W Tungsten

Reaction of the potassium salt of amido ligand [Ph2Si(NAr)2]2− (L, Ar=2,6-iPr2C6H3) and LnI2(thf)2 (Ln=Sm, Yb) gives sandwich complexes [(L)2Ln{K(Et2O)}2] (Ln=Sm (2), Yb (3)) with potassium–arene π interactions. Reaction of 2 with azobenzene gave the dimeric samarium cluster [(L)2Sm2(μ-η2:η2-N2Ph2)2{K(thf)2}2] (4) and the tetrameric [(L)Sm4 (μ-η2:η2-N2Ph2)3 (μ3-NPh)2(thf)3] (5). On the other hand, the reaction of 2 with α-diimines ligands ArNCRCRNAr (DAD, R=H, Me) gives two SmIII complexes: polymeric [(L)Sm{(ArN)RCCR(NAr)}K]n (R=H (6), Me (7)) assembled through cation–π interactions and byproduct [{(L)2Sm}{K(thf)6}] (8). Complexes 2–8 have been fully characterized by elemental analyses and X-ray crystallography. In particular, crystallographic analyses of 6 and 7 revealed that in both complexes samarium(III) is stabilized by dianionic DAD units.Unusual sandwiches: Heterometallic sandwich complex 1 reacts with azobenzene to afford [(L)2Sm2(μ-η2:η2-N2Ph2)2{K(thf)2}2] (2) and [(L)Sm4(μ-η2:η2-N2Ph2)3(μ3-NPh)2(thf)3] (3), for which crystallographic studies showed that the alkali metal cation–arene π interactions help to stabilize the divalent metal centers. In addition, complex 1 reacts with diazabutadiene ligands to give SmIII complexes that form one-dimensional networks through cation–arene π interactions.