Calcium Complexes Having Different Amidinate Ligands - Synthesis and Structural Diversity

A one-pot reaction of a-diimine ligand 1,4-disubstituted diazabutadienes (DAD) with potassium benzyl and anhydrous calcium iodide in 1:1:1 molar ratio afforded unprecedented 3-phenylprop-2-ene-di-amido calcium compound [k(2)-(THF)(4) Ca{DippNC(= CHPh) CH(2)NDipp}] (1) (Dipp = 2,6-diisopropylphenyl) in good yield. The solid-state structure of the compound 1 revealed the formation of dianionic 3-phenylprop-2ene-di-amido ligand having an exocyclic olefinic bond derived from neutral alpha-diimine fragment. However, analogous reactions with three different carbodiimides (RN=C=NR; R=Cy, iPr and Bu-t) with alkyl potassium and anhydrous calcium diiodide yielded corresponding homoleptic calcium compounds with amidinato ligand [k(2)-(THF)(2)Ca{RN= C(CH2Ph) NR}(2)] [R=Cy (2), iPr (3) and Bu-t (4)]. A separate reaction of DAD ligand, LiCH2SiMe3 and anhydrous ZnCl2 in diethylether solvent produced tri-coordinated zinc compound [k(2)-{DippN=C(CH2SiMe3)CH2 NDipp} Zn[k(1)-{DippN=C(CH2SiMe3)CH2N-Dipp}] (5) having amidinato moieties in the zinc coordination sphere in high yield. Molecular structures of compounds 2-5 in their solid states were also established.