Theoretical Study On The Meachanism Of Synthesis Of Selenium, Sulfur And Other Elements Of The Organic Germanium Compounds

Germanium (Ge) is a naturally occurring trace element found in several organic substances, and its compounds are known to have a broad of biological activities including antimicrobial, antiviral, antineoplastic, analgesic, and immuno-modulating effects. Germanium compounds are classified into inorganic and organic forms. In general, inorganic forms of germanium (such as GeO2and GeCl4) are known to possess severe toxicity in some important organs or tissues, whereas the organic germanium compounds appear to be less toxic for mammals. For this reason, much interest has been shown in organic germanium compounds since Japanese chemist first synthesized the Ge-132(carboxyethyl germanium sesquioxide), which was synthesized by the hydrolysis of trihalogenopropionic acid, followed by the addition of trihalogenogermane to acrylic acid. Since then, Researching for organic germanium compounds have opened a new era of finding efficient, low toxicity of organic germanium compounds. So far organic germanium compounds have became very active central-level topic in the Bio-inorganic chemistry, synthetic chemistry, trace elements and so on. But experimental results elucidated that majority of the biological activity of organic germanium compounds is low. The method of connecting two or more biologically active elements is intended as an often used optimization method for chemists to minimize the toxicity and improve the activity. In order to find effective, low toxicity of organic germanium drugs, some scholars home and abroad have sought to have the biological activity of elements or groups into the molecular structure of organic germanium, hoping to play synergies, and have synthesized a number of some special organic germanium containing selenium, phosphorus, sulfur elements inexperiment. The theoretical studies are scarce.The main object of this work is as follows:1. The mechanism study of the synthesis process of the organic germanium selenide:HGeCl3+CH2=CHCOCH3â†'Cl3GeCH2CH2COCH3........................(1)Cl3GeCH2CH2COCH3+H2Seâ†'Ge(SeH)Cl2CH2CH2COCH3+HCl.........(2)Ge(SeH)Cl2CH2CH2COCH3+H2Seâ†'Ge(SeH)2Cl CH2CH2COCH3+HC1(3)Ge(SeH)2Cl CH2CH2COCH3+H2Sâ†'Ge(SeH)3CH2CH2COCH3+HCl......(4) 2. The mechanism study of the synthesis process of the alkyl chloride-germanium and dithiocarbamate sodium salt reaction:The summarized result of this paper is as follow:This work is now completed by quantum chemical calculations in gas phase and in solvent. Geometries, energies, vibrational frequencies of reactions, products and TSs are obtained. In order to confirm the reaction mechanism and characterize the nature of the TSs, the intrinsic reaction coordinate (IRC) calculations on the reactions has been performed.In the reaction (1) the geometric parameters of all stationary points (including the reactants, products and transition states) in gas phase optimized at the B3LYP/6-311+G(2d,2p), MPWB1K/6-311++G(2d,2p) and BB1K/6-311++G(2d,2p) levels respectively. The MPWB1K/6-311++G(2d,2p) method is the most appropriate method for the studied system by comparison. We get four kinds of TSs, that is four reaction paths in gas phase. Thermodynamic and dynamics of the four reaction channels was analyzed. The Solvent effects are taken into account with the Onsager model. The mainly reaction pathway was located both in gas phase and in solvents.In the reaction (2)(3)(4) the geometric parameters of all stationary points (including the reactants, products and transition states) in gas phase optimized at the MPWB1K/6-311++G(2d,2p) level respectively. We get four kinds of TSs, that is four reaction paths in gas phase. Thermodynamic and dynamics of the each reaction channel was analyzed. The Solvent effects are taken into account with the Onsager model. The mainly reaction pathway was located both in gas phase and in solvents. It is noteworthy that there is different mainly reaction pathway in gas phase and in solvent in reaction (3). In the reaction (a)-(d), Geometries, energies, vibrational frequencies of reactions,products and TSs are obtained. The intrinsic reaction coordinate (IRC) calculations onthe reactions has been performed to verify the TSs. And we analysis the energy of allthe reaction pathways by comparison.