Cascade Activation of SiH, CH, and SiC Bonds at a Rhodium β‐Diiminate Complex

Abstract

The coupling of HSiEt3 and related silanes to β‐diiminate ligands is achieved through a series of SiH, CH, and SiC bond‐breaking and bond‐forming reactions. Complex 1 (see scheme) loses an Et(Si) group as ethane and couples the remaining SiEt2H fragment to a benzylic methyl group of the ligand skeleton. According to DFT calculations, the reaction involves silylene intermediates.

Synthesis and Structures of Fluorinated (β‐Diketiminato)rhodium Complexes: Si–H Activation of Silanes at a Carbonyl Complex

“…[31] The spectroscopic data of 29 Si heteronuclear multiple-bond correlation (HMBC) NMR spectrum ( Figure 7). [11,31] The NMR spectroscopic data are in accordance with those found for other bis(silyl)-rhodium(V) complexes, in which the silyl ligands are in a mutual trans orientation. [35] DFT calculations were performed to model conceivable configurations of 10a and 16.…”

“…The (hydrido)(silyl)rhodium complexes could not be isolated and were characterized by NMR spectroscopy only. In each case the 1 H NMR spectra show a characteristic doublet signal for the hydrido ligand [11,31] between δ = -11 and -13 ppm with a rhodiumhydrogen coupling constant ( The reaction of 7a with HSiMe 3 can be monitored by NMR spectroscopy. Initially, 10a is formed, followed by the formation of the dihydridobis(silyl) complex 16.…”

“…[10] Recently, [Rh{κ 2 -(N,N)-(2,6-MeC 6 H 3 )NC(Me)-CHC(Me)N(2,6-MeC 6 H 3 )}(coe)(N 2 )] was applied for the Si-H activation of HSiEt 3 . [11] In an initial step the dihydridobis(silyl)rhodium complex cis,trans-[Rh{κ 2 -(N,N)-(2,6-MeC 6 H 3 )NC(Me)CHC(Me)N(2,6-MeC 6 H 3 )}(H) 2 (SiEt 3 ) 2 ] is formed. The latter is not stable in solution and quantitatively transforms into ethane and a rhodium complex, in which one SiEt 2 moiety is bridged to a benzylic carbon atom of the β-diketiminato ligand.…”

“…The latter is not stable in solution and quantitatively transforms into ethane and a rhodium complex, in which one SiEt 2 moiety is bridged to a benzylic carbon atom of the β-diketiminato ligand. [11] One step in the coupling of HSiEt 3 to the β-diketiminato ligand might include the cyclometallation of a benzylic C-H bond of the aryl substituent of the β-diketiminate. [3,11] To avoid cyclometallation reactions of the N-bound aryl rings, the choice of the substituents of the β-diketiminato ligand might therefore be critical.…”

“…[11] One step in the coupling of HSiEt 3 to the β-diketiminato ligand might include the cyclometallation of a benzylic C-H bond of the aryl substituent of the β-diketiminate. [3,11] To avoid cyclometallation reactions of the N-bound aryl rings, the choice of the substituents of the β-diketiminato ligand might therefore be critical. One option could be the use of perfluorinated groups, because the corresponding ligands do not contain an aryl C-H bond.…”