Metal ion complexes, M

Metal ion complexes ([M(CN)6]"- M = Fe, Ru, n = 3,4) can also be incorporated into certain macromonocyclic polyammonium ligands forming complexes of complexes , i.e. supercom-... 

The metal-ion complexing properties of crown ethers are clearly evident in their-effects on the solubility and reactivity of ionic compounds in nonpolar- media. Potassium fluoride (KF) is ionic and practically insoluble in benzene alone, but dissolves in it when 18-crown-6 is present. This happens because of the electron distribution of 18-crown-6 as shown in Figure 16.2a. The electrostatic potential surface consists of essentially two regions an electron-rich interior associated with the oxygens and a hydrocarbon-like exterior associated with the CH2 groups. When KF is added to a solution of 18-crown-6 in benzene, potassium ion (K ) interacts with the oxygens of the crown ether to for-m a Lewis acid-Lewis base complex. As can be seen in the space-filling model of this... 

This reaction will proceed if the metal indicator complex M-In is less stable than the metal-EDTA complex M EDTA. The former dissociates to a limited extent, and during the titration the free metal ions are progressively complexed by the EDTA until ultimately the metal is displaced from the complex M-In to leave the free indicator (In). The stability of the metal-indicator complex may be expressed in terms of the formation constant (or indicator constant) Ku ... 

Some suggested calculation procedures and the variation in results obtained from different calculation methods for evaluation of concentration stability constants of metal ion complexes in aqueous solution. A. M. Bond, Coord. Chem. Rev., 1971,6, 377-405 (43),... 

Figure 9. Adsorption of intermediate layer (metal-ion complex) in anodic metal dissolution. A (aq), hydrated anion M2+(M), metal adion MA+(ad), adsorbed metal-ion complex MA (aq), hydrated metal-ion complex.

A.R.S. Ross, M.G. Ikonomou and K.J. Orians, Characterization of dissolved tannins and their metal ion complexes by electrospray ionization mass spectrometry, Anal. Chim. Acta, 411, 91 102(2000). 

The ligands H2L19, H2L23-H2L31 are effective dinucleating ligands towards various divalent metal ions. Complexes of composition [Mn2(LR)(p-L )]+ (M — Mn, Fe, Co, Ni, Zn, Cd)... 

Sillen, L. G. M artel 1, A. E. Stability Constants of Metal-Ion Complexes Spec. Publ. No. 25 Chemical Society London, 1971. 

It would be highly desirable to be able to correlate metal ion structure as well as the individual steric requirements of the specific substituents Ri, R2, and Ra with the equilibration studies cited above. Because of the numerous uncertainties associated with the data, however, only qualitative generalizations can be made. The higher-valent metal aldolate complexes (M = ZnL, MgL, AIL2), upon equilibration, appear to favor the threo diastereomer to a greater extent than the monovalent metal aldolates (M = Li, Na). With regard to... 

Preliminary rate measurements should allow one to make a plot of initial velocity Vq versus [metal ion], and this should provide information on the optimal metal ion concentration. (For many MgATP -dependent enzymes, the optimum is frequently 1-3 mM uncomplexed magnesium ion.) Then, by utilizing pubhshed values for formation constants (also known as stability constants) defining metal ion-nucleotide complexation, one can readily design experiments to keep free metal ion concentration at a fixed level. To compensate properly for metal ion complexation in ATP-dependent reactions, one must chose a buffer for which a stability constant is known. For example, in 25 mM Tris-HCl (pH 7.5), the stability constant for MgATP is approximately 20,000 M Thus, one can write the following equation ... 

H. Plenio, J. Hermann, R. Diodone, The coordination chemistry of fluorocarbons Difluoro-m-cyclophane-based fluorocryptands and their group I and II metal ion complexes, Inorg. Chem. 36 (1997) 5722-5729. 

The use of a fatty acid monolayer on a subphase of divalent metal ions compromises the archetypal preparation of LB films containing metal ions. Complexation of subphase metal ions to the fatty acid monolayer occurs through fatty acid proton/metal ion exchange and is pH dependent. For C,d2+ ions, at 2 X 10 4 M. for example, the onset of the exchange is at approximately pH 5 and stoichiometric exchange occurs at pH 6. This stoichiometric reaction is depicted for the general case for divalent metal ions and fatty acids in Eq. (2) ... 

FTIR has also been used to confirm hydration of (PdCI4)2- ions incorporated into LB films made from the cationic surfactant DDAB (10) and the coordination modes of amine ligands of complex metal ions of M(II) (M = Pt, Pd) in LB films... 

The designations a, /3, or y after some formulas refer to particular crystalline forms (which are customarily identified by Greek letters). Data for salts except oxalates are taken mainly from A. E. Martel and R. M. Smith, Critical Stability Constants. Vol. 4 (New York Plenum Press, 1976). Data for oxalates are from L. G. Sitlen and A. E. Martell, Stability Constants of Metal-Ion Complexes, Supplement No. 1 (London The Chemical Society, Special Publication No. 25,1971). Another source R. M. H. Verbeeck et al., Inorg. Chem. 1984, 23, 1922. 

ATP4-.242 Results indicated associations to be influenced by macrocyclic and size effects, electrostatic interactions and structural complementarity. Of particular interest in this series is the observed very strong binding of anionic metal ion complexes. The electrochemistry of M(CN)6 /M(CN)4 (M = Fe, Ru) indicates the complexed complex to be nonlabile and the system to undergo a reversible one-electron exchange. The ability of the macrocycle to protect the reactivity of the complex is evidenced by the hindered photoaquation observed for Co(CN)j e [32]NgH8.247 The results of competition studies suggest predominantly coulombic interactions between the metal complex and macrocycle for these 1 1 complexes of complexes . 

Misono, M. Saito, Y. Evaluation of softness from the stability constants of metal-ion complexes. Bull. Chem. Soc. Jpn, 1970, 43 (12), 3680-3684. 

---