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New preparative methods for halogenation of the cage producing the corresponding [2-NH3-B10X9]- species (2- to 4-, X = Cl, Br, I) have been developed using halogenations by elemental halogens in a glass pressure vessel. Compared to similar icosahedral species of formulation [1-H3N-B12X11]- (X = Cl, Br), the N-alkylation reactions in 10-vertex series proceed significantly more easily. The reason for this difference is conceivably due to the two orders of magnitude lower basicity of the amino group, with pKa values in the interval from 9.27 to 8.37, and slightly lower steric strain around the reaction centre. Thus methylations with MeI under mild conditions provided the whole series of corresponding quarternary amines of the formulation [2-Me3N-B10X9]- (5- to 7-, X = Cl, Br, I). The effect of the steric strain of the surrounding halogens on the reactivity at the NH3- centre could then be better seen from reactions with bulkier benzyl bromide. Under comparable conditions, these reactions resulted in the ready formation of disubstituted compounds in case of X = Cl (8-), mixture of mono and disubstituted derivatives for X = Br (9-, 10-) or in monosubstited product for X = I (11-) only. Dibenzyl derivative of the nonaiodinated products (12-) could be still obtained, however only under more forcing conditions. The single-crystal X-ray diffraction structures of all three polyhalogenated derivatives 2- to 4- are presented along with that for benzyl derivative 10-, spectral and physicochemical properties of these polyhalogenated systems are outlined along with specific insights into specific properties of the NH3 group.

Sequential methylation of the 8-R-nido-7,8,9-C3B8H11 tricarbollides (R = Ph, p-tol and 2-naphthyl (2-naph)) in the presence of NaH in THF proceeds on the open-face B(10,11) positions to generate mono and dimethyl derivatives, 8-R-nido-7,8,9-C3B8H10-10-Me and 8-R-nido-7,8,9-C3B8H9-10,11-Me2. To demonstrate the general character of the alkylation procedure, B-dialkyl derivatives 8-Ph-nido-7,8,9-C3B8H9-10,11-R12 (R1 = C3H5 (All) and CH2Ph) were prepared via analogous alkylation of 8-Ph-nido-7,8,9-C3B8H11 with allyl and benzyl bromides. The structures were substantiated by multinuclear (11B, 1H and 13C) NMR spectroscopy and that of 8-Ph-nido-7,8,9-C3B8H9-10,11-Me2 was determined by an X-ray diffraction analysis.

The electrophilic mercuration of 3-(η 5 -Cp)-4-SMe 2 -3,1,2-FeC 2 B 9 H 10 ( 1 ) was investigated. The reaction of 1 with the excess of mercury trifluoroacetate in dichloromethane at 20 °C gives complexes containing from two to four substituents depending on the ratio of reagents. All new compounds were separated and characterized by elemental analysis and NMR spectra. The positions of substitution were established by 11 B-NMR and 11 B- 11 B COSY NMR spectra. X-ray structure of 3-(η 5 -Cp)-4-SMe 2 -7,8-(CF 3 COO) 2 -12-HgCl-3,1,2-FeC 2 B 9 H 7 was determined.

Triallylborane reacts with most poly-1-alkynylsilanes ( 1 – 5 ), containing up to four CC units, or di(1-alkynyl)tin compounds ( 6 ) to give either siloles ( 8 , 11 , 14 , 16 ), as the result of an intermolecular 1,1-allylboration followed by an intramolecular 1,1-vinylboration, or the novel 2-alkylidene-1,3-silaborolene ( 9 ) or 2-alkylidene1,3-stannaborolene derivatives ( 17 ), as the result of intermolecular 1,1-allylboration followed by an intramolecular 1,2-allylboration. In the case of the borolene derivatives, a second intramolecular 1,2-allylboration takes place to give 1,7-borasila- or 1,7-borastannabicyclo[4.3.0]nona-5,8-diene derivatives ( 10 , 12 , 13 , 15 , 18 ). If the starting materials are di(1-alkynyl)methylsilicon hydrides ( 2 ), the latter reaction affords selectively only one diastereomer ( 10 ( H )). All products were characterised by extensive multinuclear magnetic resonance spectra ( 1 H-, 11 B-, 13 C-, 29 Si-, and 119 Sn-NMR).

Bis(silylamino)tin dichlorides 1 [X2SnCl2 with X=N(Me3Si)2 (a), N(9-BBN)SiMe3 (b), N(tBu)SiMe3 (c), and N(SiMe2CH2)2 (d)] were prepared from the reaction of two equivalents of the respective lithium amides (Li-a–d) with tin tetrachloride, SnCl4, or from the 1:1 reaction of the respective bis(amino)stannylene with SnCl4. The compounds 1 react with two equivalents of lithium alkynides LiCCR1 to give the di(1-alkynyl)-bis(silylamino)tin compounds X2Sn(CCR1)2, 2 (R1=Me), 3 (R1=tBu), and 4 (R1=SiMe3). Problems were encountered, mainly with LiCCtBu as well as with 1b, since side reactions also led to the formation of 1-alkynyl-bis(silylamino)tin chlorides 5–7 and tri(1-alkynyl)(silylamino)tin compounds 8 and 9. 1,1-Ethylboration of compounds 2–4 led to stannoles 10, 11, and in the case of propynides, also to 1,4-stannabora-2,5-cyclohexadiene derivatives 12. The molecular structure of the stannole 11b (R1=SiMe3) was determined by X-ray analysis. The reaction of 2a and d with triallylborane afforded novel heterocycles, the 1,3-stannabora-2-ethylidene-4-cyclopentenes 14. These reactions proceed via intermolecular 1,1-allylboration, followed by an intramolecular 1,2-allylboration to give 14, and a second intramolecular 1,2-allylboration leads to the bicyclic compounds 15.

The reaction of triallylborane (All 3 B, 1) with various 1-alkynylsilanes of the type Me 3 Si–CCR 1 [R 1 =H ( 2a ), Me ( 2b ), Ph ( 2c ), CC–SiMe 3 ( 2d ), SiMe 3 ( 2e )], Ph 3 Si–CCPh ( 3 ) MeCC–SiMe 2 SiMe 2 –CCMe ( 4 ) and Me 2 Si(Cl)–CCPh ( 5 ) was studied. Triallylborane 1 turned out to be much more reactive than other triorganoboranes R 3 B (e.g. R=Et, Ph). In the cases of 2 and 5 , the products are organometallic-substituted alkenes 6 and 11 , respectively, with the boryl and silyl group in cis -positions as the result of selective 1,1-allylboration (via cleavage of the Si–C bond) or mixtures of such and other alkenes 7 or 8 because of competition between 1,1- and 1,2-allylboration (the composition of these mixtures depends on the polarity of the solvent). In the case of 4 , the 1,2-dihydro-1,2-disilaborepine derivative 12 is formed selectively (twofold 1,1-allylboration). The alkyne 3 did not react with 1 . The products were characterised by 1 H-, 11 B-, 13 C- and 29 Si-NMR spectroscopy.