Аннотация:The dehydrogenation of dimethylamine-borane (DMAB) catalyzed by the iminophosphonamiderhodium(III) complexes [Cp*RhCl{Ph2P(N–p-Tol)(NR)}] (Iа, R = p-Tol; Ib, R = Me) as well as their in situformed fulvene [(η4-C5Me4CH2)Rh(NPN)] (IIa, IIb) and diene [(η4-C5Me5H)Rh(NPN)] (IIIa, IIIb) rhodium(I) derivatives is studied. Catalysts IIIa and IIIb turn out to be the most active and demonstrate a TOFactivity of 110 (IIIа) and 540 h–1 (IIIb) at 40°С in toluene. The activity decreases significantly in more polarand coordinating THF. At the same time, the rate of DMAB dehydrogenation by complexes Iа and Ib is lowerby 10–30 times, and fulvene complexes Iа and Ib are rapidly deactivated after the active initial period (<20%conversion). The kinetic studies show that the reaction has the first order with respect to the substrate and thecatalyst. The model 11В NMR experiments confirm that the reaction proceeds via the intermediate formationof a monomer Me2N=BH2, which rapidly dimerizes to (Me2N–BH2)2. The mechanism of DMAB dehydrogenationwith the formation of unstable hydride intermediate [Cp*RhH{Ph2P(N–p-Tol)(NR)}] (IVa, IVb) isproposed on the basis of the preliminarily 31Р NMR results and published data.
