Lewis Base Assisted Magnesium Complexes Incorporating Pyrrolyl and Ketiminate Ligands: Synthesis, Structural Diversity and Characterization

Abstract

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.

CO2/Epoxide Coupling and the ROP of ε-Caprolactone: Mg and Al Complexes of γ-Phosphino-ketiminates as Dual-Purpose Catalysts

“…The N1–Mg1–N1′ bond angle (α), which is the largest among the bond angles in the equatorial plane, is 139.48(13)°. Mg1–N1 and Mg1–O1 distances are comparable to those of the corresponding Mg ketiminate complexes reported in the literature . The molecular structure of 2 shows a slightly distorted octahedral geometry with the chelating ketiminate ligands occupying trans positions.…”