Reactions of molybdenum(II) azides Mo(η3-C3H5)(CO)2(L2)(N3) (L2 = en, dppe) toward dipolarophiles

Liu, Fu‐Chen; Liang, Jie-Er; Jin, Jie-Yu; Lin, Yu-Liang; Chu, Yong-Jui; Yang, Pei-Shan; Lee, Gene-Hsian; Peng, Shie‐Ming

doi:10.1016/j.jorganchem.2013.03.023

Cited by 10 publications

(3 citation statements)

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“…To further complete the characterization of the 1,3-dipole Ti azide moieties in complex 7 , its potential reactivity toward organic dipolarophiles was explored. The [3 + 2] cycloaddition reactions between metal azide complexes and dipolarophiles (known as the “i-click” (inorganic click) reaction and mostly studied with activated alkynes) leading to monodentate anionic 1,2,3-triazolate (Tz) metal complexes are well-known for most of the transition-metal azide complexes (Ta, Mo, Mn, Re, Fe, Ru, , Os, Co, Rh, Ir, Ni, , Pd , ), but are still unexplored for d 0 group 4 metal azide complexes. The reaction of the NHC titanium azide complex 7 with a 5-fold excess of DMAD (=dimethyl acetylenedicarboxylate) in dichloromethane at room temperature afforded the titanium bis-triazolato complex 8 (Scheme ) along with a minor impurity (∼10%), unreacted DMAD, and methanotriazoles CH 2 (Tz) 2 and CH(Tz) 3 arising from the reaction between chlorinated solvent and Ti–N 3 forming azidomethanes, which subsequently react with DMAD) .…”

Section: Resultsmentioning

confidence: 99%

Structural Characterization of Tridentate N-Heterocyclic Carbene Titanium(IV) Benzyloxide, Silyloxide, Acetate, and Azide Complexes and Assessment of Their Efficacies for Catalyzing the Copolymerization of Cyclohexene Oxide with CO₂

et al. 2017

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The reactivity of tridentate bis-aryloxy N-heterocyclic carbene (NHC) titanium complexes ([κ 3 -O,C,O]-NHC)-Ti(X 1 )(X 2 ) (X 1 = X 2 = Cl (1); X 1 = X 2 = OiPr (2)) via salt metathesis (with LiOBn, NaOAc), protonolysis (with (tBuO) 3 SiOH), and σ-bond metathesis (with Me 3 SiN 3 ) were investigated, leading to a series of NHC titanium complexes bearing various X and XL type coligands, ([The molecular structures of complexes 3 and 5 were identified by X-ray crystallographic studies, disclosing fivecoordinate complexes, while complexes 4 and 7 crystallize only in the presence of THF, leading to the six-coordinate Ti−THF adducts ([κ 3 -O,C,O]-NHC)Ti(X 1 )(X 2 )(THF) (4-THF and 7-THF). In contrast, the structure of 6 reveals a rare example of a seven-coordinate Ti complex in which the tridentate NHC and two bidentate OAc ligands are coordinated in a pentagonal-bipyramidal fashion around the titanium atom. The reactivity of the 1,3-dipole Ti azide 7 was also further carried out via a [3 + 2] cycloaddition reaction with the dipolarophile dimethyl acetylenedicarboxylate, exhibiting a unique coordination mode for the newly formed triazolato (Tz) ligands to titanium 8 (i.e., as ([κ 1 -N 1 ]-Tz)). Attempts to access NHC-Ti(III) species from the reduction of 1 with LiBEt 3 H•THF lead mainly to ([κ 5 -O,N,C,N,O]-imidazolidine)Ti(Cl)(THF) (9) via hydride transfer to the NHC carbene atom. The fully characterized NHC-Ti complexes 1−7 were evaluated for the copolymerization of cyclohexene oxide with CO 2 . Upon the addition of [PPN]X cocatalysts (with X = Cl, N 3 ), all of the complexes are active at low CO 2 pressure (<0.5 bar) and are highly selective (>99%) toward the formation of atactic poly(cyclohexene oxide-alt-carbonate). While the variation of the coligands has an overall moderate effect on the activity, the results mostly indicate that, in the presence of [PPN]Cl ([PPN] = (Ph 3 P) 2 N), the sterically less hindered coligands in NHC-Ti(IV) isopropoxide, azide, and acetate complexes show better activity with turnovers up to 930 in comparison to other bulky coligands. On the other hand, when the more nucleophilic [PPN]N 3 salt is employed, the sterically more hindered complexes 2−6 show an increase in activity by approximatively 20%, whereas the less encumbered complexes 1 and 7 exhibit a decrease in activity.

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Section: Resultsmentioning

confidence: 99%

Structural Characterization of Tridentate N-Heterocyclic Carbene Titanium(IV) Benzyloxide, Silyloxide, Acetate, and Azide Complexes and Assessment of Their Efficacies for Catalyzing the Copolymerization of Cyclohexene Oxide with CO₂

et al. 2017

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“…More recently, this approach was also extended to N-heterocyclic carbene complexes of the general structure [Au(N 3 )(NHC)]. , However, as far back as the mid-1970s, there have been reports on the cycloaddition reaction of metal azido complexes with electron-poor organic alkynes and other dipolar molecules, as summarized by Frühauf and Beck. , Metal-based building blocks utilized include organometal half-sandwich complexes such as [Fe(Cp)(N 3 )(CO) 2 ] and [Os(N 3 ) 2 (η 6 -C 6 H 6 )(P i Pr 3 )] as well as related ruthenium(II) arene complexes (Scheme B). − The aromatic arene ligand could also be replaced by tris(pyrazolyl)borate (tpz), as in [Ru(N 3 )(tpz)(PPh 3 ) 2 ] . In addition to group VIII metals such as iron(II), ruthenium(II), and osmium(II), Peng and co-workers extended the scope of the iClick reaction to molybdenum(II) allyl dicarbonyl complexes of the general formula [Mo(η 3 -allyl)(N 3 )(CO) 2 (L ∧ L)] with L ∧ L as a chelating N,N or P,P ligand. , …”

Section: Introductionmentioning

confidence: 99%

iClick Reactions of Square-Planar Palladium(II) and Platinum(II) Azido Complexes with Electron-Poor Alkynes: Metal-Dependent Preference for N1 vs N2 Triazolate Coordination and Kinetic Studies with ¹H and ¹⁹F NMR Spectroscopy

et al. 2019

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Two square-planar palladium(II) and platinum(II) azido complexes [M(N 3 )(L)] with L = N-phenyl-2-[1-(2-pyridinyl)ethylidene]hydrazine carbothioamide reacted with four different electron-poor alkynes R−CC−R′ with R = R′ = COOCH 3 , COOEt, COOCH 2 CH 2 OCH 3 or R = CF 3 , R′ = COOEt in a [3 + 2] cycloaddition "iClick" reaction. The resulting triazolate complexes [M-(triazolate R,R' )(L)] were isolated by simple precipitation and/or washing in high purity and good yield. Six out of the eight new compounds feature the triazolate ligand coordinated to the metal center via the N2 nitrogen atom, but fortuitous solubility properties allowed isolation of the N1 isomer in two cases from acetone. When the solvent was changed to DMSO, the N1 → N2 isomerization could be studied by NMR spectroscopy and took several days to complete. 19 F NMR studies of the iClick reaction with F 3 C−CC−COOEt led to identification of a putative early linear intermediate in addition to the N1 and N2 isomers, however with the latter as the final product. Rate constants determined by 1 H or 19 F NMR spectroscopy increased in the order Pd > Pt and CF 3 /COOEt > COOR/COOR with R = CH 3 , Et, CH 2 CH 2 OCH 3 . The second-order rate constant k 2 > 3.7 M −1 s −1 determined for the reaction of [Pd(N 3 )(L)] with F 3 C− CC−COOEt is the fastest observed for an iClick reaction so far and compares favorably with that of the most evolved strained alkynes reported for the SPAAC (strain-promoted azide−alkyne cycloaddition) to date. Selected title compounds were evaluated for their anticancer activity on the GaMG human glioblastoma brain cancer cell line and gave EC 50 values in the low micromolar range (2−16 μM). The potency of the Pd(II) complexes increased with the chain length of the substituents in the 4-and 5-positions of the triazolate ligand.

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“…The molecule exhibits the typical pseudooctahedral three-legged piano-stool geometry around the iridium atom which is η 5 -bonded to the pentamethylcyclopentadienyl group, to the nitrogen atom of the azide group, to the phosphorus atom of the allyldiphenylphosphane ligand (ADPP), and to a nitrogen atom of tetrazole ring. The tetrazolate anion is coordinated to the iridium center through the nitrogen atom N-2, in accordance with the structures reported for related tetrazolato complexes resulting from the cycloaddition of TCNE with other azido complexes. ,,, …”

Section: Resultsmentioning

confidence: 99%

Synthesis of Iridium Tetrazolato, Triazolinato, and Triazolato Complexes by [3+2] Cycloaddition of Iridium(III) Azido Complexes with Unsaturated Nitriles

et al. 2019

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The diazido complexes [Ir(η 5 -C 5 Me 5 )(N 3 ) 2 -(PPh 3 )] (1a), [Ir(η 5 -C 5 Me 5 )(N 3 ) 2 {κ(P)-R 2 PCH 2 CH CH 2 }] (R = Ph (1b), i Pr (1c)) have been synthesized and their [3+2] cycloaddition reaction toward tetracyanoethylene and fumaronitrile investigated. Complexes 1a−1c react with tetracyanoethylene, giving single (2a, 2b, 2c) or double (4a, 4b) azide-nitrile cycloadducts. The complexes [Ir(η 5 -C 5 Me 5 )-have been obtained through the [3+2] cycloaddition reaction involving the azide ligands of complexes 1a,b and two geminal nitrile groups of tetracyanoethylene. Uncommon triazolinato stable complexes [Ir(η 5 -C 5 Me 5 )(N 3 )-{κ(N 1 )-N 3 CH(CN)CH(CN)}(PPh 3 )] (5a) and [Ir(η 5 -C 5 Me 5 )(N 3 ){κ(N 1 )-N 3 CH(CN)CH(CN)}{κ(P)-Ph 2 PCH 2 CHCH 2 }] (5b) have been stereoselectively prepared from 1a,b and fumaronitrile through a single [3+2] cycloaddition reaction between the CC double bond of fumaronitrile and an azide ligand. The treatment of a dichloromethane solution of complexes 5a and 5b with basic alumina gives regioselectively the triazolato complexes 6a and 6b. The structures of complexes 2b, 3a, and 6a have been determined by single-crystal X-ray diffraction analysis.

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Reactions of molybdenum(II) azides Mo(η3-C3H5)(CO)2(L2)(N3) (L2 = en, dppe) toward dipolarophiles

Cited by 10 publications

References 52 publications

Structural Characterization of Tridentate N-Heterocyclic Carbene Titanium(IV) Benzyloxide, Silyloxide, Acetate, and Azide Complexes and Assessment of Their Efficacies for Catalyzing the Copolymerization of Cyclohexene Oxide with CO₂

Structural Characterization of Tridentate N-Heterocyclic Carbene Titanium(IV) Benzyloxide, Silyloxide, Acetate, and Azide Complexes and Assessment of Their Efficacies for Catalyzing the Copolymerization of Cyclohexene Oxide with CO₂

iClick Reactions of Square-Planar Palladium(II) and Platinum(II) Azido Complexes with Electron-Poor Alkynes: Metal-Dependent Preference for N1 vs N2 Triazolate Coordination and Kinetic Studies with ¹H and ¹⁹F NMR Spectroscopy

Synthesis of Iridium Tetrazolato, Triazolinato, and Triazolato Complexes by [3+2] Cycloaddition of Iridium(III) Azido Complexes with Unsaturated Nitriles

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Reactions of molybdenum(II) azides Mo(η3-C3H5)(CO)2(L2)(N3) (L2 = en, dppe) toward dipolarophiles

Cited by 10 publications

References 52 publications

Structural Characterization of Tridentate N-Heterocyclic Carbene Titanium(IV) Benzyloxide, Silyloxide, Acetate, and Azide Complexes and Assessment of Their Efficacies for Catalyzing the Copolymerization of Cyclohexene Oxide with CO2

Structural Characterization of Tridentate N-Heterocyclic Carbene Titanium(IV) Benzyloxide, Silyloxide, Acetate, and Azide Complexes and Assessment of Their Efficacies for Catalyzing the Copolymerization of Cyclohexene Oxide with CO2

iClick Reactions of Square-Planar Palladium(II) and Platinum(II) Azido Complexes with Electron-Poor Alkynes: Metal-Dependent Preference for N1 vs N2 Triazolate Coordination and Kinetic Studies with 1H and 19F NMR Spectroscopy

Synthesis of Iridium Tetrazolato, Triazolinato, and Triazolato Complexes by [3+2] Cycloaddition of Iridium(III) Azido Complexes with Unsaturated Nitriles

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Structural Characterization of Tridentate N-Heterocyclic Carbene Titanium(IV) Benzyloxide, Silyloxide, Acetate, and Azide Complexes and Assessment of Their Efficacies for Catalyzing the Copolymerization of Cyclohexene Oxide with CO₂

Structural Characterization of Tridentate N-Heterocyclic Carbene Titanium(IV) Benzyloxide, Silyloxide, Acetate, and Azide Complexes and Assessment of Their Efficacies for Catalyzing the Copolymerization of Cyclohexene Oxide with CO₂

iClick Reactions of Square-Planar Palladium(II) and Platinum(II) Azido Complexes with Electron-Poor Alkynes: Metal-Dependent Preference for N1 vs N2 Triazolate Coordination and Kinetic Studies with ¹H and ¹⁹F NMR Spectroscopy