Pyruvic acid thiosemicarbazone

Ligand abbreviations bi = 2,2 -bi-2-imidazoline bt = 2,2 -bi-2-thiazoline bpy = 2,2 -bipyridine phen = 1,10-phenanthroline phy = l,10-phenanthroline-2-carbaldehyde phenylhydrazone bpp = 2,6-bis(pyrazol-3-yl)pyridine paptH = 2-(2-pyridylamino)-4-(2-pyridyl)thiazole 2-pic = 2-picolylamine L = macrocyclic ligand derived from condensation of 2,6-diacetylpyridine with 3,6-dioxaoctane-1,8-diamine Hjthpu = pyruvic acid thiosemicarbazone Hjthpx = pyridoxal thiosemicarbazone salen = dianion of W,iV -ethylenebis(salicylideneimine) H2fsa2en = dianion of fV,JV -ethylenebis(3-carboxysalicylaldimine). 

The Fe(III) complexes of the dianion of pyruvic acid thiosemicarbazone (thpu2- Fig. 7), (cation+)[Fe(thpu)2]-nH20, are very similar to those of the salicylaldehyde derivatives (Fig. 6) discussed above. The spin state properties are quite sensitive to changes in the counter-cation (typically an alkali-metal cation or a protonated nitrogenous base) and the lattice water content of the material. The parent compound, NH4[Fe(thpu)2], is low spin at room temperature [113]. Li[Fe(thpu)2]-3H20 is also low spin but K[Fe(thpu)2] 2-H20 shows almost complete spin crossover between 80 and 300 K [108]. 

S—N bidentate towards VO whereas pyruvic acid thiosemicarbazone acts as a... 

N-carbodithioic acid, -pyruvic acid thiosemicarbazone ... 

N-Do/Jor Ligands. The full account of the preparation and properties of V[N(SiMc3)2]3 has been published. (Et4N)3[V(NCSe)e] has been prepared and its electronic spectrum reported in several solvents. The electronic spectra of fVL lfNCSij complexes (L = py, 3-picoline, 3,4-lutidine, or 3,5-lutidine) are consistent with tetrahedral microsymmetry about the V " atom, and the magnetic properties of V complexes with the thiosemicarbazones of salicylaldehyde and pyruvic acid have been interpreted in terms of a tetragonal environment about the metal. ... 

Substitution in position 4 displays a more complex influence. Cyclization of the 4-methyl- and 4-ethyl-thiosemicarbazones of phenylpyruvic acid and of the 4-methylthiosemicarbazone of phenyl-glyoxylic acid (103) was readily achieved (104), whereas it was not possible to cyclize the analogous 4-methyl derivatives of pyruvic and glyoxylic acids. It thus appears that cyclization is hindered by substitution in position 4 and that this unfavorable effect can be partly relieved by the known favorable effect of an aryl or aralkyl group in the a-position. 

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