Molecular Structure of the Complex of Hexano-6-lactam with Magnesium Bromide

Role of magnesium complexes in the anionic polymerization of hexano-6-lactam

“…The coordination compound of N-ethylacetamide (N-EAA) with magnesium bromide (I) was prepared according to the procedure described elsewhere [9]. The complex of N-EAA with MgBr 2 is a crystalline and strongly hygroscopic compound with a light yellow colour.…”

“…According The final product of the thermal decomposition is MgO, as was found in the case of complexes of magnesium bromide with HL [9] or with octane-8-lactam [10].…”

“…In this complex all the six molecules of HL have almost exactly equivalent positions, the carbonyl oxygen atoms forming coordination bonds to the magnesium atom and the amide protons being bound by predominantly electrostatic bonds to the bromine atoms [9]. Similarly, octano-8-lactam differed from HL by the occurrence of cis as well as transoid conformation of the amide group [10][11][12], forms a highly symmetrical complex [13] with MgBr 2 .…”

Molecular Structure of the Complex of Octano-8-lactam with Magnesium Bromide

“…Based on NMR and vibrational spectra and quantum mechanical calculations, a molecular structure of MgBr 2 N (hexano-6-lactam) 6 with almost exactly equivalent positions of all six lactam molecules was proposed. [4] At variance with hexano-6-lactam, both cis or transoid conformations of the amide group occur in octano-8-lactam, [6 -8] a mixture of both conformations being found in solutions but only the transoid form occurring in crystals. [9] These interesting structure features of the nineFull Paper: Octano-8-lactam forms a complex with magnesium bromide, which could be of importance in elucidating the mechanism of anionic polymerization of the lactam initiated by Grignard compounds.…”

“…To confirm this hypothesis, a series of model complexes of MgBr 2 with hexano-6-lactam [4] and various low-molecular-weight imides, primary amines and linear amides [5] have been prepared and characterized. MgBr 2 forms a relative stable complex with hexano-6-lactam, which is a cyclic amide with cis conformation of the amide group.…”