Titanium electronic structure

Wu H, Desai S R and Wang L S 1996 Electronic structure of small titanium clusters emergence and evolution of the 3d band Phys. Rev. Lett. 76 212... 

The theoretical studies " have been focused on TiSi2. Some attempts, with use of high-symmetry crystal structures, have been made to understand some of the other titanium silicides. This paper deals vith Ti,5Si.3. Because of the crucial interplay between structure and bonding we have studied the proposed stable low-symmetry crystal structure. This will give a better picture of the electronic structure and the bonding properties in this system. An investigation of seven members in the Ti-Si system will be presented in a future publication. ... 

The effect of electron transfer between tungsten oxide and titanium oxide is also important in photochromatic applications. In an excellent study of aqueous sols. He et al. analyze the electronic structure of the tungsten oxide-titanium oxide system, finding that titanium oxide can catalyze the generation of W+. This state is a colored state and can be generated from WO3 WH2O by the following reactions ... 

Coloma F, Marquez F, Rochester CH, Anderson JA (2000) Determination of the nature and reactivity of copper sites in Cu-Ti02 catalysts. Phys Chem Chem Phys 2 5320-5327 Umebayashi T, Yamaki T, Itoh H, Asai K (2002) Analysis of electronic structures of 3d transition metal-doped Ti02 based on band calculations. J Phys Chem Solids 63 1909-1920 Yamashita H, Ichihashi Y, Takeuchi M, Kishiguchi S, Anpo M (1999) Characterization of metal ion-implanted titanium... 

Applying ion beams, surface-sensitive analysis and modification in atomic and electronic structures of inorganic materials have been developed. Ion beam modification of titanium dioxide (Ti02), carbon-based materials, and the analysis of Nb/Cu multilayers and VO2 using ion beam are described as follows. 

H.J. Zhai et al., Probing the electronic structure and band gap evolution of titanium oxide clusters (Ti02)n (n = 1-10) using photoelectron spectroscopy. J. Am. Chem. Soc. 129, 3022-3026 (2007)... 

As regards stable metallacycle catalysts for cycloolefin polymerisation, catalysts based on Ti (titanacyclobutanes) and Ta (tantallacyclobutanes) are used [47,49]. The first demonstration of a living and well-controlled system concerned the polymerisation of norbornene in the presence of substituted biscy-clopentadienyltitanacyclobutane in which four-coordinate titanium possesses formally a d° 16-electron structure [97,98], The initial titanacycle undergoes a reaction with norbornene at 20 °C to yield the trisubstituted metallacyclobu-tane ... 

Zinc orthotitanate [12036-69-0], ZmTi04, a white solid having a density of 512(0) and a spinel structure, is obtained by heating the calculated amounts of the two oxides at 1000°C. Zinc orthotitanate forms a series of solid solutions with titanium dioxide, extending to the composition Zn2Ti04 1.5Ti02. These solid solutions begin to dissociate at 775°C with the formation of the rutile form of titanium dioxide. The properties of the rare-earth titanates and their electronic structure are available (117—119). 

Bilmes, S.A., P. Mandelbaum, F. Alvarez and N.M. Victoria (2000). Surface and electronic structure of titanium dioxide photocatalysts. Journal of Physical Chemistry B, 104, 9851-9858. 

Umebayashi, T., T. Yamaki, T. Sumita, S. Yamamoto, S. Tanaka and K. Asai (2003a). UV-ray photoelectron and ab initio band calculation studies on electronic structures of Cr- or Nb-ion implanted titanium dioxide. Nuclear Instruments and Methods in Physics Research Section B-Beam Interactions with Materials and Atoms, 206, 264-267. 

The electronic configuration of titanium is [Ar] 3d24s2, which means that Ti(IV) compounds are d° species with free coordination sites 1-27,28). H-NMR and 13C-NMR data are known and have been occasionally discussed in terms of bond polarity 19), but such interpretations are obviously of limited value. The electronic structure of methyltitanium trichloride 17 and other reagents have been considered qualitatively 52) and quantitatively S3 56> using molecular orbital procedures. It is problematical to compare these calculations in a quantitative way with those that have been carried out for methyllithium 57> since different methods, basis sets and assumptions are involved, but the extreme polar nature of the C—Li bond does not appear to apply to the C—Ti analog. Several MO calculations of the w-interaction between ethylene and methyltitanium trichloride 17 (models for Ziegler-Natta polymerization) clearly emphasize the role of vacant coordination sites at titanium 58). 

The titanium-chelated structure (18) forces the nucleophilic addition to occur from the less hindered si-face (i.e. syn to the lone pair of electrons) in contrast, the aluminum-based process proceeds via nonche-lated transition state (19). In this case, the less hindered re-face is syn to the electron pair. Unfortunately, a test of this transition state hypothesis would require an organoaluminum addition under chelation con-... 

The molecular and electronic structures of (CpM)4(//2-E)6 and (CpM)4(/x2-E)3(//3-E)3 (E = O, Se) for titanium as well as group 5 and 6 transition metals have been compared using extended Hiickel molecular orbital calculations. The conclusions indicate that the M4(/x2-0)3(/x3-0)3 structure cannot exist unless the M4-tetrahedron is severely distorted by lengthening of the M(apical)-M(basal) distance. The M4(/x2-Se)3(/x3-Se)3 structure can exist with a small distortion. The M4(/x2-E)6 structure is preferred over M4(//2-E)3(//3-E)3 when M-E multiple bonding is important, that is, when E = O. There is little M-M interaction in any of the cluster orbitals.830... 

The chemistry of early transition metal complexes containing a chalcogenido-metal bond is an area of continuing interest because of their unusual electronic structures and properties, and the relevance of such compounds as models for several important industrial catalytic processes. A variety of titanium complexes containing Ti-S bonds are known and this chemistry has been reviewed.1003,1004... 

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