Complexes of titanium

Complexes of titanium(III) can be made from the trichloride— these are either approximately octahedral, 6-coordinate (for example TiClj.SL (L = ligand) and [TiCljfHjOj, formed when TiCls dissolves in aqueous hydrochloric acid), or 5-coordinate with a trigonal bipyramid structure. 

Reaction with Lactones. Hydroxycarboxyhc acid ester complexes of titanium are formed by reaction of a tetraalkyl titanate with a lactone, such as P-propiolactone, y-butyrolactone, or valerolactone (35). For example. 

Complexes of titanium, such as 2,6-(RNCH2)2NC H2TiCl2, prepared by reaction of TiCl with 2,6((CH2)3Si)RNCH2)2NC H2, can react with various Grignard reagents to prepare conformationady rigid diamide mono- and dialkyl titanate complexes (218,219). 

The chelated organic titanates also function as adhesion promoters of the ink binder to printed substrates such as plastic films, paper, and aluminum foil (504). The acetylacetone complexes of titanium are the preferred products for promoting adhesion of printing inks to polypropylene films. 

Table 21.4 Spectroscopic tind magnetic properties of some complexes of titanium(III)...

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) ... 

One of the commonest reactions in the chemistry of transition-metal complexes is the replacement of one ligand by another ligand (Fig. 9-3) - a so-called substitution reaction. These reactions proceed at a variety of rates, the half-lives of which may vary from several days for complexes of rhodium(iii) or cobalt(m) to about a microsecond with complexes of titanium(iii). 

Several mono(amidinato) complexes of titanium containing the N,N -bis(trimethylsilyl)benzamidinato ligand have been prepared either by metathe-tical routes or ligand substitution reactions as outlined in Schemes 80 and 81. Trialkoxides are accessible as well as the dimeric trichloride, which can be... 

Desulhirization reactions of transition metal-polysulfido complexes have also been reported. The treatment of a dimetallic complex of titanium, [ Ti(Cp)(OAr) 2(yU-S)(yU-S2)] (Cp=77 -C5H5, Ar=2,6-i-Pr2C6H3), with an equimolar amount of PhsP results in the quantitative formation of [ Ti(Cp)(OAr) 2(yU-S)2] via the transformation of the 1U-S2 ligand to a /t-S ligand (Scheme 44) [93]. The reverse reaction of [ Ti(Cp)(OAr) 2(/t-S)2] with Ss proceeds in a good yield. 

The NH2 radical rapidly reacts with excess oxalic acid required to form the oxalate complexes of titanium. 

Recently, Bercaw and co-workers have described the preparation of the first ethylene complex of titanium (64). The sodium amalgam reduction of a toluene solution of (Tj-C5Me5)2TiCl2 under an ethylene atmosphere afforded (T C5Me5)2Ti(T -C2H4) in 80% yield. Treatment of this complex with CO at low temperature resulted in the displacement of C2H4 and quantitative formation of (rj-C5Me5)2Ti(CO)2 (27). 

Preparation of Bis(p-indenyl)dicarbonyl Complexes of Titanium and Zirconium... 

A variety of substituted binaphthol and bisphenol complexes of titanium and zirconium have also been investigated as ethylene polymerization initiators. Of note, (62) and (63) exhibit activities of 350 gmmol-1 h-1 bar-1 and 1,580 gmmol-1 h-1 bar-1.190-192... 

Fullerene The reaction of 1 with an equimolar amount of fullerene- 60 in toluene at room temperature gives the first fullerene complex of titanium Cp2Ti(q2-C60) 121 [60]. An X-ray diffraction study of this complex has shown that it has the structure of a titanacyclopro-pane derivative, which should have a high potential for further derivatization of the fullerene. 

An alternative means of preparing alkylidene complexes of titanium is by the elimi-nation reaction of dialkyltitanocenes (Scheme 14.14) [25]. The limitation of this method is that only dialkyltitanocenes having no (i-hydrogen, such as 26 or dicyclopropyltitano-... 

All three necks of the flask should be vertical and not set at an angle. This is to prevent the accumulation of large amounts of the methylamine complex of titanium tetrachloride on the sides of the reaction flask. 

Reaction of tris(neopentyl) complexes of titanium, zirconium and hafnium with molecular oxygen furnishes the corresponding tris(neopentoxy) complexes [42, 43, 51]. A peroxo complex is an intermediate in this reaction, being relatively stable in the case of titanium [42]. The alkoxide species can also be formed upon reaction with alcohols under mild conditions [42, 52]. The alcoholysis reaction is fast, with a low dependence on the steric hindrance of the alkyl chain [42]. Hydrolysis leads to ](=SiO)M(OH)3] or ](=SiO)2M(OH)2], depending on the precursor species. Deu-... 

Stable complexes of titanium, 281 [157], cobalt, 282 [157], and platinum, 283, with a bicyclopropylidene ligand [158] have been obtained (Fig. 7), showing that 1 is a remarkably good ligand in spite of being a tetrasubstituted alkene. The complex 282 has been fully characterized by an X-ray crystal structure analysis [157]. 

Fig. 17 Series of well-defined alkoxide complexes of titanium...

It must be remembered that several compounds or soluble complexes of titanium which, alone, and also in the presence of AIU3, do not polymerize the propylene, can effect the polymerization rate of the catalytic systems containing a-TiCla and the molecular weight of the polymers obtained (10, 11). 

Chloro- or bromocyclopentadienyl complexes of titanium and zirconium react with silver(I) tetrafluoroborate to form the corresponding fluoro complexes.81 Other complexes yielded the tetrafluoroborates. 

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