| Abstract
| - Mixed amidinato amido complexes [Me3SiNC(tBu)NSiMe3]M[N(SiMe3)2] (M = Sn 2, Ge 3) were prepared bythe reaction of [Me3SiNC(tBu)NSiMe3]Li (1a) with SnCl2 and GeCl2(dioxane) in ether. The N(SiMe3)2 ligand inthese compounds is derived from the rearrangement of the [Me3SiNC(tBu)NSiMe3]- anion with extrusion oftBuCN. The susceptibility of [Me3SiNC(tBu)NSiMe3]- to rearrangement appears to be dependent on reactionsolvent and on the coordinated metal center. Single-crystal X-ray diffraction studies of 2 and 3 are presented.Replacement of Me for tBu in the ligand allowed [Me3SiNC(Me)NSiMe3]2SnII (4) to be isolated, and an X-raystructure of this compound is reported. The isolation of 4 indicates that steric factors also play a role in thestability of [Me3SiNC(tBu)NSiMe3]-. Compounds 2 and 3 are outstanding catalysts for the cyclotrimerization ofphenyl isocyanates to perhydro-1,3,5-triazine-2,4,6-triones (isocyanurates) at room temperature. In contrast, complex4 catalytically reacts with phenyl isocyanate to produce isocyanate dimer and trimer in a 52:35 ratio.
- The reaction of RLi (R = Me, tBu) and Me3SiNCNSiMe3 in dimethyl ether leads to the amidinate anions [Me3SiNC(R)NSiMe3]-. The bulky amidinate, [Me3SiNC(tBu)NSiMe3]-, undergoes a rearrangement when reacted with SnCl2 or GeCl2(dioxane) in ether to ultimately yield the mixed amidinato amido complexes [Me3SiNC(tBu)NSiMe3]M[N(SiMe3)2] (M = Sn, Ge). Replacement of Me for tBu in the ligand allowed for the isolation of [Me3SiNC(Me)NSiMe3]2SnII. These complexes are catalysts for cyclization of aryl isocyanates and provide the first report of complexes of Sn(II) and Ge(II/IV) that function in this transformation.
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