Allyl and buta-1,3-diene complexes

Metal carbonyls Allyl and buta-1,3-diene complexes... 

An ab initio method has been employed to study the mechanism of the thermal isomerization of buta-1,2-diene to buta-1,3-diene. The results of the study have indicated619 that the transformation proceeds in a stepwise manner via a radical intermediate. Experimental free energies of activation for the bond shift in halocyclooctatetraenes have been reported and analyzed by using ab initio MO calculations.620 The isomerization of hexene using a dihydridorhodium complex in dimethyl sulfoxide has been reported,621 and it has been suggested622 that the Pd(II)-catalysed homogeneous isomerization of hexenes proceeds by way of zr-allylic intermediates. A study has been made623 of alkene isomerization catalysed by the rhodium /-phosphine-tin dichloride dimeric complex, and the double-bond isomerization of olefinic amines over potassium amide loaded on alumina has been described.624... 

TT-Allyl and related complexes can be prepared by reactions such as 23.81-23.85 the last two reactions illustrate formation of allyl ligands by deprotonation of coordinated propene, and protonation of coordinated buta-1,3-diene respectively. Reactions 23.82 and 23.83 are examples of pathways that go via a-bonded intermediates (e.g. 23.48) which eliminate CO. 

Alkenes.- Hexa-2,4-dienes are formed in the catalytic codimerisation of butadiene with ethylene in the presence of [Ti(n -l-methallyl)Cp2]f with 99% regioselectivity. The Ziegler catalyst TiCl /EtjAlCl and the Ti(II) complex [Ti(ij -CsHel (AlCli, )2 ] both induce (6+2] cycloaddition reactions of cycloheptatriene with dienes and acetylenes . [Mo(allyl) ] reacts with HCl to give [M02 (U-CD2 (allyl)e ] which catalyses the polymerisation of buta-1,3-diene. The cocondensation of Fe... 

---