The reaction of the titanium imido complex with 2-butyne leads to the formation of the titanium azadiene complex at ambient temperature instead of yielding the archetypical [2 + 2] cycloaddition product (titanaazacyclobutene) which is usually obtained by combining titanium imido complexes and internal alkynes. The formation of is presumably caused by an initial propargylic C(sp)-H activation step and quantum chemical calculations suggest that the outcome of this unexpected reactivity is thermodynamically favored. The previously reported titanaazacyclobutene (which is obtained by reacting with 1-phenyl-1-propyne) undergoes a rearrangement reaction at elevated temperature to give the corresponding five-membered titanium azadiene complex .
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http://dx.doi.org/10.1039/d1sc04334j | DOI Listing |
Dalton Trans
March 2024
Departamento de Química Orgánica y Química Inorgánica, Instituto de Investigación Química "Andrés M. del Río" (IQAR), Universidad de Alcalá, 28805 Alcalá de Henares-Madrid, Spain.
The redox chemistry of cube-type titanium(IV) nitrido complexes [{Ti(η-CMe)(R)}(μ-N)] (R = η-CMe (1), N(SiMe) (2), η-CHSiMe (3), and η-CH (4)) was investigated by electrochemical methods and chemical reactions. Cyclic voltammetry studies indicate that 1-4 undergo a reversible one-electron reduction at -1.8 V .
View Article and Find Full Text PDFInorg Chem
February 2024
Department of Chemistry, University of Minnesota─Twin Cities, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States.
Low-valent tungsten species generated from WCl and ,-bis(trimethylsilyl)-2,5-dimethyldihydropyrazine (-Me-DHP) promotes the catalytic formation of -phenyl-2,3,4,5-tetraarylpyrroles from diarylacetylenes and azobenzene (). An initial catalyst activation process is a three-electron reduction of WCl with -Me-DHP to afford transient 'WCl' species. Catalytically active bis(imido)tungsten(VI) species via successive one-electron reduction and N═N bond cleavage of was revealed by isolating W(═NPh)Cl(PMePh) from imidotungsten(V) trichloride and in the presence of PMePh.
View Article and Find Full Text PDFChem Commun (Camb)
August 2023
Department of Chemistry, University of Pennsylvania, 231 S 34th Street, Philadelphia, Pennsylvania, USA.
We report the first mononuclear Ti complex possessing a terminal imido ligand. Complex [TpTi{NSi(CH)}(THF)] (2) (Tp = hydridotris(3--butyl-5-methylpyrazol-1-yl)borate) is prepared by reduction of [TpTi{NSi(CH)}(Cl)] (1) with KC in high yield. The connectivity and metalloradical nature of 2 were confirmed by single crystal X-ray diffraction studies, Q- and X-band EPR, UV-Vis and H NMR spectroscopies.
View Article and Find Full Text PDFInorg Chem
October 2022
Department of Chemistry and Biochemistry, University of Texas at El Paso, El Paso, Texas 79968, United States.
Reduction of the diamagnetic Ti(III)/Ti(III) dimer [ClTi(μ-NIm)] () (NIm = [1,3-bis(Dipp)imidazolin-2-iminato], Dipp = CH-2,6-Pr) with 4 and 6 equiv of KC generates the intramolecularly arene-masked, dinuclear titanium compounds [(μ-N-η-Im)Ti] () and {[(EtO)K](μ-N-μ:η-Im)Ti} (), respectively, in modest yields. The compounds have been structurally characterized by X-ray crystallographic analysis, and inspection of the bond metrics within the η-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, and can be assigned respectively as possessing metal centers in formal Ti(III)/Ti(III) and Ti(II)/Ti(II) oxidation states.
View Article and Find Full Text PDFInorg Chem
May 2022
Institut de Chimie Moléculaire de L'Université de Bourgogne (ICMUB), Université de Bourgogne, 9 Avenue Alain Savary, Dijon 21000, France.
Ti-imido complex [TiCl(NBu)(BIPP)] [; BIPP = bis(iminophosphoranyl)phosphide ligand] reacts with terminal alkynes R-C≡CH (R = phenyl, isopropenyl, cyclopropyl, and 2-pyridyl) via P-P bond cleavage of the BIPP ligand. The resulting complexes [TiCl(NPN')(NPhPPh)] () contain a pincer-type NPN' phosphide ligand that incorporates the terminal alkyne and the imido ligand from complex . Complexes feature two chiral centers (Ti and P) with interdependent absolute configurations; thus, they are formed stereoselectively.
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