Abstract
[TiCp&sub2;S₅] (phase A), [TiCp&sub2;Se₅] (phase F), and five solid solutions of mixed titanocene selenide sulfides [TiCp&sub2;SexS₅-x] (Cp = C₅H₅-) with the initial Se:S ranging from 1:4 to 4:1 (phases B⁻E) were prepared by reduction of elemental sulfur or selenium or their mixtures by lithium triethylhydridoborate in thf followed by the treatment with titanocene dichloride [TiCp&sub2;Cl&sub2;]. Their 77Se and 13C NMR spectra were recorded from the CS&sub2; solution. The definite assignment of the 77Se NMR spectra was based on the PBE0/def2-TZVPP calculations of the 77Se chemical shifts and is supported by 13C NMR spectra of the samples. The following complexes in varying ratios were identified in the CS&sub2; solutions of the phases B⁻E: [TiCp&sub2;Se₅] (5&sub1;), [TiCp&sub2;Se&sub4;S] (4&sub1;), [TiCp&sub2;Se&sub3;S&sub2;] (3&sub1;), [TiCp&sub2;SSe&sub3;S] (3₆), [TiCp&sub2;SSe&sub2;S&sub2;] (2₅), [TiCp&sub2;SSeS&sub3;] (1&sub2;), and [TiCp&sub2;S₅] (0&sub1;). The disorder scheme in the chalcogen atom positions of the phases B⁻E observed upon crystal structure determinations is consistent with the spectral assignment. The enthalpies of formation calculated for all twenty [TiCp&sub2;SexS5-x] (x = 0⁻5) at DLPNO-CCSD(T)/CBS level including corrections for core-valence correlation and scalar relativistic, as well as spin-orbit coupling contributions indicated that within a given chemical composition, the isomers of most favourable enthalpy of formation were those, which were observed by 77Se and 13C NMR spectroscopy.