Malonato complexes

The kinetics are straightforward only in the case of Co(IIl) oxidation, which involves slow breakdown of a malonato complex, viz. 

Substituent effects hae been observed in a series of substituted malonato complexes (167). The 9Be resonance frequencies move to higher field as the basicity of the ligand increases, as can be seen in Table XI. Quadrupolar broadening is considerable in complexes of the hydrolyzed trimer, so much so that unless a species of this sort is present in high concentration relative to the others, its signal may be buried in the baseline noise. The tetrahedron is significantly distorted from Td symmetry in these compounds. 

In contrast to the monoclinic tris-malonato complexes, M2(OOCCH2COO)s 8 H2O (M=Nd) which contain nonacoordinated lanthanide ions in a monocapped square antiprismatic polyhedron, the orthorhombic tris-malonates Pnma) have a tricapped trigonal prismatic geometry for the coordination polyhedron. A rep-... 

Several compounds have been identified which show better antitumor activity than ciy-platin. Some have the advantage of higher water solubility and greater ease of administration. Sulfato-l,2-diaminocycIohexaneplatinum(II) is water soluble (0.5 mol l-1), active against at least three animal tumors, and about 30 times as potent as ciy-platin. A similar malonato complex is unique in that significant concentrations reach the brain (as tested in dog). ciy-Diammine-l,l-cyclobu-tanedicarboxylateplatinum(II), carboplatin, has just been released in Britain for general use, after extensive trials. 

The malonato complexes of chromium(III) are analogous to the oxalate complexes of chromium(III). Since malonic acid is a weaker acid than oxalic acid, the malonato complexes are expected to be more labile than the oxalato complexes. The dicarboxylate complexes of chromium(III) form a group of anionic complexes which are suitable for the study of octahedral complex reactivity. 

The fluorescent complex [Ru(II)(3,4,7,8-tetramethylphen)3]Cl2 is readily taken up by P388 leukemia cells in culture and is visible on the cell surface, in the cytoplasm, and in the nucleus, but it does not exhibit antitumor activity in vivo (11). The platinum complexes [Pt(en)(oxalate)], [Pt(NH3)2(H20)2l (as the dinitrato complex), and [Pt(en)3] + also cause convulsions in animals (12) the latter two complexes are positively charged and relatively inert and the former is neutral and presumably undergoes an activation step before it binds to the neuromuscular junction. Curiously, the related malonato complex is not a neurotoxin. Care is taken in the clinic to administer cisplatin in saline solutions to avoid hydrolysis and minimize the production of neurotoxic aqua or hydroxobridged Pt(II) species. 

The trans isomers of the dicarbonato, carbonatooxalato and bis(oxalato) complexes have a split second absorption band (Ha and IIb) the extent of the splitting is greatest for the dicarbonato complex and smallest for the bis(oxalato) complex (Fig. 5.5). The franj(N)-bis(malonato) complex, showed no splitting in either the... 

The absorption and CD spo tral data are collected in Tables 5.9 and 5.10. The CD spectra could be grouped into four types of patterns in the Tjg region 1) only one peak, 2) two peaks of opposite signs, 3) two peaks of the same sign, and 4) three peaks of alternating sign. The active dicarbonato complexes exhibit a symmetrical peak of type 1. The active carbonatooxalato complexes also show only one peak, which is unsymmetrical. The (+)s89[Co(C03)(mal)(NH3)2] complex exhibits the pattern of type 2. The (—)546[Co(ox)2(en)] complex has the pattern of type 3. The active oxalatomalonato and bis(malonato) complexes show the pattern of type 4. 

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