Reactivity of Mg(AlMe) towards neutral tris(pyrazolyl)alkanes.

Various new tris(pyrazolyl)alkanes of the class R'CTp (R' = Me, Et, Pr, iBu; R = Et, Pr, Cy, BuPh, Ph; Pr = cyclopropyl, Cy = cyclohexyl, BuPh = -butylphenyl) were synthesised and their reactivity towards Mg(AlMe) was examined. Along with new examples of recurring structural motifs, such as separated ion pairs and "metal in a box" complexes, , [(MeCTp)Mg][AlMe], several magnesium complexes with new structural features/compositions were obtained. Treatment of the "metal in a box" species [(MeCTp)Mg][AlMe] with THF donor gave the terminal methyl complex [(MeCTp)MgMe(thf)][AlMe].

Rare-earth-metallocene alkylaluminates trigger distinct tetrahydrofuran activation.

Thermal treatment of Cp*2YMe(thf) (Cp* = C5Me5), obtained from Cp*2Y(AlMe4) via donor-induced AlMe3 cleavage, in THF resulted in the concomitant formation of vinyl oxide Cp*2Y(OC2H3)(thf) and 2-ethylene-tetrahydrofuranyl complex Cp*2Y(2-C2H4-OC4H7) via the release of methane. In stark contrast, dissolving Cp*2La(AlMe4) in THF/n-hexane led to the quantitative formation of AlMe3-stabilized 2-tetrahydrofuranyl complex Cp*2La(2-AlMe3-OC4H7), with methane elimination.

Nanoscale Organolanthanum Clusters: Nuclearity-Directing Role of Cyclopentadienyl and Halogenido Ligands.

Tetramethylaluminato/halogenido(X) ligand exchange reactions in half-sandwich complexes [Cp La(AlMe ) ] are feasible in non-coordinating solvents and provide access to large coordination clusters of the type [Cp LaX ] . Incomplete exchange reactions generate the hexalanthanum clusters [Cp La X (AlMe ) ] (Cp =Cp*=C Me , X=I; Cp =Cp'=C H SiMe , X=Br, I). Treatment of [Cp*La(AlMe ) ] with two equivalents Me SiI gave the nonalanthanum cluster [Cp*LaI ] , while the exhaustive reaction of [Cp'La(AlMe ) ] with the halogenido transfer reagents Me GeX and Me SiX (X=I, Br, Cl) produced a series of monocyclopentadienyl rare-earth-metal clusters with distinct nuclearity.

Potential Precursors for Terminal Methylidene Rare-Earth-Metal Complexes Supported by a Superbulky Tris(pyrazolyl)borato Ligand.

A series of solvent-free heteroleptic terminal rare-earth-metal alkyl complexes stabilized by a superbulky tris(pyrazolyl)borato ligand with the general formula [Tp LnMeR] have been synthesized and fully characterized. Treatment of the heterobimetallic mixed methyl/tetramethylaluminate compounds [Tp LnMe(AlMe )] (Ln=Y, Lu) with two equivalents of the mild halogenido transfer reagents SiMe X (X=Cl, I) gave [Tp LnX ] in high yields. The addition of only one equivalent of SiMe Cl to [Tp LuMe(AlMe )] selectively afforded the desired mixed methyl/chloride complex [Tp LuMeCl].

Donor-stabilised molecular Mg/Al-bimetallic hydrides.

Treatment of dimethylmagnesium with dimethylaluminum hydride in common ethereal solvents led to the bimetallic monomagnesium addition compounds [(do)xMg{(μ2-H)(AlMe3)}2] (do = thf, x = 4, do = Et2O, x = 3; do = dme, x = 2). Utilization of methyl tert-butyl ether (mtbe) resulted in alkyl/hydrido overexchange and formation of an 8-membered ring structure of composition [(mtbe)2Mg{(μ2-H)(AlMe3)(μ2-H)(μ2-H)(AlMe2)}]2. Salt metathesis of [(thf)4Mg{(μ2-H)(AlMe3)}2] with potassium 1,2,3,4,5-pentamethyl-cyclopentadienide (KCp*) gave [Cp*Mg{(μ2-H)(AlMe3)}(thf)2] featuring a rare isolable magnesium half-sandwich hydride complex.

Lewis-Acid Stabilized Organoimide Complexes of Divalent Samarium, Europium, and Ytterbium.

Discrete organoimide complexes of the divalent rare-earth metals samarium, europium, and ytterbium are reported. Tandem salt metathesis-protonolysis reactions using Ln bis(tetramethylaluminate) precursors [Ln(AlMe ) ] and monopotassium salts of 2,6-diisopropylaniline (H NDipp) and triphenylsilylamine prove viable and efficient protocols. Depending on the ionic radius of the Ln metal centers and the steric demand of the imido carbon backbone, mono- and dilanthanide arrangements of general composition [(thf) Ln(NR)(AlMe )] (Ln=Sm, Eu, Yb; R=Dipp, SiPh ) are found in the solid state.

Synthesis of homometallic divalent lanthanide organoimides from benzyl complexes.

The reaction of LnI2(thf)2 with benzyl potassium affords the homoleptic benzyl complexes [Ln(CH2Ph)2]n of samarium, europium, and ytterbium. In the cases of Eu and Yb, the treatment of [Ln(CH2Ph)2]n with one equivalent of 2,6-diisopropylaniline gives access to tetrameric organoimide complexes [(thf)Ln(μ3-NDipp)]4, representing the first examples of homometallic Ln(ii) imides. This study revealed that the Yb(ii) organoimide chemistry is significantly different from that of calcium.

Magnesium Stung by Nonclassical Scorpionate Ligands: Synthesis and Cone-Angle Calculations.

A series of tris(pyrazolyl)alkane (RCTp) scorpionate ligands of the type RCTp (R=Me, nBu, SiMe ; R'=H, Me, Ph, iPr, tBu) were synthesized and their ability to coordinate methylmagnesium moieties was examined. The reaction of Mg(AlMe ) with neutral proligands HCTp or Me SiCTp , containing a non-innocent backbone methine moiety, led to deprotonation/rearrangement and SiMe /AlMe exchange to afford [(Me AlCTp ) Mg] and [(Me AlCTp )Mg(AlMe )], respectively, with monoanionic tripodal ligands. Treatment of sterically less demanding RCTp with Mg(AlMe ) produced isostructural dicationic "metal-in-a-box" complexes of the type [(RCTp ) Mg][AlMe ] (R=Me, nBu; R'=H, Me).

Dimethylmagnesium revisited.

A compilation of solvent-free homometallic methyl compounds of the type MMex (x = 1-6) is provided and categorised according to their method of characterisation (powder or single crystal X-ray diffraction, gas electron diffraction (GED), reactivity, unconfirmed). Recrystallisation of polymeric [MgMe2]n from excess GaMe3 led to the formation of highly pure [MgMe2]n suitable for single crystal X-ray crystallographic studies. Transient Mg(GaMe4)2 could be detected in excess GaMe3 by NMR spectroscopy, but its isolation as Mg(GaMe4)2 failed.

Dimethylcalcium.

The salt metathesis reaction between homoleptic calcium bis(trimethylsilyl)amide [Ca{N(SiMe)}] and "halide-free" methyllithium allowed for the isolation of X-ray-amorphous dimethylcalcium [CaMe] in good yields and purities. The formation of [CaMe] was proven by microanalysis and NMR/FTIR spectroscopic methods as well as a series of derivatization reactions. Despite slowly decomposing thf, [CaMe] could be crystallized from chilled thf solutions as the heptametallic adduct [(thf)CaMe].