Titanium complexes pentadienyl

Polysulfides of several metals can be prepared by reaction of the metals with excess sulfur in liquid NH3 (group IA metals) or by heating sulfur with the molten metal sulfide. The polysulfide ion binds to metals to form coordination compounds in which it is attached to the metal by both sulfur atoms (as a so-called bidentate ligand). One example is an unusual titanium complex containing the S52-ion that is produced by the following reaction (the use of h to denote the bonding mode of the cyclo-pentadienyl ion is explained in Chapter 16) ... 

The 14-electron titanium complex is monomeric and thermally robust, unlike titanocene itself (p. 290). It adds only one molecule of CO or PF, to yield 16-electron adducts Tilj/ -Me CjHJjL in which the two pentadienyl ligands are parallel and eclipsed. 

Bis(oxazolinyl)phenylrhodium complex, in styrene asymmetric hydrosilylation, 10, 821 Bis(pentadienyl) complexes preparation and properties, 5, 336 with titanium(II), 4, 265... 

Direct addition of PF3 to 5-pentadienyl metal complexes offers an alternative synthetic route (method G) and this has been reported in the case of the formation of bis(2,4-dimethylpentadienyl)trifluoro-phosphine complexes of titanium and vanadium [M(C7H11)2PF3] (M = Ti, V) (Scheme 11) 111). 

The formation of the 17-electron paramagnetic vanadium complex is not surprising in view of the known corresponding carbonyl complex, however the 16-electron titanium derivative is unexpected in view of the ready formation of the 18-electron biscarbonyl and bistrifluorophos-phine metal complexes containing the 5-cyclopentadienyl ligand. The solid-state structure of the PF3 adduct of bis[2,4-dimethyl-(pentadienyl)]titanium has recently been determined (111) and is shown in Fig. 20. The corresponding vanadium complex is isomorphous. The metal-PF3 distances are 2.326(Ti) and 2.275(V) A. 

SegTiCioHjo, Titanium(IVX bis(( -cyclo-pentadienyl)[pentaselenido(2—)]-, 27 61 SiBrCjHg, Silane, bromotrimetbyl-, 26 4 SiCgHjj, Silane, tetrametbyl-, lutetium complex, 27 161... 

Duthaler RO, Hafner A, Alsters PL, Rothe-Streit P, Rihs G. Stereoselective transformations mediated by chiral monocy-clo-pentadienyl titanium, zirconium, and hafnium complexes. PwreApp/. Chem. 1992 64 1897-1910. 

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