Hexaborate

Dibutylstibinic acid, 3 73 Dibutyltin diacetate, 24 823 Dibutyltin dilaurate, 24 823 Dicadmium triantimonide, 4 510 Dicalcium alumino monosilicate, phase in Portland cement clinker, 5 472t Dicalcium ferrite, phase in Portland cement clinker, 5 472t Dicalcium hexaborate pentahydrate,... 

Dizinc hexaborate heptahydrate, 4 242t DLVO (Derjaguin, Landau, Vervey,... 

The hexahydro-c/ftro-hexaborate dianion [B6H6]2 and its derivatives.9... 

Obviously, the basic site in KB5H8 is its basal B-B single bond and, therefore, reactions with Lewis acids are to be expected. A typical example is the reaction with diborane in ether at —78 °C which generates via its //-adduct (3c2e-BBB bond) the nido-undeca-hexaborate(l—), B6Hn, by cluster expansion. This anion can be proto nated to B Hn [53],... 

The anion Bf,Hf,2 can readily be protonated to B6H7 but further protonation to neutral B6H8 has never been achieved. Aqueous solutions of alkali metal hexahydro-doso-hexaborates give basic solutions due to hydrolysis as described by Eq. (56) ... 

Structures of type A result on protonation of monoalkyl-pentahydro-doso-hexaborate ions B6H5R2 while type B anions are observed for the halogeno derivatives [B6H5X]2 (X = Cl, Br, I) [78], This regiospecificity results from inductive... 

Fig. 2.1-32. The two possible isomers of protonated monosubstituted closo-hexaborate.

The hexaborate anions have a unique structure, in that the central oxygen atom is coordinated to three borons. This arrangement was first found in the structure of tunellite (84). 

The sodium tetraborates, borax (the decahydrate) and tincalconite (the pentahydrate), have been studied by proton (33, 281), boron-11 (101, 111), and sodium-23 (102, 111) magnetic resonance, and the data is compatible with X-ray studies. Similar agreement with crystal structures has been found with the "B NMR of the hexaborate ion in tunellite (100) and pentaborates (26, 254). Wegener et al. (192, 430)... 

The SrO 3B203 4H20 compound, occurring as tunellite, can be synthesized from the reaction between ammonium pentaborate and strontium salts. It was the first borate to be identified as possessing the hexaborate anion (Section III,A). The pentahydrate, 1 3 5, is stable in the SrO-B203-H ) system within the temperature range 0-100°C. Several routes to its preparation have been reported (206), and its dehydration has recently been studied (197). 

The thermal dehydration of the 1 1 3 (52) and, in particular, the hexaborates of general formula 1 3 x (396) have been studied intensely. Structurally, the 1 2 9 compound resembles borax and has... 

The only definite borate hydrates of cobalt are the CoO - 3B203 - 8H20 and CoO 3B203 10H2O compounds. The octahydrate is prepared by evaporation of acetic acid from cobalt acetate-boric acid mixtures, or by mixing aqueous solutions of cobalt chloride, borax, and boric acid (206). The 1 3 7.5 borate can form as a solid solution and, in the presence of 3% boric acid, affords the decahydrate (117). The crystal structure determination of this 1 3 10 compound shows it to possess the hexaborate ion (380). The IR spectra (402) and thermal decomposition (396) of these compounds have been determined. 

The borate NiO B203 8H20 is prepared from nickel salt and borax solutions after digesting with boric acid. The decahydrate is formed from the octahydrate in boric acid at temperatures below 10°C above 80°C the pentahydrate separates out (206). Both the octahydrate and decahydrate have the hexaborate ion BuO O ) - (378, 380). 

Further study has shown that the reaction actually proceeds in two steps 176). The first step is a rapid and irreversible reaction which gives the product of symmetrical cleavage of diborane(6), the undecahydro-hexaborate(— 1) ion. The alkali metal salts of this new ion rapidly decom-... 

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