Complexes alkaline-earth metals

Acetic acid, tr nj-l,2-cyclohexylenediiminotetra-metal complexes, 2,786 Acetic add, 1,2-diaminocyclohexanetetra-alkaline earth metal complexes, 3,32 Acetic add, ethylenebis[(carboxymethyl)unino-ethyleneiminojtetra-metal complexes equilibrium data, 2,788 stability, 2,787... 

Atienza et al. [657] reviewed the applications of flow injection analysis coupled to spectrophotometry in the analysis of seawater. The method is based on the differing reaction rates of the metal complexes with 1,2-diaminocycl-ohexane-N, N, N, A/Metra-acetate at 25 °C. A slight excess of EDTA is added to the sample solution, the pH is adjusted to ensure complete formation of the complexes, and a large excess of 0.3 mM to 6 mM-Pb2+ in 0.5 M sodium acetate is then added. The rate of appearance of the Pbn-EDTA complex is followed spectrophotometrically, 3 to 6 stopped-flow reactions being run in succession. Because each of the alkaline-earth-metal complexes reacts at a different rate, variations of the time-scan indicates which ions are present. 

The fact that NHCs form stable compounds with beryllium, one of the hardest Lewis acids known and without p-electrons to back donate, shows the nu-cleophilicity of these ligands. Reaction of l,3-dimethylimidazolin-2-ylidene with polymeric BeCl2 results in the formation of the neutral 2 1 adduct 23 or the cationic 3 1 adduct 24. The first NHC-alkaline earth metal complex to be isolated was the 1 1 adduct 25 with MgEt2- Whereas l,3-dimesitylimidazolin-2-ylidene results in the formation of a dimeric compound, the application of sterically more demanding l,3-(l-adamantyl)imidazolin-2-ylidene gives a monomeric adduct. ... 

Munoz, A. et al.. Identification and structural assessment of alkaline-earth metal complexes with flavonols by FAB mass spectrometry, Russ. J. Gen. Chem., 74, 438, 2004. Translated from Zh. Obshch. Khim., 74, 482, 2004. 

Table 5.6 Turnover frequencies (h ) in the methanolysis of pNPOAc catalyzed by alkaline-earth metal complexes of 10. ...

Breccia, P., Cacciapaglia, R.. Mandolini. L. and Scorsini, C. (1998) Alkaline-earth metal complexes of thiol pendant crown ethers as turnover catalysts of ester cleavage. J. Chem. Soc., Perkin Trans., 2, 1257. 

In contrast to the extensive coverage of transition metal Schiff base complexes, there is a somewhat desultory presentation of alkali and alkaline earth metal complexes of these ligands. 

Polyamino polyalkyl phosphonic acids have been investigated as potential complexors for alkaline earth metal complexes. Ligands investigated include nitrilotrimethylphosphonates (70),360 phosphoryl derivatives of polyamines (71)361 and monoalkylphosphonic acids.362 They show complexing capability towards Be2+, Mg24-, Ca2+, Sr24" and Ba, but are not as efficient... 

Different types of benzo-15-crown-5 alkali and alkaline earth metal complexes (reproduced with permission... 

The crystal structures of alkaline earth metal complexes of several (1 + 1) and (2 + 2) Schiff base macrocycles have been reported. These macrocycles are formed by the metal template-controlled condensation of the required heterocyclic dicarbonyl derivative and a, co functional diamine in alcoholic solution. (1 +1) complexes arise from the condensation reaction of one dicarbonyl with one diamine and (2 + 2) complexes from the condensation of two dicarbonyls with two diamines. 

---