Hard/soft interactions in early transition metal chemistry: synthesis, properties and structures of thioether and selenoether complexes of titanium(IV)

Abstract

Reaction of TiCl 4 with L-L [L-L = MeE(CH 2 ) n EMe; E = S or Se, n = 2 or 3, PhE(CH 2 ) 2 EPh or o-C 6 H 4 (EMe) 2 ] in anhydrous n-hexane solution under an N 2 atmosphere results in the rapid formation of [TiCl 4 (L-L)] as yellow, orange or red solids. Analogous bromo and iodo species, [TiX 4 (L-L)] [X = Br; L-L = MeE(CH 2 ) n EMe or o-C 6 H 4 (EMe) 2 ; X = I; L-L = MeSe(CH 2 ) 2 SeMe or o-C 6 H 4 (SeMe) 2 ], were obtained as intense orange or red coloured solids by treatment of TiX 4 with L-L in CH 2 Cl 2 solution. Crystallographic studies on [TiCl 4reveal a distorted octahedral arrangement with the coordinated group 16 donor ligand adopting the  form in the first three cases and the meso form in the fourth example. These studies also reveal a trans influence series of Cl > S ≈ Se on Ti(). Solution NMR studies show that the chloro-compounds undergo rapid pyramidal inversion at ambient temperature, while the bromo and iodo species also undergo rapid ligand dissociation/chelate ring-opening. At low temperature these processes are slowed significantly, such that in most of the chloro and bromo species it is possible to identify both the meso and  invertomers, although ligand exchange is still rapid at 200 K for the iodo species. The potential of these compounds as sources of titanium sulfide or titanium selenide phases via controlled decomposition is also discussed briefly. Finally, the dinuclear species, [Cl 3 Ti{MeS(CH 2 ) 2 SMe}] 2 (µ-O), formed by partial hydrolysis of [TiCl 4 {MeS(CH 2 ) 2 SMe}], has also been identified crystallographically.

Vanadium(IV) and Oxidovanadium(IV) and ‐(V) Complexes with Soft Thioether Coordination – Synthesis, Spectroscopic and Structural Studies

“…17000 cm -1 . The very significant low energy shift in the charge-transfer bands between [TiCl 4 (dithioether)] [16] and [VCl 4 (dithioether)] is also consistent with the much greater ease of reduction of the vanadium complexes.…”

“…[TiCl 4 (dithioether)]) [16] and decomposed by acetone, alcohols or thf. The complexes are paramagnetic with magnetic moments µ eff = 1.7-1.9 µ B , consistent with d 1 V…”

μ-Oxo-bis{isopropoxo[2,2′-(methylenedithio)bis(6-tert-butyl-4-methylphenolato)]titanium(IV)}

“…A cis arrangement of the thioether groups and a trans-coordination of the phenolate groups are observed, similar to what has previously been found in analogous mononuclear complexes (Capacchione et al, 2005). Some other oxo-bridged dinuclear Ti species are known, with the -O atom either occupying an inversion centre or lying on a general position (Levason et al, 2000;Willey et al, 1994).…”

μ-Oxo-bis[trichlorobis(dimethylsulfane)titanium(IV)]

“…64 (8) ]. An almost identical arrangement can be found in [(MeS(CH 2 ) 2 SMe)Cl 3 Ti] 2 ("-O) (Levason et al, 2000); here an inversion centre situated at the bridging O ligand links the two distorted octahedral titanium(IV) centres. However, compound (I) does not possess an inversion centre [TiÐO = 1.778 (2) and 1.812 (2) A Ê , and TiÐOÐTi = 171.…”

“…The quality of these ®lms was found to be as high as those obtained from the corresponding two-component processes. Along with the CVD studies, the properties of thio and seleno ethers have been investigated (Levason et al, 2000;Wilson et al, 2003;Zeltner et al, 1999). The X-ray structure determination of [(Me 2 S) 2 Cl 3 Ti] 2 ("-O), (I), is reported here.…”