1,5-Hexadiene complexes

Hexadiene complexes with gold, 12 348 with iron, 12 263, 264 with platinum, 12 319 with rhodium, 12 297-299 with silver, 12 340 Hexafluorides, structures, 27 106-108 Hexafluoroacetone, 30 223-312, 44 317-318 metal complexes, 30 279-298 of cobalt, 30 286-287 of gold, 30 295... 

The 1,5-hexadiene complex, [RhCl(C6H,0)] 2, may be prepared by this method with a reaction time of 24 hours. The temperature should not exceed 40° to avoid the deposition of metallic rhodium. Under these conditions the yield is 85% of analytically pure product. 

In contrast to the phosphine analogues already mentioned, reaction (27) does not occur with the cod and nbd complexes. Further, reaction (28) occurs quantitatively on addition of cod to the hexadiene complexes.141... 

Cyclic dienes preorganize the geometry of the two donble bonds, favoring chelation over jr-allyl formation. Acyclic dienes tend to give jr-allyl complexes. However, the reaction of allyl chloride with PdCl2(PhCN)2 at low temperatnres in the absence of solvent gives the 1,5-hexadiene complex (eqnation 40). 

The alkyne complex (68) reacts with two equivalents of ethene to give the 5-cfr-3,4-( )-diphenyl-l,3-hexadiene complex (69) as shown in Scheme 39. Use of 2-butyne leads to the metallacycle (70) via bis(alkyne) complex. " The bicyclic vanadacyclopentatriene complex (71) is formed from 1,7-nonadiyne. 

The chloro-bridged 1,5-hexadiene complex [(CaHio)RhCl]2, m.p. 115°-117°C, has been prepared by reaction of the olefin with [(C2H4)2RhCl]2 in diethyl ether at room temperature (149). When reacted with cyclopentadienylsodium, this complex produces... 

Although [(NHC)2Ni] complexes are the most common, a number of mixed Ni complexes have been recently described. For example, Hazari and co-workers reported the two-step preparation of NHC-Ni hexadiene complexes through an intermediate [(NHC)Ni(allyl)2] species [eqn (10.1)]. This hexadiene ligand is labile and can be easily replaced by other species such as phosphines, CO, olefins or isonitriles. 

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