Borate complexes solubility

Properties of nickel poly(pyrazol-l-yl)borate complexes such as solubility, coordination geometry, etc., can be controlled by appropriate substituent groups on the pyrazol rings, in particular in the 3- and 5-positions. Typical complexes are those of octahedral C symmetry (192)°02-604 and tetrahedral species (193). In the former case, two different tris(pyrazolyl)borate ligands may be involved to give heteroleptic compounds.602,603 Substituents in the 5-position mainly provide protection of the BH group. Only few representative examples are discussed here. 

The first silver(I) poly(pyrazolyl)borate complexes were reported in 1975.150 Since then, a number of silver complexes of the type Ag(L)(R B(pz)4 ) have been isolated and characterized.151,152 They were prepared by the reaction of the poly(pyrazolyl)borate anions with silver(I) salts, usually the nitrate, in the presence of donor ligands, L, and were isolated as white, thermally stable compounds. In most cases they were either insoluble, or at best only sparingly soluble, in common organic solvents. 

Clapp, C. E. (1957). High Molecular Weight Water-Soluble Muck Isolation and Determination of Constituent Sugars of a Borate Complex-Forming Polysaccharide Employing Electrophoretic Techniques. Ph.D. dissertation, Cornell University. 

The effect of neutral salts (e.g., NaCl) on the composition of borates precipitated from, or in equilibrium with, aqueous solutions doubtless arises from a reduction in water activity, metal borate complexation, and a shift in polyborate equilibria (Sections IV,A, B). The "indifferent or inert component method has frequently been used for the synthesis of borates. Potassium and sodium chlorides can be used to enhance the precipitation of specific nickel (48), aluminum (51), iron (49), and magnesium (151) borates. In the K20-B203-H20 system at 25°C (248), the presence of potassium chloride results in a reduced boric acid crystallization curve, lower borate solubilities, lower pH, and an extended B203 K20 range over which the pentaborate crystallizes. 

Table III111-114 contains the physical properties of several poly(pyrazo-lyl)borate complexes found in the literature. Group 2 poly(pyrazolyl)bor-ates are white monomeric complexes that exhibit some volatility. Ca [HB(pz)3]2, which appears to be one of the most volatile of the poly(pyrazolyl)borates, is reported to sublime at 160°C and 10 2 atm.113 The Ba[HB(3,5-Me2pz)3]2 compound is soluble in THF and hot toluene, and the M[HB(pz)3]2 compounds have good solubility in aromatic and chlorinated hydrocarbons. Ca[HB(3,5-Me2pz)3]2 and Sr[HB(3,5-Me2pz)3]2 are also soluble in aromatic and chlorinated hydrocarbons, but less so than their nonmethylated counterparts.114...

Clapp, C. E., Jr. (1957). High molecular weight water-soluble muck isolation and determination of constituent sugars of a borate complex-forming polysaccharide employing electrophoretic techniques. Ph.D. dissertation, Cornell University Dissert. Abstr. 17, 963-964. Clapp, C. E., Jr. (1969). High molecular weight water-soluble muck Isolation and determination. University Microfilms, University Microfilms Limited, 156 pp. 

The existence of at least one soluble nickel borate complex was postulated by Shchigol [61SHC]. Nickel orthoborate Ni(B02)2 4H20(s) dissolves better in orthoboric acid solutions than in pure water. The formation of the nickel borate complex in solution was believed to occur according to the reaction ... 

Although the racemic bi-2-naphthol can be resolved using S-proline via diastereomeric inclusion complexes followed by enhancement of ee using B(OH)3 and TMEDA or preparation of a borate complex followed by reaction with S-proline, it is somewhat difficult to recover the water soluble S-proline after work up. Hence, we have decided to investigate the use of readily available, inexpensive chiral amines such as a-methylbenzylamine for this purpose. After extensive investigations, it was observed that the chiral a-methylbenzylamine forms a Bronsted acid ammonium salt of the type 5 upon heating a mixture of the bi-2-naphthol, B(OH)3 and the chiral amine in CH3CN. The... 

Structure of the complex was fiirther confirmed by X-ray crystal structure analysis. We have also observed an interesting solvent effect on this reaction. Whereas the borate complex prepared fi om R-a-methylbenzylamine and S-bi-2-naphthol is insoluble in CH3CN, the complex obtained using the same amine and R-bi-2-naphthol is insoluble in THF. This interesting solubility difference has been exploited in resolving ( )-bi-2-naphthol to obtain the enantiomers in >99% ee as shown in Scheme 6. The chiral amine can be recovered in 90% yield after the resolution. 

Clapp, C. E., Jr. 1957. High molecular weight water-soluble muck isolation and determination of constituent sugars of a borate complex-forming polysaccharide employing electrophoretic techniques. Diss. Abstr. 17 963-964. 

Various polyene—ion complexes have been developed. Water-soluble complexes of amphotericin B with calcium and oxalic or succinic acids have been described [382]. Stable water-soluble borate complexes of amphotericin B, candidin, candicidin, pimaricin have been developed [383]. An advantage of producing stable water-soluble iron(Fe(II) and Fe(III))—polyene complexes was that complexes retained the in vitro antifungal properties of the parent compound [384] while water-soluble calcium complexes showed enhanced antifungal action [385] and it has been suggested that amphotericin B—meglumine complexes were less toxic when used intravenously than desoxycholate complexes [386]. 

Borate buffers should not be used in the presence of polyols, including carbohydrates and their derivatives, with which they may form chelate compounds they react in this way with many respiratory intermediates. Use of borate buffers in gel electrophoresis of proteins can result in spreading of the zones if fructose, ribose, sorbitol, catechol or other appropriate polyols are present to form borate complexes (Lerch and Stegemann, 1969). The increased solubility of adrenalin in borate buffers is due to complex formation as is also the improved separation of sugar phosphates chromatographically in the presence of borate buffers. Likewise, complexation of carbohydrates in german-ate or borate buffers is the basis of a suggested method for... 

Sodium is not found ia the free state ia nature because of its high chemical reactivity. It occurs naturally as a component of many complex minerals and of such simple ones as sodium chloride, sodium carbonate, sodium sulfate, sodium borate, and sodium nitrate. Soluble sodium salts are found ia seawater, mineral spriags, and salt lakes. Principal U.S. commercial deposits of sodium salts are the Great Salt Lake Seades Lake and the rock salt beds of the Gulf Coast, Virginia, New York, and Michigan (see Chemicals frombrine). Sodium-23 is the only naturally occurring isotope. The six artificial radioisotopes (qv) are Hsted ia Table 1 (see Sodium compounds). 

A further spectrophotometric method [3, 4] for water soluble boron in soil, boron is extracted from soil with boiling water. Borate in the extract is converted to fluoroborate by the action of orthophosphoric acid and sodium fluoride. The concentration of fluoroborate is measured spectrophotometrically as the blue complex formed with methylene blue and which is extracted into 1, 2-dichloroethane. Nitrates and nitrites interfere they are removed by reduction with zinc powder and orthophosphoric acid. 

---