph2)] (Ln = Y, Lu) with AlMe3 results in a reverse phenyl/methyl exchange. THF breaks the Y–C(phenyl) bond in Cp*Y[C5Me4(CH2Al(μ-Ph)Ph2)] yielding zwitterionic complex Cp*Y(thf)2[C5Me4(CH2AlPh3)]. The 9,9,10,10-tetraphenyl-9,10-dialumina-9,10-dihydroanthracenido derivatives Cp*Ln[(μ-C6H4)2Al2(μ–Ph)Ph3] (Ln = Y, Lu) are either formed as very minor byproducts in the reaction of Cp*2Ln(AlMe4) with benzene or upon treatment of the benzyl compounds Cp*Ln(CH2C6H4NMe2-o)2 with 5–6 equiv AlPh3. Mixed methyl/phenyl complexes Cp*2Lu(Me2AlPh2), Cp*2La(MeAlPh3), and phenyl complex Cp*2La(AlPh4) were isolated from the methyl/phenyl exchange sequence when heating Cp*2Ln(AlMe4) in benzene. Such thermally controlled benzene elimination from phenylaluminate complexes as highlighted by new structural motifs does not only extend rare-earth-metal phenyl chemistry but might inspire future investigations into inert bond activation with organolanthanide moieties at elevated temperatures.