31168-87-3Relevant articles and documents
x - a highly reactive titanium hydride and an active species in the McMurry reaction
Aleandri, Lorraine E.,Becke, Sigurd,Bogdanovic, Borislav,Jones, Deborah J.,Roziere, Jacques
, p. 97 - 112 (1994)
The complex reacts with catalytically-prepared solid magnesium hydride (MgH2*) or dissolved magnesium hydride (MgH'2) with evolution of hydrogen to give a highly reactive titanium hydride, x (1).The well-known low valent titanium species, obtained by reduction of TiCl3 with LiAlH4, utilized in the McMurry reaction, has been shown to be 1.An X-ray absorption spectroscopy study (EXAFS) of 1 reveals that the Ti absorber is surrounded by O (from THF) and Cl atoms plus two types of Ti neighbors.Possible structural models for 1 compatible with the EXAFS results are proposed.Complex 1 is an active reagent for the coupling reaction of benzophenone to give tetraphenylethene.During the reaction hydrogen is liberated and the inorganic side product has been shown to be titanium(III) oxychloride; thus the McMurry reaction employing 1 as the reagent can be described by . On the basis of these results, a new interpretation of the mechanism for the McMurry reaction is presented.Complex 1 also undergoes a number of carbenoid type reactions, which may proceed via a "titanium carbenoid" intermediate 9a-c. Key words: Titanium; Hydride; Magnesium; EXAFS
Reduction of titanium supported by a σ-/π-bonded tripyrrole ligand: Ligand C-N bond cleavage and coordination of olefin and arene with an inverse sandwich structure
Nikiforov, Grigory B.,Crewdson, Patrick,Gambarotta, Sandro,Korobkov, Ilia,Budzelaar, Peter H. M.
, p. 48 - 55 (2008/10/09)
The formally Ti(I)/Ti(II) mixed-valence toluene complex {2,5-[(C 4H3N)CPh2]2[C4H 2N(Me)]}Ti (μ,η6-C7H8)Ti[{2, 5-[(C4H3N)CPh2]2[C4H 2N(Me)]}][K(DME)2]·toluene (1) with an inverse sandwich type of structure has been obtained from the reduction of {2,5-[(C 4H3N)CPh2]2[C4H 2N(Me)]}TiCl with potassium in toluene. The bridging molecule of toluene in the paramagnetic 1 shows a visible distortion due to a substantial amount of metal-to-ring back-bonding. Complex 1 was always the only detectable product, even in cases when lower than stoichiometric amounts of reductant were employed. DFT calculations have been carried out to elucidate the electronic structure of the mixed-valence 1 in order to clarify the reason for its apparent thermodynamic stability. The most energetically favorable model comprises two divalent Ti centers connected to an organic radical anion. The olefin adducts {2,5-[(C4H3N)CPh2]2-[C 4H2N]}Ti(η2-trans-PhHC=CHPh)[K(DME)] (2) and {2,5-[(C4H3N)CPh2]2[C 4H2N (Me)]}Ti(η2-trans-PhHC=CHPh) (3) were obtained from identical reactions carried out in the presence of trans-stilbene. Complexes 2 and 3 may be regarded as the result of the oxidative addition of a transient divalent species to the trans-stilbene molecule. In the case of 2 however, the reaction is accompanied by the cleavage of the C-N bond of the π-bound alkylated pyrrole ring.
The first structurally characterized nonorganometallic titanium(III) alkoxo-bridged dinuclear complexes
Utko, Jozef,Przybylak, Szymon,Jerzykiewicz, Lucian B.,Mierzwicki, Krzysztof,Latajka, Zdzislaw,Sobota, Piotr
, p. 267 - 269 (2008/10/08)
The reaction of [Ti4(OMe)14Cl2] (1) with an excess of AlMe3 gave the cocrystallite [Ti2(μ-OMe)2(μ-Cl)Cl3 (thf)3]·[Ti2(μ-OMe)3 Cl3(thf)3] (2·3) species in a 1:1 ratio. Similar to 2, [Ti2(μ-OEt)2(μ-Cl)Cl3- (thf)3] (4) was obtained in the reaction of an equimolar mixture of TiCl4 and Ti(OEt)4 with Al/AlMe3. The short distance [2.543(1)av A in 2.3 and 2.599(1) A in 4] between Ti(+3) atoms, their diamagnetism, and ELF analysis indicate the presence of a Ti-Ti bond.
