Carboranes lithium derivatives

The lithiumbenzyl carboranes readily react with various electrophilic reagents. This was shown by taking a lithium derivative 17 as an example (Scheme 4). The reactions proceed in high yields and make it possible to obtain various derivatives of o-carborane containing a substituted benzyl group. 

The following carboranyl derivatives of La, Tm, and Yb have been prepared by interaction of the lithium derivatives of carboranes with the appropriate rare earth trichlorides in tetrahydrofuran benzene-ether in 1983 by Bregadze et al. MeCBioHioCLaCl2, m.p. 133-135°C,... 

An alternative route to poly(m-carborane-siloxane) rubbers is via the condensation reaction between w-carborane di-hydrocarbyl-disilanol and a bis-ureidosilane.20 This mild reaction allows the incorporation of desired groups into the polymer via both the dihydrocarbyl-disilanol and the bis-ureidosilane (see scheme 8). The first step involves the formation of the carborane silanol from the butyl lithium carborane derivative. The bis-ureidosilane is prepared from the phenyl isocyanate (see step 2), and the final step involves reacting the dihydrocarbyl-disilanol with bis-ureidosilane. 

Cyclic organoboranes containing mnltiple boron atoms within the ring stracture have been extensively stndied as precursors to (multidecker) transition-metal complexes and to nonclassical organoboranes (see Boron Metallacarbabo-ranes and Boron Polyhedral Carboranes). Earlier efforts have been thoroughly reviewed. Recently, a series of triboracyclopentane derivatives were reported by Bemdt and Schleyer (Scheme 6). " Reduction of these boracy-cles gave the nonclassical bishomoaromatic anions (28) and homoaromatic dianions (29). Related trishomoaromatic dianions obtained via reduction of 1,3,5-triboracyclohexane derivatives with lithium were studied by Siebert and Schleyer. i 5> ... 

TRIMETHYLSILYL-SUBSTITUTED DERIVATIVES OF 2,3-DICARBA-mCARBORANE DIANION 2,3-BIS(TRIMETHYLSILYL)-2,3-DICARBA-mrfo-HEXABORATE(2 - )... 

Carboranes are polyhedral boranes in which a BH unit has been formally replaced by an isoelectronic CH unit. An entire class of carboranes can be prepared from an alkyne and a borane by pyrolysis or by reaction in a silent electric charge. Derivatives are known, including those derived by reaction of lithium carboranes with a variety of reactants (CO2, HCHO, h, NOCl). 

Other carboranylporphyrins and boronated chlorine eg for PDT, in which porphyrin is linked to the carboranyl moiety via the boron or the carbon atoms have also been reported by OTshevskaya et al. In arecent work, boronated amide derivatives starting from 5,10,15,20-tetra(p-aminophenyl) porphyrin and 9-o- and 9-m-carborane carboxylic acid chlorides were prepared. Also, the reaction of 2-formyl-5,10,15,20-tetraphenylporphyrin with the lithium salt of 1,2-c/oso-C2BjoHj2, and... 

Iron carbonyl fragments have been incorporated into many heterometallic borane and carborane compounds. Those compounds are covered in Chapter 3.05 and will not be discussed here. Simple boryl adducts have been reported from the reaction of Na2Fe(CO)4 and ClBCat" (Cat = catecholate or a Bu-substituted derivative. Equation (8)). The same products can be obtained upon irradiating Fe(CO)s and Cat B-BCat" in toluene at 0°C. Reaction of the diboryl 6 with 1 equiv. of lithium bis(trimethylsilyl)amide in toluene solvent leads to removal of one boryl unit and the formation of an anionic iron boryl complex (Equation (9)). The anionic species can also be obtained by stoichiometric addition of the ClBCat complex to Na2Fe(CO)4. Reaction of [Fe(CO)4 B(3,5-/-Bu2-Cat) ] with ClSnMes gives the stannylated derivative Fe(CO)4 B(3,5-/-Bu2-Cat) (SnMe3). 

Boron and Thallium.—The lithium salts of orr/io-carboranes, o-RCBieHi CLi (R = Me or Ph), react with hexafluorobenzene to give only the 1,4-di-o-carboranyl derivatives, even with a deficiency of hexafluorobenzene. "... 

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