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1,3]-Dipolar cycloadditions 1-Aza-2-azoniaallene cations 3, prepared in situ from geminal chloro(alky1azo) compounds 2, react with acetylenes 4 to give either 1H-pyrazolium salts 6 or 4H-pyrazolium salts 7 or mixtures of both. 4H-Pyrazolium salts with a hydrogen atom attached to C(4) rearrange to the protonated 1H-pyrazoles 8, from which the free bases 9 are obtained upon treatment with aqueous NaOH. According to AM1 calculations the cy-cloaddition of acetylenes to 1-aza-2-azoniaallene cations is a concerted process, which can be classified as a "1,3-dipolar cycloaddition with reverse electron demand". The cycloaddition forming the intermediates 5 is followed by an [1,2] alkyl shift to furnish the final products 6-8. The direction of the [1,2] shift has been found to be governed by subtle steric effects.

Synthesis and Characterization of some thiocarbohydrazone Schiff bases and their complexes with Cu(II),Ni(II),Zn(II),Co(II) and Fe(II) are described. The Schiff bases were obtained by condensation of thiocarbohydrazide with a group of aldehydes in 1:2 molar ratios. The prepared Schiff basses are bis(pyrrole-2-carboxaldehyde)thiocarbo-hydrazone(Pytch),bis(thiophene-2carboxaldehyde)thiocarbohydrazone(Thtch),bis(furfuralthiocarbohydrazone(Futch) and bis(piperonaldehyde) thiocarbohydrazone(Pitch). The stoichiometry of the obtained complexes and the bonding modes of the ligands was found to depend on both nature of metal and ligand. The ligands (Pytch) and (Futch) produced tetracoordinate complexes of the general formual [MLCl 2 ] where they act as neutral bidentates bonding through the two imine nitrogens. However,in case of Pitch,the ligand is proposed to act as monobasic bidentate producing tetracoordinate complexes of the formual [M(Pitch) 2 ] with Co,and Ni whereas with copper it is proposed to act as tridentate forming a tetracoordinate complex of the formula,[Cu(Pitch)Cl]. Concerning the (Thtch) ligand,it is suggested to act either as neutral bidentate producing a tetracoordinate complex of the formula [Fe(Thtch)Cl 2 ] or as monobasic tridentate producing tetracoordinate [Zn(Thtch)Cl] complex or as monobasic bidentate forming tetracoordinate [M(Thtch) 2 ] complexes where M = Co,Ni and Cu. The antibacterial activity of the compounds against Acinetobacter sp gram negative and Staphylococcus gram positive strains was examined.

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