Potassium complex

The cyclopeptide described above was tailored to form stable potassium complexes. It is one of the very few examples of complex peptide syntheses which do not lead to a natural compound. 

Benzo[15]crown-5, potassium complex X-ray, 7, 735 (B-78MI52102) 10H-Benzo[5,6]cyclohepta[l,2-b]furan, 4,5-dihydro-... 

Cryptand, potassium complex equilibrium constant, 7, 743 (73T1629)... 

Cyclohexyl[l 5]crown-5, potassium complex equilibrium constant, 7, 742 (73MI52101) Cyclohexyl[15]crown-5, sodium complex equilibrium constant, 7, 742 (73MI52101) Cycloocta[ 1,2-c 5,6-c ]difuran H NMR. 4. 564 (70JA973) Cyclopenta[h][2.2.4]cyclazine... 

H-Benzo[a]carbazole, 4,4a,5,l 1,1 la,l Ib-hexahydro-synthesis, 4, 283 Benzo[b]carbazole, N-acetyl-photochemical rearrangements, 4, 204 Benzo[/]chroman-4-one, 9-hydroxy-2,2-dimethyl-synthesis, 3, 851 Benzochromanones synthesis, 3, 850, 851, 855 Benzochromones synthesis, 3, 821 Benzocinnoline-N-imide ring expansion, 7, 255 Benzocinnolines synthesis, 2, 69, 75 UV, 2, 127 Benzocoumarins synthesis, 3, 810 Benzo[15]crown-5 potassium complex crystal stmcture, 7, 735 sodium complex crystal stmcture, 7, 735 Benzo[ 18]cr own-6 membrane transport and, 7, 756 Benzo[b]cyclohepta[d]furans synthesis, 4, 106 Benzocycloheptathi azoles synthesis, 5, 120... 

The structure of K[TpBut2] has also been determined by x-ray diffraction thereby providing a rare example of a potassium complex in which the primary coordination number is three, with an average K-N bond... 

The dry solid is violently pyrophoric, exploding on contact with oxygen [1], or air [2], The solid produced by passing oxygen into a THF solution of the potassium complex must be kept wet with solvent, as it is shock-sensitive when dry [2],... 

The sensor layer consists of a selective ionophore (e.g. valinomycin for potassium), a lipophilic anionic site (borate) and the cationic PSD. Before interaction with potassium, a lipophilic ion pair between the cationic PSD and borate anion is formed in the polymer layer. When valinomycin (also contained in the layer) selectively extracts potassium into the layer, then the positively charged valinomycin-potassium complex forms an ion pair with... 

Figure 4.4. Structure of the bis-ligand potassium complex of benzo-15-crown-5. The complex shown is cationic (Mallinson Truter, 1972).

A stability enhancement in methanol of about 104 occurs for the potassium complex of 18-crown-6 (169) compared to its non-macrocyclic analogue (223) in methanol (Frensdorff, 1971 Petersen Frensdorff, 1972) (Figure 6.3). A comparative study of this and the corresponding... 

Figure 6.3. Stability constants for the 1 1 potassium complexes of some polyether ligands at 25 °C. The values for (223) and (169) were determined in methanol those for 2.2.2, (276) and (277) in methanol/water (95 5).

The macrotetrolide group (Figure 9.1) also form complexes with the alkali metals. Once again, such species preferentially complex with potassium the potassium complex of monactin in methanol at 30°C exhibits a stability constant of 2.5 x 105 mol-1 dm3 whereas the value for the sodium derivative is considerably lower at 1.1 x 103 mol-1 dm3. The kinetics of complex formation by compounds of the type so far discussed with alkali metals is known to be fast. For example, members of the... 

The symmetrical ring enniatin (304) forms a potassium complex (Figure 9.3) whose crystal structure indicates that the cation is contained in the macrocyclic cavity and is coordinated by the six carbonyl oxygen atoms which are orientated such that three lie above and three lie below the main plane of the molecule (Dobler, Dunitz Krajewski, 1969). Apart from those just discussed, it needs to be noted that a range of other structures of antibiotic molecules and their metal complexes have been determined (Hilgenfeld Saenger, 1982). 

Figure 9.3. The potassium complex of enniatin B (from Fenton, 1977).

Further investigation of allylpotassium complexes have shown that 2-isopropylallyl potassium does not show diastereotopism of the methyl groups at temperatures as low as —155 °C54,59. Therefore, the activation barrier for interconversion is on the order of 4 kcal mol 1 or lower. Both crotyl (19) and prenyl (20) potassium complexes are further examples of the preference for allylpotassium compounds to exist as symmetric it species. The potassium has the appropriate atomic radius to reach both C(i) and C(3). No increase in stabilization is gained upon addition of solvent. Allylcesium behaves in the same manner. In general, the theoretically calculated rotational barriers (Table 9) are higher... 

The first heavier alkali metal phosphide species to be structurally characterized were the sodium and potassium complexes [M P(mes) (SiFBu2) (THF)2]2 (M = Na, K) (67). These isostructural complexes adopt an eight-membered (MPSiF)2 ring motif in which each alkali... 

Although potassium complexes of phosphinomethanide ligands have been used in the synthesis of lanthanide phosphinomethanides (143), it is only very recently that a heavier alkali metal phosphinomethanide complex has been isolated and structurally characterized. 

The sodium atoms are both bound rf to one phospholide ring and 171 to the phosphorus atom of the other phospholide ring of the dianion. Each Na atom is further coordinated by one of the phosphole phosphorus atoms and two oxygen atoms of the DME coligand. The potassium complex is quite different reduction of the phosphole tetramer with 4 equiv of potassium yields a tetraanion, which, after crystallization from DME containing 18-crown-6, gives the solvent sepa-... 

According to modem standards mineral fertilizers are partitioned into two groups standardized and non-standardized. The standardized fertilizers include nitrogen, phosphoms, potassium, complex, and micro-fertilizers that contain the nutrients at the standard basis. The non-standardized fertilizers are municipal wastewater effluents, municipal solid wastes, polluted river waters used for irrigation, etc., which are not characterized by standard content of nutrients. However one should add that in all fertilizers including standardized type there are the admixtures, which pollute the agrolandscape. The known examples are phosphoms fertilizers and any municipal waste and wastewater with a pool of heavy metals and various organic pollutants. 

---