Bis alkenyl complex

Reaction of the coordinatively saturated bis-alkenyl complex [Ru(PTr3)2(GO)2 ( )-GH=GHG(Me)=GH2 (GH= GH2)] with 1 equiv. of HBF4 affords a mixture of products, the major one (50%) being the a,/ -unsaturated allyl complex [Ru(PTr3)2(GO)2 77 -GH2GHGHGH=GMe2 ](BF4) 69. The mechansism of formation is proposed to involve... 

The bis-zirconocene complex CpjClZrCHjCHjZrCpjCl has been isolated upon double hydrozirconation of acetylene with 1 [102]. Recently, the preparation of a heterogeneous bis-zirconocene catalyst was succesfully achieved from zirconocene dichloride complexes containing alkenyl or alkynyl substituents [224]. 

The complex OsHCl(CO)(P Pr3)2 also reacts with diynes.35 Thus, it has been reported that the treatment of this compound with 0.5 equiv. of 1,7-octadiyne affords, after 6 h at 333 K, the binuclear p,-bis-alkenyl derivative (P Pr3)2(C0)C10s CH=CH(CH2)4CH=CH OsCl(CO)(P,Pr3)2 in 83% yield (Eq. 3). 

Scheme 2. Synthesis of the bis(carbene)alkenyl complex [(TIME )2Cu2] PFe)2 (2 - "-Cu).

Acetylene-vinylidene rearrangements of silylacetylene-iron carbonyl complexes have been observed,537 while iron-acetylide hydride complexes of the type [Fe(H)(C=CR)(dmpe)2], where dmpe=l,2-bis(dimethylphosphino)ethane, have been found to react with anions to afford substituted alkenyl complexes. It has been proposed538 that a likely reaction course for this latter rearrangement involves initial protonation of the cr-bound acetylide ligand at the carbon (I to the metal centre to form a vinylidene complex. Metal-to-carbon hydride migration in this vinylidene complex with attack by the anion would then lead to the neutral complex (see Scheme 106). A detailed mechanistic investigation has been carried out539 on the novel metathetical... 

As with aryls, the sp2 hybridization of o-alkenyls may contribute to both an increased BDE and also access to decomposition routes homoleptic examples, e.g. Zr(CPh=CMe2)4, are particularly rare. Decomposition of c/s-bis lkenyl) complexes via reductive elimination of buta-1,3-dienes is occasionally observed however, the butadiene may remain coordinated (Figure 4.11). 

Protonation of (/u.-alkenyl)bis(zirconocene) complexes under nonnucleophilic conditions takes a different regio-chemical course than the B(C6p5)3 addition (equation 27). The X-ray crystal structure of (60) is consistent with distorted square-pyramidal pentacoordinated geometry at the central atom Cl. 

Photochemical [2 + 2]-cycloaddition of unbridged bis(alkenyl-Cp)zirconocene complexes provides a unique approach for the synthesis of 6 -hydrocarbyl-bridged -precursor leads to the corresponding meso-ansa-zhconoccne. 

This reaction has been extended to the reaction between aldehydes and alkenyl complexes of boranes, silanes, and stannes to give allylic alcohols, " where the reaction with alkenyl complexes of silanes is known as the silyl-Prins reaction. In addition, several Lewis acids-mediated or -promoted Prins reactions have recently been developed, including the application of TMSI, hafnium (IV) bis(perfluorooctanesulfonyl)amides (in fluorous biphase system),iron (III) species," and 2,6-di-f rf-butylphenoxy(difluoro)borane. J... 

Toste and coworkers have developed effective gold(I)-catalyzed protocols for the intramolecular enantioselective hydroalkoxylation of y- and 8-hydroxy allenes employing chiral, enantiomerically pure silver salts [107]. For example, treatment of y-hydroxy allene 66 with a catalytic 1 2 mixture of the achiral bis(gold) complex (dppm)Au2Cl2 [dppm = bis(diphenylphosphino)methane] and chiral silver phos-phonate Ag-(J )-67 in benzene at room temperature led to isolation of 2-alkenyl tetrahydrofuran 68 in 90% yield with 97% ee (Eq. (12.36)). A combination of chiral bis(gold) complex with a chiral silver salt proved effective for terminally unsubstituted allenyl alcohols. For example, reaction of 5,6-heptadienol catalyzed by a mixture of [(S,S)-DIPAMP]Au2Cl2 [DIPAMP = l,2-ethanediylbis[(2-methoxyphenyl) phenylphosphine] and Ag-(J )-67 gave 2-vinyltetrahydropyran 69 in 96% yield with 92% ee (Eq. (12.37)). 

Ferrocene is a very robust organometallic complex that has been incorporated into an impressive number of molecules with various applications and properties. Therefore, ferrocene-containing polymers have been pursued for many possible applications by different routes. Three metathesis-based approaches toward metallocene-containing polymers (mainly ferrocenes) have been reported so far (i) homo-ROMP or co-ROMP of olefins bearing a metallocenyl substituent, (ii) ROMP of strained an.ya-metallocenes, and (iii) ADMET polymerization of bis(alkenyl)metallocenes, including ADMET copolymerization with a.ty-dienes. 

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