ISSN:
0948-5023
Keywords:
Keywords Titanium nitride, Ab initio calculations, Chemical vapor deposition, Ammonolysis, Donor-acceptor complexes
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract The mechanism of TiCl4 ammonolysis has been studied theoretically at ab initio Hartree-Fock, B3LYP, MP2 and CCSD(T)//B3LYP levels using effective core potentials for Ti and Cl and 6-31G* basis sets for N and H. TiCl4 and products of its ammonolysis form five- and six-coordinated complexes with ammonia, which intermediate substitution of Cl atoms by NH2 groups. Transition state energies for the subsequent steps of ammonolysis decrease with increasing number of NH2 groups bound to Ti. The energy of the transition state for the first step of ammonolysis is 19 kcal mol-1 above the energy of the reactants (TiCl4+NH3) and 8 kcal mol-1 above the products (TiCl3NH2 + HCl). The following steps have transition states energetically located below the products, indicating weak hydrogen bonded complex formation as intermediate between transition state and product. A thermodynamic estimation shows the last step of ammonolysis to be endothermic, while the first three steps are exothermic if the adduct formation energy is taken into account.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/PL00010740
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