Metal diphenyl compounds

A large number of stable planar, tetrahedral, or octahedral complexes of lb, lib, and Vlllb elements (Cu2+, Zn2+, Co2+, Ni2+, Ru2+, Rh2+, Pd2+, Pt2+, Pt4+) using cyclopropenones (preferentially the diphenyl compound) as ligands has been evaluated mainly by Bird281. Their preparation may start either with metal salts or with carbonyls, as the octahedral Co(II) complex [Co(Dcp)6]2+ may exemplify ... 

The reactions of electrophiles with metallated aromatic compounds obtained in this way provide access to products that are not accessible at all or not selectively through classic Ar-SE reactions. Phenyllithium, for example, unlike benzene, reacts with ketones to form tertiary alcohols or with elemental selenium to form first phenylselenol and thereafter, through oxidation, diphenyl diselenide (Figure 5.35). 

Oxazoles with a free 2-position are metallated thereat by n-butyllithium, while 2,4,5-trimethyloxazole forms the anion (142) (81JOC1410). In the presence of a carboxyl or methoxycarbonyl group at C(4) the metallation is directed to the 5-position, even in the absence of a 2-substituent, to give, for example, the lithio compounds (143) and (144) (81TL3163). 2-Lithiooxazoles can equilibrate with open-chain isocyanides and the diphenyl compound has been trapped as a mixture of cis- and /rans-trimethylsilyl ethers (equation 9). 

The synthesis and uses of alkali metal phosphides have been reviewed. Alkali metal diphenyl-phosphides are readily obtained by cleavage of a phenyl group from PPh, by lithium in tetra-hydrofuran (THF), sodium or lithium in liquid ammonia or potassium in dioxane (equation 3). The metal-phenyl product can be destroyed by addition of a calculated amount of Bu Cl or NH4X. Usually MPPhj compounds are prepared in situ, but they can be isolated, usually as solvates. These compounds can also be obtained from Ph2PCl and the alkali metal, or from Ph2PH and alkyl-lithium. ... 

Polyquinolines form another class of heteroaromatic polymers exhibiting photoconductivity. The interest in the synthesis of polyquinolines has increased rapidly during the last decade because of their excellent oxidative and thermal stability. When doped with alkali metal donor compounds like sodium naphthalide or sodium anthracide, several polyquinolines show electrical conductivity as high as 10 S/cm [336,337], When doped with electron-donor compounds such as TNF or 2,3-dichloro-5,5-dicyano-l,4-benzoquinone some poly-quinolines show distinct photoconductivity. One such polyquinoline is poly(4-phenyl-2,6-(p-phenoxy)-quino-line) (54b) [338,339]. It is obtained by the acid catalysed self-condensation reaction of 4-amino-4 -acetyl-3-benzoyl diphenyl ether (54a). 

The addition product, C QHgNa, called naphthalenesodium or sodium naphthalene complex, may be regarded as a resonance hybrid. The ether is more than just a solvent that promotes the reaction. StabiUty of the complex depends on the presence of the ether, and sodium can be Hberated by evaporating the ether or by dilution using an indifferent solvent, such as ethyl ether. A number of ether-type solvents are effective in complex preparation, such as methyl ethyl ether, ethylene glycol dimethyl ether, dioxane, and THF. Trimethyl amine also promotes complex formation. This reaction proceeds with all alkah metals. Other aromatic compounds, eg, diphenyl, anthracene, and phenanthrene, also form sodium complexes (16,20). 

Directed lithiation of aromatic compounds is a reaction of broad scope and considerable synthetic utility. The metalation of arenesulfonyl systems was first observed by Gilman and Webb and by Truce and Amos who reported that diphenyl sulfone is easily metalated at an orf/io-position by butyllithium. Subsequently, in 1958, Truce and coworkers discovered that metalation of mesityl phenyl sulfone (110) occurred entirely at an orf/io-methyl group and not at a ring carbon, as expected. Furthermore, refluxing an ether solution of the lithiated species resulted in a novel and unusual variation of the Smiles rearrangement and formation of 2-benzyl-4,6-dimethyl-benzenesulfinic acid (111) in almost quatitative yield (equation 78). Several other o-methyl diaryl sulfones have also been shown to rearrange to o-benzylbenzenesulfinic acids when heated in ether solution with... 

The models were run for two different electronic additives, one metal - lead (Pb) and one organic compound - decabrominated diphenyl ether (DeBDE). 

Another type of dimerization was observed by Japanese authors198. In the presence of Ni°, compounds like bis(l,5-cyclooctadiene) nickel(0), diphenyl and di-n-propyl cyclopropenone, and cyclohepteno cyclopropenone are transformed to tetra-substituted p-benzoquinones (261/262) by formal (2 + 2) or (3 + 3) cycloaddition of two cyclopropenone moieties effected by metal complexing. 

All of the organohalogen compounds studied were commercial products obtained from various manufacturers and used as received. Only the DBDPO was purified further by recrystallization for some of the chromatography and thermal analysis experiments. Samples of antimony trioxide and antimony pentoxide were also obtained from commercial sources. The ultrapure antimony trioxide, bismuth trioxide, bismuth metal, antimony metal, dibenzofuran and diphenyl ether were all obtained from Aldrich Chemicals. The poly(propylene) (PP) resin was 0.7 mfi, food grade from Novamont and the poly(ethylene) was unstabilized, high molecular weight, HDPE from American Hoechst. 

Lehnert and Tuczek further studied end-on terminal coordination by density functional theory (DFT) calculations on the compounds [Mo(N2)2(dppe)2], [MoF(NNH)(dppe)2], and [MoF(NNH2)(dppe)2]+, where dppe= 1,2-bis(diphenyl-phosphino)ethane.50 They proposed a reaction scheme, shown in reaction 6.13, for asymmetric dinitrogen reduction and protonation. The end-on model favored by Lehnert in reference 50, as shown in reaction 6.13, appears to be a less thermodynamically unfavorable pathway, at least to reach the M-NNH3 intermediate. Step 1 produces a metal-attached diazenido ion (NNH-), step 2 produces a hydrazido ion (NNH2 ), and step 3 produces a hydrazidium ion (NNHj). 

The solution structure of the dilithium compound 237, generated by treating frawi-1,2-diphenyl-l,2-bis(trimethylsilyl)ethylene (236) with excess lithium metal in THF (Scheme 83), was studied by ID and 2D NMR techniques in the group of FUrstner". As a conclusion, the dilithium compound 237 adopts a C2-symmetric twisted frawi-arrangement with two bridging lithium centres in solution, underlining the various X-ray structural studies in the solid state by Sekiguchi and coworkers. 

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