Synthesis and Structure of a New Type of Sandwich-Like Yttrium Complex Derived from Tetraphenylethylene: [Na(THF)6][Y(Ph2CCPh2)2]

Syntheses and crystal structures of new naphthalene– and anthracene–vanadate salts and an unprecedented dimetallabis(anthracene) sandwich complex: [Na(tetrahydrofuran)3][V2(anthracene)2]

Reduction of bis(naphthalene)vanadium(0) by potassium naphthalene (KNp) in tetrahydrofuran (THF) provides a highly reactive, thermolabile, and so far unisolable brown substance, which affords the first reported derivatives of bis(naphthalene)vanadates. From these solutions, thermally stable (298 K) and structurally characterized compounds have been obtained, including dark-red rods of catena-poly[bis(μ3-η4:η6:η4-naphthalene)tetrakis(tetrahydrofuran)dipotassiumvanadium], [K2V(C4H8O)4(C10H8)2] n or [K(THF)2]2[V(C10H8)2] (3), and red plates of (4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane)potassium [1,2-bis(dimethylphosphanyl)ethane]bis(η4-naphthalene)vanadium tetrahydrofuran monosolvate, [K(C18H36N2O6)][V(C10H8)2(C6H16P2)]·C4H8O or [K([2.2.2]cryptand)][V(C10H8)2(dmpe)]·THF [dmpe is 1,2-bis(dimethylphosphanyl)ethane] (4b). Notably, [V(C10H8)2]2− is the only example of a structurally authenticated homoleptic bis(arene)metallate dianion and was obtained by further reduction of the brown material by KNp in THF, in the presence of trimethylphosphane (PMe3). Addition of anthracene (An) to the brown material in THF afforded deep-violet and paramagnetic crystalline (1,4,7,10,13,16-hexaoxacyclooctadecane)bis(tetrahydrofuran)potassium [(η4-anthracene)(tetrahydrofuran)vanadium]-μ-η4:η2-anthracene-[(1,4,7,10,13,16-hexaoxacyclooctadecane)potassium]-μ-η2:η4-anthracene-[(η4-anthracene)(tetrahydrofuran)vanadium] tetrahydrofuran disolvate, [K(C12H24O6)(C4H8O)2][KV2(C12H24O6)(C4H8O)2(C14H10)4]·2C4H8O or [K(18-crown-6)][K(18-crown-6)(THF)2][V(C14H10)2(THF)]2·2(THF) (5), which readily reacted with PMe3 and dmpe to give new vanadate salts. These were structurally characterized as (1,4,7,10,13,16-hexaoxacyclooctadecane)bis(tetrahydrofuran)potassium bis(η4-anthracene)(trimethylphosphane)vanadium tetrahydrofuran monosolvate, [K(C12H24O6)(C4H8O)2][V(C14H10)2(C3H9P)]·C4H8O or [K(18-crown-6)(THF)2][V(C14H10)2(PMe3)]·THF (6), and tetrakis(1,2-dimethoxyethane)potassium bis(η4-anthracene)[1,2-bis(dimethylphosphanyl)ethane]vanadium, [K(C4H10O2)4][V(C14H10)2(C6H16P2)] or [K(DME)4][V(C14H10)2(dmpe)] (DME is 1,2-dimethoxyethane) (7b). The last three structures contain the first known bis(anthracene)vanadates and are thereby derivatives of the unknown bis(anthracene)vanadium(0). Attempts to obtain the sodium salt analog of 5 in THF resulted instead in the formation of a unique substance, (μ3-η6:η6:η6-anthracene)(μ2-η6:η6-anthracene)tris(tetrahydrofuran)sodiumdivanadium, [NaV2(C14H10)2(C4H8O)3] or [Na(THF)3][V2(C14H10)2] (8), containing the first reported dimetallabis(anthracene) sandwich compound.

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)]·0.5C₇H₈ or [(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}_n or [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 1D ¹H and ¹³C{¹H}, and 2D COSY ¹H-¹H and ¹³C-¹H NMR data are presented for M[Sc(Ph₄C₂)₂]·xTHF [M = Na and x = 4 for (1a); M = K and x = 3.5 for (2a)] in THF-d₈ media. Complex (5b) exhibits an unsymmetrical bis-η³-allyl coordination mode of the dianion, but this changes to a η⁴ coordination mode for (1,3-Ph₂C₅H₃)Sc(Ph₄C₂)(THF)₂, (5a), in THF-d₈ solution. A ⁴⁵Sc NMR study of (2a) and UV-Vis studies of (1a), (2a) and (5a) indicate a significant covalent contribution to the Sc-Ph₄C₂ bond 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 units via short contacts with [K(THF)₂]⁺ cations, forming a two-dimensional coordination polymer framework parallel to (001).

Rare-earth metal π-complexes of reduced arenes, alkenes, and alkynes: bonding, electronic structure, and comparison with actinides and other electropositive metals

Rare-earth metal complexes of reduced π ligands are reviewed with an emphasis on their electronic structure and bonding interactions.

Bis{bis-[1-meth-oxy-2-(2-meth-oxy-eth-oxy)ethane-κ(3) O,O',O'']sodium} 1,1,2,2-tetra-phenyl-ethane-1,2-diide

Crystals of the title salt, [Na(C₆H₁₄O₃)₂]₂(C₂₆H₂₀), were grown from a tetra­hydro­furan/diglyme/Et₂O solvent mixture [diglyme is 1-meth­oxy-2-(2-meth­oxy­eth­oxy)ethane]. The cations and dianion are separated in the crystal structure, unlike in the other three structurally characterized dialkali metal tetra­phenyl­ethyl­ene salts. The asymmetric unit contains one [Na(diglyme)₂]⁺ cation and one half of the [Ph₂CCPh₂]²⁻ dianion. The latter lies on a twofold rotation axis. C—C bond-length redistribution displays that excessive electron density of the dianion is predominantly located at the C atoms of a former double bond and at all eight ortho positions. The studied crystal was a twin, with the ratio of two major components being 0.2143 (9):0.7857 (9). The twin operation is a twofold rotation around the a axis.

Group 3 metal stilbene complexes: synthesis, reactivity, and electronic structure studies

Group 3 metal (E)-stilbene complexes supported by a ferrocene diamide ligand were synthesized and characterized. Reactivity studies showed that they behave similar to analogous naphthalene complexes. Experimental and computational results indicated that the double bond was reduced and not a phenyl ring, in contrast to a previously reported uranium (E)-stilbene complex.