| Abstrakt: |
A general synthetic strategy for the systematic synthesis of group 4 MIVheterometallic complexes LMIII(H)(μ-O)Si(μ-O)(OtBu)2}nMIV(NR2)4–n(L= {[HC{C(Me)N(2,6-iPr2C6H3)}2; MIII= Al or Ga; n= 1 or 2; MIV= Ti, Zr, Hf; R = Me, Et), based on alumo- or gallosilicate hydride ligands bearing a Si–OH moiety, is presented. The challenging isolation of these metalloligands involved two strategies. On the one hand, the acid–base reaction of LAlH2with (HO)2Si(OtBu)2yielded LAlH(μ-O)Si(OH)(OtBu)2(1), while on the other hand, the oxidative addition of (HO)2Si(OtBu)2to LGa produced the gallium analog (2). These metalloligands successfully stabilized two hydrogen atoms with different acid–base properties (MIII–H and SiO–H) in the same molecule. Reactivity studies between 1and 2and group 4 amides MIV(NR2)4(MIV= Ti, Zr, Hf; R = Me, Et) and tuning the reactions conditions and stoichiometry led to isolation and structural characterization of heterometallic complexes 3–11with a 1:1 or 2:1 metalloligand/MIVratio. Notably, some of these molecular heterometallic silicate complexes stabilize for the first time terminal (O3Si–O−)MIV(NR2)3moieties known from single-site silica-grafted species. Furthermore, the aluminum-containing heterometallic complexes possess Al–H vibrational energies similar to those reported for modified alumina surfaces, which makes them potentially suitable models for the proposed MIVspecies grafted onto silica/alumina surfaces with hydride and dihydride architectures. |
