Zirconocene dimethyl complex

The reaction of tris(pentafluorophenyl)borane, B(C6F5)3, with a variety of zirconocene dimethyl complexes proceeds rapidly and quantitatively at room temperature in noncoordinating solvents to yield cationic alkylzirconocene methyltriarylborate complexes (34 eq 26). Reaction with excess of... 

On the other hand, recrystallization of the diastereomeric product mixture of the bis(phospholyl)zirconocene afforded the pure C2-symmetric rac-phosphazirconocene and phosphahafnocene 284.227 The rac-phosphazirconocene dichloride binds as a bidentate ligand to Mo(CO)4 to give bimetallic r -phosphazirconocene 285. Alkylation of the dichloride compounds with MeMgBr produces the dimethyl derivatives rac-286 and rac-287. Upon activation with MAO, the rac-phosphazirconocene dichloride and dimethyl complexes exhibit high activity toward co-polymerization of ethylene and 1-hexene. Interestingly, the bimetallic r -phosphazirconocenes 285 and 287 are inactive, presumably due to decomposition of the complexes under polymerization conditions. A reactivity study and an... 

Treatment of the phosphorus-functionalized zirconocene dichloride 608 with 2equiv. of MeMgBr affords the dimethyl complex 609, which, on reaction with 0.5 equiv. of PbCl2, gives the monochloro methyl complex 610441 (Scheme 137). Both the dimethyl and the monochloro methyl complexes can insert one molecule of CO to afford products 611, which interconvert between an acyl complex and a phosphonium alkoxide at ambient temperature. 

The optically pure, structurally characterized zirconocenium tert- butoxide complex l(S,S)-(EBIH)Zr(OBut)(THF)]BPh4 (967, Scheme 242) was prepared by treatment of the corresponding dimethyl complex (A,A)-(EBIH)ZrMe2 966 with /< 7/-butanol in toluene followed by in situ protonolysis with [HNEt3]BPh4 in THF. The complex catalyzes the asymmetric Diels-Alder reaction between cyclopentadiene and various dienophiles.732 The enantiopure zirconocene bis(triflate) complex (A, ST)-(EBIH)Zr(OTf)2 968 also efficiently catalyzes the asymmetric Diels-Alder reaction between cyclopentadiene and oxazolidinones.733,734... 

Chiral biphenyl-bridged zirconocene dichlorides 1171 and the dimethyl derivative 1172 are obtained by salt metathesis routes according to Scheme 276.908 The reaction of the dimethyl complex with 0.5 equiv. of (i )-binaphthol gives the corresponding binaphtholate 1173. 

Another group of compounds that were recently reported as capable of initiating cationic polymerizations are metallocene/borate complexes. Such material can, for instance, be generated from zirconocene dimethyl compounds (Cp2ZrMe2) and anUinium borate. Thus, [HNMe2Ph] -1- [B ( 5115)4] will polymerize amine-functionalized a-olefins [51] as well as isobutylene homo and copolymerizations [52]. Also, when compounds, like Cp MMe3 (M = Ti, Zr, and Hf where... 

The compounds 2 and 3, have all been isolated from reactions of phenylsilane with either dimethyltitanocene (1 2) or dimethyl-zirconocene (r ). All of the evidence points to the fact that these compounds are probably resting species and are not involved in the catalytic cycle. They do nevertheless give some indication of the complex series of reactions that transform the dimethyl-metallocene to active catalyst. 

Some of the bicyclo[3.1.0]hexene zirconocene derivatives, especially those containing a phenyl group, rearrange quantitatively to the corresponding 4-vinyl-l-metalla-2-cyclobutene derivatives when heated in toluene to 60-80 °C for several hours (equation 131). The 6,6-dimethyl-2,3-diphenyl-2-zirconabicyclo[3.1.0]hex-3-ene derivative prefers ring-opening to the isomeric j/. -allylic complex upon thermolysis. 

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