Synthesis and Structure of the [Co(NioxH)2(Thio)2]2[SiF6] Complex

Anhydrous compound [Co(NioxH)₂(Thio)₂]₂[SiF₆] (I) was synthesized. Its structure was determined by X-ray diffraction analysis. The structures and character of intramolecular and intermolecular hydrogen bonds of complex Iand the previously studied [Co(NioxH)₂(Thio)₂]₂[SiF₆] · 3H₂O complex were compared.     

Double exchange in polynuclear mixed-valence clusters

A method for calculating the energies of the tunnel states of mixed-valence, clusters is proposed. It is based on the secondary quantization technique and allows one to obtain analytical expressions for all matrix elements that appear in double exchange theory as well as to determine the microstructures of the parameters of this theory. The energy spectra of trimeric systems are calculated with allowance made for the three-center transfer integrals, and the magnetic properties of these systems are investigated. Moldova State University. Translated fromZhurnal Struktumoi Khimii, Vol. 36, No. 4, pp. 644–653, July–August, 1995. Translated by I. Izvekova     

Magnetic properties of tetrameric tetrahedral clusters with two-electron transfer

Tunnel-exchange states of tetrahedral tetrameric clusters dⁿ-dⁿ-dⁿ⁺¹-dⁿ⁺¹ with double transfer are considered to calculate the energy levels and wave functions. A method based on the second quantization technique and group-theoretical approach is developed. The nature of the ground spin state of the above systems is determined. It is shown that the structures have magnetic properties that radically differ from the properties of clusters with one migrating electron (hole). Moldova State University. Translated fromZhurnal Strukturnoi Khimii, Vol. 37, No. 3, pp. 458–470, May–June, 1996.     

Supramolecular structure organization and the biological properties of [Co(DH)<Subscript>2</Subscript>(PP)<Subscript>2</Subscript>][BF<Subscript>4</Subscript>]

The coordination compound [Co(DH)₂(PP)₂][BF₄]₂ · 2H₂O (DH⁻ is the dimethylglyoxime residue, PP is nicotinamide) was synthesized and studied by X-ray diffraction. The equatorial plane of the octahedral Co(III) complex contains two DH⁻ residues combined by intramolecular hydrogen bonds O-H…O, while the apical positions are occupied by two PP molecules. A method for the optimal use of the complex for enhancement of the biosynthesis of standard and acid-stable amylases of the micromycete Aspergillus niger 33–19 CNMN FD 02A and lipases of the micromycete Rhizopus arrhizus Fischer CNMN FD 03L was depeloped. The introduction of the complex in a concentration of 1–5 mg/l into the culture medium of Aspergillus niger 33-19 CNMN FD 02A reduces the process cycle by 24 h. The stimulating effect of the introduction of the complex (5 mg/l) into the culture medium of the Rhizopus arrhizus Fischer CNMN FD 03L strain is 55.5%.     

The Use of Co(III) Dimethylglyoximates in the Biosynthesis of Rhizopus arrhizus Pectinases

Novel coordination compounds of Co(III) with dimethylglyoxime were synthesized, namely, [Co(DH)₂(Thio)₂]₃F[SiF₆] · 1.5H₂O (I) and [Co(DH)(Thio)₂]₂[SiF₆] · 3H₂O (II)], in which the central atom coordinates dimethylglyoxime moieties (DH), thiocarbamide (Thio), and hexafluorosilicate anions. These compounds were tested as stimulators in the biosynthesis of extracellular enzymes in the Rhizopus strain. It was established that the effect produced by complex compounds depends on the type of hydrolytic enzyme complex used, the composition of the complex, and its concentration in the cultivation medium.     

Synthesis and structure of the mixed-ligand cobalt(III) complex [Co(DH)(Hthsc)2][SiF6] · 2.3H2O

The compound [Co(DH)(Hthsc)₂][SiF₆] · 2.3H₂O, where DH^? is a dimethylglyoxime residue and Hthsc is a thiosemicarbazide molecule, was synthesized and studied by X-ray diffraction. The coordination polyhedron of the central metal ion (distorted octahedron) is formed by two sulfur atoms, two nitrogen atoms of two Hthsc molecules coordinated in the bidentate mode, and two nitrogen atoms of the DH^? ligand. The positions of three metal rings are fixed by two intramolecular hydrogen bonds (N-H…O). A bifurcated system of intermolecular hydrogen bonds forms a framework structure in the crystal.     

Electronic spectra of low-spin bioctahedral Fe(II)−Fe(III) mixed-valence dimers

Moldavian State University. Translated fromZhurnal Struktumoi Khimii, Vol. 36, No. 1, pp. 185–189, January–February, 1995.     

Group-theoretical classification of the resonance states of mixed-valence clusters

Moldova State University. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 4, pp. 743–747, July–August, 1995.     

Shallow acceptors in ionic semiconductors with a degenerate band

The energy spectrum of an impurity-phonon system in semiconductors with a degenerate valence band ₈ edge is calculated. The matrix Hamiltonian of the problem is represented as a sum of two matrices containing operators of the s and d type respectively. Neglecting the latter matrix, the partition function of the system is represented as a path integral, which is calculated with the help of the variational principle based on the introduction of a trial quadratic Lagrangian. The matrix with operators of the d-type is taken into account as a perturbation. The results are compared with experiment.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 51–53, January, 1991.