Amido Compounds Research Articles

Molecular Capacitors: Accessible 6- and 8-Electron Redox Chemistry from Dimeric "Ti(I)" and "Ti(0)" Synthons Supported by Imidazolin-2-Iminato Ligands.

Reduction of the diamagnetic Ti(III)/Ti(III) dimer [Cl2Ti(μ-NImDipp)]2 (1) (NImDipp = [1,3-bis(Dipp)imidazolin-2-iminato]-, Dipp = C6H3-2,6-iPr2) with 4 and 6 equiv of KC8 generates the intramolecularly arene-masked, dinuclear titanium compounds [(μ-N-η6-ImDipp)Ti]2 (2) and {[(Et2O)2K](μ-N-μ-η6:η6-ImDipp)Ti}2 (3), respectively, in modest yields. The compounds have been structurally characterized by X-ray crystallographic analysis, and inspection of the bond metrics within the η6-coordinated aryl substituent of the bridging imidazolin-2-iminato ligand shows perturbation of the aromatic system most consistent with two-electron reduction of the ring. As such, 2 and 3 can be assigned respectively as possessing metal centers in formal Ti(III)/Ti(III) and Ti(II)/Ti(II) oxidation states. Exploration of their redox chemistry reveal the ability to reduce several substrate equivalents. For instance, treatment of 2 with excess C8H8 (COT) forms the novel COT-bridged complex [(ImDippN)(η8-COT)Ti](μ-η2:η3-COT)[Ti(η4-COT)(NImDipp)] (4) that dissociates in THF solutions to give mononuclear (ImDippN)Ti(η8-COT)(THF) (5). Addition of COT to 3 yields heterometallic [(ImDippN)(η4-COT)Ti(μ-η4:η5-COT)K(THF)(μ-η6:η4-COT)Ti(NImDipp)(μ-η4:η4-COT)K(THF)2]n (6). Compounds 4 and 5 are the products of the 4-electron oxidation of 2, while 6 stands as the 8-electron oxidation product of 3. Reduction of organozides was also explored. Low temperature reaction of 2 with 4 equiv of AdN3 gives the terminal and bridged imido complex [(ImDippN)Ti(═NAd)](μ-NAd)2[Ti(NImDipp)(N3Ad)] (7) that undergoes intermolecular C-H activation of toluene at room temperature to afford the amido compound [(ImDippN)Ti(NHAd)](μ-NAd)2[Ti(C6H4Me)(NImDipp)] (8-tol). These complexes are the 6-electron oxidation products of the reaction of 2 with AdN3. Furthermore, treatment of 3 with 4 equiv of AdN3 produces the thermally stable Ti(III)/Ti(III) terminal and bridged imido [K(18-crown-6)(THF)2]{[(ImDippN)Ti(NAd)](μ-NAd)2K[Ti(NImDipp)]} (10). Altogether, these reactions firmly establish 2 and 3 as unprecedented Ti(I)/Ti(I) and Ti(0)/Ti(0) synthons with the clear capacity to effect multielectron reductions ranging from 4 to 8 electrons.

N-Heterocyclic Carbene-Coordinated M(II) (M = Yb, Sm, Ca) Bisamides: Expanding the Limits of Intermolecular Alkene Hydrophosphination.

A series of NHC-stabilized amido compounds (NHC)nM[N(SiMe3)2]2 (M = Yb(II), Sm(II), Ca(II); n = 1, 2) showed remarkable catalytic efficiency in addition of PhPH2 and PH3 to alkenes under mild conditions and low catalyst loading. The effect of σ-donor capacity of NHCs on catalytic activity in hydrophosphination of styrene with PhPH2 and PH3 was revealed. For the series of three-coordinate complexes 1-4M, a tendency to increase the catalytic activity with growth of σ-donating strength of the carbene ligand was clearly demonstrated. The complex (NHC)2Sm[N(SiMe3)2]2 (NHC = 1,3-diisopropyl-2H-imidazole-2-ylidene) (5Sm) proved to be the most efficient catalyst, which enabled hardly realizable transformations such as PhPH2 addition across internal C═C bonds of norbornene and cis- and trans-stilbenes, providing the highest reaction rate for addition of PH3 to styrene. Excellent regio- and chemoselectivities of alkylation of PH3 with styrenes allow for a selective and good-yield synthesis of desired organophosphines─either primary, secondary, or tertiary. Stepwise alkylation of PH3 with various substituted styrenes can be efficiently applied as an approach to nonsymmetric secondary phosphines. The rate equation of the addition of styrene to PH3 promoted by 5Sm was found: rate = k[styrene]1[5Sm]1.

Experimental and Computational Mechanistic Studies of the β-Diketiminatoiron(II)-Catalysed Hydroamination of Primary Aminoalkenes.

A comprehensive mechanistic study by means of complementary experimental and computational approaches of the exo-cyclohydroamination of primary aminoalkenes mediated by the recently reported β-diketiminatoiron(II) complex B is presented. Kinetic analysis of the cyclisation of 2,2-diphenylpent-4-en-1-amine (1 a) catalysed by B revealed a first-order dependence of the rate on both aminoalkene and catalyst concentrations and a primary kinetic isotope effect (KIE) (kH /kD ) of 2.7 (90 °C). Eyring analysis afforded ΔH≠ =22.2 kcal mol-1 , ΔS≠ =-13.4 cal mol-1 K-1 . Plausible mechanistic pathways for competitive avenues of direct intramolecular hydroamination and oxidative amination have been scrutinised computationally. A kinetically challenging proton-assisted concerted N-C/C-H bond-forming non-insertive pathway is seen not to be accessible in the presence of a distinctly faster σ-insertive pathway. This operative pathway involves 1) rapid and reversible syn-migratory 1,2-insertion of the alkene into the Fe-Namido σ bond at the monomer {N^N}FeII amido compound; 2) turnover-limiting Fe-C σ bond aminolysis at the thus generated transient {N^N}FeII alkyl intermediate and 3) regeneration of the catalytically competent {N^N}FeII amido complex, which favours its dimer, likely representing the catalyst resting state, through rapid cycloamine displacement by substrate. The collectively derived mechanistic picture is consonant with all empirical data obtained from stoichiometric, catalytic and kinetics experiments.

Reactions of Neutral Cobalt(II) Complexes of a Dianionic Tetrapodal Pentadentate Ligand: Cobalt(III) Amides from Imido Radicals.

Neutral cobalt(II) complexes of the dianionic tetrapodal pentadentate ligand B2Pz4Py, in which borate linkers supply the anionic charges, are reported. Both the six-coordinate THF adduct 1-THF and the five-coordinate THF-free complex 1 are in a high-spin S = 3/2 configuration in the ground state and have been structurally characterized by X-ray crystallography. These two Co(II) starting materials react rapidly with aryl azides of moderate steric bulk. The thermodynamic products of these reactions are low-spin, diamagnetic, Co(III) amido complexes that are either monomeric, when an external hydrogen atom source such as 1,4-cyclohexadiene is present, or dimeric products formed via C-C coupling of the azide aryl group and internal transfer of H• to the nitrogen. These products are fully characterized and are rare examples of octahedral Co amido compounds; structural determinations reveal significant pyramidalization of the amido nitrogens due to π-π repulsion wherein the amido ligand is primarily a σ donor. The amido products arise from highly reactive Co(III) imido radical intermediates that are the kinetic products of the reactions of 1 or 1-THF with the azide reagents. The imido radicals can be detected by X-band EPR spectroscopy and have been probed by density functional theory computations, which indicate that this doublet species is characterized by a high degree of spin localization on the imido ligand, accounting for the reactivity with hydrogen atom sources and dimerization chemistry observed. The high coordination number and the electron-rich nature of the dianionic B2Pz4Py ligand framework render the imido ligand formed highly reactive.

Reactivity of the parent amido complexes of iridium with olefins: C-NH2 bond formation versus C-H activation.

Herein we report on the different chemical reactivity displayed by two mononuclear terminal amido compounds depending on the nature of the coordinated diene. Hence, treatment of amido-bridged iridium complexes [{Ir(μ-NH2)(tfbb)}3] (1; tfbb = tetrafluorobenzobarrelene) with dppp (dppp = bis(diphenylphosphane)propane) leads to the rupture of the amido bridges forming the mononuclear terminal amido compound [Ir(NH2)(dppp)(tfbb)] (3) in the first stage. On changing the reaction conditions, the formation of a C-NH2 bond between the amido moiety and the coordinated diene is observed and a new dinuclear complex [{Ir(1,2-η2-4-κ-C12H8F4N)(dppp)}2(μ-dppp)] (4) has been isolated. On the contrary, the diiridium amido-bridged complex [{Ir(μ-NH2)(cod)}2] (2; cod = 1,5-cyclooctadiene) in the presence of dppb (dppb = bis(diphenylphosphane)butane) allows the isolation of a mononuclear complex [Ir(1,2,3-η3-6-κ-C8H10)H(dppb)] (5), as a consequence of the extrusion of ammonia. The monitoring of the reaction of 2 with dppb (and dppp) allowed us to detect terminal amido complexes [Ir(NH2)(P-P)(cod)] (P-P = dppb (6), dppp (7)) in solution, as confirmed by an X-ray analysis of 7. Complex 7 was observed to evolve into hydrido species 5 at room temperature. DFT studies showed that C-H bond activation occurs through the deprotonation of one methylene fragment of the cod ligand by the highly basic terminal amido moiety instead of C-H oxidative addition to the Ir(i) center.

Templating Influence of Molecular Precursors on Pr(OH)3 Nanostructures.

Four new praseodymium alkoxo and amido compounds ([Pr3(μ3-OtBu)2(μ2-OtBu)3(OtBu)4(HOtBu)2] (1), [Pr{OC(tBu)3}3(THF)] (2), [PrCl{N(SiMe3)2}2(THF)]2 (3), and [PrCl{OC(tBu)3}2(THF)]2 (4)) were synthesized and structurally characterized by single-crystal X-ray diffraction analysis. Application of these compounds in solvothermal synthesis of praseodymium oxide/hydroxide nanostructures showed their templating influence on the morphology and phase composition of the resulting solid-state materials. Differential reactivity of the chosen alkoxide ligands toward water and the different arrangements of metal-oxygen units in the studied precursor compounds strongly influenced the kinetics of hydrolysis and cross-condensation reactions as manifested in the morphological changes and phase composition of the final products. Thermal decomposition studies of 1-4 confirmed their conversion into the corresponding oxide phases. Activation of compounds 1, 2, and 4 by either a base or a stoichiometric amount of water showed the distinct influence of their chemical configuration on the obtained nanopowders: whereas 1 solely produced nanorods of Pr(OH)3, 2 predominantly formed a mixture of rod-shaped and spherical particles. The solvothermal decomposition of 4 resulted in Pr(OH)2Cl or PrOCl due to the presence of Cl ligands in the molecular precursor. The resultant materials were thoroughly characterized to demonstrate the relationship between precursor chemistry and the processing parameters that are clearly manifested in the morphology and phase of the final ceramics.

A new class of MPV type reduction in group 4 alkoxide complexes of salicylaldiminato ligands: Efficient catalysts for the ROP of lactides, epoxides and polymerization of ethylene

New titanium (IV), zirconium (IV) and hafnium (IV) alkoxide complexes supported by the tridentate [O,N,N] salicylaldiminato ligands were synthesized in high yields and characterized by conventional spectroscopic techniques and single crystal X-ray analysis. The structural composition for some of these complexes was as a result of in situ intramolecular Meerwein–Ponndorf–Verley (MPV) type reduction of the imine moiety from the ligand, resulting in the formation of unexpected amido compounds. Theoretical calculations were performed at the DFT level to calculate the energy barrier for this reduction and rationalize the reactivity pattern. These complexes were found to be active towards the bulk ring opening polymerization (ROP) of rac-lactide (rac-LA), l-lactide (l-LA) and ε-caprolactone (CL), resulting in polymers with good number average molecular weight (Mn) and controlled molecular weight distributions (MWDs). The poly(lactic acid) (PLA) resulting from rac-LA were predominately heterotactic. Interestingly, these compounds were found to catalyze the ROP of epoxides such as rac-cyclohexene oxide (rac-CHO), rac-styrene oxide (rac-SO) and rac-propylene oxide (rac-PO) under solvent free condition. The kinetic and mechanistic studies associated with the polymerization have been included. In addition, these compounds were found to be useful as precatalysts for the polymerization of ethylene.

Intermolecular hydroamination of vinylarenes by iminoanilide alkaline-earth catalysts: a computational scrutiny of mechanistic pathways.

A thorough computational exploration of the mechanistic intricacies of the intermolecular hydroamination (HA) of vinylarenes by a recently reported class of kinetically stabilised iminoanilide [{N^N}Ae{N(SiMe3)2}⋅(THF)n] alkaline-earth amido compounds (Ae = Ca, Sr, Ba) is presented. Two distinct mechanistic pathways for catalytic HA mediated by alkaline-earth and rare-earth compounds have emerged over the years that account equally well for the specific features of the process. On one hand, a concerted proton-assisted pathway to deliver the amine product in a single step can be invoked and, on the other, a stepwise σ-insertive pathway that comprises a rapid, reversible migratory olefin insertion step linked to a less facile, irreversible Ae-C alkyl bond aminolysis. The results of the study presented herein, which employed a heavily benchmarked and reliable DFT methodology, supports a stepwise σ-insertive pathway that involves fast and reversible migratory C=C bond insertion into the polar Ae-N pyrrolido σ bond. This proceeds with strict 2,1 regioselectivity via a highly polarised four-centre transition state (TS) structure, linked to irreversible intramolecular Ae-C bond aminolysis of the alkaline-earth alkyl intermediate as the energetically favourable mechanism. Turnover-limiting aminolysis is consistent with the significant KIE measured; the DFT-derived effective barrier matches the Eyring parameter empirically determined for the best-performing {N^N}Ba(NR2) catalyst gratifyingly well. It also predicts the observed trend in reactivity (Ca<Sr<Ba) correctly and the computationally estimated primary KIE is close to the observed values. Non-competitive kinetic demands militate against the operation of the alternative concerted proton-assisted pathway, which describes N-C bond formation triggered by concomitant amino proton transfer at the C=C linkage via a multi-centre TS structure. A detailed comparison of {N^N}Ae(NR2) catalysts revealed that the variation in the Ae-pyrrolido bond strength together with the degree of protection of the alkaline earth by a sterically encumbering iminoanilide ligand scaffold not only profoundly influences the performance in HA catalysis, but also the likelihood of traversing rival mechanistic pathways.

Probing the metallating ability of a polybasic sodium alkylmagnesiate supported by a bulky bis(amido) ligand: deprotomagnesiation reactions of nitrogen-based aromatic substrates

Exploring the reactivity of sodium butylmagnesiate reagent [{Na(THF)6}(+){(Ph2Si(NAr*)2)Mg(Bu)(THF)}(-)] (1) supported by the bulky chelating silyl(bisamido) ligand {Ph2Si(NAr*)2}(2-) (Ar* = 2,6-iPr2-C6H3) towards N-methylbenzimidazole (bIm(Me)), pyrrole and 2,6-diisopropylaniline (NH2Ar*), this study provides new insights into the ability of this bimetallic base to facilitate direct Mg-H exchange reactions as well as to exhibit polybasicity. Thus 1 effectively promotes the deprotomagnesiation of bIm(Me) under mild reaction conditions to give the α-metallated intermediate [{Na(THF)5}2(+){(Ph2Si(NAr*)2)Mg(bIm(Me)*)}2(-)] (2) (bIm(Me)* = 2-N-methylbenzimidazolyl). Analysis of crystallographic and NMR data of 2 combined with DFT calculations show that the metallated C in the bIm(Me)* ligands possesses a significant carbenic character. Contrasting with previous studies of benzothiazole (btz), 1 does not react with an excess of bIm(Me) even under forcing refluxing conditions. Contrastingly, the amination reactions of equimolar amounts of 1 with pyrrole and 2,6-diisopropylaniline allowed the isolation of [{(Ph2Si(NAr*)(NHAr*))Mg(NC4H4)2(THF)Na(THF)2}] (3) and [{Na(THF)6}(+){(Ph2Si(NAr*)(NHAr*))Mg(NHAr*)2(THF)}(-)] (4) respectively as crystalline solids. Highlighting the ability of 1 to act as a polybasic reagent, 3 and 4 are formed as the result of the deprotonation of two molecules of the relevant amine via its butyl group and one amido arm of the silyl(bisamido) ligand. Similarly, the reactions of 1 with 3 molar equivalents of the relevant amine yielded homoleptic tris(amido) compounds [(THF)2NaMg(NC4H4)3] (5) and [{Na(THF)6}(+){Mg(NHAr*)3}(-)] (7), with the concomitant formation of bis(amine) Ph2Si(NHAr)2, as a result of the complete amination of 1 using its three basic sites. The structures in the solid state of 3 and 4 were elucidated by X-ray crystallography. Despite their similar constitution, these heteroleptic tris(amido)magnesiates adopt contrasting structures, with the former displaying a contacted ion-pair structure, where Na and Mg are connected by two bridging pyrrolyl anions, whereas the latter gives rise to a solvent-separated ion pair motif. To the best of our knowledge 3 represents the first crystallographically characterized magnesium compound containing an anionic non-substituted form of pyrrole. Noticeably, Mg interacts exclusively with the N atoms of the pyrrolyl ligands, forming strong σ-bonds, whereas Na prefers to engage with the π-systems of both NC4-rings.

(Iminophosphoranyl)(thiophosphoranyl)methanide {CH(PPh2NSiMe3)(Ph2PS)}− as a Ligand in Rare-Earth-Element Chemistry

The (iminophosphoranyl)(thiophosphoranyl)methanide {CH(PPh2═NSiMe3)(PPh2═S)}− has been introduced as a ligand into the chemistry of yttrium and the lanthanides. First, the bimetallic potassium reagent [K{CH(PPh2═NSiMe3)(PPh2═S)}]2 was synthesized by deprotonation of [CH2(PPh2═NSiMe3)(PPh2═S)] with KH. [K{CH(PPh2═NSiMe3)(PPh2═S)}]2 forms a dimeric structure in the solid state. The potassium atoms are bridged by the sulfur atom of the ligand. Moreover, an η6 coordination of one phenyl ring is observed. The salt metathesis of [K{CH(PPh2═NSiMe3)(PPh2═S)}]2 with LnCl3 led to the dichloro complexes [{CH(PPh2═NSiMe3)(PPh2═S)}LnCl2(THF)] (Ln = Dy, Er). The bis(amido) compounds [{CH(PPh2═NSiMe3)(PPh2═S)}Ln{N(SiHMe2)2}2] (Ln = Y, Sm, Er, Lu) were obtained by amine elimination from [CH2(PPh2═NSiMe3)(PPh2═S)] and [Ln{N(SiHMe2)2}3(THF)2]. The amido complex [{CH(PPh2═NSiMe3)(PPh2═S)}Er{N(SiHMe2)2}2] could also be accessed by the reaction of [{CH(PPh2═NSiMe3)(PPh2═S)}ErCl2(THF)] with KN(SiHMe2)2.

Fused heterocyclic amido compounds as anti-hepatitis C virus agents

We identified a fused heteroaromatic amido structure based on the phenanthridine skeleton as a superior scaffold for candidate drugs with potent anti-HCV activity. Among the compounds synthesized, a phenanthridine analogue with a 1,3-dioxolyl group ( 24) possessed the most potent anti-HCV activity (EC 50 value: 50 nM), with acceptable cytotoxicity. The structural development and structure–activity relationships of these compounds are described.

Catalytic dehydrogenation of dimethylamine borane by group 4 metallocene alkyne complexes and homoleptic amido compounds

Dehydrogenation of Me(2)NH·BH(3) (1) by group 4 metallocene alkyne complexes of the type Cp(2)M(L)(η(2)-Me(3)SiC(2)SiMe(3)) [Cp = η(5)-cyclopentadienyl; M = Ti, no L (2Ti); M = Zr, L = pyridine (2Zr)] and group 4 metal amido complexes of the type M(NMe(2))(4) [M = Ti (8Ti), Zr (8Zr)] is presented.

Synthesis of Rare Earth (Oxo)nitridocarbonates by Employment of Supercritical Carbon Dioxide, Single‐source Precursor, Solid‐State, and Ion Exchange Reactions

AbstractNovel synthetic approaches to rare earth nitrido‐ and oxonitridocarbonates are described. Dioxy mono‐carbodiimides (Ln2O2CN2) from the second half of the lanthanide series are accessible by insertion of supercritical CO2 into lanthanide amido compounds (e.g. [(Cp2ErNH2)2]), forming single‐source precursors. Ammonolyses of amorphous carbamate compounds afford phase pure Ln2O2CN2, which are also accessible via the crystalline carbamate compound [Ln2{μ‐η1:η2‐OC(OtBu)NH}Cp4] (Ln = Y, Ho, Er, Yb). Urea complexes and homoleptic cyanates of europium and strontium were synthesized by solid‐state reaction of urea with the respective metals. Subsequent thermal treatment (160–240 °C) results in formation of solvent‐free homoleptic cyanates. The Eu2+‐doped compounds [Sr(OCN)2(urea)]:Eu2+ and Sr(OCN)2:Eu2+ as well as the respective pure europium compounds exhibit strong broad band emissions due to 4f65d1–4f7 transitions in the bluish green region. Furthermore, rare earth dicyanamides Ln[N(CN)2]3·2H2O as well as Ln[N(CN)2]3 (with Ln = Eu, Tb, and Gd) were prepared by ion exchange in aqueous solution, followed by evaporation of the solvent at room temperature. Condensed nitridocarbonates such as rare earth tricyanomelaminates [NH4]Ln[HC6N9]2[H2O]7·H2O (Ln = La–Nd, Sm–Dy) were obtained through ion exchange reactions. The luminescence properties of the europium and terbium dicyanamides as well as the tricyanomelaminates have been explored in detail.

Simple, Versatile, and Efficient Catalysts for Guanylation of Amines

Commercially available products such as ZnEt2 (1), MgBu2 (2), and n-BuLi (3) can act as excellent catalytic precursors for the catalytic addition of amines to carbodiimides. Aromatic primary amines bearing different substituents, secondary amines, and heterocyclic amines can undergo this reaction. The synthesis and structural characterization of the zinc guanidinate complex [Zn(Et){(4-t-BuC6H4)N═C(N-i-Pr)(NH-i-Pr)}]2 (15) and the synthesis and characterization of the lithium guanidinate complex [Li{(2,4,6-Me3C6H4)N═C(N-i-Pr)(NH-i-Pr)}(THF)] (16), both of which act as catalysts in the guanylation reaction, allowed us to propose a mechanism involving the formation of amido intermediates. These amido compounds subsequently react with the carbodiimide in an insertion process.

Bicyclic amido compounds with antiprotozoal activity

Aroyl derivatives of 2-aminobicyclo-octanes and 2-azabicyclo-nonanes have been synthesized and tested for their activities against the causative organisms of East African trypanosomiasis and malaria tropica. The acylation induced in general loss of antiprotozoal activity, but a single compound showed good antiplasmodial activity against a multiresistant strain of Plasmodium falciparum.

Structures and stability of Cl–M–N–H rings and cages (M = Si, Ge, Sn, Ti)

Structures and thermodynamic properties of amido and imido monomer and oligomer compounds as potential single-source precursors for group 14 nitrides have been obtained at the B3LYP/DZP level of theory. The thermodynamic analysis shows that Cl3MNH2 amido compounds are stable with respect to both HCl elimination and oligomerization processes. In contrast, Cl2MNH and ClMN species should undergo oligomerization. Formation of trimer compounds is more exothermic compared to the corresponding dimers. The M(IV) and M(II) cubanes are found to be the most promising precursors for group 14 nitrides: the ammonolysis reaction of cubanes is thermodynamically allowed in a wide temperature range for all M.

Heteroleptic ytterbium(ii) complexes supported by a bulky β-diketiminato ligand

Heteroleptic beta-diketiminatoytterbium(ii) complexes [{Yb(L)(mu-I)(thf)}(2)] [: L = {N(Ar*)C(Me)}(2)CH = L(1), : L = {N(SiMe(3))C(Ph)}(2)CH = L(2); Ar* = C(6)H(3)(i)Pr(2)-2,6] were prepared by a salt elimination [from YbI(2)(thf)(2) and KL] or by a ligand redistribution [from YbI(2)(thf)(2) and YbL(2)] reaction. Complexes and were convenient precursors to some new Yb(ii) heteroleptic compounds. Thus, reaction of and with KN(SiMe(3))(2) yielded the mononuclear amido compounds [Yb(L){N(SiMe(3))(2)}(thf)] (: L = L(1) and : L = L(2)). Similarly, with K{N(H)Ar*} gave [Yb(L(1)){N(H)Ar*}(thf)] (). Complex was also obtained via a protolytic reaction of [Yb{N(SiMe(3))(2)}(2)(thf)(2)] with HL(1) at an elevated temperature. Treatment of with slightly less than a stoichiometric amount of K{CH(SiMe(3))(2)} afforded [Yb(L(1)){CH(SiMe(3))(2)}(thf)] (), while using even a small excess of the alkyl reagent resulted in the deprotonation of the beta-diketiminato ligand and the formation of the known dimer [{Yb(L(3))(thf)}(2)] [, L(3) = N[combining macron](Ar*)C(Me)C(H)C(C[combining macron]H(2))N(Ar*)]. Compounds or reacted with KCPh(3) in thf yielding [Yb(L(1)){eta(5)-C(6)H(5)CPh(2)}(thf)] () or [Yb(CPh(3))(2)(thf)(2)] (), respectively; the latter has two differently coordinated CPh(3) ligands. The molecular structures of 1, 2, 4, 5, 6, 8 and 9 were determined by X-ray diffraction.

From Charge Transfer Complexes to Nanorods

In this Centennial Feature Article we outline theoretical efforts in modeling the gas phase reactions along the way to formation of 13−15 binary materials from the donor−acceptor complexes. Recent advances in theoretical studies of structures, stability, and reactivity of 13−15 donor−acceptor complexes, amido and imido compounds, as well as large 13−15 clusters and nanotubes are highlighted. Use of 13−15 compounds as single-source precursors to 13−15 alloys and their potential as hydrogen storage materials are also discussed. We also present directions for further theoretical and experimental studies in this area.

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 &amp; Co. KGaA, 69451 Weinheim, Germany, 2008)

N–H Group Transfer and Oxidative Addition Chemistry Promoted by Isolable Bis(cyclopentadienyl)titanium Sandwich Complexes

AbstractAddition of propylenimine (2‐methylaziridine) to the bis(cyclopentadienyl)titanium sandwich complexes, (η5‐C5Me4R)2Ti (R = iPr, SiMe3), resulted in rapid [NH] group transfer followed by C–H activation of a cyclopentadienyl methyl group to yield the corresponding cyclometalated titanocene amido compounds. Exposure of these molecules to 4 atm of H2 at 55 °C resulted in hydrogenolysis of the metal–carbon bond to form the titanium amido hydride compounds, (η5‐C5Me4R)2Ti(NH2)H. Deuteriolysis with DCl gas confirmed exclusive cyclometalation from the positions adjacent to the isopropyl and trimethylsilyl substituent. Oxidative addition of the N–H bonds of amines has also been observed. Addition of NH3 to either (η5‐C5Me4SiMe3)2Ti or (η5‐C5Me4iPr)2Ti yielded the corresponding titanocene amido hydrides along with the titanocene(III) amides, (η5‐C5Me4R)2TiNH2, arising from formal deprotonation by unreacted sandwich from the putativetitanocene ammonia complex.(© Wiley‐VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2007)