Diphenylbutadiene complexes

Mixed cyclopentadienyl-diene titanium complexes, Cp TiX(diene)(X = Cl, Br, I), have been prepared in 30-60% yield by the stoichiometric reaction of CpTiXs with (2-butene-l,4-diyl)magnesium derivatives or by the reduction of CpTiXs with RMgX (R = i-Pr, f-Bu, Et X = Cl, Br, I) in the presence of conjugated dienes, as shown in Scheme 4. The butadiene, 1,3-pentadiene, and 1,4-diphenylbutadiene complexes of Cp TiX exhibit a unique prone (endo) conformation (13), while the isoprene, 2,3-dimethylbutadiene, and 2,3-diphenylbutadiene complexes prefer the supine (exo) conformation (14). Reduction of Cp TiX(diene) with RMgX or Mg gives a low-valent species, which catalyzes a highly selective (>99%) tail-to-head linear dimerization of isoprene and 2,3-dunethylbutadiene. " ... 

Reaction of [Wl2(CO)3(NCMe)2] with equimolar quantities of 1,4-diphenylbutadiyne afforded397 the iodo-bridged dimer [ W(p,-I)(I)(CO)(NCMe)(Tl2-PhCCCCPh) 2] whereas with excess 1,4-diphenylbutadiyne the monomeric product [Wl2(CO)(NCMe)(T 2-PhCCCCPh)2] was obtained, which on reaction with further [Wl2(CO)3(NCMe)2] afforded the bimetallic 1,4-diphenylbutadiene complex [W2l4(CO)2(NCMe)2(li, n2 -T)2, q2. pijCCCcPh)2]. 

Within the general description of ligand exchange, the relative stability of a variety of magnesium-olefin complexes/magnesacycles has been studied. For example, 1,4-diphenylbutadiene replaces the parent butadiene in equation 20 to form the penta-coordinated magnesium compound. ... 

The interaction of Cr(CO)g with 1,4-diphenylbutadiene produces only arene-type n complexes (92, 393). 

The magnesium-1,3-diene complex (s-m-PhCH=CHCH=CHPh)Mg-(THF)3 (65) was synthesized from 1,4-diphenylbutadiene and activated... 

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