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

Reaction of the bis-ligand-chelated samarium complex [Sm(Hbptd)(H<sub>2</sub>bptd)] (<b>1</b>; H<sub>3</sub>bptd =1,9-bis(2-pyrrolyl)-2,5,8-triazanona-1,8-diene), in which a pyrrolyl ring is dangling and metal-free, with Ti(NMe<sub>2</sub>)<sub>4</sub> yielded the heterometallic complex [Sm(Hbptd)(THF)(bptd)Ti(NMe<sub>2</sub>)<sub>2</sub>] (<b>2</b>). Treatment of the H<sub>3</sub>bptd ligand with 1 equiv of Ti(NMe<sub>2</sub>)<sub>4</sub> gave the titanium amido complex [Ti(bptd)(NMe<sub>2</sub>)] (<b>3</b>). Complexes <b>2</b> and <b>3</b> 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 <b>1</b> and <b>2</b> were active catalysts for the ring-opening polymerization of ε-caprolactone. <b>2</b> showed higher activity for the polymerization reactions, due to a decrease in the coordination number of the samarium atom (from 9 in <b>1</b> to 8 in <b>2</b>) by sharing its ligand with the titanium center.