Synthesis, Structural Characterization, and Catalytic Properties of Group 4 Metal Complexes Incorporating a Phosphorus-Bridged Indenyl-Carboranyl Constrained-Geometry Ligand

l- and rac-lactide polymerisation using scandium and aluminium permethylindenyl complexes

Scandium and aluminium constrained geometry permethylindenyl complexes are reported and their lactide polymerisation study discussed.

Synthesis and characterization of 2-t-butylimino-functionalized indolyl rare-earth metal amido complexes for the catalytic addition of terminal alkynes to carbodiimides: the dimeric complexes with the alkynide species in the μ–η1:η2 bonding modes

Dimeric complexes [(μ–η¹:η²-RCC)REL2]₂ (L = 2-(^tBuNCH)C₈H₅N), with alkynyl in the μ–η¹:η² modes, were isolated in the study of the catalytic reaction.

Reactivities of zero-valent group 10 complexes toward organic isocyanates: synthesis of metallacycles containing dimeric isocyanate units, isocyanate cyclotrimerization, and computational chemistry

Five-membered metallacycles involving dimeric isocyanate units converted into cyclic tetramers and isocyanurates, depending on the central metal or organic isocyanates, and their synthetic and theoretical studies were carried out.

Theoretical insight on ethylene polymerization catalyzed by carborane-containing metal complexes: the role of carborane

Theoretical calculations indicate carborane rather than Cp* plays a decisive role in ethylene polymerization catalyzed by carborane-containing metal complexes.

Large, weakly basic bis(carboranyl)phosphines: an experimental and computational study

Bis(carboranyl)phosphines and their {AuCl} and {Se} derivatives have been the subject of experimental and computational studies.

Imidazolin-2-iminato Ligand-Supported Titanium Complexes as Catalysts for the Synthesis of Urea Derivatives

The reactions of tetrakis(dimethylamido)titanium(IV) [Ti(NMe2)4] with three different imidazolin-2-imines (Im(R)NH; R = tert-butyl (tBu), mesityl (Mes), and 2,6-diisopropylphenyl (Dipp)) afforded the corresponding titanium imidazolin-2-iminato complexes [(Im(R)N)Ti(NMe2)3] (R = tBu, 1a; R = Mes, 1b; R = Dipp, 1c). Treatment of complex 1a with two different carbodiimides [R'N═C═NR'; R' = cyclohexyl (Cy) and isopropyl (iPr)] resulted in the formation of imidazolin-2-iminato titanium mono(guanidinate) complex of the type [(Im(R)N)Ti(R'NC(NMe2)NR') (NMe2)2 (R' = iPr; R = tBu (2a), R = Dipp (2c); R' = Cy, R = tBu (3a)], as yellow solid in 94% yield. However, a similar reaction of 1b and 1c with 2 equiv of phenyl isocyanates at ambient temperature resulted in the formation of corresponding titanium bis(ureate) complexes [(Im(R)N)Ti{κ(2)-OC(NMe2)NPh}2(NMe2)] (R = Mes, 4b and R = Dipp, 4c). Three equivalents of phenyl isothiocyanate reacted with complex 1c to afford respective titanium tris(thioureate) complex [(Im(Dipp)N)Ti{κ(2)-SC(NMe2)NPh}2{κ(1)-SC(NMe2)NPh}] (6c). The molecular structures of 1a-c, 2a, 2c, 3a, 4c, and 6c were established by X-ray diffraction analyses, and, from the solid-state structures of 1a-c, 2a, 2c, 3a, 4c, and 6c, it was confirmed that the imidazolin-2-iminato titanium bond in each case is very short and possesses a multiple-bonding character. The imidazolin-2-iminato titanium complex 1c was utilized as a precatalyst for the addition of amine N-H bond to phenyl isocyanate. High yields of the corresponding urea derivatives were achieved under mild conditions. The mechanistic study of the aforementioned catalytic reaction was performed, and the active catalyst complex 7b was isolated using 2 equiv of iminopyrrole [2-(2,6-iPr2C6H3N═CH)C4H3NH] and the complex 4b. The molecular structure of 7b was thereafter established.

A unique cooperative catalytic system carrying metallic iron and 2-hydroxyethyl 2-bromoisobutyrate for the controlled/living ring-opening polymerization of ε-caprolactone

Iron and 2-hydroxyethyl 2-bromoisobutyrate cooperatively initiates the ε-caprolactone polymerization, yielding polymers with high molecular weight and narrow molecular weight distribution.

Carboranes in the chemist's toolbox

Once seldom encountered outside of a few laboratories, carboranes are now everywhere, playing a role in the development of a broad range of technologies encompassing organic synthesis, radionuclide handling, drug design, heat-resistant polymers, cancer therapy, nanomaterials, catalysis, metal-organic frameworks, molecular machines, batteries, electronic devices, and more. This perspective highlights selected examples in which the special attributes of carboranes and metallacarboranes are being exploited for targeted purposes in the laboratory and in the wider world.

Cyclic tetramers of a five-membered palladacycle based on a head-to-tail-linked isocyanate dimer and their reactivity in cyclotrimerization of isocyanates

Cyclic tetramers of a five-membered palladacycle involving an isocyanate dimer were prepared, and catalytic cyclotrimerization from a palladium zero-compound or a single palladacycle with organic isocyanates was performed.

Titanium complexes supported by imidazo[1,5-a]pyridine-containing pyrrolyl ligand as catalysts for hydroamination and polymerization reactions, and as an antitumor reagent

The syntheses, structures, catalytic properties and antitumor activities of three titanium complexes supported by an imidazo[1,5-a]pyridine-containing pyrrolyl ligand are reported.

Isocyanate diinsertion into the N-H bond of the 2-pyridylamino ligand of organolanthanides

[Cp2LnNHPy]2 (Py = 2-pyridyl) (1a-e) react with phenyl isocyanate to form the N-H diinsertion products Cp2Ln[eta2:eta1-PyNCON(Ph)CONHPh](THF) (Ln = Yb (3a), Er (3b), Y (3c), Dy (3d), Gd (3e)). It has been proven that nPr2NH can abstract one PhNCO unit from 3c to form Cp2Y[eta3-OC(NHPh)NPy] (2c) and nPr2NHCONHPh (4), representing a rare example of selective release of a functional group of ligands in organolanthanide chemistry. Hydrolysis of 2c gives the organic nitrogen-containing product PyNHCONHPh (5). Moreover, 3c can also be obtained by the reaction of 2c with PhNCO. These results demonstrate that the diinsertion of PhN=C=O into the N-H bond of coordinated amino ligands might proceed in a stepwise manner. All the compounds were characterized by elemental analysis and spectroscopic properties. The structures of compounds 3a-e and 4 are also determined through X-ray single-crystal diffraction analysis.

(Diethyl ether){1-[2-(1-methyl-1H-imidazol-2-yl-κN)-1,1-diphenyl-ethyl]-(1,2,3,3a,7a-η)-inden-yl}lithium(I)

In the title compound, [Li(C₂₇H₂₃N₂)(C₄H₁₀O)], the Li atom possesses a nearly planar trigonal coordination environment (assuming the cyclo­penta­dienyl ring of the indenyl group occupies one coordination place). The diethyl ether ligand adopts a nearly planar W-type conformation.

Synthesis, Structural Characterization, Reactivity, and Thermal Stability of [η5:σ-Me2C(C5H4)(C2B10H10)]Ti(R)(NMe2)

Reaction of [eta:(5)sigma-Me2C(C5H4)(C2B10H10)]TiCl(NMe2) (1) with 1 equiv of PhCH2K, MeMgBr, or Me3SiCH2Li gave corresponding organotitanium alkyl complexes [eta:(5)sigma-Me2C(C5H4)(C2B10H10)]Ti(R)(NMe2) (R = CH2Ph (2), CH2SiMe3 (4), or Me (5)) in good yields. Treatment of 1 with 1 equiv of n-BuLi afforded the decomposition product {[eta:(5)sigma-Me2C(C5H4)(C2B10H10)]Ti}2(mu-NMe)(mu:sigma-CH2NMe) (3). Complex 5 slowly decomposed to generate a mixed-valence dinuclear species {[eta:(5)sigma-Me2C(C5H4)(C2B10H10)]Ti}2(mu-NMe2)(mu:sigma-CH2NMe) (6). Complex 1 reacted with 1 equiv of PhNCO or 2,6-Me2C6H3NC to afford the corresponding monoinsertion product [eta:(5)sigma-Me2C(C5H4)(C2B10H10)]Ti(Cl)[eta(2)-OC(NMe2)NPh] (7) or [eta:(5)sigma-Me2C(C5H4)(C2B10H10)]Ti(Cl)[eta(2)-C(NMe2)=N(2,6-Me2C6H3)] (8). Reaction of 4 or 5 with 1 equiv of R'NC gave the titanium eta(2)-iminoacyl complexes [eta:(5)sigma-Me2C(C5H4)(C2B10H10)]Ti(NMe2)[eta(2)-C(R)=N(R')] (R = CH2SiMe3, R' = 2,6-Me2C6H3 (9) or tBu (10); R = Me, R' = 2,6-Me2C6H3 (11) or tBu (12)). The results indicated that the unsaturated molecules inserted into the Ti-N bond only in the absence of the Ti-C(alkyl) bond and that the Ti-C(cage) bond remained intact. All complexes were fully characterized by various spectroscopic techniques and elemental analyses. Molecular structures of 2, 3, 6-8, and 10-12 were further confirmed by single-crystal X-ray analyses.