Four‐Membered Heterometallacyclic d 0 and d 1 Complexes of Group 4 Metallocenes with Amidato Ligands

A study of the coordination chemistry of different amidato ligands [(R)NC(Ph)O] (R=Ph, 2,6‐diisopropylphenyl (Dipp)) at Group 4 metallocenes is presented. The heterometallacyclic complexes [Cp 2 M(Cl){κ 2 ‐ N , O ‐(R)NC(Ph)O}] M=Zr, R=Dipp ( 1 a ), Ph ( 1 b ); M=Hf, R=Ph ( 2 )) were synthesized by reaction of [Cp 2 MCl 2 ] with the corresponding deprotonated amides. Complex 1 a was also prepared by direct deprotonation of the amide with Schwartz reagent [Cp 2 Zr(H)Cl]. Salt metathesis reaction of [Cp 2 Zr(H)Cl] with deprotonated amide [(Dipp)NC(Ph)O] gave the zirconocene hydrido complex [Cp 2 M(H){κ 2 ‐ N , O ‐(Dipp)NC(Ph)O}] ( 3 ). Reaction of 1 a with Mg did not result in the desired Zr(III) complex but in formation of Mg complex [(py) 3 Mg(Cl) {κ 2 ‐ N , O ‐(Dipp)NC(Ph)O}] ( 4 ; py=pyridine). The paramagnetic complexes [Cp′ 2 Ti{κ 2 ‐ N , O ‐(R)NC(Ph)O}] (Cp′=Cp, R=Ph ( 7 a ); Cp′=Cp, R=Dipp ( 7 b ); Cp′=Cp*, R=Ph ( 8 )) were prepared by the reaction of the known titanocene alkyne complexes [Cp 2 ′Ti(η 2 ‐Me 3 SiC 2 SiMe 3 )] (Cp′=Cp ( 5 ), Cp′=Cp* ( 6 )) with the corresponding amides. Complexes 1 a , 2 , 3 , 4 , 7 a , 7 b , and 8 were characterized by X‐ray crystallography. The structure and bonding of complexes 7 a and 8 were also characterized by EPR spectroscopy.