Molybdenum complexes tris

Molybdenum, tris(phenylenedithio)-structure, 1,63 Molybdenum alkoxides physical properties, 2,346 synthesis, 2,339 Molybdenum blue liquid-liquid extraction, 1,548 Molybdenum cofactor, 6,657 Molybdenum complexes acrylonitrile, 2,263 alkoxides, 3,1307 alkoxy carbonyl reactions, 2,355 alkyl, 3,1307 alkyl alkoxy reactions, 2,358 alkyl peroxides oxidation catalyses, 6,342 allyl, 3,1306... 

Simple 1,3-dienes also undergo a thermal monocyclopropanation reaction with methoxy(alkyl)- and methoxy(aryl)carbene complexes of molybdenum and chromium [27]. The most complete study was carried out by Harvey and Lund and they showed that this process occurs with high levels of both regio-and diastereoselectivity. The chemical yield is significantly higher with molybdenum complexes [27a] (Scheme 7). Tri- and tetrasubstituted 1,3-dienes and 3-methylenecyclohexene (diene locked in an s-trans conformation) fail to react [28]. The monocyclopropanation of electronically neutral 1,3-dienes with non-heteroatom-stabilised carbene complexes has also been described [29]. 

Certain molybdenum complexes, such as MoO(02)(PhCONPhO)22 and the peroxo-molybdenum compound derived from tris(cetylpyridinium) 12-molybdophosphate and hydrogen peroxide (PCMP),28 are able to selectively oxidize secondary alcohols. PCMP is able to perform selective oxidations in catalytic amounts in the presence of hydrogen peroxide as secondary oxidant.29... 

A catalytic asymmetric oxidation of mono-, di-, and tri-substituted alkenes using a chiral bishydroxamic acid (BHA) complex of molybdenum catalyst in air at room temperature leads to good to excellent selectivity. It has been suggested that the Mo-BHA complex combines with the achiral oxidant to oxidize the alkene in a concerted fashion by transfer of oxygen from the metal peroxide to the alkene.78 The chiral BHA-molybdenum complex has been used for the catalytic asymmetric oxidation of sulfides and disulfides, utilizing 1 equiv. of alkyl peroxide, with yields up to 83% and ees up to 86%. An extension of the methodology combines the asymmetric oxidation with kinetic resolution providing excellent enantioselectivity (ee = 92-99%).79... 

A large range of different ionic liquids have been screened in the epoxidation of cyclooctene with dioxomolybdenum(VI) complexes and ferf-butyl hydrogenperoxide as oxidant, as shown in Table 5.2.[32] With the diazabutadiene complex, 48, as catalyst, inferior turnover frequencies were observed relative to the reaction in neat substrate or in dichloromethane and the recycling potential of the catalyst turned out to be only limited. Catalyst immobilisation was better with the cationic tris(methylaminomethyl)ethane complex, 49, however at the expense of selectivity. Of the ionic liquids tested, [C4Ciim][Tf2N] gave the best results for both molybdenum complexes. 

As indicated in Section 14.20.3.4, borepins can react with organometallics to form complexes in which the borepin ring serves as an rf ligand to the metal. Thus, 1-methylborepin 15 reacted with tris(pyridine)molybdenum tricarbonyl to afford the corresponding molybdenum complex 16 as a red, air-sensitive oil, as in Equation (1) <19970M1884>. 

A wide series of ferrocenyl-molybdenum complexes of known redox properties bear the tris(3,5-dimethylpyrazolyl)borato ligand or the N,iV, N"-trimethyl-l,4,7-triazacyclononane ligand. They are illustrated in Scheme 7-7 [55 — 59]. 

Recent work by Stone provides additional examples of the photoreactivity of carbyne carbonylmetal complexes. Irradiation of the 2,6-xylylcar-byne molybdenum complex 209 in the presence of triphenylphosphine affords the ketenyl complexes 210, which slowly transform into the tri-phenylphosphine-substituted carbyne complexes 211 [Eq. (165)] (J5). In... 

PRhC32H38, Rhodium, (l,4-butanediyi)(Ti -pentamethylcyclopentadienyI)(tri-phenylphosphine)-, 22 173 PS2C4H11, Phosphinodithioic acid, diethyl-molybdenum complexes, 23 120, 121 PS3C,2H27, Phosphorotrithious acid tributyl ester, 22 131... 

PUC24H27, Uranium(IV), tris(n -cyclopenta-dienyl)[(dimethylphenylphosphoranyli-dene)methyl], 27 177 P2, Phosphorus, di-, molybdenum complex, 27 224... 

Y. Ishii, K. Yamawaki, T. Yoshida, T. Ura, M. Ogawa, Oxidation of olefins and alcohols by peroxo-molybdenum complex derived from tris(cetylpyridinium) 12-molybdophosphate and hydrogen peroxide, /. Org. Chem. 52 (1987) 1868. 

Jonas and co-workers have pointed out that often a compromise must be found between sensitivity and resolution in NMR spectroscopy [76]. Line narrowing is optimum in regions of low supercritical fluid density (where the viscosity is low), but then the solubility of compounds is also low. Sometimes, admixtures with small amounts of low-viscosity solvents such as acetone may be tried to obtain a reasonable concentration of the compounds studied, i.e. coordination compounds such as (R-N=CH)2Mo(CO)4. However, line widths for this compound decrease by a factor of about four to six when comparing benzene-dg solutions to supercritical CO2 (with 8% acetone-de). The dispersion of the nitrogen chemical shift ensures identification of coordinated ligands by using NMR, in the above molybdenum complex, where A5( n) = -36 ppm) [75]. 

H, Hydrogen, molybdenum complex, 27 3 tungsten complex, 27 6, 7 H2AUF5OP5RUC73HJ0, Ruthenium(l+), carbonyl-di-p-hydrido-tris(triphenyl-phosphine)[(triphenylphos-phine)gold]-, hexafluorophos-phate(l-), 29 281... 

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