REACTION OF SULFUR DIIMIDES WITH ORGANOBORANES - STUDIED BY MULTINUCLEAR MAGNETIC-RESONANCE IN SOLUTION

Reactions between sulfur diimides R(NSN)R' (R=R'=(t)Bu (1a), SiMe(3) ( 1b), SnMe(3) (1c); R=(t)Bu, R'=SnMe(3) (1d); R=SiMe(3), R'=SnMe(3) (1e )) and various organoboranes were studied, and the products were chara cterised by multinuclear magnetic resonance data (H-1, B-11, C-13, N-1 5, Si-29 and Sn-119 NMR). Tetraalkyldiboranes(6) (Et(2)BH(2)BEt(2) (2) , dimeric 9-borabicyclo[3.3.1]nonane (3)) react with 1a and 1b by 1,3- hydroboration to give the N-sulfanyl-dialkylaminoboranes 4 and 5 which are instable with respect to elimination of short-lived [R-NS]. Trial kylboranes (Et(3)B (8)) react only sluggishly with 1a, but more readil y with 1b mainly via S-ethylation, formally a 1,2-ethyloboration, to g ive the diethylborylamido-imino-ethanesulfinic acid 9b. Compound 9b de composes slowly at room temperature via ethene elimination to give 4b, followed by further decomposition via [R-NS] elimination. The compoun ds 9 can be prepared independently from the reaction between the N-lit hio-imino-ethanesulfinic acid amide 10 and diorganoboron halides. The molecular structure of the lithium amide 10a (R=R'=tBu) was determined by X-ray analysis as a dimer in which the four nitrogen, two sulfur a nd two lithium atoms adopt a boat conformation, in contrast with other known derivatives of this type. If the sulfur diimides bear at least one trimethylstannyl group (1c-e), their reactions with Et(3)B (8), iP r(3)B (12) or 9-iso-butyl-9-borabicyclo[3.3.1]nonane (13) lead to the novel aminoboranes 14-16. These are products of a 1,1-organoboration, since the Me(3)Sn group moves from one nitrogen atom to the other, and both the boryl and an alkyl group end up at the same nitrogen atom.