Homoleptic alkyl

Allyl Complexes. Allyl complexes of uranium are known and are usually stabilized by cyclopentadienyl ligands. AEyl complexes can be accessed via the interaction of a uranium halide and an allyl grignard reagent. This synthetic method was utilized to obtain a rare example of a "naked" homoleptic allyl complex, U(T -C2H )4 [12701 -96-17, which decomposes at 0°C. Other examples, which are more stable than the homoleptic allyl complex have been synthesized, ie, U(allyl)2(OR)2 (R = alkyl), U(allyl)2X (X = halide), and U(allyl)(bipy)2. 

Hydrocarbyl Complexes. Stable homoleptic and heteroleptic uranium hydrocarbyl complexes have been synthesized. Unlike the thorium analogues, uranium alkyl complexes are generally thermally unstable due to P-hydride elimination or reductive elimination processes. A rare example of a homoleptic uranium complex is U(CH(Si(CH2)3)2)3, the first stable U(I11) homoleptic complex to have been isolated. A stmctural study indicated a triganol... 

Methyl derivatives, octahedral [EnMeg] " species, are known for most of the lanthanides. The first homoleptic, neutral lanthanide alkyl was obtained using the bulky alkyl CH(SiMe3)2 ... 

Chromium alkyls [(>j -(3-t-Bu-5-Mepz)3B)CrR] (R = Et, CH2SiMc3, Ph) follow from the corresponding homoleptic complexes and alkyllithium compounds (97CEJ1668). 

Homoleptic lanthanide(III) tris(amidinates) and guanidinates are among the longest known lanthanide complexes containing these chelating ligands. In this area the carbodiimide insertion route is usually not applicable, as simple, well-defined lanthanide tris(alkyls) and tris(dialkylamides) are not readily available. A notable exception is the formation of homoleptic lanthanide guanidinates from... 

Examples of silver(l) alkyl and alkenyl (including aryl) complexes have been known from as early as 1941 6-9 however, the number of examples is fairly limited with respect to that of the heavier congeners, copper(l) and gold(l). Such a phenomenon can readily be attributed to the relatively low stability of this class of complexes, both photochemically and thermally. Simple homoleptic alkyl and alkenyl complexes of silver(i) are known to be very unstable under ambient temperature and light, and successful isolation of this class is fairly limited and mainly confined to those involving perfluoroorganics.10 The structures and the metal-carbon bond-dissociation energies for... 

Surface organometallic chemistry with rare-earth metals (or lanthanides) on various inorganic oxides has advanced considerably during the past decade but is still in its infancy. A major drawback has been the difficult access and handling of pure (homoleptic) Ln alkyl precursors with reactive Ln-C(alkyl) bonds [101]... 

Iron, as found in the porphyrin derivative hemoglobin, complexes CO to form a stable metal carbonyl. Iron also forms a variety of metal carbon monoxide derivatives such as the homoleptic Fe(CO)5, Fe2(CO)9 and Fe3(CO)i2, the anionic [Fe(CO)4] and its covalent derivative Fe(CO)4Br2, [CpFe(CO)2] and its alkylated covalent derivatives CpFe(CO)2-R with its readily distinguished n (and and a (and / ) iron carbon bonds. By contrast. Mg in its chlorin derivative chlorophyll, which very much resembles porphyrin, forms no such bonds with CO nor is there a rich magnesium carbonyl chemistry (if indeed, there is any at all). 

The method of alkane elimination is a versatile approach for the synthesis of inorganic heterocycles comprised of alternating electropositive and electronegative p-block elements. Typically, this method involves the reaction of a homoleptic alkyl derivative of the more electropositive element with a hydride of the more electronegative element with the elimination of a volatile alkane. 

Homoleptic complexes with bidentate C C donor ylide derivatives are well known. Oxidative addition of some gold(I) [Au2 (CH2)2PR2 2] species by addition of halogen, pseudo-halogen, or alkyl halide affords dinuclear Au(II) complexes which... 

Homoleptic Nbv and Tav dialkylamides have been obtained (equation S).263,264 Extensive reduction, increasing with the length of the alkyl chain, was observed with niobium, the predominant products then being [Nb(NR2)4] (R = Et, Pr , Bun Section 34.3.5.4). Oxidation... 

Hexaalkoxides are only known for the two elements tungsten and uranium. In both cases, physical and spectroscopic data are consistent with monomeric, octahedral complexes. Tungsten hexaalkoxides are pale yellow or colorless substances that readily sublime and exhibit the expected H NMR and mass spectra.189 The totally symmetric v(W—O) stretch occurs between 530 and 600 cm-1 in the IR spectrum, depending on the alkyl substituents. In contrast, the homoleptic phenoxide W(OPh)6 is intense red in color due to the presence of a strong oxygen-to-metal charge transfer band in this d° complex which absorbs in the visible part of the spectrum.36... 

The term homoleptic is analogous to binary just as SiCl4 is a binary chloride, Si(CH3)4 is a homoleptic alkyl in which Si is combined with just one type of group. 

Preparative routes to homoleptic alkyls/aryls must take account of the sensitivities of the products, as well as the usual thermodynamic and kinetic factors. The following will serve as examples. 

Homoleptic carbonyl ligands, in palladium complexes, 8, 197 Homoleptic chromium alkyl compounds, preparation,... 

Homoleptic germylenes, preparation and properties, 3, 773 Homoleptic lanthanide(II) alkyl compounds, properties, 4, 4 Homoleptic manganese aryl complexes, preparation, 5, 816 Homoleptic manganese isonitrilates, preparation, 5, 773—774 Homoleptic molybdenum complexes, preparation and characteristics, 5, 514... 

Homoleptic tetrazincates, characteristics, 2, 346 Homoleptic titanium(III) complexes, with -ligands, 4, 282 Homoleptic trizincates, characteristics, 2, 345 Homoleptic vanadium(III) alkyl complexes synthesis and structure, 5, 12 VMes3 reactivity, 5, 12... 

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