1,3,5,7-Tetraketones metal complexes

Tetraazaporphyrin, octaphenyl-metallation, 858 Tetraazaporphyrins synthesis, 857 Tetraethylenepentamine metal complexes, 56 Tetraglycine metal complexes, 764 Tetraketones metal complexes, 399 1,3,5,7-Tetraketones metal complexes, 400 Tetramines cyclic... 

The tetraketone 1,7-diphenyl 1,3,5,7 heptanetetraone (dbbaHs, 134), containing three enolizable protons, has been prepared and several heterotrinuclear metal complexes 135, containing the uranyl cation U02 + and other bivalent metal cations, have been isolated and characterized ... 

Polynuclear complexes with more than two metal ions have been prepared with polyketone ligands but no such complexes have been reported with V02+. With the tetraketone l,l -(2,6-pyridyl)-bis-l,3-butanedione (H2L), several polynuclear complexes have been prepared including [(VO)2(L)2] for which jj,Tc = 1.21 BM was obtained.908... 

A series of heterotrinuclear complexes of the tetraketone 134 has been characterized. In such complexes the two outer O4 compartments are occupied by a [U02] + ion, whereas the central O4 compartment is occupied by a M(II) ion (M = Mn, Co, Ni, Cu, Zn). As a typical example of the electrochemical behaviour of such complexes, Figure 9 compares the cyclic voltammetric response of (U02)2Zn(dbba)2(py)4 with that of (U02)2Ni(dbba)2(py)4. The complex containing the redox-inactive zinc(II) centre, (U02)2Zn(dbba)2(py)4, affords two separate reductions at about —1.1 and —1.3 V (vs. SCE), which are assigned to the U(VI) U(V) reduction of each uranyl ion. The insertion of the redox-active nickel(II) as central metal ion causes the appearance of the further Ni(II) Ni(I) reduction at about —1.5 V. A similar behaviour is exhibited by (U02)2Cu(dbba)2(py)4, with the only difference that the Cu(II) Cu(I) reduction occurs at about —0.5 V, thus preceding the two separate U02 + reductions. 

Interested by the effect of other structural modifications on the thermal behavior, and the possibility to combine several metal centers within the same compound, Swager and co-workers pursued this research, and reported series of homo-dinuclear, hetero-dinuclear 1,3,5-triketonate (79), and 1,3,5,7-tetraketonate Schiff-base complexes (80). " Providing a minimum of at least six lateral chains and short diamine spacers ((79) M, M = Cu, Ni, Mn, Pd, Co X = C2H4, CsHg), complexes (79) displayed Colh mesophases, being as such the first heterodinuclear metallomesogens (Table 48). The mesophase existed over broader temperature ranges than those of the related... 

As carriers for metal cations especially the lower rim functionalized p-rert-butylcalix[4]arenes have been used. The calixarenes la, lb with a crown-5 over two opposite aryl moieties are selective for potassium, whereas the tetraamide 2a, tetraketone 2b and tetraester 2c (Figure 1) selectively form complexes with sodium. These neutral receptors are suitable as carriers because of their high lipophilicity and complexation selectivity. 

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