Hydride diborane

Localized Bonds. Because boron hydrides have more valence orbitals than valence electrons, they have often been called electron-deficient molecules. This electron deficiency is partiy responsible for the great interest surrounding borane chemistry and molecular stmcture. The stmcture of even the simplest boron hydride, diborane(6) [19287-45-7] 2 6 sufficientiy challenging that it was debated for years before finally being resolved (57) in favor of the hydrogen bridged stmcture shown. 

Diakyl carbamyl chlorides Diakyl aluminum hydrides Diborane Dibromoketone Dichloromethyl chloroformate Diphosgene Fuming nitric acid Gngnard reagents Hydrides nonvolatile... 

Die elektrophilen Hydride Diboran, Aluminiumhydrid und Lithiumala-nat/Aluminiumchlorid (1 1) reduzieren Lactame meist schneller und selektiver als Li-thiumalanat. Die Reduktion mit Diboran ist ahnlich wie bei den Carbonsaure-amiden3 in siedendem THF in einigen Stunden4 unter Erhalt der Alkoxycarbonyl-5 und Sulfo-Grup-pen6 beendet (s.a. S. 238f., 242). 

Durch Einsatz elektrophiler Hydride (Diboran, Natriumboranat/Aluminiumchlorid) wird die Hydrogenolyse der C-O-Bindung erleichtert, so daB sich in schneller Reaktion hauptsachlich das Thiol isolieren laGt3. 

Figure D shows some olefin insertion reactions. Hydride additions to olefins have been known for a long while. Among these many examples, manganese hydrocarbonyl, and cobalt hydrocarbonyl, magnesium hydride, diborane, alkylalu-minum hydrides, germanium and tin hydrides all add quite readily to olefins. These last two cases are questionable because the mechanism is not clear. Some of these additions occur without a catalyst some are speeded up by ultraviolet light some are catalyzed by Group VIII metals. So it is not clear whether all these reactions are the same or whether there are several different mechanisms.

The first step, a 1,3-dipolar addition, results in the formation of a primary ozonide (1 equation 6). This intermediate then opens to give a carbonyl and a zwitterion that can recombine to give the more stable normal ozonide (2 equation 7). Reduction of (2), without isolation, by lithium aluminum hydride, diborane or sodium borohydride dten gives either primary or secondary alcohols, depending on the nature of starting alkene (equation 8). 

SYNS BOROETHANE BORON HYDRIDE DIBORANE MIXTURES (NA 1911) DIBORON HEXAHYDRIDE... 

Similarly, the parent hydride, diborane(4), has been prepared only in the form of complexes with Lewis bases 30, 43, 72). Attempted reduction of B2CI4 with various metallic hydrides leads to the formation of diborane(6) and other boron hydrides 104, 109). 

Valence theory, boron hydride, diborane and, 124-126 electron deficiency and, 121-122 higher hydrides and, 126-128 molecular orbitals and, 128-131 three-center bond and, 122-124... 

The electronic formulation of the structure of the boron hydrides encounters a number of difficulties. The ordinary concepts of valence will not suffice to explain their stmcture this is shown by the fact that in the simplest hydride, diborane B2H6, which has 2x3 + 6= 12 electrons, as many bonds must be explained as are required for C2H6 which has two more (2x4 + 6 = 14) electrons available. Thus it is that any structural theory for these compounds requires new hypotheses. 

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