Benzenes adducts

Tetracyanoethylene oxide [3189-43-3] (8), oxiranetetracarbonitnle, is the most notable member of the class of oxacyanocarbons (57). It is made by treating TCNE with hydrogen peroxide in acetonitrile. In reactions unprecedented for olefin oxides, it adds to olefins to form 2,2,5,5-tetracyanotetrahydrofuran [3041-31-4] in the case of ethylene, acetylenes, and aromatic hydrocarbons via cleavage of the ring C—C bond. The benzene adduct (9) is 3t ,7t -dihydro-l,l,3,3-phthalantetracarbonitrile [3041-36-9], C22HgN O. 

A few routes to new silenes, usually involving flash vacuum pyrolysis at high temperatures, have been reported. Silenes were proposed as the result of the thermal expulsion of trimethylmethoxysilane, or a similar volatile fragment, from the starting material but frequently, proof that the silenes proposed to account for the observed products were in fact formed was not provided.116 119 The other thermal route employed was the retro-Diels-Alder regeneration of a silene from an adduct with an aromatic compound—often a 9,10-anthracene or 1,4-naphthalene adduct or, in some cases, a 1,4-benzene adduct, as illustrated in Eq. (19).120... 

The increase in stability with the DMSO content is a general feature for Meisenheimer adduct formation and is observed to similar extents for pyridine as well as benzene adducts. It is mainly caused by the enhanced nucleophilicity of the RO ion, resulting from a decreased specific solvation of the charged reagent as the concentration of the protic solvent is decreased and dispersion interactions between the large, polarizable adduct and the dipolar aprotic solvent.36,83... 

Os(NH3)5 r 2-(C,0)-acetone) ] [105164-47-4], and benzene adducts, [Os(NH3)5(q2-C6H6)]2+ [107202-74-4] and [Os(NH3)5(C6H6)Os(NH3)5]4+ [107202-75-5] (106,107). The chemistry of osmium clusters is replete with examples of ligands engaged in intimate and unusual bonding modes with multiple metal centers. 

The photolysis of anthracene-benzene adducts 111 and 112 has been studied in detail [128], Photodissociation of 111 was found to give electronically excited anthracene with a quantum yield of 0.80, but the isomeric 47i + 27i adduct 112 photodissociates mainly diabatically, leading to electronically excited anthracene with a quantum yield of 0.08. The different efficiencies of adiabatic cycloreversions have been rationalized by correlation diagrams involving doubly excited states. Evidence for biradicals as intermediates in the photolyses of 111 and 112 has not been obtained. 

Ph—C=C COOMe x COOMe OX 6.25mM alkyne in benzene adduct undergoes ring opening as well as ring closure, depending on conditions 60,62,63... 

The most unusual geometries among these types of clusters are clearly the multiple-decker sandwich structures observed for vanadium ion-benzene clusters Vn(C6H6)+ [142, 151-157]. One interesting finding is that early transition metals all appear to form sandwich compounds with benzene but for the late metals the benzene adducts coat a central metal cluster [158]. 

The supersilyl anions [4], (Fig. 2) work as excellent reaction partners. The tetrahydrofuran adduct NaR 2THF (4) of supersilyl sodium is easily prepared from supersilyl bromide and sodium in refluxing THF. It crystallizes in beautiful yellow needles which — according to the X-ray structure analysis — contain contact pairs of the molecule. On the other hand, the PMDTA adduct (5) of NaR and the benzene adduct 6 of KR form monomeric molecules in the crystals. Donor-free NaR (7) is dimeric, whereby silicon gains the coordination number 5, which is very unusual for supersilyl silicon. 

Platinum-based t -arene complexes have only recently been characterized and extensive study has been done to exploit their properties for efficient C-H bond activation reactions. " In one of these examples Templeton and co-workers through their elegant studies have demonstrated the synthesis of a surprisingly stable Pt(II)-ri -benzene adduct [r -(HTp )Pt(C,C-ri2-C6H6)(H)][BAr 4] 61 (Scheme 15). ... 

Polyimide films are based on dianhydride of dicyclodecene tetracarbonic acid and oxydianiline ODA - Figure 19. The dianhydride was s)mthesized by Solar-irradiation technology of a mixture of benzene/toluene fraction with maleic anhydride to produce highly reactive monomer - benzene adduct (AB) - Figure 20. 

The first investigations of the photochemical reaction of MA with benzene can be credited to three groups of workers.Thus, when a benzene solution of MA was irradiated with UV light, a 2 1 MA benzene adduct was formed. The adduct has been assigned the structure 1. Schenck and Steinmetz have... 

Bohn, B., Zetzsch, C. Gas-phase reaction of the OH-benzene adduct with O2 reversibility and secondary formation of HO2. Phys. Chem. Chem. Phys. 1, 5097-5107 (1999)... 

Cyanocarbenes, for example, have a triplet ground state, as confirmed by ESR spectroscopy. Their stereospecific addition to olehns gives cyclopropanes. The benzene adduct is norcaradiene (262), not cycloheptatriene (Scheme 50). ... 

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