| Abstract
| - The complexation chemistry of the protio and lithium bamam complexes (H)bamam-1 and(Li)bamam-1 [bamam-1 = {DippN(Ph)B(NtBu)CnBu(NtBu)}, Dipp = 2,6-diisopropylphenyl]with magnesium is explored. Emphasis is placed on the preparation and characterization ofboth solvated and unsolvated aryl/alkylmagnesium bamam complexes (RMgL)bamam-1 (1,R = tBu, L = none; 2, R = Mes, L = none; 3, R = Me, L = OEt2; 4, R = Ph, L = THF; 5, R= iPr, L = THF; 6, R = nBu, L = OEt2). X-ray structural analyses reveal that the Mg bamam-1complexes are six-membered rings, which adopt a distorted boat structure as a result of atransannular Mg−N interaction (2.39−2.85 Å). Variable-temperature NMR spectra indicatethis interaction is maintained in solution. Preliminary studies of the polymerization of rac-lactide with complexes 3−6 revealed that 3 and 4 promote the polymerization processproducing hetero-biased polylactide, whereas 5 and 6 are inactive.
- The synthesis and structural characterization of six organomagnesium bamam complexes (RMgL)bamam-1 [L = none, THF, or OEt2; bamam-1 = {DippN(Ph)B(NtBu)CnBu(NtBu)}, Dipp = 2,6-diisopropylphenyl] are reported. These six-membered rings adopt folded boat structures with a transannular Mg−N interaction (2.39−2.85 Å) and localized π-bonding in the ligand backbone. The solvated complexes act as initiators for the polymerization of rac-lactide when R = Me or Ph, but they are inactive for R = iPr or nBu. Activity is apparently not directly related to the strength of the Mg−N interaction.
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