Synthesis and structures of vinamidine Mn-II, Zn-II, and Cd-II iodine derivatives

We have focused on the synthesis of monomeric, functionalized starting materials containing manganese(II), zinc(II), and cadmium(II) by taking advantage of the sterically demanding and chelating property of the substituted vinamidine ligand 2-[(2,6-diisopropylphenyl) amino]-4-[ (2,6-diisopropylphenyl) imino]pent-2-ene (NacNacH). Metal iodine derivatives containing vinamidines as the bulky ligand can be regarded as interesting precursors for preparing complexes with low-valent metal centers by reduction as long as they are free of coordinated ether. The vinamidine complexes NacNacM(mu -I)(2)Li(OEt2)(2) [M = Mn (3), Zn (4), Cd (5)] are obtained from the corresponding vinamidine lithium complex and MI, (M = Mn, Zn, Cd) in good yields. A crystal structure analysis of 3, 4, and 5 shows them to be isostructural. All three structures have the vinamidine backbone in a boat conformation with the tetrahedrally coordinated metal center at the prow and the opposing carbon atom at the stern.