Butadienyl complexes

Butadienylboronic esters, in Diels-Alder reactionos, 9, 179 7 1 7 2-Butadienyl complexes, in Ru and Os half-sandwiches,... 

Butadienyl complexes, with platinum, 8, 656 7]3-l,3-Butadienyl complexes, with tungsten carbonyls and isocyanides, 5, 689... 

The cyclo addition of the alkene to the ruthenium vinylidene species leads to a ruthenacyclobutane which rearranges into an allylic ruthenium species resulting from / -elimination or deprotonation assisted by pyridine and produces the diene after reductive elimination (Scheme 16). This mechanism is supported by the stoichiometric C-C bond formation between a terminal alkyne and an olefin, leading to rf-butatrienyl and q2-butadienyl complexes via a ruthenacyclobutane resulting from [2+2] cycloaddition [62]. 

Similarly to the reaction of 1 with phenylacetylene to afford 2, the addition of 1 equiv of 2-methyl-l-buten-3-yne to toluene solutions 1 leads to the butadienyl complex Ru ( )-CH=CHC(CH3)=CH2 Cl(CO)(P Pr3)2 (11) as a result of the selective addition of the Ru-H bond of 1 to the carbon-carbon triple bond of the enyne (Scheme 4). 

Treatment of CpMo(SCgF5)(CF30CCF3)2 with alkynes ROCR affords ti -butadienyl complexes CpMo Ti4-C(CF3)C(CF3)=CRCR(SC6F5) (CF30CCF3) as the prone isomer. This isomerizes to the supine isomer upon warming.243... 

Our final route to using rj -butadienyl complexes is without doubt the most interesting from a synthetic standpoint. In the example given, activation of the cyclopalladated complex 119, as in Eq. 8, is not... 

Molybdenum and tungsten complexes of the type [M(SR(GP30CCF3)2Cp)] have been reacted with tertiary phosphines and phosphites and alkynes and the related conqilexes [M ii -C(CF3)C(CF3)SR)(CF3CsCCF3)(Cp)], M = Mo, W R Me, Pr, Bu have been reacted with alkyncs to give a series of new ii -vinyl or Ti -butadienyl complexes. Nucleophilic additions to [CpMo(CO)2(Ti -cyclq)entadienone)] salts yield a series of stable neutral coiqilexes containing the ii -o-substituted cyclt ntenoyl products. ... 

Further support has been reported for the proposal that important intermediates in the reactions of [PdCl2(PhCN)2] with acetylenes... 

Nickel. The anion [Ni2(CN)e] " bears some resemblance to the much-studied [Co(CN)6] . Hence kinetics of reduction of butadiene in aqueous solution in the presence of the former anion have been investigated. The first step is slow formation of the complex [Ni2(CN)e( -C4H,)] ". This intermediate then gives rise to species containing Tr-l-methylallyl or tt-butadienyl complexes of nickel cyanide which are the immediate precursors of the reduction process. Two precursors with two subsequent reduction paths are needed to accommodate observations of different product distributions under different experimental conditions. Rates of hydrogenation of styrene and of phenylacetylene depend on solvent and on composition for mixed Ni +-acac-AlEt3 catalysts. ... 

CpFe(CO)2] anions (Fp anions) also react with allenic electrophiles in an Sn2 fashion to generate Fp-substituted 1,3-dienyl complexes.Thermal and photochemical reactions with these Fp complexes result in the formation of 77 -butadienyl complexes. 

The related 77 77 -butadienyl complex 54 is obtained by the reaction of the allyl carbene 53 with PPh3 (Equation (7)), revealing that this carbene is acting as pseudo-16-electron species (see Section 6.15.2.6.3). ... 

Photolysis of [CpFe(CX))2(il -l,3-butadienyl)] complexes afforded intomediates of the type [CpFe(T) -pentadienoyl)], observed spectroscopically at low tenq)erature, which underwent electrocyclic ring closure, followed by keto-enol tautomoism to give complexes of the i) -hydroxycycl(q)entadienyl ligand. 

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