We report a series of titanium and zirconium complexes supported by dianionic amidophosphine−borane ligands, synthesized by amine elimination and salt metathesis reactions. The Ti IV complex [{Ph 2 P(BH 3 )N} 2 C 6 H 4 Ti(NMe 2 ) 2 ] (1) was obtained by the reaction between tetrakis-(dimethylamido)titanium(IV) and the protic aminophosphine−borane ligand [{Ph 2 P(BH 3 )NH} 2 C 6 H 4 ] (LH2) at ambient temperature. Both the heteroleptic zirconium complexes[η 5 -(C 5 H 5 ) 2 Zr{Ph 2 P-(BH 3 )N} 2 C 6 H 4 ] (2) and [[{Ph 2 P(BH 3 )N} 2 C 6 H 4 ]ZrCl 2 ] (3)and the homoleptic zirconium complex [[{Ph 2 P(BH 3 )-N} 2 C 6 H 4 ] 2 Zr] (4) were obtained in good yield by the salt metathesis reaction of either zirconocene dichloride [η 5 -(C 5 H 5 ) 2 ZrCl 2 ] or zirconium tetrachloride with the dilithium salt of the ligand [{Ph 2 P(BH 3 )NLi} 2 C 6 H 4 ] ( LLi2), which was prepared in situ. The molecular structures of the complexes 1, 2, and 4 in their solid states were confirmed by single-crystal X-ray diffraction analysis. Of these complexes, only titanium complex 1 acts as an effective catalyst for the facile hydroboration of terminal alkynes, yielding exclusive E-isomers. The hydroboration of organic nitriles yielded diborylamines with a broad substrate scope, including broad functional group compatibility. The mechanism of hydroboration occurs through the formation of titanium hydride as an active species.

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A novel amidophosphine sulfur-supported magnesium complex, [Ph 2 P(S)NCH 2 CH 2 NÀ (CH 2 CH 2 )O]Mg(C 4 H 9 )(THF)] (2) enabling efficient ring-opening polymerization of rac-lactide (LA) and ɛcaprolactone (CL) is disclosed. Achieved incredible selectivity for ROP of rac-lactide for the first time using a magnesium catalyst affording isoselective PLA with a P i value of 0.77. The polymerization of rac-LA as well as ɛ-CL proceeded under mild reaction conditions in absence of any external initiator, to yield corresponding polyesters with a great control over the molecular weight. The kinetic studies reveal that both sulfur and magnesium centers simultaneously work together to drive high yield and selectivity.

Synthesis of heteroleptic and homoleptic alkaline earth metal complexes supported by bulky bis-iminopyrrolyl ligands are reported. The catalytic hydroamination of isocyanates and isothiocyanates with aryl amines using calcium complex is presented.