H/D scrambling in a chromium-catalyzed dehydrocoupling reaction of a borane-dimethylamine adduct.

H/D scrambling took place in a chromium-catalyzed dehydrocoupling reaction of a deuterium-labeled borane-dimethylamine adduct. In the hydrogen elimination of BH·NDMe (1a-dN), H, HD and D were generated in 65 : 30 : 5 ratio, and 62% of deuterium atoms were incorporated into the major product, the dimethylaminoborane dimer. Proton and deuteron nuclei were thus concentrated into the evolved dihydrogen and aminoborane dimer, respectively.

Dehydrocoupling reactions of borane-secondary and -primary amine adducts catalyzed by group-6 carbonyl complexes: formation of aminoboranes and borazines.

Photoirradiation of a solution of BH(3).NHR(2) (1a: R = Me, 1b: R = 1/2C(4)H(8), 1c: R = 1/2C(5)H(10), 1f: R = Et) containing a catalytic amount of a group-6 metal carbonyl complex, [M(CO)(6)] (M = Cr, Mo, W), led to dehydrogenative B-N covalent bond formation to produce aminoborane dimers, [BH(2)NR(2)](2) (2a-c, f), in high yield. During these reactions a borane sigma complex, [M(CO)(5)(eta(1)-BH(3).

Investigation of the stability of the M-H-B bond in borane sigma complexes [M(CO)5(eta1-BH2R.L)] and [CpMn(CO)2(eta1-BH2R.L)] (M=Cr, W; L=tertiary amine or phosphine): substituent and Lewis base effects.

We investigated the influence of a substituent and a Lewis base on boron upon the thermodynamic stability of metal complexes of borane-Lewis base adducts, [M(CO)5(eta1-BH(2)R.L)] (M=Cr, W) and [CpMn(CO)2(eta1-BH2R.L)], where R=Cl, I, m-C6H4F, Ph, H, Me, Et; L=PMe3, PPh3, NMe3, quinuclidine.