François Nief

Heterocyclopentadienyl Complexes of Group‐3 Metals

Heterocyclopentadienyl complexes of group-3 metals (scandium, yttrium, lanthanum and the lanthanides, and uranium) are compounds in which one or more −CH units of a cyclopentadienyl-like ligand have been replaced by a heteroelement (nitrogen, phosphorus, arsenic, or antimony). These ligands can have very diverse substitution patterns, notably with bridged and cavitand-like structures. In addition to the classical η5-coordination behaviour, the heterocyclopentadienyl ligand can adopt a very large array of coordination patterns. Some complexes have a very promising chemistry since they have been found to activate small molecules such as nitrogen and ethylene.

Complexes containing bonds between group 3, lanthanide or actinide metals and non-first-row main group elements (excluding halogens)

Abstract A comprehensive review of coordination complexes exhibiting bonds between a group 3, lanthanide or actinide metal and a group 14, group 15 or group 16 heteroelement, excluding those of the first row of the periodic table, is presented.

Insights into the Mechanism of Reaction of [(C5Me5)2SmII(thf)2] with CO2 and COS by DFT Studies

Reaction mechanisms for the oxidative reactions of CO(2) and COS with [(C(5)Me(5))(2)Sm] have been investigated by means of DFT methods. The experimental formation of oxalate and dithiocarbonate complexes is explained. Their formation involve the samarium(III) bimetallic complexes [(C(5)Me(5))(2)Sm-CO(2)-Sm(C(5)Me(5))(2)] and [(C(5)Me(5))(2)Sm-COS-Sm(C(5)Me(5))(2)] as intermediates, respectively, ruling out radical coupling for the formation of the oxalate complex.

Synthesis of η1 and η5 complexes of samarium(II) with benzophospholyl ligands

Abstract Reaction of bis(cyclopentadienyl)-2,3-dimethylzirconaindole, obtained by addition of 2-butyne to benzynezirconocene, with PCl 3 , affords 1-chloro-2,3-dimethylphosphindole (1-chloro 2,3-dimethylbenzophosphole in a one-pot reaction and in moderate yield. Treatment of this compound with potassium and subsequent reaction with [SmI 2 (THF) 2 ] afforded bis(η 5 -2,3-dimethylphosphindolyl) bis(tetrahydrofuran)samarium. Treatment of the PP bonded bis(dibenzophospholyl with Sm metal activated by HgCl 2 also affords a complex of Sm II that was shown to be bis(η 1 -dibenzophospholyl tetrakis(tetrahydrofuran)samarium, a σ-Sm phosphide complex. Both complexes were analysed by X-ray crystallography.

Synthesis of a new stable, neutral organothulium(II) complex by reduction of a thulium(III) precursor

The new stable, neutral Tm(II) complex (Cp(ttt))2Tm [Cp(ttt) = 1,2,4-tris(tert-butyl)cyclopentadienyl] can be obtained either by direct reaction of NaCp(ttt) with TmI2 or by reduction of (Cp(ttt))2TmI in non-polar solvents; this latter route may prove itself useful for the isolation of other neutral non-classical low-valent organolanthanide species.

NEW SYNTHESIS AND REACTIONS OF SM(OTF)2(DME)2, A SALT-FREE SAMARIUM(II) TRIFLATE

Abstract A new, simple and high-yield synthesis of a salt-free samarium(II) triflate, [Sm(OTf) 2 (DME) 2 ] is described. In stoichiometric amounts this derivative mediates typical samarium (II) coupling reactions such as pinacolisation, dimerisation of imines and Barbier-type reactions. It can also acts as a precatalyst for Mukaiyama aldol and Michael reactions and Diels-Alder reactions.

Synthesis of mixed phospholyl/cyclooctatetraenyl–lanthanide complexes. Crystal and molecular structure of (cyclooctatetraenyl)[3,4-dimethyl-2,5-bis(trimethylsilyl)-phospholyl](tetrahydrofuran)neodymium

Abstract New mixed phospholyl/cyclooctatetraenyl lanthanide complexes have been prepared by metathesis of phospholylpotassium salts with cyclooctatetraenyllanthanide halide precursors: [(cot)Sm(Tmp)(THF)] ( 5 ), [(cot)Sm(Dsp)] ( 6 ), and [(cot)Nd(Dsp)(THF)] ( 7 ) have been thus prepared (cot=cyclooctatetraenyl, Tmp=2,3,4,5-tetramethylphospholyl, Dsp=3,4-dimethyl-2,5-bis(trimethylsilyl)-phospholyl). Complex 7 has been structurally characterised. Formation of 5 has also been observed in the reaction of [(Tmp) 2 Sm] with cyclooctatetraene. An alternative synthesis of the [{(cot)SmCl(THF)} 2 ] precursor has been reported, and the X-ray crystal structure of this complex determined.

New examples of lanthanide(II) phosphides and arsenides with planar coordination at the heteroatom: Crystal structures of [(Mesityl)2P]2Sm(THF)4 and of [(Mesityl)2 As]2 Sm(THF)4

Reaction of potassium bis(tetramesitylphosphide) or potassium bis(tetramesitylarsenide) with samarium diiodide in THF afforded the title compounds, [(Mesityl)2P]2Sm(THF)4 and [(Mesityl)2As]2Sm(THF)4 respectively. The crystal structures of the two title compounds have been determined, and are similar to that of the already described [(Mesityl)2P]2Yb(THF)4: in all of these compounds the coordination around the heteroatom (P or As) is planar. [(Mesityl)2As]2Sm(THF)4 is the first structurally described compound with an SmAs bond.

Reactivity of a diphosphazirconocene dichloride, (η5-C4Me4P)2ZrCl2. Crystal and molecular structure of a metal-bridged bis(π-heterocyclopentadienyl)zirconium complex, (CO)3Fe(μ-η5,η1-C4Me4P)2ZrCl2

Abstract Reaction at the Zr centre in (η 5 -C 4 Me 4 P) 2 ZrCl 2 ( 1 ) is exemplified by the reaction with MeLi or PhLi to give (η 5 -C 4 Me 4 P) 2 ZrR 2 , with R = Me or Ph. Complex 1 can also react through the lone pair on the P atom with L 2 M(CO) n to give chelates (CO) n M(μ-η 5 ,η 1 -C 4 Me 4 P) 2 ZrCl 2 where M(CO) n = Fe(CO) 3 or W(CO) 4 , in which a new type of bridging η 5 -ligand is present. The crystal structure of (CO) 3 Fe(μ-η 5 ,η 1 -C 4 Me 4 P) 2 ZrCl 2 is described.

New mono- and bis-carbene samarium complexes: synthesis, X-ray crystal structures and reactivity

New samarium carbene complexes have been synthesized and characterized by X-ray diffraction analysis; the carbenic nature was assessed by reactivity studies.