Titanium Nitrogen Complex Research Articles

Infrared spectroscopy and density functional calculations on titanium-dinitrogen complexes

Titanium-nitrogen complexes were generated by laser ablated titanium (Ti) atoms and N2 gas molecules in this study. These complexes were isolated on the pre-deposited solid Ar matrix on the pre-cooled KBr window (T ∼ 5.4 K), allowing infrared spectra to be measured. Laser ablation experiments with 15N2 isotope provided distinct isotopic shifts in the infrared spectra that strongly implicated the formation of titanium-nitrogen complexes, Ti(NN)x. Density functional theory (DFT) calculations were employed to investigate the molecular structures, electronic ground state, relative energies, and IR frequencies of the anticipated Ti(NN)x complexes. Based on laser ablation experiments and DFT calculations, we were able to assign multiple Ti(NN)x (x = 1–6) species. Particularly, Ti(NN)5 and Ti(NN)6, which have high nitrogen content, may serve as good precursors in preparing polynitrogens.

Synthesis of Nitrogen Heterocycles Utilizing Molecular Nitrogen as a Nitrogen Source and Attempt to Use Air Instead of Nitrogen Gas

Nitrogen fixation using transition metals is a challenging subject. Using a titanium-nitrogen complex, discovered by Yamamoto in 1967, and titanium isocyanate complex, molecular nitrogen could be incorporated into organic compounds to afford various heterocyclic compounds. Furthermore, novel titanium-catalyzed nitrogenation procedure was developed. That is, a THF solution of TiCl 4 or Ti(O i Pr) 4 , and an excess amount of Li and TMSCl was stirred under nitrogen (1 atm) at room temperature overnight and to this solution was added phthalic anhydride. The whole solution was refluxed overnight to afford a phthalimide in over 100 % yield. Using the stoichiometric conditions of the novel nitrogenation, various indole, pyrrole, pyrrolizine, indolizine derivatives and lactams were obtained in good to moderate yields after usual workup. Although the structure of the titanium-nitrogen complex has not been determined yet, the complex is thought to be a mixture of N(TMS) 3 , TiX 2 N(TMS) 2 and XTi=NTMS. Nitrogen in air could be directly fixed using this method, and the natural products, such as monomoline I, lycopodine and pumiliotoxin C, could be synthesized from nitrogen in air as a nitrogen source.

Activation of Nitrogen for Organic Synthesis

AbstractFor Abstract see ChemInform Abstract in Full Text.

Nitrogen Fixation: Synthesis of Heterocycles Using Molecular Nitrogen as a Nitrogen Source.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Activation of nitrogen for organic synthesis

Nitrogen fixation using transition metals is a fascinating process. We have already reported the incorporation of molecular nitrogen into organic compounds using a titanium–nitrogen complex reported by Yamamoto. A novel titanium-catalyzed nitrogenation procedure was developed using TiCl 4 in the presence of an excess amount of Li and TMSCl. One atm pressure of nitrogen gas can be used in this reaction, and the reaction proceeds at room temperature. The procedure is very simple: a THF solution of TiCl 4 or Ti(OiPr) 4, Li, and TMSCl is stirred under an atmosphere of nitrogen at room temperature overnight to give titanium–nitrogen complexes. Although the structures of the titanium–nitrogen complexes have not been determined yet, the complexes are thought to consist of N(TMS) 3, TiX 2N(TMS) 2 and XTi NTMS. To this solution was added a compound having a keto-carbonyl group and the solution was refluxed overnight to give heterocycles. Indole, quinoline, pyrrole, pyrrolizine, indolizine derivatives and lactams could be synthesized from molecular nitrogen in good to moderate yields by a one-pot reaction. Furthermore, nitrogen in an atmosphere could be fixed using this nitrogen fixation method. pumiliotoxin C and lycopodine could be synthesized from nitrogen in air as a nitrogen source. Transmetalation of nitrogen on a titanium–nitrogen complex to a palladium complex could be realized, and aniline, benzamide, allylamide and allylamine derivatives could be synthesized from titanium–nitrogen complexes, a palladium catalyst and the corresponding aryl or allyl halide in the absence or in the presence of carbon monoxide.

Nitrogen Fixation: Synthesis of Heterocycles Using Molecular Nitrogen as a Nitrogen Source

Abstract Nitrogen fixation using transition metals is a fascinating process. We have already reported on the incorporation of molecular nitrogen into organic compounds using a titanium–nitrogen complex reported by Yamamoto. We developed a novel titanium-catalyzed nitrogenation procedure using TiCl4 in the presence of an excess amount of Li and TMSCl. In this reaction, a 1 atm pressure of nitrogen gas can be used and the reaction proceeds at room temperature. The procedure is very simple. A THF solution of TiCl4 or Ti(OiPr)4 (1 equiv.), Li (10 equiv.), and TMSCl (10 equiv.) was stirred under an atmosphere of nitrogen at room temperature overnight to give titanium–nitrogen complexes. Although the structures of the titanium–nitrogen complexes have not yet been determined, they would consist of N(TMS)3, X2TiN(TMS)2, and XTi=NTMS. Using this procedure, various heterocycles, such as indole, quinoline, pyrrole, pyrrolizine, and indolizine derivatives, could be synthesized from molecular nitrogen in good-to-moderate yields as a stoichiometric reaction based on a titanium complex by a one-pot reaction. Furthermore, monomorine I and pumiliotoxin C were synthesized from molecular nitrogen as a nitrogen source. This procedure was further extended for the syntheses of heterocycles using a catalytic amount of titanium complex; also, indole and pyrrole derivatives were obtained in high yields.

Synthesis of allylamides from allyl halides, carbon monoxide, and titanium–nitrogen complexes prepared from molecular nitrogen

4-Phenylbut-3-enamide could be synthesized from corresponding 3-chloroprop-2-enylbenzene, carbon monoxide (1 atm), and titanium–nitrogen complexes, prepared from Ti(O i Pr) 4, Li, TMSCl, and molecular nitrogen (1 atm), using a palladium catalyst. The reaction proceeds via transmetalation of the titanium–nitrogen complex to an acylpalladium complex. P t Bu 3 as a ligand of the palladium catalyst, afforded a good result, and the amounts of Li and TMSCl affected the yield of amide. When the reaction was carried out using a bidentate ligand on the palladium complex under an atmosphere of argon instead of carbon monoxide, an allylamine derivative was obtained.

Nitrogen Fixation Using Titanium Complex: Reinvestigation of the Reaction Conditions

The amounts of Li and TMSCl of a TiX 4 -Li-TMSCl system for a nitrogen fixation method, previously reported by our group, were examined. As the results, the reactivity of titanium-nitrogen complexes prepared from 4 equiv. of Li and 6 equiv. of TMSCl for Ti(OPr-i) 4 (1 equiv.) under an atmosphere of nitrogen was same as that of titanium-nitrogen complexes reported previously.

ChemInform Abstract: Synthesis of Heterocycles from Molecular Nitrogen as a Nitrogen Source

Nitrogen fixation is a very attractive process. We succeeded in nitrogen fixation using a TiCl4- or Ti(O-i-Pr)4-Li-TMSCl system. Nitrogen fixation proceeds at room temperature under 1 atmosphere pressure of nitrogen to give a mixture of titanium nitride complex 12, titanium nitrogen complex 13, and N(TMS)4. Using the titanium nitrogen complexes 1, various heterocycles were synthesized from the corresponding ketocarbonyl compounds. Nitrogen in air could be fixed using this method. The total syntheses of lycopodine and monomolin I were achieved from nitrogen in air as the nitrogen source. On the other hand, transmetalation of the nitrogen moiety of titanium nitrogen complexes 1 to a palladium complex was realized, and the non-substituted anilines could be synthesized from ArX and N2 in the presence of the palladium catalyst. Furthermore, amide could be synthesized from ArX, CO, and N2 using the palladium catalyst.

Synthesis of heterocycles from molecular nitrogen as a nitrogen source

Nitrogen fixation is a very attractive process. We succeeded in nitrogen fixation using a TiCl4- or Ti(O-i-Pr)4-Li-TMSCl system. Nitrogen fixation proceeds at room temperature under 1 atmosphere pressure of nitrogen to give a mixture of titanium nitride complex 12, titanium nitrogen complex 13, and N(TMS)4. Using the titanium nitrogen complexes 1, various heterocycles were synthesized from the corresponding ketocarbonyl compounds. Nitrogen in air could be fixed using this method. The total syntheses of lycopodine and monomolin I were achieved from nitrogen in air as the nitrogen source. On the other hand, transmetalation of the nitrogen moiety of titanium nitrogen complexes 1 to a palladium complex was realized, and the non-substituted anilines could be synthesized from ArX and N2 in the presence of the palladium catalyst. Furthermore, amide could be synthesized from ArX, CO, and N2 using the palladium catalyst.

ChemInform Abstract: Synthesis of Tetrahydroindole Derivatives Using Titanium—Nitrogen Complexes Derived from Molecular Nitrogen.

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Synthesis of Tetrahydroindole Derivatives Using Titanium-Nitrogen Complexes Derived from Molecular Nitrogen

Abstract Synthesis of tetrahydroindole derivatives was realized from keto-alkyne using titanium-nitrogen complexes generated from Ti(OiPr)4, Li, and TMSCl. In this reaction, the electron-withdrawing group on the alkyne gave a good yield, and keto-alkynes having an aromatic ring on the alkyne also gave tetrahydroindole derivatives in good to moderate yields.

チタン‐窒素錯体を用いた有機合成反応の開発 新規Ｎ１ユニット試剤の開発研究

Molecular nitrogen was incorporated into organic compounds via titanium nitrogen complex [TiNMg2Cl2·THF]. Namely, the reaction of titanium isocyanate complex [3THF· Mg2Cl2OTiNCO] prepared from titanium nitrogen complex [TiNMg2Cl2·THF] and CO2 with acid anhydrides afforded cyclic imides and quinazoline derivatives. Using the combination system of nitrogenation and palladium catalyzed carbonylation, phthalimide, isoindolinone, and quinazolines were synthesized from an aryl halide. Furthermore, coupling reaction of ketones with an aryl or vinyl halides in the presence of Pd (0) and titanium isocyanate complexes smoothly proceeded to give divinyl amines or arylvinyl amine via transmetalation.

Incorporation of molecular nitrogen into organic compounds: IV. Novel lactam synthesis by nitrogenation of enol lactones

Enol lactones 7, which are readily prepared from o-haloacetophenone derivatives 15 by palladium-catalyzed carbonylation, react with the titaniumisocyanate complex [3THF·Mg 2Cl 2OTiNCO] ( 1) generated by fixation of CO 2 with titaniumnitrogen complex [TiNMg 2Cl 2·THF] to give the isoindolinone derivatives 8 in good yields.

Incorporation of molecular nitrogen into organic compounds III. Reaction of titanium-nitrogen complexes with acid halides and acid anhydrides

The titanium-nitrogen complex 1, [TiNMg2Cl2·THF] prepared from TiCl3 or TiCl4 and Mg in THF under nitrogen reacts with acid chloride to give amide and/or imide. The cyclic imides were obtained by the reaction of titanium-isocyanate complex 3, [3THF·Mg2Cl2OTiNCO], made from titanium-nitrogen complex 1 and carbon dioxide, and the corresponding cyclic acid anhydrides. Benzoxazone derivatives afforded the corresponding quinazoline derivatives in a similar procedure. These results indicate that molecular nitrogen was incorporated into organic compounds via titanium nitrogen complexes.

ChemInform Abstract: Incorporation of Molecular Nitrogen into Amides and Imides by Use of Titanium‐Nitrogen Complexes.

AbstractMolecular nitrogen is fixed under very mild conditions by a TiCl3‐Mg‐THF system to give the titanium nitrogen complex (IV).

Incorporation of molecular nitrogen into amides and imides by use of titanium nitrogen complexes

Molecular nitrogen was incorporated into amides and imides by the reaction of titanium-nitrogen complex 1 [TiNM g2Cl 2·THF] prepared from TiCl 3 and Mg under N 2 in THF with acyl chlorides 3 . The cyclic imides 10 , 12 , 14 and quinazoline 16 were obtained by the reaction of isocyanate complex[3THF·M g2Cl 2O·TiNCO] ( 6 ) generated by fixation of CO 2 into titanium-nitrogen complex 1 with the corresponding cyclic acid anhydrides 9 , 11 , 13 andbenzoxazone 15 .