Access Type

Open Access Dissertation

Date of Award

1-1-2010

Degree Type

Dissertation

Degree Name

Ph.D.

Department

Chemistry

First Advisor

Charles H. Winter

Abstract

Heavier alkaline earth metal tetrazolates have been prepared as cryatals contain aqua ligands and as anhydrous powders, and were characterized by spectral and analytical methods. Potassium bis(tetrazolyl)borate complexes K(BH2(RCN4)2)(H2O)n (R = H, Me, NMe2, and NiPr2) and their 18-crown-6 adducts have been synthesized. In the solid state, complexes where R = H and Me have B-N bonds to the nitrogen atoms proximal to the carbon atom, whereas those with R = NMe2 and NiPr2 possess isomeric B-N bonds to the nitrogen atoms distal to the core carbon. With small R groups, the bis(tetrazolyl)borate ligands adopt bridging μ2 coordination modes to the [18-crown-6]+ fragments, while with larger R groups, they adopt chelating κ3-N,N',H coordination modes in the 18-crown-6 adducts. Bis(5-methyltetrazolyl)borate complexes of lithium and heavier alkaline earth metals have been prepared. The new group 2 metal complexes were structurally characterized. Crystals of sodium cyano(tetrazolyl)borate complexes with or without methanol ligands have been prepared. The methanol ligands are lost rapidly at 23 °C from crystals of Na(H2B(CN)(HCN4))(CH3OH) and Na(H2B(CN)(MeCN4))(CH3OH)·(CH3OH) once they are isolated from the solution.

All of the new complexes mentioned above are air stable and thermally stable between 210 °C and 325 °C. They are insensitive toward impact, friction, and electrostatic discharge. The new complexes have potential use as propellants or secondary energetic materials; the barium tetrazolates may behave as primary energetic materials. The group 2 metal complexes are good candidates for colorants in pyrotechnic compositions. The potassium and sodium complexes can serve as starting materials to make other high nitrogen content bis(tetrazolyl)borate and cyano(tetrazolyl)borate complexes, respectively.

A series of rhenium isocyanate complexes (ç5-C5H5)Re(CO)(NCO)(N2Ar) was obtained by treatment of the specific rhenium aryldiazenido complexes [(ç5-C5H5)Re(CO)2(N2Ar)][BF4] (ç5-C5H5)Re(CO)(NCO)(N2Ar) (Ar = 4-methoxyphenyl, 2,4-dimethoxyphenyl, 3,4,5-trimethoxyphenyl, 2-trifluoromethylphenyl, and phenyl) with sodium azide. Treatment of CpRe(CO)2(THF) with Et2NC6H5N5 made in situ affords the isocyanate complex (ç5-C5H5)Re(CO)(NCO)(N2C6H5NEt2) and the methoxycarbonyl complex (ç5-C5H5)Re(CO)(COOCH3)(N2C6H5NEt2). The attempted preparation of rhenium aryl pentazole complexes did not proceed to form the desired products.

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