Heterobimetallic Samarium(III) and Titanium(IV) Complexes with Bifunctional Catalytic Properties

Reaction of the bis-ligand-chelated samarium complex [Sm(Hbptd)(H2bptd)] (1; H3bptd =1,9-bis(2-pyrrolyl)-2,5,8-triazanona-1,8-diene), in which a pyrrolyl ring is dangling and metal-free, with Ti(NMe2)4 yielded the heterometallic complex [Sm(Hbptd)(THF)(bptd)Ti(NMe2)2] (2). Treatment of the H3bptd ligand with 1 equiv of Ti(NMe2)4 gave the titanium amido complex [Ti(bptd)(NMe2)] (3). Complexes 2 and 3 were able to catalyze the hydroamination of phenylacetylene with 2,4-dichloroaniline and 4-methoxyaniline, and high regioselectivities were observed for the two amines. Both 1 and 2 were active catalysts for the ring-opening polymerization of ε-caprolactone. 2 showed higher activity for the polymerization reactions, due to a decrease in the coordination number of the samarium atom (from 9 in 1 to 8 in 2) by sharing its ligand with the titanium center.