Cyclopentadienyl complexes of titanium

The dissociation of coordinatively sufficient organometallic complexes in solution. For instance, for the system based on cyclopentadienyl complexes of titanium the active centers of catalytic polymerization (C Hj) -TiR]+ are caused by the following process (178, 179) ... 

Table 3. Preparation of tt-Cyclopentadienyl Complexes of Titanium, Zirconium, and Hafnium ...

The in situ formed basic cyclopentadienyl complex of titanium, ethylene-bis( f-tetrahydroindenyl)-titanium hydride (EBTHI)TiH) containing a planar element of chirality, is active for the reduction of a C=N double bond of both N-aryl-imines (Schiff bases) and unsubstituted imines (108,109). (EBTHl)TiX2 derivatives are used as precursors of the hydride analogue. The chiral zirconium analogues of the above-mentioned complexes provided a breakthrough in asymmetric polymerization of terminal oleflns (110). 

DICARBONYLBIS(v -CYCLOPENTADIENYL) COMPLEXES OF TITANIUM, ZIRCONIUM, AND HAFNIUM... 

Preparation of Functionally Substituted rj-Cyclopentadienyl Dicarbonyl Complexes of Titanium and Zirconium... 

A number of facile procedures were developed for the synthesis of mono and bis cyclopentadienyl derivatives of titanium, e.g., the (tt-CsH )-trialkoxytitanium derivatives, (77-C5H5)-titanium trihalides (406, 407-409), (77-C5H5)-titanium internal complexes (409), triaroxytitanium cyclopentadienyls (410), compounds containing different groups (alkoxy, aryloxy. 

The preparation of two cyclo-octatetraene-gold complexes, (ct)AuCl and (cot)-AU2CI4, has been reported. The structures of biscyclo-octatetraenyl complexes of titanium, vanadium, thallium, and uranium, were deduced from their i.r. spectra. Protonation of (p-cyclo-octatetraene) (p-cyclopentadienyl) complexes has been studied. For the ruthenium and osmium complexes protonation occurs on the eight-membered ring to give CgH moiety co-ordinated to the metal atom via both an T -alkyl and an olefin-metal bond. For the cobalt and rhodium complexes a bicyclic cation (287) is produced which undergoes isomerization to the monocyclic (288). ... 

The same oxidizing agents are also utilized for oxidation of cyclopentadienyl complexes of the titanium group metals ... 

In many cases, such as for cyclopentadienyl compounds of titanium, the attachment of the complex to the support prevents polymerization and other side reactions. This additionally increases the activity and lifetime of the heterogenized catalyst. 

No allyl complexes of titanium or vanadium have yet been reported. We have prepared allyl-bis(cyclopentadienyl)-titanium [I] by various methods, of which the following is the most convenient one. Red bis(cyclopentadienyl)-titanium dichloride [II] in tetrahydrofuran solution was reduced to the green monochloride by means of zinc powder (1). When the reduction was completed, one equivalent of allylmagnesium chloride was added to the solution, the col r of which changed to violet. The reaction mixture was evaporated in vacuo, and the residue exuacted with pentane. When the violet pentane solution was concentrated to saturation and cooled to -80 , purple crystals of [I] precipitated. After two recrystallizations from pentane pure [I] was obtained in 36%yield. Analysis found 21,8%Ti 70,89%C 7,01%H calc, for (CgHg TifC Hg) 21,86%Ti 71,24%C 6,89%H. Melting point . 118 C (decomp.). Reaction of [I] with octanol gave propene in 80% of the theoretical yield. 

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