Heterometallic Potassium Rare-Earth-Metal Allyl and Hydrido Complexes Stabilized by a Dianionic (NNNN)-Type Macrocyclic Ancillary Ligand

The macrocyclic diamino diamine (1,7-Me2TACD)­H2 (1,7-Me2TACD = 1,7-dimethyl-1,4,7,10-tetraazacyclododecane, 1,7-Me2[12]­aneN4), reacted under propylene elimination with [Ln­(η3-C3H5)3(diox)] (Ln = Y, La) to give the mono­(allyl) complexes [(1,7-Me2TACD)­Ln­(η3-C3H5)]2 (Ln = Y (1a), La (1b)). A single-crystal X-ray diffraction study shows 1b to be a centrosymmetric dimer with lanthanum atoms bridged by one of the two amido nitrogen atoms. Complexes 1a,b were treated with 2 equiv of the potassium allyl KC3H5 to give the corresponding heterometallic allyl complexes [(1,7-Me2TACD)­Ln­(η3-C3H5)2K­(THF)]n (Ln = Y (2a), La (2b)). A single-crystal X-ray diffraction study revealed that 2a,b are polymeric in the solid state with allyl ligands bridging the metal centers in addition to the presence of μ2-amido functions of the 1,7-Me2TACD ligand. Hydrogenolysis of the yttrium compound 2a with 1 bar of H2 led to the formation of the heterometallic Y4K2 hydrido complex [(1,7-Me2TACD)2Y2H3K­(THF)2]2 (3a), which can also be synthesized from a 1:1 mixture of 1a and KC3H5 with 1 bar of H2. A single-crystal X-ray diffraction study of 3a revealed a dimer of heterotrinuclear Y2K trihydride aggregate. Treatment of 2b with 1 bar of H2 afforded the heptanuclear La3K4 heptahydrido complex [(1,7-Me2TACD)3La3H7K4(THF)7] (3b).