Ligand complexes with linear

Figure 1 Geometric isomers of octahedral complexes with linear tetradentate ligands...

A number of molecular mechanics studies of metal-cyclopentadienyl complexes have been reported recently. The systems studied include linear metallocenes (in particular ferrocene), ferrocene derivatives (such as complexes with substituted cy-clopentadienyl ligands, bis(fulvalene)diiron complexes, ferrocenophanes and mixed-ligand complexes with carbonyls and phosphines), and nonlinear cyclopentadienyl complexes 8,153,221 231]. 

Fig. 3. Possible isomers of complexes with linear hexadentate ligands...

Nieboer and McBryde (44) have developed what they term a correlating numerical index 0, which is a function of the ionic charge and electronegativity of a particular metal cation, and of the type of ligand complexing with it. Linear relations are obtained when Q is plotted against log values for complexes... 

Fig. 60. List of ligands in copper(I) and silver complexes with linear chain, 2-D and 3-D networks.

The fluorescence properties of several europium and samarium ) -diketonates have been measured and assignments of the transitions made. Rare-earth element hexafluoroacetylacetonates with amino-acids have also been reported to fluoresce. The luminescence of the heptafluoroheptane-2,4-dione complexes of Sm, Eu, and Tb has been measured in dilute ethanol at pH8 and 610nm mixed-ligand complexes with 1,10-phenanthroline exhibited an enhanced luminescence. Photolysis of the Tb chelate of 2,2,6,6-tetramethylheptane-3,5-dione has been examined at 311 nm in various alcohols, and loss of one -diketone ligand found to be the primary photochemical step. A linear correlation was demonstrated between the quantum yield of dissociation of the complex and the formation constant of the complex-alcohol adduct. 

The effect of a unit of positive charge was estimated to give an approximate increase of plus 100 cm associated with a net unit positive charge on the metal complexes with linear NO ligands. 

Cobalt(n) complexes with linear quinquedentate Schiff-base ligands have been prepared and their reaction with Og studied. Both monomeric superoxo- and dimeric peroxo-complexes have been identified depending on the ligand type. In one instance the adduct is considered to be of the form LCo —Og Co fiL in which the super-... 

Mercury(I) forms few complexes, one example is the linear [H2O-Hg Hg- H20] found in the mercury(I) nitrate dihydrate (above, p. 437), In contrast, mercury(II) forms a wide variety of complexes, with some peculiarities (a) octahedral complexes are rare, (b) complexes with nitrogen as the donor atom are common, (c) complexes are more readily formed with iodine than with other halogen ligands. 

Silver ions form a number of complexes with both TT-bonding and non-TT-bonding ligands. Linear polynuclear complexes are known. The usual species are AgL and AgL2, but silver complexes up to AgL have been identified. Many of these complexes have commercial appHcation. 

Bidentate dithiolate ligands afford complexes like Au(S2CNR2) (R = Et, Pr, Bu) and Au(S2PR2) (R = Pr), which have dimeric structures based on 8-membered rings with linear S—Au—S coordination and short Au-Au distances. These in turn are associated into chains (Figure 4.16) (Au-Au c. 3.0-3.4 A) [99],... 

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