Scandium complexes with the tetraphenylethylene and anthracene dianions

Abstract

The structural study of Sc complexes containing dianions of anthracene and tetraphenylethylene should shed some light on the nature of rare-earth metal–carbon bonding. The crystal structures of (18-crown-6)bis(tetrahydrofuran-κO)sodium bis(η6-1,1,2,2-tetraphenylethenediyl)scandium(III) tetrahydrofuran disolvate, [Na(C4H8O)2(C12H24O6)][Sc(C26H20)2]·2C4H8O or [Na(18-crown-6)(THF)2][Sc(η6-C2Ph4)2]·2(THF), (1b), (η5-1,3-diphenylcyclopentadienyl)(tetrahydrofuran-κO)(η6-1,1,2,2-tetraphenylethenediyl)scandium(III) toluene hemisolvate, [Sc(C17H13)(C26H20)(C4H8O)]·0.5C7H8or [(η5-1,3-Ph2C5H3)Sc(η6-C2Ph4)(THF)]·0.5(toluene), (5b), poly[[(μ2-η3:η3-anthracenediyl)bis(η6-anthracenediyl)bis(η5-1,3-diphenylcyclopentadienyl)tetrakis(tetrahydrofuran)dipotassiumdiscandium(III)] tetrahydrofuran monosolvate], {[K2Sc2(C14H10)3(C17H13)2(C4H8O)4]·C4H8O}nor [K(THF)2]2[(1,3-Ph2C5H3)2Sc2(C14H10)3]·THF, (6), and 1,4-diphenylcyclopenta-1,3-diene, C17H14, (3a), have been established. The [Sc(η6-C2Ph4)2]−complex anion in (1b) contains the tetraphenylethylene dianion in a symmetrical bis-η3-allyl coordination mode. The complex homoleptic [Sc(η6-C2Ph4)2]−anion retains its structure in THF solution, displaying hindered rotation of the coordinated phenyl rings. The 1D1H and13C{1H}, and 2D COSY1H–1H and13C–1H NMR data are presented forM[Sc(Ph4C2)2]·xTHF [M= Na andx= 4 for (1a);M= K andx= 3.5 for (2a)] in THF-d8media. Complex (5b) exhibits an unsymmetrical bis-η3-allyl coordination mode of the dianion, but this changes to a η4coordination mode for (1,3-Ph2C5H3)Sc(Ph4C2)(THF)2, (5a), in THF-d8solution. A45Sc NMR study of (2a) and UV–Vis studies of (1a), (2a) and (5a) indicate a significant covalent contribution to the Sc—Ph4C2bond character. The unique Sc ate complex, (6), contains three anthracenide dianions demonstrating both a η6-coordination mode for two bent ligands and a μ2-η3:η3-bridging mode of a flat ligand. Each [(1,3-Ph2C5H3)2Sc2(C14H10)3]2−dianionic unit is connected to four neighbouring unitsviashort contacts with [K(THF)2]+cations, forming a two-dimensional coordination polymer framework parallel to (001).