Reactions of Group 13 and 14 hydrides and group 1, 2, 13 and 14 organyl compounds with (tert-butylimino)(2,2,6,6-tetiramethylpipeiridino)borane

(tert-Butylimino)(2,2,6,6-tetramethylpiperidino)borane (1) is a highly reactive species. Its Bequivalent toN triple bond inserts into the B-H bond of boranes, R2BH, generating diborylamines of the type tmp-BH-NtBu-BR2 (tmp = 2,2,6,6-tetramethylpiperidino; R = H, Cl, Br, or organyl). Thexylborane reacts analogously, but only one of its two B-H bonds is used for the hydroboration of 1. However, dihaloboranes HB(Hal)(2)-SMe2 (Hal = Cl, Br) give B-haloboration products tmp-B(Hal)-NtBu-BH(Hal), while reactions with H2B(Hal)-SMe2 produce a mixture of two isomers by competing hydroboration and haloboration reactions. Tmp-BH-NtBu-AIH(2) was obtained from 1 and AIH(3)-NMe3. It is a dimer in the solid state with pentacoordinate Al atoms and AIH(2)Al bridges. Hydrosilylation of 1 was achieved with Me2SiHCl, SiHCl3 or Ph2SiH2 to give the N-silyl-substituted diaminoboranes tmp-BH-NtBu-SiX3-nRn. Me3SnH and Bu3SnH behave similarly, giving the corresponding N-stannylated diaminoboranes. However, when Ph3SnH was treated with 1, the stannylborane tmp-B(SnPh3)-NHtBu was formed showing an umpolung of the hydrostannylation. Organyllithium compounds provide access to N-lithiodiaminoboranes of the type tmp-BR-NtBu-Li. The stability of these compounds depends on the substituent R. The least stable compound was the B-tBu derivative followed by the B-methyl compound. However, in the presence of TMEDA tmp-BMe-NtBu-Li is sufficiently stable to allow reactions, e.g. with B-chlorocatecholborane, to produce tmp-BMe-NtBu-BO2C6H4. The most stable lithium compound so far is tmp-BPh-NtBu-Li-OEt2, whose structure has been determined by X-ray crystallography. MgBu2 behaves like LiR and both of its Mg-C bonds can be used for the insertion reaction. The same is also true of ZnMe2. In contrast, at ambient temperature, only one of the E-C bonds of triorganylalanes, triorganylgallanes and InPh3 is used for the insertion reaction. In the solid state, most of the new compounds show a weak to strong coordinate bond between the electrophilic centre (Li, Mg, Zn, Cd, B, Al, Ga and In) and the nitrogen atom of the tmp group which generates a four-membered ring. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004).