The Theoretic Study Of Aluminum Hydrazide And Gallium Hydrazide By The Means Of Molecular Design

By the means of molecular design we study aluminum hydrazide andgallium hydrazide systemically with ab intio tool.At first, the optimized geometries, population, infrared spectra and chemical thermodynamics of H₆Al₄(iPrNNiPr)₃ cage compound in gas phase were investigated by using density function theory (DFT) at B3LYP/6-31G* level. According to the results, Al-N, N-N bonds are single, and every aluminum atom has a weak bond, which make recombination easy. N-N bond is easy to split, which can reduce living energy. So H₆AL₄(iPrNNiPr)₃ is suitable as a precursor to group 13 nitrides. From the vibrational spectra calculation we know that the cluster compound is stable.On the basis of the study of H₆AL₄(iPrNNiPr)₃, in order to make the bond characteristic clear and to forecast precursors to group 13 nitrides, six molecules were designed by changing iPr groups on the N atoms with H, CH₃, OH. The optimized geometries, population, infrared spectra and chemical thermodynamics of cage compounds in gas phase were investigated by using density function theory (DFT) at B3LYP/6-31G* level, and compared with H₆AL₄(iPrNNiPr)₃. From the vibrational spectra calculations we know that all molecule are stable. In molecules Al-N, Ga-N, N-N are single bonds. With sizes of groups changed, M-N, N-N have fewer changes. With nucleophiliciry of groups changed, M-N are stronger and stronger, and N-N are weaker and weaker. We can forecast that some weak M-Nbonds and N(2)-N(4) bond are easy to split. From comparison H₆AL₄(iPrNNiPr)₃ isthe most suitable precursor to nitride.On the basis of the study of H₆AL₄(iPrNNiPr)₃ and six molecules, we designed sixteen molecules. These geometries were optimized at B3LYP/6-31G* level. The optimized configurations, population, molecular orbital, vibration frequencies and NBO were investigated. From the vibrational spectra calculations we know that all molecule are stable. The results of calculation show that triangular compounds are not existent, and quadrangular, pentagonal and hexagonal compounds have coplanar bond, which rings are constituted by it conjugative systems. Al-N and Ga-N bonds are double. Polygonal hydrazide compounds are more stable. But they are not suitable as precursors to group 13 nitrides.From the study of chapter two and chapter three, we collect data about aluminum hydrazide and gallium hydrazide. On the basis of tthese data four molecules are designed. These geometries were optimized at B3LYP/6-31G* level. From the vibrational spectra calculations we know that all molecule are stable. There are three kinds of M-N bonds in every molecule, which included single and double bonds. These molecules are less stable than H₆Al₄(iPrNNiPr)₃, and unsuitable as precursors to group 13 nitrides.From the theoretic study of twenty-six molecules the structural characteristic of hydrazide compounds were analyzed, we forecasted the precursors of group 13 nitrides. All data are important for the study of hydrazide compounds.