Vanadium amides

Very unstable modifications, like the reddish, chlorine-free a-copper phthalocyanine, can be stabilized with amides or salts of copper phthalocyanine sulfonic acids (59—63). Mixture with other metal phthalocyanines, eg, tin, vanadium, aluminum, or magnesium, also inhibits crystallization change and poor performance in binders and prints (flocculation) due to the hydrophobic character of unsubstituted phthalocyanines. 

Another interesting asymmetric epoxidation technique using metal catalysis involves the vanadium complexes of A-hydroxy-[2.2]paracyclophane-4-carboxylic amides (e.g., 19), which serve as catalysts for the epoxidation of allylic alcohols with f-butyl hydroperoxide as... 

Various five-coordinate compounds are known for the configuration d of the oxovanadium(IV) and titanium(III). The complexes of the oxo-vanadium can have structures (more or less distorted) referable to the trigonal bip5n amid or more commonly to the square p n amid. 

R = R = Cy R = 1-adamantyl, R = CfiH 5. Te2-3,5 5 ). The vanadium analogue of the latter [V N(l-Ad)(C6H3Me2-3,5) 3] " 4 has also been characterized. Furthermore, a more efficient route to [Cr N(SiMe3)2 3] and a new crystal structure determination has been described. Three-coordinate metal amides have been treated in a general review that covers three-coordinate transition metal species with hard ligands. The electronic structure and bonding in tricoordinate amido complexes of transition metals have also been detailed... 

Comman, C.R., K.M. Geiser-Bush, and P. Singh. 1994. Structural and spectroscopic characterization of a novel vanadium(V)-amide complex. Inorg. Chem. 33 4621 -622. 

The monoammine complex K2[Os(NH3)C15], made by reduction of K[0s03N] with SnCl2 in HC166 or with vanadium(II) or europium(II),55 was once thought to be an amide, K2[Os(NH2)Cl5].67... 

One-step partial oxidation of propane to acrylic acid (an essential chemical widely used for the production of esters, polyesters, amides, anilides, etc.) has been investigated so far on three types of catalysts, namely, vanadium phosphorus oxides, heteropolycompounds and, more successfully, on mixed metal oxides. The active catalysts generally consist of Mo and V elements, which are also found in catalysts used for the oxidation of propene to acrolein and that of acrolein to acrylic acid. 

SMP amides have been used in vanadium(II)-promoted pina-col cross-coupling and in asymmetric oxidations with chiral oxaziridines, The diastereoselective addition of thiocar-boxylic acids to 1 -(2-methylacryloy 1) SMP amides and the stere-ocontrolled addition of various organometallics to a-keto SMP amides have been studied. 

Low-valent metal salts have been used to bring about reductive cleavage of oximes. Corey and Rich-man used chromium(II) acetate to convert O-acetyl ketoximes into imines, which were hydrolyzed to ketones. " Aqueous titanium(III) chloride and vanadium(II) salts also reduce oximes again, the imines are usually hydrolyzed in situ, but some hindered imines, such as compound (37), are isolable." A method of preventing hydrolysis is to carry out the reduction in anhydrous conditions in the presence of an acylating agent. The products of such reactions, when applied to oximes of enolizable ketones, are en-amides. For example, these ketoximes are converted into A/-formylenamines when heated in acetonitrile with anhydrous titanium(III) acetate and acetic formic anhydride cyclohexanone oxime gives the en-amide (38 97% Scheme 22)." This type of reduction has been used by Barton and coworkers to prepare enamides from steroidal oximes. They reported that the reaction could be performed by acetic... 

A patent (726) has described the preparation of 2methyl-pyrazine by reaction with ammonia and air at 350° over a catalyst containing vanadium pentoxide and potassium sulfate a series of cyanomethylpyrazines has been prepared from the corresponding methylpyrazines by reaction with sodium amide in liquid ammonia followed by Af-methyl-A -phenylcyanamide in dioxane (644). 2-Hydroxyiminomethylpyrazine has been prepared from 2-methylpyrazine, sodium amide, and liquid ammonia with butyl nitrite (727, 728), and 2-hydroxy-iminomethyl-3,6-dimethyI-5-pentylpyrazine similarly from 2,3,5-trimethyl-6-pentylpyrazine (648). Nitrones (28) have been prepared from 23-and 2,5-dimethyl-and tetramethylpyrazine through the substituted methylpyridinium (perchlorates) (27) by reaction with p-nitroso-A, fV-dimethylaniline (729). Dehydrogenation of ethylpyrazine at 600° over a calcium cobaltous phosphate catalyst gives 2-vinyl-pyrazine (658). 

Trichlorobis(trimethylamine)vanadium (7.16 g, 0.026 mole), prepared in sealed tubes, is added slowly by means of a transfer tube to a cooled sodium-dried benzene solution of 12.86 g (0.077 mole) of lithium bis(trimethylsilyl)amide (total volume about 120 mL) contained in a 250-mL, round-bottomed flask. A dark-red solution forms. This is stirred at room temperature for 48 hours and the white precipitate is filtered in the usual way. The filtrate is concentrated to about a third of its original bulk and stored under nitrogen at 0° for 24 hours, by which time small brown needles have crystallized. These are filtered off rapidly, washed with a small amount of cold benzene, dried under vacuum, and transferred into Pyrex ampules, which are then sealed. The yield of tris [bis(tri-methylsilyl)amido] vanadium(III) is about 5 g (35%). Anal. Calcd. for V N [Si-(CH3)3] 2 3 V, 9.57 C, 40.63 H, 10.23, N, 7.90. Found V, 9.52 C, 40.41 H, 10.01 N, 7.74... 

Simple complexes of hydroxamic acids with vanadium(V) have been reported, including ones with a variety of nuclearities.249,250 A wide range of TV-substituted mono- and dihydroxamic acids undergo oxygen abstraction upon reaction with V111 and Vlv to form Vv hydroxamate complexes and the respective amides and diamides.251... 

The first example of a /r-oxo-bis(/r-carboxylato)dioxovanadium(IV,V) complex has been reported (68).380 Coupling reactions have been used in the preparation of ligands containing amide groups. One condensation reaction led to the first structurally characterized, deprotonated vanadium(V)-amide product (69).381 This coordination mode was later observed for other amide... 

A theoretical evaluation of ligands that would stabilize a vanadium-vanadium triple bond was undertaken and concluded that O- and N-donors in amidates would yield the greatest stability.890 A lantern-type metal-metal bonded dinuclear V11 complex was synthesized by the reduction of [VCl3(thf)3] with NaHBEt3 followed by addition of the lithium salt of V,V -di-p-tolylformamidate (215). 65 The crystal structure shows the V V distance to be 1.98 A, which is consistent with a fairly strong metal-metal triple bond.865... 

Vanadium pentoxide, 39, 1057 Vanillic acid, 898, 937,1012, 1013 Vanillin, 30, 31, 479, 864, 937, 1012, 1031, 1288-1289 o-Vanlllin, 31,468 Vegetable ivory, 838 Veratraldehyde, 468,1025 Veratramine derivative, 780 Veratric acid, 66 Veratric amide, 469 Veratrole, 127, 495, 898, 1018,1019 Veratronilrile, 479 Vernamycin Ba, 181 Vetivazulene, 368-369 Vilsmeier reagent, see Dimethylformamide-Phosphotyl chloride Vinca alkaloids, 648 Vincadiffbrmine, 648-649 Vinyl acetate, 492, 648,1020,1271 Vinylacetylene, 375, 698 Vinylamines, 41 Vinyl-n-butyl ether, 172 Vinyi d-carbomethoxyethyl ketone, 682, 1271-1272... 

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