Borate compound

The principal borate minerals are Hsted ia Table 2. A much more complete listing is available ia the Hterature (3,4). Crystal stmctures of known borate compounds have been compiled (5). 

There has been much activity in this field of corrosion inhibition in recent years which appears to have been prompted by health and safety requirements. As with engine coolants, the use of nitrites, particularly where amines may also be present, needs to be considered carefully. Nitrites have been widely used in cutting, grinding, penetrating, drawing and hydraulic oils. Suggested replacements for nitrites and/or amines make use, inter alia, of various borate compounds, e.g. monoalkanolamide borates. Molybdates have also been proposed in conjunction with other inhibitors, e.g. carbox-ylates, phosphates, etc . Water-based metalworking fluids usually contain other additives in addition to corrosion inhibitors, e.g. for hard-water stability, anti-foam, bactericidal proderties and so on. Thus, claims are made for oil-in-water emulsions with bactericidal and anti-corrosion properties. 

Borate compound (PhjCBfCaFsld 20 pmol and using OctsAl 20 pmol as a staiven. ... 

Comparison of zinc alkoxide and zinc hydroxide bond energies has been made. The relative heterolytic bond energies for hydroxide, methoxide, ethoxide, and tert-butoxide were determined from studies of a series of alkoxide exchange equilibria using a four-coordinate monomeric zinc tris(pyrazolyl)borate compound.335... 

REACTIONS OF OsHCI(CO)(P Pr3)2 WITH C5H6 AND Na[HBpz3] CYCLOPENTADIENYL AND TRIS(PYRAZOLYL)BORATE COMPOUNDS... 

Workers at Spectra Group, Ltd. (5) have recently investigated use of borate compounds (tetramethylammonium triphenylbutyl borate (1), and butyryl choline triphenyl butylborate (5) in conjunction with DIBF, OPPI and DIDMA. 

Recently Isbell and coworkers have published the results of an extensive study of the behavior of solutions of sorbitol and D-mannitol in the presence of tetraborates. They found that sorbitol appears to form three complex borate compounds, whereas D-mannitol forms only two. Since the specific rotation in the tetraborate-D-mannitol system is a function of the ratio of the components and is independent of concentration at constant tetraborate-D-mannitol ratios, D-mannitol can be determined quantitatively by this method. However, sorbitol cannot be determined this way because the change in observed rotation at constant tetraborate concentration shows a reversal with increasing amounts of sorbitol. 

Since 1979 Chen s group has turned its attention to borates. They recognized that borate compounds have numerous structural types since borate atoms may have either three or four-fold coordination. This complex structural nature of borate compounds leads to a great variation in the selection of structural types... 

These are the most extensively studied class of poly(pyrazolyl)borate compounds for platinum and palladium, and rank among the most numerous and varied. The literature includes examples of M(II) and M(IV) centers in cationic, neutral, and anionic complexes, with all possible coordination numbers four to six represented moreover, many of these complexes are readily interconverted. This section will therefore be organized according to oxidation state, as the most logical approach. 

Glass fibers of various compositions Frits of various compositions Lead silicates Borate compounds... 

Borate compounds (zinc borate/calcium borate)... 

Ca, Sr, and Ba Poly(pyrazolyl)borate Compounds and Their Physical Properties0... 

These complexes are the first examples of multifunctional catalysts and demonstrate impressively the opportunities that can reside with the as yet hardly investigated bimetallic catalysis. The concept described here is not limited to lanthanides but has been further extended to main group metals such as gallium [31] or aluminum [32]. In addition, this work should be an incentive for the investigation of other metal-binaphthyl complexes to find out whether polynuclear species play a role in catalytic processes there as well. For example, the preparation of ti-tanium-BINOL complexes takes place in the presence of alkali metals [molecular sieve ( )]. A leading contribution in this direction has been made by Kaufmann et al, as early as 1990 [33], It was proven that the reaction of (5)-la with monobromoborane dimethyl sulfide leads exclusively to a binuclear, propeller-like borate compound. This compound was found to catalyze the Diels-Alder reaction of cyclopentadiene and methacrolein with excellent exo-stereoselectivity and enantioselectivity in accordance with the empirical rule for carbonyl compounds which has been presented earlier. 

A new free radical class of polymerization agents consisting of amido-borate compounds have been prepared by reacting an organoborate with a hydrocarbyl amine. These reagents are particularly useful as hardeners in polymer formulations. 

Table 1 shows the optimal compositions of the initial reaction mixtures and crystallization conditions for obtaining highly crystalline single phases of the borate compounds. 

Substituted tris(pyrazolyl)borates were recently employed as silver(l) ligands due to their ability to yield heat and air stable metal complexes. Two research groups have prepared very similar sUver(l)-tris(pyrazolyl)borate compounds for catalyzing carbene insertion chemistry. Both systems require electron-withdrawing groups on the tris(pyrazolyl)borate ligands to stabilize the sUver(l) complexes and enhance the electrophilicity of the putative silver-carbenoids (129,130). Dias et al. (129) found that, with CF3 substitutes, a complex of [HB(3,5-(Cp3)2pz)3] Ag(thf) could activate ethyl diazoacetate (EDA) to react with different C X (X = Cl, Br, 1) bonds to afford either C—X bond insertion products or 1,1-hydrochlorination products. At the time of this writing, this unique reactivity was reported only with a silver catalyst (Fig. 27). 

Some types of borate compounds act as co-catalysts for the syndiospecific polymerization of styrene in these catalyst systems. The active borate compounds have a tetraphenylborate anion. The effect of anions on the catalytic activity is summarized in Table 17.3. Fluorine substituents at the of 3,4,5-positions increase the catalytic activity and tetrapentafluorophenylborate showed the highest performance. 

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