Novel double substrate insertion versusisocyanateextrusion in reactions of imidotitanium complexes with CO2: critical dependence on imido N-substituents

Abstract

Reaction of the cyclopentadienyl–amidinate supported imidotitanium complexes [Ti(η-C₅Me₅){MeC(NⁱPr)₂}(NR)] (R = ^tBu 1a or Ar 1b where Ar = 2,6-C₆H₃Me₂) with CO₂ proceed via initial cycloaddition reactions, but depending on the imido N-substituent go on to yield products of either isocyanate extrusion or double CO₂ insertion, the latter forming [Ti(η-C₅Me₅){MeC(NⁱPr)₂}{O(CO)N(Ar)(CO)O}] 4; the double CO₂ insertion reaction leading to 4 is the first example for any transition metal imide.