Molybdenum arenes

Bis(Tj6-jV,-/V-dimethylaniline)molybdenum has been prepared in good yield by cocondensation of molybdenum atoms with a fifty-fold excess of Af,Af-dimethyl-aniline vapor on a liquid nitrogen cooled surface. This method has been extended to the synthesis of other molybdenum arene complexes and is at present the only synthetic route to such compounds. 

Keywords Dearomatization Osmium Rhenium Molybdenum Arene... 

Hydroxylamine, IV-benzoyl-lV-phenyl-in gravimetry, 1, 532 liquid-liquid extraction, 1, 544 Hydroxylamine, A -cinnamoyl-A -phenyl-liquid-liquid extraction, 1,544 Hydroxylamine, Ar,A -di-(-butyl-metal complexes, 2, 798 Hydroxylamine, Ay/V-diethyl-metal complexes, 2,798 Hydroxylamine, AAmethyl-metal complexes, 2,798 Hydroxylamine, A -2-naphthol-A -nitroso-ammonium salt — see Ncocupferron Hydroxylamine, A -nilrosophenyl-ammonium salt — see Cupferron Hydroxylamine ligands, 2, 101 Hydroxylamine oxido reductase, 6, 727 Hydroxylases molybdenum, 6,658,662 Hydroxylation arenes... 

A set of oxygen donor atoms, providing both a and tt donation to a metal center, is not appropriate to stabilize any low oxidation state of a metal.19 This is, however, a synthetic advantage since very reactive, unstable, low-valent metalla-calix[4]arenes can be generated in situ and intercepted by an appropriate substrate. In the absence of a suitable substrate, the reactive fragment, however, can collapse to form metal-metal bonded dimers. The formation of metal-metal bonds has been, however, so far observed in the case of Group V and VI metals only. The most complete sequence so far reported has been for tungsten, molybdenum, and niobium. 

A molybdenum-mediated oxidative coupling of aniline 1 with cyclohexene 2a provides carbazole 3. Alternatively, the same overall transformation of aniline 1 to carbazole 3 is achieved by iron-mediated oxidative coupling with cyclo-hexa-1,3-diene 2b or by palladium-catalyzed oxidative coupling with arenes 2c. The use of appropriately substituted anilines and unsaturated six-membered hydrocarbons opens up the way to highly convergent organometallic syntheses of carbazole alkaloids. 

As well as organic chiral auxiliaries, organometallic fragments have found some application as chiral auxiliaries in conjugate addition reactions. Particularly noteworthy are chiral molybdenum allyl complexes [69], chiral iron complexes [70], and planar chiral arene chromium species [71]. 

The first systematic investigations of the catalytic Friedel-Crafts-type reaction with alcohols and olefines were performed by Yamamoto and colleagues. After reporting the development of a Pd-catalyzed method for the allylation of different naphthol derivatives [24], the authors used Mo(CO)g for the Friedel-Crafts-type alkylation of electron-rich arenes with allyl acetates [25], The same molybdenum catalyst was additionally used for a Friedel-Crafts-type alkylation of arenes using 1-phenylethanol and styrene as alkylating reagents [26], However, Mo(CO)g is toxic and must be handled under strictly inert conditions. Thus, more stable Lewis acids were necessary. 

Molybdenum and tungsten atoms seem to react with alkylbenzenes more efficiently than chromium atoms yields of 30 to 50% are reported (113). Conventional routes to the synthesis of tungsten-arene complexes are difficult and inefficient so that the ability to prepare these compounds in high yield via tungsten atoms is of special significance. Unfortunately, tungsten has a very high vaporization temperature and the scale of work with its vapor is necessarily limited. 

Methyl benzoate, anisole, and diphenyl ether each give sandwich compounds with chromium vapor, although in rather low yield (32, 55, 110). Chromium appears to attack alkyl ethers and this deoxygenation probably competes with complexation with the aromatic oxygen compounds. No simple product has been isolated from chromium atoms and aniline, but bis(7V,7V-dimethylaniline)chromium has been prepared (32). The behavior of molybdenum and tungsten vapors closely resembles that of chromium in reactions with oxygen- and nitrogen-substituted arenes (113). 

Carbon-based 7]4-ligands, in molybdenum carbonyls, 5, 448 Carbon-based 7]5-ligands, in molybdenum carbonyls, 5, 453 Carbon-based 7]6-ligands, with molybdenum carbonyls arenes, 5, 478 cycloheptatrienes, 5, 480... 

Density functional theory studies arene chromium tricarbonyls, 5, 255 beryllium monocyclopentadienyls, 2, 75 chromium carbonyls, 5, 228 in computational chemistry, 1, 663 Cp-amido titanium complexes, 4, 464—465 diiron carbonyl complexes, 6, 222 manganese carbonyls, 5, 763 molybdenum hexacarbonyl, 5, 392 and multiconfiguration techniques, 1, 649 neutral, cationic, anionic chromium carbonyls, 5, 203-204 nickel rj2-alkene complexes, 8, 134—135 palladium NHC complexes, 8, 234 Deoxygenative coupling, carbonyls to olefins, 11, 40 (+)-4,5-Deoxyneodolabelline, via ring-closing diene metathesis, 11, 219... 

Heterostannenes, preparation and characteristics, 3, 870 Heterosubstituted arenes, metallation, 9, 17 Hexaaryldiplumbanes, preparation, 3, 887 Hexabutyldistannane, preparation, 3, 856 Hexacarbenes, in cobalt(III) complexes, 7, 19 Hexacarbonyl complexes, with molybdenum kinetics and reactivity, 5, 395 photochemistry, 5, 393 solid-support studies, 5, 394 spectroscopic and theoretical studies, 5, 392 Hexadentate iV-substituted triazacyclononane, synthetic applications, 1, 70... 

Molybdenum trioxide, intercalation into, 12, 823 Molybdocenes, as anticancer agents, 1, 892 MOMNs, see Metal-organometallic coordination networks Monisocyanides, with silver(I) complexes, 2, 223 Monitoring methods, kinetic studies, 1, 513 Mono(acetylacetonate) complexes, with Ru and Os halfsandwich rf-arenes, 6, 523 tj2-Monoalkene monodentate ligands, with platinum divalent derivatives, 8, 617 tetravalent derivatives, 8, 625 theoretical studies, 8, 625 zerovalent derivatives, 8, 612... 

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