Monomeric magnesium and calcium complexes containing the bidentate, dianionic 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene ligand

The reduction of 1,2-bis[(2,6-diisopropylphenyl)imino]-acenaphthene (2,6-iPr(2)C(6)H(3)-BIAN) with metallic magnesium or calcium in THF affords the monomeric complexes (2,6-iPr(2)C(6)H(3)-BIAN)Mg(THF)(3) (1) and (2,6-iPr(2)C(6)H(3)-BIAN)Ca(THF)(4)(.)(THF)(1/2) (2). The crystallisation of 1 and 2 from benzene causes the removal of one of the coordinated THF molecules, yielding (2,6-iPr(2)C(6)H(3)-BIAN)Mg(THF)(2)(.)(C6H6)(1/2) (3a) and (2,6-iPr(2)C(6)H(3)-BIAN)Ca(THF)(3) (4). Repeated recrystallisation of 1 from benzene gives (2,6-iPr(2)C(6)H(3)-BIAN)Mg(THF)(2)(.)(C6H6)(2) (3b). Although the crystals of 3a and 3b differ in colour and in their crystallographic parameters, their molecular dimensions are very similar. Recrystallisation of 1 from pyridine produces (2,6-iPr(2)C(6)H(3)-BIAN)Mg(py)(3)(.)(py)(2) (5). Complexes 1-5 have been characterised by elemental analysis, UV, IR and H-1 NMR spectroscopy, as well as by single-crystal X-ray diffraction.