Sr. Foley et al., Synthesis of Mn[N(SiMe3)(2)][Me3SiNC(Bu-t)NSiMe3] (M = Sn, Ge) from amidinate precursors: Active catalysts for phenyl isocyanate cyclization, INORG CHEM, 39(5), 2000, pp. 924-929
Mixed amidinato amido complexes [Me3SiNC(Bu-t)NSiMe3]M[N(SiMe3)(2)] (M = Sn
2, Ge 3) were prepared by the reaction of [Me3SiNC(Bu-t)NSiMe3]Li (la) wit
h SnCl2 and GeCl2(dioxane) in ether. The N(SiMe3)(2) ligand in these compou
nds is derived from the rearrangement of the [Me3SiNC(Bu-t)NSiMe3](-) anion
with extrusion of (BuCN)-Bu-t. The susceptibility of [Me3SiNC(Bu-t)NSiMe3]
(-) to rearrangement appears to be dependent on reaction solvent and on the
coordinated metal center. Single-crystal X-ray diffraction studies of 2 an
d 3 are presented. Replacement of Me for Bu-t in the ligand allowed [Me3SiN
C(Me)NSiMe3](2)Sn-II (4) to be isolated, and an X-ray structure of this com
pound is reported. The isolation of 4 indicates that steric factors also pl
ay a role in the stability of [Me3SiNC(Bu-t)NSiMe3](-). Compounds 2 and 3 a
re outstanding catalysts for the cyclotrimerization of phenyl isocyanates t
o perhydro-1,3,5-triazine-2,4,6-triones (isocyanurates) at room temperature
. In contrast, complex 4 catalytically reacts with phenyl isocyanate to pro
duce isocyanate dimer and trimer in a 52:35 ratio.