Alkane Elimination Research Articles

Structural Tracking of the Potassium‐Mediated Magnesiation of Anisole

The potassium-mediated magnesiation of anisole has been monitored by a combination of X-ray crystallographic and NMR spectroscopic studies. Departing from a heteroleptic alkyl-amido base and anisole, the reaction first stops at an ortho-magnesiated anisole intermediate, but the final destination is an ortho-magnesiated anisole complex with reincorporation of the amine ligand and elimination of alkane (see picture).

Synthesis and Reactivity of Dialkyl Lutetium Complexes Supported by a Novel Bis(phosphinimine)carbazole Pincer Ligand

The synthesis of a novel bis(phosphinimine) ancillary ligand based on a carbazole framework is described (HLPh, 4a; HLPipp, 4b; Ph = phenyl, Pipp = para-isopropylphenyl). Protonolysis with Lu(CH2SiMe3)3(THF)2 afforded the corresponding lutetium dialkyl complexes (LuLPh(CH2SiMe3)2, 5a; LuLPipp(CH2SiMe3)2, 5b), which were thermally sensitive and rapidly underwent intramolecular metalative alkane elimination to generate LuLPh*(CH2SiMe3)(THF), 6a, and LuLPipp*(CH2SiMe3)(THF), 6b, as highly reactive intermediates. Complexes 6a and 6b further decomposed, cleanly generating doubly metalated complexes LuLPh**(THF), 7a, and LuLPipp**(THF), 7b, respectively, as the thermodynamic products. Kinetic analysis of the decomposition of 5a revealed a first-order mechanism with activation parameters ΔH⧧ = 19.2(1) kcal·mol−1 and ΔS⧧ = −8.2(2) cal·K−1·mol−1. Compounds 4a, 4b, 6b, and 7b were characterized by single-crystal X-ray diffraction studies.

Photo‐Driven Si‐C Bond Cleavage in Hexacoordinate Silicon Complexes

AbstractHexacoordinate diorganosilicon complexes of the type (ONNO)SiRR′, with (ONNO) being a di‐anionic salen‐type Schiff base ligand, were shown to undergo Si–C bond cleavage and intramolecular rearrangement (1,3‐shift of R’ to a former imine carbon atom) upon irradiation with UV. The course of this reaction depends on the nature of silicon‐bound substituents: Whereas complexes (ONNO)SiMe2 and (ONNO)SiPh2 give rise to the rearrangement of a methyl and a phenyl group, respectively, complexes of the type (ONNO)Si(aryl)(alkyl) were found to undergo Si–C(alkyl) bond cleavage exclusively.Furthermore, such alkyl groups bearing β‐hydrogen atoms may lead to β‐hydride transfer to the imine carbon atom accompanied by olefin elimination. Irradiation of compounds (ONNO)SiRX, with X being a non‐carbon sacrificial ligand, was shown to give rise to further side reactions: In case of X = F the unexpected formation of (ONNO)SiF2 was observed. In analogy to the photo‐induced rearrangement of (ONNO)SiPh2 the heavier congenor (ONNO)GePh2 exhibits similar behavior, whereas the related tin compound (ONNO)SnPh2 proved inert under these reaction conditions applied.

Synthesis and Structural Characterization of Five-Coordinate Aluminum Complexes Containing Diarylamido Diphosphine Ligands

A series of five-coordinate aluminum complexes supported by o-phenylene-derived amido diphosphine ligands, [N(o-C(6)H(4)PR(2))(2)](-) ([R-PNP](-); R = Ph, (i)Pr) and [N(o-C(6)H(4)PPh(2))(o-C(6)H(4)P(i)Pr(2))](-) ([Ph-PNP-(i)Pr](-)), have been prepared and structurally characterized. Alkane elimination reactions of trialkylaluminum with H[Ph-PNP] (1a), H[(i)Pr-PNP] (1b), and H[Ph-PNP-(i)Pr] (1c) in toluene at -35 degrees C respectively produced the corresponding dialkyl complexes [Ph-PNP]AlR(2), [(i)Pr-PNP]AlR(2), and [Ph-PNP-(i)Pr]AlR(2) (R = Me (2a-c), Et (3a-c), (i)Bu (4a-c)) in high isolated yield. The dihydride complexes [Ph-PNP]AlH(2) (6a), [(i)Pr- PNP]AlH(2) (6b), and [Ph-PNP-(i)Pr]AlH(2) (6c) were prepared in one-pot reactions of in situ prepared dichloride precursors (5a-c) with LiAlH(4) in THF at room temperature. X-ray diffraction studies of 2a-c, 3b-c, 5b, and 6b revealed a distorted trigonal-bipyramidal structure for these molecules in which the two phosphorus donors are mutually trans. The solution structures of these organoaluminum complexes were all characterized by (1)H, (13)C, and (31)P NMR spectroscopy. The NMR data are indicative of solution C(2) symmetry for [Ph-PNP](-) and [(i)Pr-PNP](-) complexes, whereas they are indicative of C(1) for [Ph-PNP-(i)Pr](-) derivatives. The (1)H NMR spectra of 3a-c and 4a-c revealed diastereotopy for the alpha-hydrogen atoms in these molecules.

Low-Coordinate Organoyttrium Complexes Supported by β-Diketiminato Ligands

Several organoyttrium complexes stabilized by β-diketiminato ligands (Ar)NC(R)CHC(R)N(Ar) (Ar = 2,6-iPr2C6H3; R = CH3 (ligand a), R = iBu (ligand b)) have been prepared. Ligand-supported yttrium diiodides LYI2(THF)n were alkylated with organolithium or potassium reagents, yielding low-coordinate bis-alkyl derivatives. Several of these compounds have been characterized by X-ray crystallography, and a discussion of these structures in comparison to similar scandium complexes is presented. An out-of-plane bonding mode is observed in the solid state, analogous to that seen in scandium bis-alkyls, and spectroscopic studies reveal that fluxional behavior in solution is also comparable to that observed for the scandium species. The bis-alkyls LYR2 are susceptible to metalative alkane elimination at room temperature in solution. Activation of (Liga)YR2 with [HNMe2Ph][B(C6F5)4] generates alkyl cations stabilized with η6-arene-bound NMe2Ph. This unique coordination mode was studied via 1D 1H, 13C, and 15N NMR and 2D ROESY spectroscopy and appears to stabilize the alkyl cations against metalative alkane elimination.

Binuclear aluminum complex as an efficient orange emitter in single-layer electroluminescent devices

A binuclear aluminum complex with a chelating anilido-imine conjugated Schiff base ligand, 1,4-{ o-C 6H 4[N(2,6- i Pr 2C 6H 3)][CH N]Al(CH 3) 2} 2C 6H 4 (3), was synthesized from the alkane elimination reaction of trimethylaluminum with the free ligand, 1,4-{ o-C 6H 4[NH(2,6- i Pr 2C 6H 3)][CH N]} 2C 6H 4 (2), at room temperature. The photophysical properties of complex 3 were briefly examined and it was found that complex 3 displays bright orange luminescence in solution and in solid state. Electroluminescent devices were fabricated by doping complex 3 in polymer blend host of poly(vinylcarbazole) and 2- tert-butylphenyl-5-biphenyl-1,3,4-oxadiazol using simple solution spin-coating technique. Efficient orange light emission was obtained from the fabricated single-layer organic light-emitting devices with a maximum current efficiency of 3.2 cd/A.

Monoalkyllanthanide Complexes with New β-Diketiminato Derivative Dianionic Ligands

A new class of β-diketiminato derivative dianionic ligands was designed, and three ligand precursors [CH3C(ArNH)CHC(CH3)(NCH2CH2-NHR)] (Ar = 2,6-(iPr)2C6H3; R = tBu (H2L1), 2,6-(CH3)2C6H3 (H2L2), 2,6-(iPr)2C6H3 (H2L3)) were synthesized. The alkane elimination reactions between these ligand precursors and Ln(CH2SiMe3)3(THF)n provided eight five-coordinate monoalkyllanthanide complexes, in which the ligand serves as a tridentate dianionic donor, with one −CH2SiMe3 and one THF molecule completing the five-coordinate center. These monoalkyl complexes exhibited low to very high catalytic activities for intramolecular hydroamination of 2,2-dimethyl-1-aminopent-4-ene. The catalytic activity increased with increasing metal ion size. For the Nd complex, 98% yield was obtained in 1 h at 60 °C with 0.5 mol % catalyst loading.

An Organozinc Hydrazide-Thiolate Aggregate with a Zn3N4S2 Core

The first organometallic zinc hydrazide-thiolate cluster, [(MeZn)2(PhSZn)(HNNMe2)(H2N-NMe2)(SPh)2]2 (1) has been prepared by alkane elimination from dimethylzinc solutions upon treatment with N,N-dimethylhydrazine and thiophenol and characterised by NMR spectroscopy, elemental analysis and single crystal X-ray diffraction. Compound 1 forms asymmetric aggregates containing a Zn3N4S2 core. The core features rings with different connectivities. A seven-membered ZnSZnNNZnS ring comprises three fivemembered rings, two of a ZnSZnNN and one of a ZnNZnNN atom sequence. Intermolecular S···H bonding is observed in the crystal.

Effect of the structure of alkoxy radicals on the mass-spectral fragmentation of dialkyl alkylphosphonates

Basic fragmentation reaction of dialkyl alkylphosphinates under the conditions of electron ionization proceeds in two steps. In the first step occurs cleavage of C-O bond and splitting the olefin radical off. The intermediate ion formed therewith exerts further fragmentation by the similar way. Peaks of the intermediate ions occurs in the spectra of all dialkyl alkylphosphonates except O-methyl derivatives. In the case of branching at α-carbon atoms of alkoxy radicals cleavage of the first carbon-carbon bond of the alkoxy radical unlike the case of alkyl fluorophosphonates, in the intermediate ion rather than in molecular ion and accompanied by the elimination of alkane. These found regularities allow to explain principal fragmentation pathways of a wide series of phosphoric acids esters of general formula (RO) n P(O)X n−3 (where X is R, Hal, or OMe) with both linear and branched in α-position alkoxy radicals.

Bis[(amidomethyl)pyridine] Zirconium(IV) Complexes: Synthesis, Characterization, and Activity as Olefin Polymerization Catalysts

This contribution describes the synthesis, characterization, and olefin polymerization reactivity of bis(chelate)zirconium complexes bearing (amidomethyl)pyridine ligands [(6-X-C5H3N)CH2NC6F5, X = CH3 (Lig1H), Br (Lig2H), H (Lig3H)]. Metathesis reaction, alkane elimination, and amine elimination provided routes to compounds (Lig1)2ZrCl2 (1), (Lig1)2ZrBz2 (4; Bz = CH2C6H5), and (Lig2)2Zr(NMe2)2 (5). Attempts to prepare (Lig1)2Zr(NMe2)2 in a reaction between Zr(NMe2)4 and Lig1H led instead to compound (Lig1)(Lig1*)ZrF(NMe2) (2), in which one dimethylamino group had been exchanged with one ortho fluoride on the perfluorophenyl ring of the ligand via an aromatic nucleophilic substitution reaction. Halide displacement reaction performed on compound 2 afforded the dichloride compound (Lig1)(Lig1*)ZrCl2 (3). Reaction between Zr(NMe2)4 and Lig3H provided a mixture of (Lig3)2Zr(NMe2)2 and (Lig3)(Lig3*)ZrF(NMe2), the latter being analogous to 2. X-ray crystallographic analysis showed for compound 1 a distorted octa...

Group 4 Metal Complexes of Fluorous (Di)Alkoxide-(Di)Imino Ligands: Synthesis, Structure, Olefin Polymerization Catalysis, and Decomposition Pathways

The coordination chemistry of fluorous (di)alkoxide-(di)imino ligands onto Ti(IV), Zr(IV), and Hf(IV) centers has been studied. The diimino-diol [(CF3)2C(OH)CH2C(Me)═NCH2−]2 ({ONEtNO}H2) reacts selectively with Ti(OiPr)2Cl2 and Zr(CH2Ph)4 to give the corresponding complexes {ONEtNO}TiCl2 (1) and {ONEtNO}Zr(CH2Ph)2 (2), with concomitant alcohol and alkane elimination, respectively. Reactions of the imino-alcohols (CF3)2C(OH)CH2C(R1)═NR2 ({ONR1,R2}H; R1 = Me, Ph; R2 = Ph, CH2Ph) with Ti(OiPr)4 and M(CH2Ph)4 (M = Zr, Hf) gave the corresponding complexes Ti(OiPr)2{ONR1,R2}2 (3a,b) and M(CH2Ph)2{ONR1,R2}2 (M = Zr, 7a,b,c; M = Hf, 8a,b). Dibenzyl complexes 7 and 8 decompose above −30 °C by abstraction of a hydrogen from the methylene ligand backbone by a benzyl group to give M(CH2Ph){ONR1,R2}{ON−R1,R2} complexes (M = Zr, 9a−c; M = Hf, 10a), in which a ligand unit ({ON−R1,R2}) has been transformed to an α,β-unsaturated amido-alkoxy dianionic moiety. A slightly different process was observed for the pentafluoroph...

Aggregation and Reactivity of Organozincate Anions Probed by Electrospray Mass Spectrometry

Electrospray ionization (ESI) of mixtures of organolithium compounds and zinc chloride in tetrahydrofuran produced manifold mono- and polynuclear organozincate anions. Formation of the latter is strongly favored by the incorporation of chloride ligands, which apparently adopt bridging binding modes. Analysis of LinBu/ZnCl2 solutions at different concentrations showed that the relative ESI signal intensities for anions in different aggregation states closely correlate with their expected equilibria in solution. Moreover, the uni- and bimolecular gas-phase reactivity of the mass-selected anionic organozincates was studied. Upon collision-induced dissociation, most of these complexes lose a neutral metal fragment, and only the tributylzincates ZnBu3− react by elimination of alkenes. The tributylzincate complexes were also found to undergo ion−molecule reactions with formic acid. The relative rates for these proton-transfer processes decrease in the series ZnnBu3−, ZnsBu3−, and ZntBu3−, and they also decrease if the butyl groups are substituted for chloride ligands. These trends fully agree with the known solution-phase chemistry of organozinc compounds.

A Mass Spectrometry Study of Alkanes in Air Plasma at Atmospheric Pressure

The positive APCI-mass spectra in air of linear (n-pentane, n-hexane, n-heptane, n-octane), branched [2,4-dimethylpentane, 2,2-dimethylpentane and 2,2,4-trimethylpentane (i-octane)], and cyclic (cyclohexane) alkanes were analyzed at different mixing ratios and temperatures. The effect of air humidity was also investigated. Complex ion chemistry is observed as a result of the interplay of several different reagent ions, including atmospheric ions O(2)(+*), NO(+), H(3)O(+), and their hydrates, but also alkyl fragment ions derived from the alkanes. Some of these reactions are known from previous selected ion/molecule reaction studies; others are so far unreported. The major ion formed from most alkanes (M) is the species [M - H](+), which is accompanied by M(+*) only in the case of n-octane. Ionic fragments of C(n)H(2n+1)(+) composition are also observed, particularly with branched alkanes: the relative abundance of such fragments with respect to that of [M - H](+) decreases with increasing concentration of M, thus suggesting that they react with M via hydride abstraction. The branched C(7) and C(8) alkanes react with NO(+) to form a C(4)H(10)NO(+) ion product, which upon collisional activation dissociates via HNO elimination. The structure of t-Bu(+)(HNO) is proposed for such species, which is reasonably formed from the original NO(+)(M) ion/molecule complex via hydride transfer and olefin elimination. Finally, linear alkanes C(5)-C(8) give a product ion corresponding to C(4)H(7)(+)(M), which we suggest is attributed to addition of [M - H](+) to C(4)H(8) olefin formed in the charge-transfer-induced fragmentation of M. The results are relevant to applications of nonthermal plasma processes in the fields of air depuration and combustion enhancement.

Gas-Phase Reactions of Doubly Charged Lanthanide Cations with Alkanes and Alkenes. Trends in Metal(2+) Reactivity

The gas-phase reactivity of doubly charged lanthanide cations, Ln2+ (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu), with alkanes (methane, ethane, propane, n-butane) and alkenes (ethene, propene, 1-butene) was studied by Fourier transform ion cyclotron resonance mass spectrometry. The reaction products consisted of different combinations of doubly charged organometallic ions-adducts or species formed via metal ion induced hydrogen, dihydrogen, alkyl, or alkane eliminations from the hydrocarbons-and singly charged ions that resulted from electron, hydride, or methide transfers from the hydrocarbons to the metal ions. The only lanthanide cations capable of activating the hydrocarbons to form doubly charged organometallic ions were La2+, Ce2+, Gd2+, and Tb2+, which have ground-state or low-lying d1 electronic configurations. Lu2+, with an accessible d1 electronic configuration but a rather high electron affinity, reacted only through transfer channels. The remaining Ln2+ reacted via transfer channels or adduct formation. The different accessibilities of d1 electronic configurations and the range of electron affinities of the Ln2+ cations allowed for a detailed analysis of the trends for metal(2+) reactivity and the conditions for occurrence of bond activation, adduct formation, and electron, hydride, and methide transfers.

Synthesis and Reactivity of Tantalum Complexes Supported by Bidentate X2 and Tridentate LX2 Ligands with Two Phenolates Linked to Pyridine, Thiophene, Furan, and Benzene Connectors: Mechanistic Studies of the Formation of a Tantalum Benzylidene and Insertion Chemistry for Tantalum−Carbon Bonds

Using either alkane elimination or salt metathesis methods, tantalum complexes have been prepared with new ligand systems with tridentate bis(phenolate)donor (donor = pyridine, furan, and thiophene) or bidentate bis(phenolate)benzene arrangements. The ligand framework has two X-type phenolates connected to the flat heterocyclic L-type donor at the 2,6- or 2,5- positions or to the 2,6- positions of benzene via direct ring−ring (sp_2−sp_2) linkages. Solid-state structures of these complexes show that in all cases the ligands bind in a mer fashion, but with different geometries of the LX_2 frameworks. The pyridine-linked system binds in a Cs-fashion, the furan-linked system in a C2_v-fashion, and the thiophene-linked system in a C_1-fashion. A bis(phenolate)pyridine tantalum tribenzyl species (7), upon heating in the presence of dimethylphenylphosphine, generates a stable benzylidene complex by α-hydrogen abstraction with loss of toluene and PMe_2Ph trapping. This process was found to be independent of PMe_2Ph concentration with ΔH = 31.3 ± 0.6 kcal·mol−1 and ΔS = 3 ± 2 cal·mol−1·K−1, and the kinetic isotope effect kH/kD = 4.9 ± 0.4, consistent with a mechanism involving rate determining α-hydrogen abstraction with loss of toluene, followed by fast phosphine coordination to the resulting benzylidene species. An X-ray structure determination reveals that the benzylidene π-bond is oriented perpendicular to the oxygen−oxygen vector, in accord with the prediction of DFT calculations. Tantalum alkyl complexes with the benzene-linked bis(phenolate) ligand (Ta(CH_3)2[(OC_6H_2-tBu_2)2C_6H_3] (16), Ta(CH_2Ph)2[(OC_6H_2-tBu_2)2C_6H_3] (17), and TaCl_2CH_3[(OC_6H_2-tBu_2)2C_6H_4] (18)) are obtained with (to afford pincer complexes) or without cyclometalation at the ipso-position. Deuterium labeling of the phenol hydrogens and of the linking 1,3-benzene-diyl ring reveals an unexpected mechanism for the metalation of bis(phenol)benzene with TaC_l2(CH_3)3 to generate 18. This process involves protonolysis of a methyl group, followed by C-H/Ta-CH_3 σ bond metathesis leading to cyclometalation of the linking ring, and finally protonation of the cyclometallated group by the pendant phenol. TaCl_2CH_3[(OC_6H_2-tBu_2)2C_6H_4] was found to undergo σ bond metathesis at temperatures over 90 °C to give the pincer complex TaCl_2[(OC_6H_2-tBu_2)2C_6H_3] (1_9) and methane (ΔH = 27.1 ± 0.9 kcal·mol−1; ΔS≠ = −2 ± 2 cal·mol^1·K^1; k_H/k_D = 1.6 ± 0.2 at 125 °C). Ta(CH_3)_2[(OC_6H_2-tBu_2)_2C_6H_3] (16) was found to react with tBuNC to insert into the Ta-CH_3 bonds and generate an imino-acyl species (23). Reaction of 16 with Ph_2CO or PhCN leads to insertion into the Ta-Ph bond to give 21 and 22. Complexes 6, 7, 10, 11-P, 12, 13, 17, 18, 19-OEt_2, 21, 22, and 23 have been structurally characterized by single crystal X-ray diffraction, and all show a mer binding mode of the diphenolate ligands, but the ligand geometry varies leading to C_2v-, pseudo-C_s-, pseudo-C_2-, and C_1-symmetric structures.

Synthesis and Structural Characterization of Constrained-Geometry Organolanthanide Chlorides and Alkyls Incorporating the Ligand [η5:σ-(C9H6)C2B10H10]2−

Interaction of 1-indenyl-1,2-carborane (1) with 2 equiv of KH in refluxing THF gave the dipotassium salt [K2][(C9H6)C2B10H10]. Treatment of [K2][(C9H6)C2B10H10] with 1 equiv of LnCl3 in THF generated the ionic complex [K(THF)6][{η5:σ-(C9H6)C2B10H10}2La(THF)] (2) for early lanthanide or organolanthanide chloride complexes [{η5:σ-(C9H6)C2B10H10}Ln(THF)2(μ-Cl)2K(THF)2]2 (Ln = Y (3a), Gd (3b), Er (3c), Yb (3d)) for late lanthanides. Reaction of 3 with nucleophile NaCp or KCH2C6H4-o-NMe2 afforded the corresponding salt metathesis products [η5:σ-(C9H6)C2B10H10]Ln(η5-C5H5)(THF)2 (Ln = Y (4a), Gd (4b)) or [η5:σ-(C9H6)C2B10H10]Ln(CH2C6H4-o-NMe2)(DME) (Ln = Y (5a), Er (5c)), respectively. Complexes 5 were also synthesized via the alkane elimination reaction of 1-indenyl-1,2-carborane with Ln(CH2C6H4-o-NMe2)3. They represent the first examples of organolanthanide alkyl complexes incorporating a carboranyl ligand. These complexes were fully characterized by various spectroscopic techniques and elemental analyses. Som...

Zinc Hydrazides and Hydrazide‐Alkoxides with Cyclic and Acyclic Hydrazide Substituents

AbstractThe tetrameric organometallic zinc hydrazides the {(RZn)4[NHN(CH2)n]4} (R = Me, Et, iPr and n = 5, 4) (1–6), were prepared by alkane elimination from dialkyl zinc solutions and the ring‐substituted hydrazine derivatives 1‐aminopiperidine and 1‐aminopyrrolidine at ambient temperature. They were characterized by NMR (1H, 13C) and IR spectroscopy, by mass spectrometry and by elemental analyses. The compounds form asymmetric aggregates, containing Zn4N8 cores. Zinc trisalkoxide‐monohydrazides can be prepared in one‐pot syntheses by reacting dialkylzinc solutions simultaneously with alcohols and hydrazines. Reactions of dimethylzinc with isopropanol and monomethylhydrazine or mono‐t‐butylhydrazine in 2:1:1.03 ratio resulted in the formation of [(MeZn)4(NHNHR)(OiPr)3] [R = Me (7), tBu (8)]. In a similar fashion, dialkylzinc compounds react with 1‐aminopiperidine and alcohol in 5:4:4 ratio to give {(RZn)4[NHN(CH2)5](OR′)3]} [R = Me, R′ = iPr (9); R = Et, R′ = Et (10), iPr (11)]. These compounds were characterized as the above compounds. The structures of compounds 8 and 9 were also determined by crystal structure analyses. These compounds show an unsymmetrical aggregation with a Zn4N2O3 cage structure, confirmed by spectroscopic methods in solution.

An Organocadmium Hydroxylamide

The first organometallic cadmium hydroxylamide [Cd(MeCd)(4)(ONEt2)(6)] (1) has been prepared by alkane elimination from dimethylcadmium upon treatment with N,N-diethylhydroxylamine and characterized by variable-temperature NMR spectroscopy (H-1, C-13, Cd-113), single-crystal X-ray diffraction, and elemental analysis. In the solid state compound 1 comprises an Cd5N6O6 backbone with a central octahedral coordinate Cd atom, while all 12 donor atoms are attached to the 5 Cd nuclei whereas in solution it is of highly dynamic nature.

Scandium Alkyl Complexes Supported by a Ferrocene Diamide Ligand

Synthesis of a scandium dimethylbenzyl complex supported by a ferrocene diamide ligand was accomplished by alkane elimination from Sc(CH2Xy-3,5)3(THF)2. The scandium dimethylbenzyl complex Sc(fc[NSi(t-Bu)Me2]2)(CH2Xy-3,5)(THF), 2-(CH2Xy-3,5)(THF), was used as a starting material for the synthesis of the corresponding chloride-bridged dimer, (2-Cl)2, which, in turn, led to a scandium bis(neo-pentyl) ate salt, Li[2-Np2]. Attempts to remove the coordinated THF molecule from 2-(CH2Xy-3,5)(THF) with AlMe3 led to the isolation of a scandium methyl complex with two coordinated AlMe3 molecules, 2-Me(AlMe3)2. Compound 2-Me(AlMe3)2 led to a scandium methyl complex, 2-Me(THF)2, by stirring in THF. All ferrocene diamido compounds were characterized by X-ray crystallography. DFT calculations on model compounds were used to explain the stability of the compounds synthesized and to probe the existence of an iron−scandium interaction. Compounds 2-(CH2Xy-3,5)(THF) and 2-Me(AlMe3)2 polymerize l-lactide.

Zinc Complexes with the Chelating Amido‐Imino Ligand [1‐n‐Butyl‐2‐(2,6‐diisopropylphenyl)iminoacenaphthen‐1‐yl]‐2,6‐diisopropylphenylamide (L): Synthesis, Molecular Structure and Reactivity of [(L)­ZnCl]2, (L)Zn‐nBu and (L)ZnN(SiMe3)2

AbstractDimeric [(L)ZnCl]2 (4) {L = [1‐n‐butyl‐2‐(2,6‐diisopropylphenyl)iminoacenaphthen‐1‐yl]‐2,6‐diisopropylphenylamide} was prepared by treatment of the lithium salt of the ligand (LLi) with equimolar amounts of anhydrous ZnCl2. Treatment of 4 with KN(SiMe3)2 affords the bis(trimethylsilyl)amido compound (L)ZnN(SiMe3)2 (5). The alkylzinc complex (L)Zn‐nBu (6) is the product of the reaction between the adduct LLi·nBuLi (3) and ZnCl2. Compounds 4–6 were characterized by 1H NMR and IR spectroscopy. The molecular structures of 4 and 6 were determined by single‐crystal X‐ray analysis. In the solid state, the molecules of 4 exist as centrosymmetric, heterochiral dimers bridged by chlorine atoms, while compound 6 consists of monomeric molecules with three‐coordinate zinc atoms. The reactions of 6 with tert‐butanol, adamanthanol, 2,5‐di‐tert‐butylaniline and diphenylacetonitrile do not proceed with alkane elimination but with protonation of the ligand affording the amino‐imine LH (7). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)