Dipivaloyl methane

Precisely the last condition explains the fact that mainly ICC have been obtained by the immediate interaction of ligands and zero-valent metals. Thus, a large series of metal p-diketonates was synthesized in the absence of a solvent [513,634-638], for example, iron bis- and tra-acetylacetonates [635]. It was shown that other ligands can serve as activators or promoters in these processes. In particular, the introduction of a,a or y,y -bipy into the reaction mixture gives the possibility of isolating copper acetylacetonates and adducts of similar complexes of cobalt and nickel [636], meanwhile the p-diketonates of the metals above are not formed under conditions similar to those reported in Ref. 635. Under dissolution of more active metallic barium in the mixture of another p-dikctone - dipivaloyl-methane (DPM) - with dyglime (DG) or tetraglime (TG) in absolute pentane, the mononuclear complex [Ba(DPM)2(TG)] and binuclear complex [Ba2(DPM)4 ( t-H20)(DG)] were isolated and structurally characterized [637]. 

DPM = 2,2,6,6-tetramethylheptane-3,5-dionato(dipivaloyl methane). FOD = 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octane dionato. 

Initially non-fluorinated ligand like dipivaloyl methane (dpm) was used. Later on it was observed that fluorine substitution in the ligand resulted in greater resolution of the spectrum as in the case of di-n-butyl ether which is shown in Fig. 10.12. 

Tris(dipivaloylmethanato)technetium(IIl) (dipivaloyl methane = 2,2.6,6-tetra-methyl-3,5-heptancdione) was obtained by refluxing a mixture of dipivaloylmcthane. (NH4)7 TcClft], sodium methoxide and zinc powder in methanol. The red solid is readily oxidized at A /2 = + 0.12 V vx SCE to the cationic Tc(lV) complex. Tris(trifluoro-acetylacctonato)technctium(III) (trifluoroacctylacetone CF3-CO-CH2-CO-CH3) and tris(hexafluoroacetylacetonato)technetium(III) (hexafluoroacetylacetonc CF3-CO-CH2-CO-CF3) were prepared by reaction of the ligands with NH4TCO4 in refluxing ethanol and reduction with dithionite. These complexes are much more difficult to oxidize [423]. 

The displacement of the heavy ligand by the lighter molecule HCN yields an increase in the sensitivity, a concept identified as "mass amplification", and was not applied to piezoelectric detectors before. As mass is lost from the coated crystal when exposed to HCN, the frequency increases whereas a decrease in frequency is expected if moisture is absorbed by the coating. The effect of humidity was studied over the range of 40-92% RH, and it was shown that humidity plays a part in the reacation. Since the reaction is irreversible and the nickel complex is prone to hydrolysis, the coated crystal could be used once only. Substitution of other ligands in nickel complexes, including dibenzoylmethane, dipivaloyl-methane, formate and acetate, did not improve the selectivity towards HCN. 

The most commonly used shift reagents are based on europium (downfield shifts) and praseodymium (upheld shifts) and contain either dipivaloyl methane (Ri = Ra = r-butyl, Rg = H) or fluoroalkyl derivatives of jS-diketones as ligands. 

The purpose of the experimental part of the project was a functional test of the theoretical model on real films. We chose films of divalent copper phthalocyanine and dipivaloyl methanate obtained by sedimentation of volatile complexes on the surface of quartz plates. We tried to obtain the most ordered films and for this purpose changed the temperature of the... 

Most frequently used (albeit not unique) lanthanide ligands serving as shift reagents are pivaloyl-D-camphorate (pvc), trifluorohydroxymethylene-D-camphorate (tfc) and heptafluorohydroxymethane-D-camphorate (hfc), dipivaloyl methane (dpm), 2,2,6,6-tetramethyl-3,5-heptanedione (thd), and 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedione (fod) (Figure 2.7). 

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