Vinylidene compound

Unfortunately, no data are extant on any other physical property of vinylidene compounds, such as infrared spectra. This area is again one which would repay investigation. 

In favor of a dihydrogen intermediate, the following should be noted (i) the addition of HX molecules to OsHCl(CO)(P Pr3)2 is a useful synthetic route for dihydrogen compounds (vide infra), (ii) the electrophilic character of the dihydrogen complexes has been demonstrated,38 and (iii) the addition of electrophiles to metal alkynyl complexes is a general method of preparing vinylidene compounds.39... 

Besides the chain transfer in Eq. (13.52), another important process called p scission can also produce unsaturations in the polymer chain. Secondary radicals (31) as well as tertiary radicals such as 34 formed according to Scheme 13.4 may produce low-molecular-weight vinyl or vinylidene compounds, respectively, and new radicals. 

Another route to heteroatom stabilized carbenes involves first the interaction of a terminal alkyne with an iridium complex to yield an iridium vinylidene compound. The vinylidene complex then reacts with nucleophiles, typically alcohols, to form oxa stabilized carbene complexes. O Connor extended this strategy to form a carbene ligand on the same iridium center as a metallacycle (76) and was also able to... 

Two side reactions can occur during ring closure a spiro diether can be formed from the trichloropentaerythritol monoacetate in a simultaneously occurring reaction or a vinylidene compound, CH2= (CH2C1)2, can form from the monomer 3,3-bis(chloromethyl) oxetane [2,2-bis(chloro-methyl)oxacyclobutane] by a consecutive reaction. 

The carbyne complexes (J ) can be readily deprotonated by base, [Bu4N]0H, to give the corresponding vinylidene compounds, and this constitutes a convenient route for the synthesis of the vinylidene-fluoro species trans-[ReF(=C=CHR)(dppe)9] (eq.5) which, upon protonation,can regenerate the ca.rbyne complexes (eq. 6) [7c]. 

A related cathodic behaviour has been detected for the carbyne complexes (J ) which, upon reduction, generate the corresponding vinylidene compounds, thus following a process which involves the cathodic C-H bond cleavage at the carbyne ligand CCH2R to give C=CHR [34, 36]. 

The reluctance of the carbyne carbon to react with nucleophiles is revealed by the reaction with LiEt3BH (see Scheme 6). Here the most electrophilic site is not the carbyne carbon but the ipara position of the aryl ring in the carbyne substituent Both ruthenium and osmium five coordinate, cationic, carbyne complexes undergo this reaction. The structure of a representative example, the osmium compound derived from the p-tolyl carbyne complex, has been determined by X-ray crystallography [16]. The unusual vinylidene complex reacts with HCl to produce a substituted benzyl derivative. The reaction may proceed through the intermediate a-vinyl complex depicted in Scheme 6 although there is also the possibility that the vinylidene compound is in equilibrium with the carbene tautomer as shown below. 

The iridium dimer tIr2l2(CO)(jt-CO)(dppm)2l reacted with ethyne to afford363 [Ir2l2(CO)( i-HCX HKdppm)2] in which the alkyne was parallel to the Ir-Ir vector. The compound underwent a transformation in solution at ambient temperature to afford the vinylidene compound [Ii2l2(00)(fi-CXIH2)(dppm)2]. A mechanism for the reaction was proposed. 

A general description to prepare copolymers is given in Ref. [207]. Methacrolein copolymers were described with the following comonomers (1) styrene and vinyl compounds [255-262], (2) vinylidene compounds [263], (3) acrylic acid, derivatives, and substituted acroleins [255,261,264—266], and (4) derivatives of methacrylic acid [255,266]. 

Propose a mechanism for the reaction of (q -C5H5)RuCl(PPh3)2 with HC=CPh to give the vinylidene compound [(q -C5H5)Ru(=C=CHPh)-(PPh3)2]-". 

In two publications, Moro-oko and coworkers describe the synthesis of organyl-bridged iton-manganese complexes from the non metal-metal bonded vinylidene compound [Cp Mn(CO)2 =C=CHFe(CO)2Cp ] (Cp =C5H4Me). Thus protonation affords [Cp (CO)2Mn(p-C=CH2)Fe(CO)2Cp] while addition of Bu"Li followed by quenching with methanol yields... 

Vinyl compounds 23, 40. 6H Vinyl compounds, esters 70, 136 Vinyl compounds, ethers 70 Vinylenes 23, 68, 257 Vinylidene compounds 23, 68... 

U.S. 4,187,105. Photosensitive Imi e Forming Composition Containing At Least One Substituted Bis-Diaryl Vinylidene Compound And/Or At Least One Substituted Bis-Diaryl Imine Compound. Wainer, Eugene and Lewis James, M. February 5, 1980. A non-silver photosensitive image forming composition containing at least one substituted bis-diaryl vinylidene compound... 

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