Terminal Titanium-Ligand Multiple Bonds. Cleavages of CO and CS Double Bonds with Ti Imido Complexes

Treatment of t-BuNTiCl2Py3 with 2 equiv lithium ketiminate compound, Li[OCMeCHCMeN(Ar)] (where Ar =
2,6-diisopropylphenyl), in toluene at room temperature gave t-BuNTi[OCMeCHCMeN(Ar)]2 (1) in high yield.
The reaction of 1 with phenyl isocyanate at room-temperature resulted in imido ligand exchange producing
PhNTi[OCMeCHCMeN(Ar)]2 (2). Compound 1 decomposed at 90 °C to form a terminal titanium oxo compound
OTi[OCMeCHCMeN(Ar)]2 (3) and t-BuNHCMeCHCMeNAr (4). Also, the compound 3 could be obtained by reacting
1 with CO2 under mild condition. Similarly, while 1 reacts with an excess of carbon disulfide, a novel terminal
titanium sulfido compound STi[OCMeCHCMeN(Ar)]2 (5) was formed via a CS bond breaking reaction. A novel
titanium isocyanate compound Ti[OCMeCHCMeN(Ar)]2(NCO)(OEt) (6) was formed on heating 1 with 1 equiv of
urethane, H2NCOOEt. Compounds 1−6 have been characterized by 1H and 13C NMR spectroscopies. The molecular
structures of 1, 3, 5, and 6 were determined by single-crystal X-ray diffraction. A theoretical calculation predicted
that the cleavage of the C−S double bonds for carbon disulfide with the TiN bond of compound 1 was estimated
at ca. 21.8 kcal·mol-1 exothermic.