A series of dimeric magnesium derivatives containing substituted pyrrolyl or ketiminato ligands was synthesised and the application of these derivatives for the ring opening polymerisation of ϵ‐caprolactone has been carried out. Reactions of [Mg{N(SiMe3)2}]2 (1) with one equiv. of 2‐dimethylaminomethyl pyrrole and 2‐diethylaminomethyl pyrrole in toluene generates [Mg{C4H3N(2‐CH2NMe2)}{N(SiMe3)2}]2 (2) and [Mg{C4H3N(2‐CH2NEt2)}{N(SiMe3)2}]2 (3), respectively, in high yield. Similarly, the reaction of 1 with one equiv. of 2‐tert‐butylaminomethyl pyrrole in toluene at room temperature affords [Mg{C4H3N(2‐CH2NHtBu)}{N(SiMe3)2}]2 (4). Furthermore, reactions of 1 with one equiv. of HOCMeCHCMeN(C6H3‐2,6‐iPr2) or HOCMeCHCMeN(C6H4‐2‐OMe) in toluene yielded the dimeric magnesium complexes, [Mg{OCMeCHCMeN(C6H3‐2,6‐iPr2)}{N(SiMe3)2}]2 (5) and [Mg{OCMeCHCMeN(C6H4‐2‐OMe)}{N(SiMe3)2}]2 (6), respectively, in satisfactory yields by means of deamination. All the complexes were characterised by NMR spectroscopy and X‐ray diffraction analysis in the solid state. They show moderate reactivity towards the ring opening polymerisation of ϵ‐caprolactone in dichloromethane or tetrahydrofuran.

A series of four, five and six-coordinated magnesium derivatives integrating with substituted pyrrole and ketimine ligands are conveniently synthesized. Reaction of two equiv of 2-dimethylaminomethyl pyrrole with Mg[N(SiMe 3 ) 2 ] 2 in THF affords the monomeric magnesium complex Mg[C 4 H 3 N(2-CH 2 NMe 2 )] 2 (THF) 2 (1) in high yield along with elimination of two equiv of HN(SiMe 3 ) 2 . Similarly, the reaction between two equiv of 2-t-butylaminomethyl pyrrole and Mg[N(SiMe 3 ) 2 ] 2 in THF renders the magnesium derivative, Mg[C 4 H 3 N(2-CH 2 NH t Bu)] 2 (THF) 2 (2) in good yield. Interestingly, reaction between two equiv of 2-t-butylaminomethyl pyrrole and Mg[N(SiMe 3 ) 2 ] 2 in toluene, instead of THF, generates Mg[C 4 H 3 N(2-CH 2 NH t Bu)] 2 (3), also in high yield. Furthermore, the assembly of two equiv of ketimine ligand, HOCMeCHCMeNAr (Ar = C 6 H 3 -2,6-i Pr 2 ) and Mg[N(SiMe 3 ) 2 ] 2 , yields five-coordinated magnesium derivatives, Mg(OCMeCHCMeNAr) 2 (THF) (4) and Mg(OCMeCHCMeNAr) 2 (OEt 2 ) (5), using THF and diethyl ether, respectively. All the aforementioned derivatives are characterized by 1 H and 13 C NMR spectroscopy as well as 1, 3, 4 and 5 are subjected to X-ray diffraction analysis in solid state.