Preparation of all N-coordinated zirconium amide amidinates and studies of their reactions with dioxygen and water

Lamb, Adam C.; Wang, Zheng; Cook, Tabitha M.; Sharma, Bhavna; Chen, Shu-Jian; Lü, Zheng; Steren, Carlos A.; Lin, Zhenyang; Chen, Xue-Tai

doi:10.1016/j.poly.2015.07.045

Cited by 8 publications

(7 citation statements)

References 101 publications

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“…They interpret their results with a higher degree of intercalation of the more polar alkanol amines. Thus, tertiary amines with two or three hydroxylated alkyl groups like TEA, TIPA and MDEA appear promising candidates, whereas TRIS and DIPA as primary and secondary amines respectively may impart nucleophilic attack on zirconium 40,41 . PYR as least and DMEA as most basic amines were included in this series as reference points with regard to α -ZrP hydrolysis (cf.…”

Section: Resultsmentioning

confidence: 99%

“…Nevertheless, tetra(triethanolamine)zirconium (CAS 101033-44-7) is claimed as an adhesion promoter, commercialized as ZCA-TEAZ for catalytic (trans)esterifications, used as a cross-link agent for carboxymethylcellulose based hydraulic fluid 46 and reported to circumvent oxygen inhibition in radical acrylate photopolymerization 47 . Furthermore, zirconium amide complexes are known to react with oxygen to form peroxo complexes 41 . This leaves unanswered questions to the authors why swapping one hydroxyethyl group for a methyl group entirely suppresses the formation of chromophores.…”

Section: Resultsmentioning

confidence: 99%

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Hierarchically Ordered α-Zirconium Phosphate Platelets in Aqueous Phase with Empty Liquid

Lin

Schmelter

Imanian

et al. 2019

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Platelets of α-zirconium phosphate (α-ZrP) obtained from the reflux method in H3PO4 are successfully exfoliated into water via the intercalation of alkanol amines. With volume fractions greater than 0.02 they are stacked into tactoids of few layers with a repeat distance in the order of 10 nm. The tactoids align into nematic liquid crystalline phases with irregularly wide interstices of empty liquid. Colloidal processing involves the freeze-drying of such anisotropic fluids and the dispersion of the restacked tacoids into aqueous dispersions of colloidal polymer particles of largely varying size which occupy the otherwise empty liquid between the α-ZrP tactoids and induce piling of the tactoids into columns. Real-time SAXS on drying films and TEM of the obtained coatings demonstrate that the stacked α-ZrP platelets and the polymer particles comprising liquid dry separately without polymer intercalation, while the morphology of the obtained composites can be tuned primarily by the size of the polymer colloids. Concomitant α-ZrP hydrolysis in the exfoliation step is scrutinized as a function of amine basicity and temperature. The role of zirconium based hydrolysis products in the hierarchical α-ZrP assembly is indirectly though consistently confirmed by opposing impacts of ultra-filtration and added oxoanions on the platelets’ spacing, smoothness and aggregation. HAADF-TEM imaging of scattered, singular platelets and XRD peak analysis of the pristine solid shed light on the α-ZrP synthesis. Coexisting flakes and lacunae, both similar in size to the intra-layer crystal domains, suggest the stitching of proto-α-ZrP flakes into extended layers in accordance with our observations on the aging behaviour of α-ZrP dispersions as well as with literature data on related systems.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Hierarchically Ordered α-Zirconium Phosphate Platelets in Aqueous Phase with Empty Liquid

Lin

Schmelter

Imanian

et al. 2019

Sci Rep

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“…The reactions of early-transition-metal complexes with H 2 O have been studied intensely. − The reactions of d 0 complexes with H 2 O have been used to prepare highly uniform, conformal films of metal oxides in the microelectronic industry. , An understanding of the elementary steps in the reactions may facilitate the design of organometallic precursors for such surface growth or modification. Metal complexes have also been grafted onto a support material, such as silica or alumina, to develop supported heterogeneous catalysts. , Protonolysis of ligands on the metal complexes by surface hydroxyl groups is a strategy commonly used to immobilize a metal complex on a support medium. − Investigation of the hydrolysis of metal precursors may therefore shed light on the formation of a catalytically active site of the heterogeneous catalysts .…”

Section: Introductionmentioning

confidence: 99%

Density Functional Theory Study of the Reaction between d⁰ Tungsten Alkylidyne Complexes and H₂O: Addition versus Hydrolysis

et al. 2017

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The reactions of early-transition-metal complexes with HO have been investigated. An understanding of these elementary steps promotes the design of precursors for the preparation of metal oxide materials or supported heterogeneous catalysts. Density functional theory (DFT) calculations have been conducted to investigate two elementary steps of the reactions between tungsten alkylidyne complexes and HO, i.e., the addition of HO to the W≡C bond and ligand hydrolysis. Four tungsten alkylidyne complexes, W(≡CSiMe)(CHSiMe) (A-1), W(≡CSiMe)(CHBu) (B-1), W(≡CBu)(CHBu) (C-1), and W(≡CBu)(OBu) (D-1), have been compared. The DFT studies provide an energy profile of the two competing pathways. An additional HO molecule can serve as a proton shuttle, accelerating the HO addition reaction. The effect of atoms at the α and β positions has also been examined. Because the lone-pair electrons of an O atom at the α position can interact with the orbital of the proton, the barrier of the ligand-hydrolysis reaction for D-1 is dramatically reduced. Both the electronic and steric effects of the silyl group at the β position lower the barriers of both the HO addition and ligand-hydrolysis reactions. These new mechanistic findings may lead to the further development of metal complex precursors.

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“…NMR is one of the primary techniques to probe chemical or conformational exchanges. ,− EXSY (exchange spectroscopy) has proven useful to observe exchanges slow on the NMR timescale. − , EXSY and NOESY are the same experiment except that, for compounds of low molecular weights, EXSY and NOESY cross-peaks are easily recognized as they have opposite phases . Cross-peaks of EXSY have the same phase of the diagonal peaks, while those of NOESY have the opposite phase.…”

Section: Resultsmentioning

confidence: 99%

Syntheses of Group 5 Amide Amidinates and Their Reactions with Water: Different Reactivities of Nb(V) and Ta(V) Complexes

et al. 2022

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Chemistries of Nb(V) and Ta(V) compounds are essentially identical as a result of lanthanide contraction. Hydrolysis of M(NMe 2 ) 5 (M = Nb, Ta), for example, yields [M(μ 3 -O)(NMe 2 ) 3 ] 4 (M = Nb, 1; Ta, 2) reported earlier. The similar reactivities of Nb(V) and Ta(V) compounds make it challenging, for example, to separate the two metals from their minerals. We have found that the reactions of H 2 O with amide amidinates M(NMe 2 ) 4 [MeC(N i Pr) 2 ] (M = Nb, 3; Ta, 4) show that the niobium and tantalum analogues take different principal paths. For the Nb(V) complex 3, the amidinate and one amide ligand are liberated upon treatment with water, yielding [Nb(μ 3 -O)(NMe 2 ) 3 ] 4 (1). For the Ta(V) complex 4, the amide ligands are released in the reaction with H 2 O, leaving the amidinate ligand intact. [Ta(μ 3 -O)(NMe 2 ) 3 ] 4 (2), the analogue of 1, was not observed as a product in the reaction of 4 with H 2 O. To our knowledge, this is the first example of the formation of two different complexes that maintain the (V) oxidation state in both metals. The new complexes M(NMe 2 ) 4 [MeC(N i Pr) 2 ] (M = Nb, 3; Ta, 4) have been prepared by the aminolysis of M(NMe 2 ) 5 (M = Nb, Ta) with i PrN(H)C(Me)=N i Pr (5). The hydrolysis of 3 and 4 has been investigated by DFT electronic structure calculations. The first step in each hydrolysis reaction involves the formation of a hydrogen-bonded complex that facilitates a proton transfer to the amidinate ligand in 3 and protonation of an axial dimethylamide ligand in 4. Both proton transfers furnish an intermediate metal-hydroxide species. The atomic charges in 3 and 4 have been computed by Natural Population Analysis (NPA), and these data are discussed relative to which of the ancillary ligands is protonated initially in the hydrolysis sequence. Ligand exchanges in 3 and 4 as well as the exchange in i PrN(H)C(Me)=N i Pr (5) were probed by EXSY NMR spectroscopy, giving rate constants of the exchanges: 0.430(13) s −1 (3), 0.033(6) s −1 (4), and 2.23(7) s −1 (5), showing that the rate of the Nb complex Nb(NMe 2 ) 4 [MeC(N i Pr) 2 ] (3) is 13 times faster than that of its Ta analogue 4.

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Preparation of all N-coordinated zirconium amide amidinates and studies of their reactions with dioxygen and water

Cited by 8 publications

References 101 publications

Hierarchically Ordered α-Zirconium Phosphate Platelets in Aqueous Phase with Empty Liquid

Hierarchically Ordered α-Zirconium Phosphate Platelets in Aqueous Phase with Empty Liquid

Density Functional Theory Study of the Reaction between d⁰ Tungsten Alkylidyne Complexes and H₂O: Addition versus Hydrolysis

Syntheses of Group 5 Amide Amidinates and Their Reactions with Water: Different Reactivities of Nb(V) and Ta(V) Complexes

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Preparation of all N-coordinated zirconium amide amidinates and studies of their reactions with dioxygen and water

Cited by 8 publications

References 101 publications

Hierarchically Ordered α-Zirconium Phosphate Platelets in Aqueous Phase with Empty Liquid

Hierarchically Ordered α-Zirconium Phosphate Platelets in Aqueous Phase with Empty Liquid

Density Functional Theory Study of the Reaction between d0 Tungsten Alkylidyne Complexes and H2O: Addition versus Hydrolysis

Syntheses of Group 5 Amide Amidinates and Their Reactions with Water: Different Reactivities of Nb(V) and Ta(V) Complexes

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Density Functional Theory Study of the Reaction between d⁰ Tungsten Alkylidyne Complexes and H₂O: Addition versus Hydrolysis