Scandium complexes with the tetraphenylethylene and anthracene dianions

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).