C-PhosphorylatedN 2-2-thiazolylformamidines

C-Phosphorylation of 2-thiazolylformamidines by phosphorus tribromide was studied. It was shown that the 1,3-diazabut-1-enyl (formamidine) substituent can be used as both an activating and protective group. 5-Phosphorylated thiazoles containing either a formamidine fragment or an amino group were obtained. Some properties of the compounds synthesized were studied. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1353–1359, July, 1999.     

Computation of ultraviolet and visible spectra for cobalt acetylacetonate

A computation is made for the Co(acac)₃ molecule by the semiempirical method of Mulliken, Helmholz, and Wolfsberg. The results indicate a high degree of covalence in the metal—ligand bond. Analysis of the obtained system of energy levels and oscillator forces for the possible transitions makes it possible to interpret the 1100 nm and 800 nm bands as transitions from the -orbitals of the carbon atoms in the ortho position to the metal to the d orbitals of the metal; the bands in the 400- to 610-nm region are interpreted as d()-d transitions, which cannot be regarded as pure d-d transitions. The bands in the region below 400 nm are attributed to - transitions. The calculation also shows that in complexes with covalent metal-ligand bonds the levels, to which the main contribution is made by the atomic orbitals of the metal and the directly coordinated atoms, are mixed.     

Rotational energy cluster formation in XY3 molecules: Excited vibrational states of BiH3 and SbH3

Previous theoretical work on energy cluster formation at high rotational excitation in the vibrational ground state of PH₃ [S.N. Yurchenko, W. Thiel, S. Patchkovskii, P. Jensen, Phys. Chem. Chem. Phys. 7 (2005) 573] is extended to BiH₃ and SbH₃. By means of variational calculations of the rotation–vibration energies based on ab initio potential energy surfaces, we analyze the rotational energy clustering of BiH₃ and SbH₃ at J  70 for a number of vibrational states. We show that BiH₃ and SbH₃, with their pronounced local mode behaviour, exhibit cluster formation already at moderate rotational excitation. In addition, owing to its quasi-spherical-top character, BiH₃ undergoes an imperfect bifurcation at high J. This gives rise to an energy cluster type not present in PH₃ and SbH₃. We present a semi-classical approach to the construction of the rotational energy surfaces for vibrationally excited states.