Effective Hamiltonian method for environmental effects

Some novel physical ideas and mathematical techniques are described, useful in the development of effective Hamiltonian methods for studying molecular environmental effects.     

A systematic preparation of new contracted Gaussian-type orbital sets. VIII. MINI-1 and MIDI-1 sets for Ga through Cd

Minimal contracted Gaussian basis sets are presented for Ga through Cd. Characteristically these Gaussian-based minimal sets give far better d orbital energies than those by minimal STO basis sets. These new basis sets were tested on Br₂ for which a new benchmark calculation was also performed. The test result is satisfactory in that these basis sets produce good general agreement with the near Hartree–Fock calculation with respect to the molecular spectroscopic constants.     

Penicillin-cephalosporin conversion X. New synthesis of dithioazetidinones from thiazoline-azetidinones

New ring-opening reaction of thiazoline-azetidinones 1 to dithioazetidinones 2 was achieved with 2-benzothiazolyl disulfide in aqueous acidic media and its potentiality for the preparation of a variety of cephalosporins 3 from various thiazoline-azetidinones 1 is demonstrated.     

A facile access to α-phenylselenenyl carbonyl compounds by electrochemical oxidation

A novel α-phenylselenenylation of carbonyl compounds has been performed by electrolysis of a solution of ketones, diphenyl diselenide, tetraethylammonium bromide, and magnesium bromide in polar solvents (MeOH, AcOH, MeCN). The electrolysis enables us to prepare the desired seleno-carbonyl compounds without employing strong bases and the activated selenenyl reagents PhSeX.     

Structure and properties of transition-metal compounds. A systematic study of basis set effects in ab initioSCF calculations

The recently developed Gaussian basis functions [2] were used in calculations on the ground electronic states of molecules containing transition-metal atoms: ScF₃, TiCl₄, ZrCl₄, Cr(CO)₆, Ni(CO)₄, CuF, CuCl, Zn(CH₃)₂, and Cd(CH₃)₂. The usefulness of minimal basis sets, the importance of splitting of the valence part of the minimal basis sets, the role of the triple splitting of the d-block functions, and the need for p-, d-, and f-type polarization functions were discussed in the context of the geometrical structure and the firstorder electronic properties of the transition-metal atom compounds.     

Approximate relativistic correction term

It is demonstrated that the first-order relativistic correction term to the Schrödinger hamiltonian for the hydrogen-like atom,

cannot be used safely even for small values of atomic number, Z, in the variational calculation. A modified form of the operator R is proposed so that one may incorporate it into the variational treatment of molecular systems.     

A novel selenium-mediated spiroannelation : one-step preparation of d1-theaspirane fron α-dihydroionol

d1-Theaspirane (1) was prepared by the selenium-mediated electrochemical oxidation of α-dihydroionol (3), via a novel selenium-mediated spiroannelation.     

Well-tempered GTF basis sets for the atoms K through χe

Well-tempered GTF basis sets have been prepared for the atoms K (Z = 79) to χe (Z = 54). They are close to the Hartree-Fock solution and virtually saturated. The size of the basis sets is large but the number of disticnt exponent values remains relatively small.     

Pd(O)-catalyzed electroreductive cleavage of allylic acetates

Pd(O)-catalyzed electroreductive cleavage of allylic acetates yielding alkenes and/or allyltrimethylsilanes is described. Deprotection of allyl esters can be performed in the same electrolysis system.     

Penicillin-cephalosporin conversion-XI. Synthesis of 7-(α-substituted phenylacetoamide) cephalosporins by utilization of all the framework elements of penicillin G

A successful synthesis of clinically significant cephalosporins 2a-c with use of all the framework elements of penicillin G is described.