Divalent ansa-Octaphenyllanthanocenes: Synthesis, Structures, and EuII Luminescence.

Reductive dimerization of fulvenes using low-valent metal precursors is a straightforward one-step approach to access ethylene-bridged metallocenes. This process has so far mainly been employed with fulvenes carrying one or two substituents in the exocyclic position. In this work, a new synthesis of the unsubstituted exocyclic 1,2,3,4-tetraphenylfulvene (1), its full structural characterization by NMR spectroscopy and single-crystal X-ray diffraction, as well as some photophysical properties and its first use in reductive dimerization are described. This fulvene reacted with different lanthanoid metals in thf to provide the divalent ansa-octaphenylmetallocenes [Ln(C5Ph4CH2)2(thf)n] (Ln = Sm, n = 2 (2); Ln = Eu, n = 2 (3); and Ln = Yb, n = 1 (4)). These complexes were characterized by X-ray diffraction, laser desorption/ionization time of flight mass spectrometry, and, in the case of Sm and Yb, multinuclear NMR spectroscopy, showing the influence of the ansa-bridge on solution and solid-state structures compared to previously reported unbridged metallocenes. Furthermore, the luminescence properties of the Eu ansa complex 3 were studied in solution and the solid state, revealing significant differences with the known octa- and deca-phenyleuropocenes, [Eu(C5Ph4H)2(dme)] and [Eu(C5Ph5)2].

Lanthanoid Biphenolates as a Rich Source of Lanthanoid-Main Group Heterobimetallic Complexes.

Several new trivalent dinuclear rare earth 2,2'-methylenebis(6-tert-butyl-4-methylphenolate) (mbmp2- ) complexes with the general form [Ln2 (mbmp)3 (thf)n ] (Ln=Sm 1, Tb 2 (n=3), and Ho 3, Yb 4 (n=2), and a tetravalent cerium complex [Ce(mbmp)2 (thf)2 ] (5) have been synthesised by RTP (redox transmetallation/protolysis) reactions from lanthanoid metals, Hg(C6 F5 )2 and the biphenol mbmpH2 . These new complexes and some previously reported partially protonated rare earth biphenolate complexes [Ln(mbmp)(mbmpH)(thf)n ] react with lithium, aluminium, potassium and zinc organometallic reagents to form lanthanoid-main group heterobimetallic species. When reaction mixtures containing the Ln biphenolate complexes were treated with n-butyllithium, both molecular ([Li(thf)2 Ln(mbmp)2 (thf)n ] (Ln=La 6, Pr 7 (n=2) and Er 8, Yb 9, and Lu 10 (n=1)) and charge separated ([Li(thf)4 ][Ln(mbmp)2 (thf)2 ] (Ln=Y 11, Sm 12, Dy 13, and Ho 14) complexes were isolated. Treatment with trimethylaluminium also led to isolation of molecular ([AlMe2 Ln(mbmp)2 (thf)2 ] (Ln=Pr 15, Sm 16, and Tb 17)) and ionic [La(mbmp)(thf)5 ][AlMe2 (mbmp)] (18) complexes. One gadolinium-potassium ([K(thf)3 Gd(mbmp)2 (thf)2 ] (19)), and one ytterbium-zinc species ([ZnEtYb(mbmp)2 (thf)] (20)) were isolated from treatment of reaction mixtures with potassium bis(trimethylsilyl)amide and diethylzinc respectively.

Selective carbon-phosphorus bond cleavage: expanding the toolbox for accessing bulky divalent lanthanoid sandwich complexes.

The synthesis of two new tetra- and penta-phenycyclopentadienyldiphenylphosphine pro-ligands which readily undergo selective C-P bond cleavage has allowed for the facile synthesis of bulky divalent octa- and deca-phenylmetallocenes of europium, ytterbium and samarium.

New lanthanoid biphenolate complexes, their further reactivity with trimethylaluminium and catalytic activity for the polymerisation of rac-lactide.

A series of rare earth biphenolate complexes of the general form [Ln(mbmp)(mbmpH)(thf)3] (Ln = Y (1), Nd (2), Gd (3), Dy (4), Er (5), Tm (6) and Lu (7)) have been synthesised by redox transmetallation/protolysis (RTP) from the free rare earth metal, Hg(C6F5)2 and 2,2'-methylenebis(6-tert-butyl-4-methylphenol) (mbmpH2). The rare earth metal is six coordinate with one chelating biphenolate mbmp2- ligand and one unidentate monophenolate mbmpH- ligand. The yttrium complex, when crystallised from hot toluene or deuterated benzene, loses a coordinated thf and exhibits coordination through all three phenolate oxygen atoms, as well as the oxygen of the phenol, yielding two solvates [Y(mbmp)(mbmpH)(thf)2]·nsolv (solv = PhMe, n = 1 (8a) or C6D6, n = 2 (8b)). Of these rare earth complexes, the yttrium derivative (1) yielded the heterobimetallic complex [AlMe2Y(mbmp)2(thf)2] (9) when treated with trimethylaluminium, whereas all other complexes produced the transmetallation product [AlMe(mbmp)(thf)] (11). The dinuclear dysprosium complex [Dy2(mbmp)3(thf)3] (10) was isolated alongside 11 from the reaction of 4 with trimethylaluminium, suggesting trimethylaluminium instigates a redistribution reaction. The ROP activity of the mononuclear neodymium, dysprosium, lutetium, and aluminium complexes towards rac-lactide in toluene at 70 °C was found to be poor compared to rare earth complexes of monodentate aryloxides, but increased with increased rare earth ion size.