Alkoxo titanium complexes

The reactivity of the dialkyl complexes TiR2(LL)2 (LL = N,N -dimethylaminotroponiminato) has been widely studied. Reactions with CO and aldehydes or ketones afford unsymmetrical diolato complexes that convert to the corresponding vicinal diols after hydrolysis. CO and acetylene react to form the oxametallacyclopentene complex. Treatment with RNC yields the free imine and low-valent titanium species (Scheme 131). In the reaction with BucNC, free ButN=CMe2 is formed and the addition of benzaldehyde or benzyl reagents affords titanium diolato or enediolato complexes. Thiolato-alkoxo or amido-alkoxo titanium complexes can also be similarly prepared (Scheme 132).123-125... 

Density functional calculations on the chain initiation reaction shown in Scheme 136 for the ethylene polymerization catalyzed by bis-alkoxo titanium complexes have been studied. Activation barriers of 6.4kcal mol-1 are found for the titanium sulfur-bridged catalysts with higher insertion barriers of 10-15 kcalmol-1 for the GH2-bridged catalysts. 

The aryloxo and alkoxo titanium complexes were reported to catalyze intermolecular hydroamination of terminal alkynes. Depending on the auxiliary ligands, a... 

These titanium compounds can be described as an alkene 7r-complex or a metallacyclopropane, which is of practical importance. According to several computational studies, it has been concluded that the alkene titanium complexes are best represented as titanacyclopropane derivatives. The synthesis of titanium-alkyne complexes Ti(Me3SiC=CG6H13)(OR)2 from reaction between l-(trimethylsilyl)oct-l-yne with achiral or chiral alkoxo titanium compounds Ti(OR)4 has been described (Scheme 95).184 A series of organotitanium compounds (Scheme 96) are obtained by metathesis reactions.41... 

The synthesis of the Ind-amido titanium complexes [(C9H5R)SiMe2NBut]TiX2 (Scheme 304) with alkoxo and amido substituents at 2- and 3-indenyl position has been reported and the molecular structures of the derivatives for R = NMe2 and N(CH2)4 have been determined by X-ray diffraction. The methyl derivatives are activated with B(C6F5)3 and studied as catalytic systems for the ethylene/l-octene co-polymerization. A dramatic effect of the indenyl substituent nature on catalyst efficiency and polymer properties is observed.740... 

The reaction of the amido complex (CsH4CH2CH2NPr 2)Ti(NMe2)3 with 3 equiv. of isopropanol affords the tris-alkoxo compound (C5H4CH2CH2NPr 2)Ti(OPr )3.374 A series of aminoalkyl-substituted mono-Cp trichloro, triiso-propoxo, and mono(indenyl) triisopropoxo titanium complexes that contain pyridyl (2-picolyl), diisopropylaminoethyl and dimethylaminoethyl, and phenylethyl pendant arms have been prepared (Scheme 159 Section 4.05.3.1.l.(iii)). The utility of these complexes for the polymerization of ethylene, propylene, and styrene has been investigated.332... 

Stereoselective aldol reactions of menthyl acetate enolates, and allylations with benzaldehyde mediated by mono-Cp monochloro bis-alkoxo chiral titanium complexes have been reported.972... 

Allyltitanium compounds and Ti enolates derived from mono-Gp chloro titanium complexes with two chiral alkoxo ligands add to aldehydes with high enantioface discrimination.973... 

Indenyl-alkoxo derivatives have been employed to catalyze the syndiospecific polymerization of styrene.985 Ab initio investigations of the synthesis of the tetramethyl-Gp-propoxo dichloro titanium complex Ti[C5Me4(CH2)30]Cl2 from Ti[G5Me4(CH2)30Me]Gl3 have been reported.986... 

In the case of zirconium, only Zr30(OH)(OBu )g has a similar structure to the corresponding titanium complex (Ti30(OR)io) with a c.n. of 6 for the metal. Although fewer oxo-alkoxo compounds were isolated than for titanium, different structures are to be expected, because zirconium generally favors higher coordination numbers (>7). An example is Zri30g(0Me)36 with 7- and 8-coordinate Zr. ... 

Bis(adamantylimido) compounds, with monomeric chromium(VI) complexes, 5, 348 Bis(alkene) complexes conjugated, Rh complexes, 7, 214 mononuclear Ru and Os compounds, 6, 401 -02 in Ru and Os half-sandwich rj6-arenes, 6, 538 with tungsten carbonyls and isocyanides, 5, 685 Bis(u-alkenylcyclopentadienyl) complexes, with Ti(II), 4, 254 Bis(alkoxide) nitrogen-donor complexes, with Zr(IV), 4, 805 Bis(alkoxide) titanium alkynes, in cross-coupling, 4, 276 Bis(alkoxo) complexes, with bis-Cp Ti(IV), 4, 588 Bis[alkoxy(alkylamino)carbene]gold complexes, preparation, 2, 288... 

The dimethyl binuclear titanium compounds [TiMe(/x-OR)(ft3-tbop)]2 (R = Me, Et) tbop = 2,2 -thiobis[4-(l,l,3,3-tetramethylbutyl)phenoxo] are prepared by reaction of the alkoxo complexes[Ti(OR)(/x-OR)(ft3-tbop)]2... 

Mono-Cp alkoxo and aryloxo titanium thiolates and sulfides have been widely reported. These complexes show an interesting reactivity, including C-H and G-S bond activation and reduction of Ti(iv) to Ti(m). The incorporation of bulky aryloxo ligands in the coordination environment of the titanium center limits some of this reactivity and alters the chemistry of the compounds considerably. The implications of the electronic and steric effects of these ancillary ligands have been considered.1005-1008... 

Mono-Cp and bis-Cp titanium hydrido derivatives have been reviewed.1027 The hydrido alkoxo complex Cp 2Ti(H)(OMe) is obtained by oxidative addition of CH3OH to Cp 2Ti, generated from Cp 2Ti(Me3SiC=CSiMe3).1363... 

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