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Synthesis of various compounds containing the l-carba-c1oso-dodecaborane cage is reported. The isolated derivatives include zwitterionic I-L-I-CBlt Htl (L = H3N and (CH3hS) and 12-L-I-CB tt Htl (L = (CH3)2S and CH 3 SCH 2 SCH 3 ) compounds along with C-substituted derivatives of the general formula [I-X-CBII HI tl-(X = HOOC, HO, CH 3 0, HS and CH 3 S).Direct halogenation of [1-CB II H I2 1-produces [7,8,9,1O,12-CI s -I-CB II H 7 1-, [7,8,9,10,11,12--X6-I-CBIIH61-(X = CI, Br), [12-1-CB II H I tl-and [7,12-I 2 +CB II H I0 1-substituted species. Constitution of all produ(ts was established by t H, liB, IR and mass spectrometry and is supported by some chemical reactions of the compounds.The [1-CBl.lH12]-anion (I) was first isolated in 1967 by Knoth!, who later 2 improved the synthesis and made initial attempts at substitution, impure samples of B-bromo and 1-(CH 3 hSi-derivatives being the only products. We have recently found a more convenient route 3 .4 to the parent anion I and to some of its uncharged l-L-I-CBllHll (II) (L = CH3NH 2, (CH3)2NH and (CH3hN) congeners. We wish to report in this paper some other possibilities of synthetizing a series of new substituted derivatives in this area of borane chemistry.Several new derivatives of the anion I and its zwitterionic analogues II can be obtained either from the relevant 7-substituted 7-carba-nido-undecaboranes, 7-L-7--CBlOHI2 (III), by inserting the missing boron vertex or by modifying the present exoskeletal functional group in the compounds of the type II.If 7-H3N-7-CBlOHI2 (IlIa) is treated with sodium tetrahydroborate followed by prolonged heating with triethylamine borane at 200°C and the intermediate product is then hydrolyzed with hydrochloric acid, l-amine-l-carba-closo-dodecaborane(ll), I-H3N-I-CBuHu (lIa), can be obtained in good yield as the parent compound of the loN-substituted species. Its N-monomethylderivative lIb is available from the N,N-dimethyl derivative 3 lIe by a curious demethylation with iodine 4 and the N,N,N-trimethyl derivative lId results from successive methylation of any of compounds 11 a-e. Derivatives II a -e behave as weak N-acids with pK" values 6'0, 6'5, and 5'7, respectively (50% ethanol), giving rise to anions [1-H 2N-I-CB IIH II] -(Ia). [1-CH3NH-I-CB1.1HII]-(Ib)4 and [1-(CH3)2N-I-CBtIHu]-(Ie)3.

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Treatment of 7-(CH3)3N-7-CB10H12 with triethylamineborane(3) at 180-200 °C proceeds under splitting off one methyl group and inserting one boron vertex to obtain 1-(CH3)2NH-1-CB11H11. Methylation of the latter compound produces 1-(CH3)3N-1-CB11H11 which can be reduced to the parent 1-CB11H12- anion with sodium in liquid ammonia. The constitution of all compounds was established by NMR and mass spectroscopy.

Syntheses and structures of [8,8′-µ-(OSO 2 O)(1,2-C 2 B 9 H 10 ) 2 -3-Co] -and [(8-Ph-1,2-C 2 B 9 H 10 )-3-Co-(1′,2′-C 2 B 9 H 11 ] -ions and of [(8-dioxane-1,2-C 2 B 9 H 10 )-3-Co-(1′,2′-C 2 B 9 H 11 )] zwitterion are described. All compounds result on dimethyl sulfate induced nucleophilic B-substitution of the parent cobalta-carborane sandwich ion under acid catalysis. A general mechanism is proposed. Constitutions of all compounds are inferred from the mass and multinuclear NMR spectroscopy and all structures are established by X-ray diffraction. Selected NMR and X-ray data are presented.