Me Me

The latter compound showed moderate activity as an ethylene polymerization catalyst.

Azaborolinyl-Ti complexes have been reported, including TiBr2(^5-(But)NB(Me)C3H3). X-ray data revealed an interaction between B and Br.5

4.2.2.2 Silicon-based Ligand Complexes

Isolable Ti-Si compounds that lack ancillary Cp-ligands are rare. The metathetical reaction of TiCl(CH2R)3 (R = But, SiMe3) with Li[Si(SiMe3)3] afforded the crystallographically characterized complexes Ti(Si(SiMe3)3)(CH2R)3.6,7 Ab initio calculations suggested synthetic strategies to Ti—Si multiple bonds, although these have not been prepared as of yet.8-10

4.2.2.3 Nitrogen-based Ligand Complexes 4.2.2.3.1 Neutral nitrogen ligand complexes

A number of articles have focused on the general issues of structure, stability, donor properties, and ligand strength of neutral ligand-TiCl4 adducts. Generally these works have involved use of various spectroscopic techniques including NQR, X-ray fluorescence, and NMR spectroscopy.11-15

In more specific work, adducts of the form TiCl4L2 have been prepared and reported. These include complexes where L = TMEDA,16 benzotriazole,17 benzothiazole, 8 2-aminobenzimidazole,19 2-methyl-2-oxazoline, thiazole and a variety of oxazole-derivatives.20 Similarly, complexes of the form TiCl4L (L = RC6H4NH2, R = But, Cl, NO2, Me21,22 isoxazole, 5-methylisoxazole,20 2-amino-benzimidazole, 2(2'-aminophenyl)benzimidazole,19 2-pyridylphenylacetonitrile22) have been reported. Schiff base adducts of TiCl4 derived from N-methylpyrrole-2-carboxaldehyde, 4-methyl-benzaldehyde, salicylaldehyde, and aromatic or aliphatic amines have also been characterized.23-25 A variety of 2:1 substituted silyl-amine-Ti adducts have also been reported.26-28

Matrix isolation work and IR spectroscopy have identified the amine adducts TiF4(NH3) and TiF4(NMe3) at low temperature.29 Winter and co-workers have prepared TiCl4(NH3)2, and have used it as a single-source precursor for the deposition of TiN films.3

The reaction of TiCl4 with SbCl5 in MeCN afforded the salt /ac-[TiCl3(MeCN)3][Sba6]. Crystallographic data revealed a distorted octahedral Ti environment.31

A number of related Ti/N-donor complexes have been synthesized and crystallographically characterized. These include monomeric adducts of TiCl4 such as TiCl4(NC5H5)2,32' 3 TiCl4(NC5H3Me2), TiCl4(NC5H4Me)34, TiX4(NC5H3Me2), TiX4(NC5H4Me) (X = Cl, Br),35-37 In contrast, the trimethylsilylimidazole adduct was confirmed as Ti2Clg(^-Cl)2(NC3H3NSiMe3)2.38 In addition, the ionic complexes [HNC3H3NMe]2[TiCl5(NC3H3NMe2)][Tia6]0 5,34 [HNC5H4Mel [TiCl5(NC5H4Me)],39 and [TiL2]Cl4 (L = furfuraldazine, 2-thiophenaldazine, 2-pyridinaldazine)40 have been reported. TiCl4(Si(SCN)((OCH2CH2)3N)) was reported as the first example of a silatrane adduct. IR data suggested coordination via the thiocyanate nitrogen atom.41

S4N4 reacted with TiCl4 forming what was thought to be the 1:1 adduct TiCl4(S4N4).42 This complex was subsequently shown to be dimeric, forming an eight-membered Ti2N4S2 ring (2).43

ci^tTN

Cl I Cl Cl

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